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Sample records for weight polyethylene uhmwpe

  1. Delamination toughness of ultra high molecular weight polyethylene (UHMWPE composites

    Directory of Open Access Journals (Sweden)

    Casas-Rodriguez J.P.

    2012-08-01

    Full Text Available Ultra high molecular weight polyethylene (UHMWPE fibre reinforced composites are an important group of material for armours solutions, where their unique combination of properties could be utilized. A commonly observed failure mode in this kind of unidirectional laminated composites under impact ballistic is delamination between the composite layers. In the present study, an investigation on the delamination toughness behaviour exhibited by UHMWPE composites laminated was made. The interlaminar Mode II critical strain energy release rates of (UHMWPE fibre reinforced composites were characterized using the End Notch Flexural (ENF test. Critical strain energy release rate was obtained from the load – deflection test data using the beam theory expression. It was found that the energy release rate of the composite exhibited a very low value of around 60J/m2 using a moulding pressure of approximately 1200 psi. In order to analyse the delamination resistance of composite, the effects of changing the manufacture process variables and the use of a thermoplastic adhesive film in the composites were investigated. The composite laminates were produced by hot compressing moulding using a film-stacking procedure. It was found that the damage resistance of the UHMWPE composite was influenced by the manufacture method, which affects the Mode II interlaminar fracture toughness and the ballistic response of composites.

  2. Synthesis and Tribological Behavior of Ultra High Molecular Weight Polyethylene (UHMWPE-Lignin Composites

    Directory of Open Access Journals (Sweden)

    Surojit Gupta

    2016-08-01

    Full Text Available In this paper, we report the synthesis and characterization of ultra-high molecular weight polyethylene (UHMWPE-lignin composites. During this study four different compositions, namely UHMWPE, UHMWPE-13 wt. % lignin, UHMWPE-25 wt. % lignin and UHMWPE-42.5 wt. % lignin were fabricated by hot pressing. Detailed microstructural studies by scanning electron microscopy (SEM showed that UHMWPE and UHMWPE-13 wt. % lignin had a uniform microstructure, whereas UHMWPE-25 wt. % lignin and UHMWPE-42.5 wt. % lignin samples were riddled with pores. UHMWPE and UHMWPE-13% lignin showed comparable flexural strengths of ~32.2 MPa and ~32.4 MPa, respectively. However, the flexural strength dropped drastically in UHMWPE-25 wt. % lignin and UHMWPE-42.5 wt. % samples to ~13 MPa and ~8 MPa, respectively. The tribology of UHMWPE-lignin composites is governed by the tribofilm formation. All the compositions showed similar µmean values and the specific wear rates (WR decreased gradually as the concentration of lignin in UHMWPE was increased.

  3. Development of Ultra-High Molecular Weight Polyethylene (UHMWPE) Coating by Cold Spray Technique

    Science.gov (United States)

    Ravi, Kesavan; Ichikawa, Yuji; Deplancke, Tiana; Ogawa, Kazuhiro; Lame, Olivier; Cavaille, Jean-Yves

    2015-08-01

    Ultra-high molecular weight polyethylene or UHMWPE is an extremely difficult material to coat with, as it is rubbery and chemically very inert. The Cold Spray process appears to be a promising alternative processing technique but polymers are in general difficult to deposit using this method. So, attempts to develop UHMWPE coatings were made using a downstream injection cold spray technique incorporating a few modifications. A conventional cold spray machine yielded only a few deposited particles of UHMWPE on the substrate surface, but with some modifications in the nozzle geometry (especially the length and inner geometry) a thin coating of 45 μm on Al substrate was obtained. Moreover, experiments with the addition of fumed nano-alumina to the feedstock yielded a coating of 1-4 mm thickness on Al and polypropylene substrates. UHMWPE was seen to be melt crystallized during the coating formation, as can be seen from the differential calorimetry curves. Influence of nano-ceramic particles was explained by observing the creation of a bridge bond between UHMWPE particles.

  4. Investigation of Plasma Eects in Ultra High Molecular Weight Polyethylene (UHMWPE) Cords

    DEFF Research Database (Denmark)

    Teodoru, Steluta; Kusano, Yukihiro; Rozlosnik, Noemi

    modication for improved wetting and/or adhesion with other polymeric materials. Atmospheric pressure plasma treatment is promising for this purpose due to its environmental compatibility, high treatment eects without aecting the textural characteristics of the bulk material, its applicability to a variety......Ultra-high-molecular-weight polyethylene (UHMWPE) has been widely used because of its high chemical stabil- ity, high impact strength, exibility and low cost. Its eld of applications includes use in composites, packing for microelectronic components and biomaterials, usually requiring its surface...... of shapes, and easy up-scaling and construction of in-line production processes. An atmospheric pressure dielectric barrier discharge (DBD) plasma is used to study surface modication eect on UHMWPE cords, operated at a frequency of ca. 40 kHz in He, He/O2, O2 and N2 gases. The cords were continuously...

  5. PREPARATION OF MICROPOROUS ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE (UHMWPE) BY THERMALLY INDUCED PHASE SEPARATION OF A UHMWPE/LIQUID PARAFFIN MIXTURE

    Institute of Scientific and Technical Information of China (English)

    Lie Shen; Mao Peng; Fei Qiao; Jie-lai Zhang

    2008-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) with a microporous structure was prepared via thermally induced phase separation (TIPS).Liquid paraffin (LP) was used as a diluent in the preparation of microporous UHMWPE.Small angle laser light scattering (SALLS) and differential scanning calorimetry (DSC) were used to determine the phase separation temperatures,I.e.the cloud points and the dynamic crystallization temperatures,respectively.It was found that the cloud points were coincident with the crystallization temperatures,indicating that a solid-liquid phase separation occurred during thermal quenching of the UHMWPE/LP solution,while,no liquid-liquid phase separation above the crystallization temperature was observed.The effects of the content and the molecular weight of UHMWPE on the morphology and average pore size were investigated with field emission scanning electron microscopy (FE-SEM) and mercury porosimetry.With the increase of the content of UHMWPE,the average pore size of the microporous material decreased and the molecular weight of UHMWPE could also influence the pore size slightly.

  6. Laser surface modification of ultra-high-molecular-weight polyethylene (UHMWPE) for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Riveiro, A., E-mail: ariveiro@uvigo.es [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, Vigo 36310 (Spain); Centro Universitario de la Defensa, Escuela Naval Militar, Plaza de España 2, 36920 Marín (Spain); Soto, R.; Val, J. del; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J. [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, Vigo 36310 (Spain)

    2014-05-01

    Ultra-high-molecular-weight polyethylene (UHMWPE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore, this material is being used in human orthopedic implants such as total hip or knee replacements. Surface modification of this material relates to changes on its chemistry, microstructure, roughness, and topography, all influencing its biological response. Surface treatment of UHMWPE is very difficult due to its high melt viscosity. This work presents a systematic approach to discern the role of different laser wavelengths (λ = 1064, 532, and 355 nm) on the surface modification of carbon coated UHMWPE samples. Influence of laser processing conditions (irradiance, pulse frequency, scanning speed, and spot overlapping) on the surface properties of this material was determined using an advanced statistical planning of experiments. A full factorial design of experiments was used to find the main effects of the processing parameters. The obtained results indicate the way to maximize surface properties which largely influence cell–material interaction.

  7. Notch fatigue of ultrahigh molecular weight polyethylene (UHMWPE) used in total joint replacements.

    Science.gov (United States)

    Ansari, Farzana; Gludovatz, Bernd; Kozak, Adam; Ritchie, Robert O; Pruitt, Lisa A

    2016-07-01

    Ultrahigh molecular weight polyethylene (UHMWPE) has remained the primary polymer used in hip, knee and shoulder replacements for over 50 years. Recent case studies have demonstrated that catastrophic fatigue fracture of the polymer can severely limit device lifetime and are often associated with stress concentration (notches) integrated into the design. This study evaluates the influence of notch geometry on the fatigue of three formulations of UHMWPE that are in use today. A linear-elastic fracture mechanics approach is adopted to evaluate crack propagation as a function of notch root radius, heat treatment and Vitamin E additions. Specifically, a modified stress-intensity factor that accounts for notch geometry was utilized to model the crack driving force. The degree of notch plasticity for each material/notch combination was further evaluated using finite element methods. Experimental evaluation of crack speed as a function of stress intensity was conducted under cyclic tensile loading, taking crack length and notch plasticity into consideration. Results demonstrated that crack propagation in UHMWPE emanating from a notch was primarily affected by microstructural influences (cross-linking) rather than differences in notch geometry.

  8. XRD and FTIR study of the effect of ultra high molecular weight polyethylene (UHMWPE) as binder on kaolin geopolymer ceramics

    Science.gov (United States)

    Ahmad, R.; Abdullah, Mohd Mustafa Al Bakri; Hussin, K.; Sandu, A. V.

    2017-04-01

    The effect of addition of Ultra High Molecular Weight Polyethylene (UHMWPE) as binder on Kaolin Geopolymer Ceramics was study using infrared spectroscopy (FTIR) and X-ray diffraction (XRD) method. UHMWPE is added to the optimum kaolin geopolymer ceramics that obtained by mechanical performance, phase and microstructure analysis with the concentration of NaOH, solid/liquid and Na2SiO3/NaOH ratio of 12 M, 1.0 and 0.24 respectively. Kaolin geopolymer powders with addition of Ultra High Molecular Weight Polyethylene content of 2, 4, 6 and 8 (wt. %) were pressed into pellets followed by sintering at 1200 °C. At this temperature, the amorphous phase of geopolymer were fully crystallized. The results obtained by the XRD testing confirm that amorphous geopolymer transform to crystalline nepheline ceramics upon heating. The phase analysis for Kaolin geopolymer ceramics with addition of UHMWPE are similar to the kaolin geopolymer ceramics without UHMWPE indicates that the incorporation of a little amount of UHMWPE does not affect the structure feature of geopolymer. The increasing in intensity of nepheline peak contribute to high strength. The FTIR spectra showed the disappearance of water band after sinter at high temperature.

  9. Tribological characteristics of polyethylene glycol (PEG) as a lubricant for wear resistance of ultra-high-molecular-weight polyethylene (UHMWPE ) in artificial knee join.

    Science.gov (United States)

    Kobayashi, Masanori; Koide, Takayuki; Hyon, Suong-Hyu

    2014-10-01

    For the longevity of total knee joint prostheses, we have developed an artificial lubricant using polyethylene glycol (PEG) for the prevention of wear of ultra-high-molecular-weight polyethylene (UHMWPE). In the present study, the lubricative function of this PEG lubricant was evaluated by a wear test using Co-Cr alloy and UHMWPE counter surface samples. As a result, human synovial fluid including the PEG lubricant showed good result regarding the wear volume and a worn surface of UHMWPE. Considering its lubrication mechanism, it is suspected that interaction between the PEG molecules and the proteins in synovial fluid was involved. Since PE molecules are also organic compounds having a hydroxyl group at one or both ends, the albumin and PEG molecule complex would have bound more strongly to the metal oxide surface and UHMWPE surfaces might enhance and stabilize the lubricating film between the contact surfaces under the boundary lubrication. This study suggests that PEG lubricant as an intra-articular viscous supplement has the potential to prevent wear of UHMWPE by mixing with synovial fluid and to contribute to the longevity of knee joint prostheses.

  10. Effects of vitamin E blending on plastic deformation mechanisms of highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) in total hip arthroplasty.

    Science.gov (United States)

    Takahashi, Yasuhito; Yamamoto, Kengo; Pezzotti, Giuseppe

    2015-03-01

    The molecular mobility and crystalline texture development in highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) blended with antioxidant vitamin E (VE, dl-α-tocopherol) were studied via uniaxial compression at room temperature by means of confocal/polarized Raman spectroscopy. The results were compared to morphological analyses under the same compression conditions performed on HXL-UHMWPE prepared in exactly the same way but blending VE into the polyethylene resin (VE-free HXL-UHMWPE). These comparative analyses allow us to evaluate the physical role of VE in morphological alterations of HXL-UHMWPE induced by compression deformation, which can greatly affect its micromechanical behavior. Molecular rearrangement and phase transitions in crystalline and non-crystalline phase, i.e. amorphous and intermediate (third) phase, were found to be part of a reconstruction process after plastic deformation in the samples. Although VE-blended HXL-UHMWPE exhibited more pronounced molecular mobility, as evidenced by its significant deformation-induced texturing, crystallinity change was totally inhibited by the presence of VE during deformation. On the other hand, amorphous-to-intermediate phase transition was confirmed. VE-free HXL-UHMWPE also presented significant crystallization after deformation, but its surface texture evolution occurred to a much lesser extent. This study suggests that the addition of VE induced earlier activation of compression deformation modes in crystalline and non-crystalline phases (e.g. chain slip, interlamellar shear and rotation) due to an increase in polyethylene chain mobility.

  11. Surface modification of ultra-high molecular weight polyethylene (UHMWPE) by argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hengjun; Pei Yanan [Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Xie Dong [Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031 (China); Deng Xingrui [Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Leng, Y.X., E-mail: yxleng@263.net [Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Jin Yong, E-mail: jyct@163.com [Interventional Therapy Department, The Second Affiliated Hospital, Soochow University, Suzhou 215004 (China); Huang Nan [Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2010-04-01

    In this work, argon (Ar) plasma generated by microwave electron cyclotron resonance (MWECR) has been used to modify the UHMWPE in order to increase the wear resistance. The results showed that the wettability, anti-scratch and wear resistance of UHMWPE treated by the Ar plasma had been improved, comparing with native UHMWPE. The FTIR and XPS spectra indicated the improvement of wettability should come from the oxygen based functional groups generated on the surface of UHMWPE. The improvement of anti-scratch and wear resistance may come from the enhancement of crosslinking of UHMWPE by Ar plasma treatment.

  12. Thermal Characteristic Of Waste-Derived Hydroxyapatite (HA) Reinforced Ultra High Molecular Weight Polyethylene (UHMWPE) Composites For Fused Deposition Modeling (FDM) Process

    Science.gov (United States)

    Ansari, Mohamad Helmi Bin Md; Ibrahim, Mohd Halim Irwan Bin

    2017-01-01

    The present study provides a hydrothermal synthesis to obtain Hydroxyapatite (HA) powder from waste eggshells. This waste-derived HA has been characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis. Waste-derived HA will be reinforced the Ultra-High Molecular Weight Polyethylene (UHMWPE) to develop a material composite for biomedical applications because of impressive mechanical properties owned by UHMWPE. Main challenger is UHMWPE has an ultra-high viscosity that renders continuous melt- state processes including one of the additive manufacturing processes which is Fused Deposition Modeling (FDM). To develop this material as feedstock in FDM process, it has been overcome by blending UHMWPE with waste-derived HA as filler. It exhibit the inclusion of 50wt% HA has reduced the degradation temperature in TGA and DSC thus enhances the processability in FDM process.

  13. Ultra high molecular weight polyethylene (UHMWPE) fiber epoxy composite hybridized with Gadolinium and Boron nanoparticles for radiation shielding

    Science.gov (United States)

    Mani, Venkat; Prasad, Narasimha S.; Kelkar, Ajit

    2016-09-01

    Deep space radiations pose a major threat to the astronauts and their spacecraft during long duration space exploration missions. The two sources of radiation that are of concern are the galactic cosmic radiation (GCR) and the short lived secondary neutron radiations that are generated as a result of fragmentation that occurs when GCR strikes target nuclei in a spacecraft. Energy loss, during the interaction of GCR and the shielding material, increases with the charge to mass ratio of the shielding material. Hydrogen with no neutron in its nucleus has the highest charge to mass ratio and is the element which is the most effective shield against GCR. Some of the polymers because of their higher hydrogen content also serve as radiation shield materials. Ultra High Molecular Weight Polyethylene (UHMWPE) fibers, apart from possessing radiation shielding properties by the virtue of the high hydrogen content, are known for extraordinary properties. An effective radiation shielding material is the one that will offer protection from GCR and impede the secondary neutron radiations resulting from the fragmentation process. Neutrons, which result from fragmentation, do not respond to the Coulombic interaction that shield against GCR. To prevent the deleterious effects of secondary neutrons, targets such as Gadolinium are required. In this paper, the radiation shielding studies that were carried out on the fabricated sandwich panels by vacuum-assisted resin transfer molding (VARTM) process are presented. VARTM is a manufacturing process used for making large composite structures by infusing resin into base materials formed with woven fabric or fiber using vacuum pressure. Using the VARTM process, the hybridization of Epoxy/UHMWPE composites with Gadolinium nanoparticles, Boron, and Boron carbide nanoparticles in the form of sandwich panels were successfully carried out. The preliminary results from neutron radiation tests show that greater than 99% shielding performance was

  14. Continuous Plasma Treatment of Ultra-High-Molecular-Weight Polyethylene (UHMWPE) Fibres for Adhesion Improvement

    DEFF Research Database (Denmark)

    Teodoru, Steluta; Kusano, Yukihiro; Rozlosnik, Noemi

    2009-01-01

    A dielectric barrier discharge in Ar, He, He/O2, N2 or O2 at atmospheric pressure was used for the continuous plasma treatment of UHMWPE fibres. The influence of the input power of the discharge and the gas flow rate on surface modification is studied with the aim of adhesion improvement. Surface...... characterization using X-ray photoelectron spectroscopy and atomic force microscopy shows a significant increase in polar functional groups and roughness at the surfaces after plasma treatment, indicating that adhesive properties can be improved....

  15. Evaluation of environmental degradation effects in morphology of ultra-high molecular weight polyethylene (UHMWPE) fibers; Avaliacao dos efeitos da degradacao ambiental na morfologia das fibras de polietileno de ultra-alto peso molecular (PEUAPM)

    Energy Technology Data Exchange (ETDEWEB)

    Vivas, Viviane; Zylberberg, Marcel P.; Cardoso, Andre Luis V.; Pereira, Iaci M., E-mail: iacipere@gmail.com [Centro Tecnologico do Exercito (CTEx), RJ (Brazil); Weber, Ricardo P.; Suarez, Joao C. Miguez [Instituto Militar der Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    This study aims to evaluate changes in the morphology of ultra-high molecular weight polyethylene fiber (UHMWPE), before and after exposure to environmental agents. Fibers produced by two different manufacturers were analyzed. To characterize the morphology, we used the technique of small angle x-ray scattering (SAXS). The results demonstrate that the original morphology of the fibers was UHMWPE affected by the defects caused by exposure to environmental agents. (author)

  16. Antioxidant impregnated ultra-high molecular weight polyethylene wear debris particles display increased bone remodeling and a superior osteogenic:osteolytic profile vs. conventional UHMWPE particles in a murine calvaria model.

    Science.gov (United States)

    Chen, Yu; Hallab, Nadim J; Liao, Yen-Shuo; Narayan, Venkat; Schwarz, Edward M; Xie, Chao

    2016-05-01

    Periprosthetic osteolysis remains a major limitation of long-term successful total hip replacements with ultra-high molecular weight polyethylene (UHMWPE) bearings. As intra and extracellular reactive oxygen species are know to contribute to wear debris-induced osteoclastic bone resorption and decreased osteoblastic bone formation, antioxidant doped UHMWPE has emerged as an approach to reduce the osteolytic potential of wear debris and maintain coupled bone remodeling. To test this hypothesis in vivo, we evaluated the effects of crosslinked UHMWPE wear debris particles (AltrX(™) ), versus similar wear particles made from COVERNOX(™) containing UHMWPE (AOX(™) ), in an established murine calvaria model. Eight-week-old female C57B/6 mice (n = 10/Group) received a pre-op micro-CT scan prior to surgical implantation of the UHMWPE particles (2mg), or surgery without particles (sham). Dynamic labeling was performed by intraperitoneal injection of calcein on day 7 and alizarin on day 9, and the calvaria were harvested for micro-CT and histology on day 10. Surprisingly, we found that AOX particles induced significantly more bone resorption (1.72-fold) and osteoclast numbers (1.99-fold) vs. AltrX (p UHMWPE particles have decreased osteolytic potential due to their increased osteogenic properties that support coupled bone remodeling. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:845-851, 2016.

  17. Effect of gamma irradiation on the optical properties of UHMWPE (Ultra-high-molecular-weight-polyethylene) polymer

    Energy Technology Data Exchange (ETDEWEB)

    Raghuvanshi, S.K., E-mail: sraghu06@gmail.com [Department of Physics, Faculty of Natural Science, Jamia Millia Islamia, New Delhi 110025 (India); Ahmad, Bashir; Siddhartha [Department of Physics, Faculty of Natural Science, Jamia Millia Islamia, New Delhi 110025 (India); Srivastava, A.K. [Department of Applied Science, Sharda University, Plot No. 32-34, Knowledge Park-III, Greater Noida, Uttar Pradesh 201306 (India); Krishna, J.B.M. [UGC-DAEF Consortium for Scientific Research, Kolkata Center, III/LB-8 Bidhannagar, Kolkata 700098 (India); Wahab, M.A. [Department of Physics, Faculty of Natural Science, Jamia Millia Islamia, New Delhi 110025 (India)

    2012-01-15

    The UV-Visible absorption spectra of virgin and high dose gamma irradiated (up to 2000 kGy) UHMWPE polymer have been studied by using UV-Visible spectrophotometer (JASCO, V-570). The existence of the peaks, their shifting and broadening as a result of gamma irradiation has been observed. In the present work the Urbach energy is calculated by using Urbach edge method. Also the direct and indirect energy band gap in virgin and gamma irradiated UHMWPE polymer has been calculated. The values of indirect energy band gap have been found to be lower than the corresponding values of direct energy band gap. A decrease in the optical energy band gap with increasing gamma irradiation has been discussed on the basis of gamma-irradiation-induced modification in the UHMWPE polymer. The correlation between optical energy band gap and the number of carbon atoms in a cluster with modified Tauc's equation has been discussed in this polymer. We have also observed the color formation which became more and more prominent with increasing dose and at the highest dose the fully transparent sample became completely opaque. Looking at the trend of the absorption curve this polymer can be used as a very good dosimeter for the gamma ray irradiation.

  18. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    Sangeeta Hambir; J P Jog

    2000-06-01

    Ultra high molecular weight polyethylene (UHMWPE) is a high performance polymer having low coefficient of friction, good abrasion resistance, good chemical resistance etc. It is used in shipbuilding, textile industries and also in biomedical applications. UHMWPE is processed by powder processing technique because of its high melt viscosity at the processing temperature. Powder processing technique involves compaction of polymeric powder under pressure and sintering of the preforms at temperature above its melting point. In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering temperatures and strength development.

  19. High-speed gel-spinning of ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Pennings, A.J.; Hooft, R.J. van der; Postema, A.R.; Hoogsteen, W.; Brinke, G. ten

    1986-01-01

    This communication is concerned with the gel-spinning of ultrahigh molecular weight polyethylene (UHMWPE) at speeds up to 1500 m/min. It was found that 5 wt% solutions of UHMWPE in paraffin oil could be extruded through a conical die at a rate of 100 m/min. without the appearance of filament irregul

  20. Short aramid-fiber reinforced ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Hofste, JM; Bergmans, KJR; deBoer, J; Wevers, R; Pennings, AJ

    1996-01-01

    Ultra-High Molecular Weight Polyethylene (UHMWPE) is frequently used in artificial joints because of its high wear resistance. To extend the lifetime of these joints even further, it is necessary to decrease the wear rate. The wear rate may be decreased by blending UHMWPE with short aramid fibers. O

  1. Enhancement of Adhesive Strength of Ultrahigh Molecular Weight Polyethylene Fibers Prepared by Polar Polymer Implantation

    Institute of Scientific and Technical Information of China (English)

    YU Jun-rong; YANG Xin-ge; HU Zu-ming; LIU Zhao-feng

    2007-01-01

    A new technique was proposed to enhance the adhesive strength of ultrahigh molecular weight polyethylene (UHMWPE) fibers. Polar polymer was implanted into UHMWPE gel fibers during extracting process and can then be trapped en the surface of the fibers after subsequent ultra-drawing. The physical and chemical changes in the fiber structure were examined with scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The mechanical and interfacial adhesion properties of UHMWPE fibers were investigated with tensile testing. The results showed that there wee polar groups on the surface of pretreated UHMWPE fiber. The interracial shear strength of UHMWPE fibers with epoxy resin was greatly improved without socrificing the excellent mechanical properties of fibers. After pretreated with ethylene/vinyl acetate copolymer (EVA), the shear strength of the interface between fiber and epoxy resin increased from 1.06 to 2.49 MPa, while the integrated mechanical properties of the pretreated UHMWPE fibers ware still optimal.

  2. Fatigue crack propagation behavior of ultrahigh molecular weight polyethylene.

    Science.gov (United States)

    Connelly, G M; Rimnac, C M; Wright, T M; Hertzberg, R W; Manson, J A

    1984-01-01

    The relative fatigue crack propagation resistance of plain and carbon fiber-reinforced ultrahigh molecular weight polyethylene (UHMWPE) was determined from cyclic loading tests performed on compact tension specimens machined from the tibial components of total knee prostheses. Both materials were characterized by dynamic mechanical spectroscopy, X-ray diffraction, and differential scanning calorimetry. The cyclic tests used loading in laboratory air at 5 Hz using a sinusoidal wave form. Dynamic mechanical spectroscopy showed that the reinforced UHMWPE had a higher elastic storage modulus than the plain UHMWPE, whereas X-ray diffraction and differential scanning calorimetry showed that the percent crystallinity and degree of order in the crystalline regions were similar for the two materials. Fatigue crack propagation in both materials proved to be very sensitive to small changes in the applied cyclic stress intensity range. A 10% increase in stress intensity resulted in approximately an order of magnitude increase in fatigue crack growth rate. The fatigue crack propagation resistance of the reinforced UHMWPE was found to be significantly worse than that of the plain UHMWPE. This result was attributed to poor bonding between the carbon fibers and the UHMWPE matrix and the ductile nature of the matrix itself.

  3. TENSILE FORCE AT BREAK OF GEL-SPUN HOT-DRAWN ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    PENNING, JP; PENNINGS, AJ

    1991-01-01

    Fibres obtained by gel spinning of ultrahigh molecular weight polyethylene (UHMWPE) were drawn to various ratios, and the improvement of the tensile strength of the hot-drawn filaments with increasing draw ratio has been studied. The tensile force at break of gel-spun/hot-drawn UHMWPE fibres appeare

  4. Increasing the wear resistance of ultra-high molecular weight polyethylene by adding solid lubricating fillers

    Energy Technology Data Exchange (ETDEWEB)

    Panin, S. V., E-mail: svp@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055, Russia and National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Kornienko, L. A.; Poltaranin, M. A.; Ivanova, L. R. [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Suan, T. Nguen [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2014-11-14

    In order to compare effectiveness of adding solid lubricating fillers for polymeric composites based on ultra-high molecular weight polyethylene (UHMWPE) with graphite, molybdenum disulfide and polytetrafluoroethylene, their tribotechnical characteristics under dry friction, boundary lubrication and abrasive wearing were investigated. The optimal weight fractions of fillers in terms of improving wear resistance have been determined. The supramolecular structure and topography of wear track surfaces of UHMWPE-based composites with different content of fillers have been studied.

  5. Nanocrystalline Cellulose Improves the Biocompatibility and Reduces the Wear Debris of Ultrahigh Molecular Weight Polyethylene via Weak Binding.

    Science.gov (United States)

    Wang, Shiwen; Feng, Qiang; Sun, Jiashu; Gao, Feng; Fan, Wei; Zhang, Zhong; Li, Xiaohong; Jiang, Xingyu

    2016-01-26

    The doping of biocompatible nanomaterials into ultrahigh molecular weight polyethylene (UHMWPE) to improve the biocompatibility and reduce the wear debris is of great significance to prolonging implantation time of UHMWPE as the bearing material for artificial joints. This study shows that UHMWPE can form a composite with nanocrystalline cellulose (NCC, a hydrophilic nanosized material with a high aspect ratio) by ball-milling and hot-pressing. Compared to pure UHMWPE, the NCC/UHMWPE composite exhibits improved tribological characteristics with reduced generation of wear debris. The underlying mechanism is related to the weak binding between hydrophilic NCC and hydrophobic UHMWPE. The hydrophilic, rigid NCC particles tend to detach from the UHMWPE surface during friction, which could move with the rubbing surface, serve as a thin lubricant layer, and protect the UHMWPE substrate from abrasion. The biological safety of the NCC/UHMWPE composite, as tested by MC3T3-E1 preosteoblast cells and macrophage RAW264.7 cells, is high, with significantly lower inflammatory responses/cytotoxicity than pure UHMWPE. The NCC/UHMWPE composite therefore could be a promising alternative to the current UHMWPE for bearing applications.

  6. High-speed spinning of ultra-high molecular weight polyethylene fibres

    NARCIS (Netherlands)

    Roukema, Mees

    1991-01-01

    This thesis deals with the spinning of ultra-high molecular weight polyethylene ( UHMWPE ) fibres at high speeds, and the effects of the spinning parameters on the fibre properties. Polyethylene fibres with strengths up to 7.2 GPa can be produced in a gel-spinning and hot-drawing procedure. In this

  7. High-speed spinning of ultra-high molecular weight polyethylene fibres

    NARCIS (Netherlands)

    Roukema, Mees

    1991-01-01

    This thesis deals with the spinning of ultra-high molecular weight polyethylene ( UHMWPE ) fibres at high speeds, and the effects of the spinning parameters on the fibre properties. Polyethylene fibres with strengths up to 7.2 GPa can be produced in a gel-spinning and hot-drawing procedure. In this

  8. Knee simulator wear of vitamin E stabilized irradiated ultrahigh molecular weight polyethylene.

    Science.gov (United States)

    Micheli, Brad R; Wannomae, Keith K; Lozynsky, Andrew J; Christensen, Steven D; Muratoglu, Orhun K

    2012-01-01

    Wear and damage of ultrahigh molecular weight polyethylene (UHMWPE) tibial inserts used in total knee arthroplasty are accelerated by oxidation. Radiation crosslinking reduces wear but produces residual free radicals adversely affecting stability. One alternative to stabilize radiation-crosslinked UHMWPE is to infuse the material with vitamin E (vit E). We investigated the properties of 100-kGy e-beam-irradiated UHMWPE that was subsequently doped with vitamin E in comparison with conventional UHMWPE. Both polymers were sterilized with gamma irradiation in vacuum packaging. Vitamin E-doped UHMWPE showed lower wear before and after aging (2.4 ± 0.5 and 2.5 ± 0.8 mg/million cycle, respectively, vs 26.9 ± 3.5 and 40.8 ± 3.0 mg/million cycle for conventional UHMWPE). Conventional UHMWPE showed oxidation after accelerated aging, and its mechanical properties were adversely affected, whereas vit E-doped UHMWPE showed no oxidation or changes in its mechanical properties. Vitamin E stabilization of radiation-crosslinked UHMWPE resulted in low wear and high oxidation resistance; it is an alternative load-bearing material for total knee applications.

  9. Ultra High Molecular Weight Polyethylene/Graphene Oxide Nanocomposites: Thermal, Mechanical and Wettability Characterisation

    OpenAIRE

    2015-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is the material most commonly used among hard-on-soft bearings in artificial joints. However, the eventual failure of joint implants has been directly related to the wear and oxidation resistance of UHMWPE. The development of novel materials with improved wear and oxidative characteristics has generated great interest in the orthopaedic community and numerous carbon nanostructures have been investigated in the last years due to their excellent...

  10. Radiation cross-linking in ultra-high molecular weight polyethylene for orthopaedic applications

    OpenAIRE

    Oral, Ebru; Muratoglu, Orhun K.

    2007-01-01

    The motivation for radiation cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is to increase its wear resistance to be used as bearing surfaces for total joint arthroplasty. However, radiation also leaves behind long-lived residual free radicals in this polymer, the reactions of which can detrimentally affect mechanical properties. In this review, we focus on the radiation cross-linking and oxidative stability of first and second generation highly cross-linked UHMWPEs develo...

  11. Preparation, tribological properties and biocompatibility of fluorinated graphene/ultrahigh molecular weight polyethylene composite materials

    Science.gov (United States)

    Xu, L.; Zheng, Y.; Yan, Z.; Zhang, W.; Shi, J.; Zhou, F.; Zhang, X.; Wang, J.; Zhang, J.; Liu, B.

    2016-05-01

    Fluorinated graphene (FG)/ultra-high molecular weight polyethylene (UHMWPE) composites were successfully prepared by ultrasonic dispersion and liquid thermoforming method. The mechanical and tribological properties of pure UHMWPE and FG/UHMWPE composites were investigated using micro-hardness tester and high-speed reciprocating friction tester. The results showed that: adding FG could not only increase the micro-hardness of the composites, but also decrease the wear volume of the composite significantly. The friction coefficients of the composites were also reduced with the increasing of FG content. In addition, the MC3T3-E1 cells adhered and grew well on the surface of the FG/UHMWPE composites as observed by SEM and fluorescence microscope, indicating the addition of FG did not affect the morphology and activity of the cells. The FG/UHMWPE composites exhibited excellent mechanical properties, tribological properties and biocompatibility, which could be used as the potential artificial joint replacement material.

  12. THE EFFECTS OF HIGH DOSE IRRADIATION ON THE CROSS-LINKING OF VITAMIN E-BLENDED ULTRAHIGH MOLECULAR WEIGHT POLYETHYLENE

    Science.gov (United States)

    Oral, Ebru; Beckos, Christine Godleski; Malhi, Arnaz S.; Muratoglu, Orhun K.

    2008-01-01

    Vitamin E-stabilized, highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is a promising oxidation and wear resistant UHMWPE with improved mechanical strength in comparison with the first generation, irradiated and melted UHMWPE. One approach of incorporating vitamin E in UHMWPE is through blending of vitamin E in UHMWPE powder followed by consolidation and radiation crosslinking. However radiation crosslinking efficiency of UHMWPE decreases in the presence of vitamin E. Therefore an optimum vitamin E concentration and radiation dose level needs to be determined to achieve a cross-link density comparable to 100-kGy irradiated and melted UHMWPE, which has shown excellent wear properties in vivo. We investigated the cross-link density and mechanical properties of vitamin E-blended UHMWPEs as a function of vitamin E concentration in the blend and gamma irradiation doses up to 200 kGy. We found that 0.3 wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 65 kGy for virgin UHMWPE and 1.0 wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 25 kGy for virgin UHMWPE even when the former were irradiated to a radiation dose of 200 kGy. In addition, higher plasticity at vitamin E concentrations at and above 0.3 wt% indicated that increased chain scissioning may be prevalent. Since the wear resistance of this irradiated UHMWPE would be expected to be low, vitamin E concentrations equal to or above 0.3 wt% are not recommended for subsequent irradiation to achieve a wear resistant cross-linked UHMWPE. The long–term oxidative stability of irradiated blends with low vitamin E concentrations has yet to be studied to determine an optimum between cross-link density and long-term oxidative stability. PMID:18514813

  13. 超高分子量聚乙烯管材应用现状%Present Situation of Application of Ultra High Molecular Weight Polyethylene Pipe

    Institute of Scientific and Technical Information of China (English)

    何继敏; 薛平

    2011-01-01

    概述了超高分子量聚乙烯(UHMWPE)管材的几种成型方法,介绍了UHMWPE管材在各个工程领域的实际应用效果和现状.%Several processing methods of ultra high molecular weight polyethylene (UHMWPE) pipe were summerized, and also the practical effects and present situation of application of the UHMWPE pipe in various engineering fields were introduced.

  14. Study on crystallization behavior of ultra-high molecular weight polyethylene/carbon nanotubes composite fiber%UHMWPE/CNTs复合纤维的结晶行为研究

    Institute of Scientific and Technical Information of China (English)

    王新鹏; 梁琳俐; 赵辉鹏; 王依民; 王燕萍

    2005-01-01

    分别用DSC、X衍射、热台偏光显微镜对超高分子质量聚乙烯(UHMWPE)和UHMWPE/CNTs(碳纳米管)复合纤维的结晶行为进行了研究.结果表明:碳纳米管的加入使得复合材料的熔点较UHMWPE有所提高,碳纳米管起到了成核剂的作用,晶片厚度较UHMWPE增加.

  15. Equal channel angular extrusion of ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Reinitz, Steven D; Engler, Alexander J; Carlson, Evan M; Van Citters, Douglas W

    2016-10-01

    Ultra-high molecular weight polyethylene (UHMWPE), a common bearing surface in total joint arthroplasty, is subject to material property tradeoffs associated with conventional processing techniques. For orthopaedic applications, radiation-induced cross-linking is used to enhance the wear resistance of the material, but cross-linking also restricts relative chain movement in the amorphous regions and hence decreases toughness. Equal Channel Angular Extrusion (ECAE) is proposed as a novel mechanism by which entanglements can be introduced to the polymer bulk during consolidation, with the aim of imparting the same tribological benefits of conventional processing without complete inhibition of chain motion. ECAE processing at temperatures near the crystalline melt for UHMWPE produces (1) increased entanglements compared to control materials; (2) increasing entanglements with increasing temperature; and (3) mechanical properties between values for untreated polyethylene and for cross-linked polyethylene. These results support additional research in ECAE-processed UHMWPE for joint arthroplasty applications.

  16. The effect of chromic acid treatment on the mechanical and tribological properties of aramid fibre reinforced ultra-high molecular weight polyethylene composite

    NARCIS (Netherlands)

    Hofste, JM; Pennings, AJ; Schut, J.A.

    1998-01-01

    Surface oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder has an influence on the mixing procedure of chopped fibres and UHMWPE powder. Due to this oxidation hydrogen bonds can be formed between the fibres and powder particles, leading to a more homogeneous fibre-powder mixture.

  17. Oxidation in ultrahigh molecular weight polyethylene and cross-linked polyethylene acetabular cups tested against roughened femoral heads in a hip joint simulator.

    Science.gov (United States)

    Taddei, Paola; Affatato, Saverio; Fagnano, Concezio; Toni, Aldo

    2006-06-01

    This study was aimed at comparing the oxidative degradation of commercial acetabular cups made of cross-linked polyethylene (XLPE) and conventional ultrahigh molecular weight polyethylene (UHMWPE). After testing against deliberately scratched CoCrMo femoral heads in a hip joint simulator, the cups, microtomed parallel to the articulating surface, were analyzed by IR spectroscopy. Due to the potential for artifacts caused by absorbed contaminants, the IR spectra were compared only after hexane extraction; actually, XLPE was found to absorb more serum than UHMWPE. The two sets of unworn acetabular cups showed different oxidation patterns with consequently different distributions of carbonyl species; unworn XLPE was characterized by lower contents of carbonyl species and hydrogen-bonded alcohols and higher contents of trans-vinylene species than unworn UHMWPE. Upon simulator testing, UHMWPE showed more significant changes in oxidation indexes and distribution of carbonyl compounds than XLPE, confirming a better wear behavior for XLPE under the adopted testing conditions.

  18. Wear behaviour of discontinuous aramid fibre reinforced ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Hofste, JM; Smit, HHG; Pennings, AJ

    1996-01-01

    The wear of Ultra-High Molecular Weight Polyethylene has generated new concern regarding the long-term clinical performance of total joint replacements. To extend the lifetime of artificial joints, it is necessary to decrease tt-le wear rate of UHMWPE. One possible solution is the incorporation of a

  19. Biotribological behavior of ultra high molecular weight polyethylene composites containing bovine bone hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-long; ZHU Yuan-yuan; WANG Qing-liang; GE Shi-rong

    2008-01-01

    Wear particles of ultrahigh molecular weight polyethylene (UHMWPE) are the main cause of long-term failure of total joint replacements. Therefore, increasing its wear resistance or bioactivity will be very useful in order to obtain high quality artificial joints. In our study, UHMWPE composites filled with the bovine bone hydroxyapatite (BHA) were prepared by the method of compression moulding. A ball-on-disc wear test was carried out with a Universal Micro-Tribometer to investigate the friction and wear behavior of a Si3N4 ceramic ball, cross-sliding against the UHMWPE/BHA composites with human plasma lubrication. At the same time, the profiles of the worn grooves on the UHMWPE/BHA surface were scanned. The experimental results indicate that the addition of BHA to UHMWPE had a significant effect on the biotribological behavior of UHMWPE cross-sliding against the Si3N4 ceramic ball. The addition of BHA powder enhanced the hardness and modulus of elasticity of these composites and decreased the friction coefficients and wear rates under conditions of human plasma lubrication. When the added amount of BHA powders was up to 20%~30%, UHMWPE/BHA composites demonstrated the designed performance of the mechanical properties and biotribological behavior.

  20. Tribological characteristics of UHMWPE composite and relationship with its compressive behavior

    Institute of Scientific and Technical Information of China (English)

    LI Jian; GUO Zhiguang; HUA Meng; QIN Xiangpei; WEN Shizhu

    2004-01-01

    The triboogical characteristics and the mechanics compress behaviors of pure and composite ultra high molecular weight polyethylene (UHMWPE) were investigated using tribological apparatus and universal materials testing apparatus respectively.Results show that there are direct relationships between the sliding friction, wear characteristics, and compression behaviors of UHMWPE composite. The composite of UHMWPE with added copper particles had great improvement in tribological characteristics and mechanics behaviors. Based on the experimental results, a microstructure model of UHMWPE-copper composite is preliminarily proposed.

  1. The antioxidant and non-antioxidant contributions of vitamin E in vitamin E blended ultra-high molecular weight polyethylene for total knee replacement.

    Science.gov (United States)

    Turner, Alex; Okubo, Yasushi; Teramura, Satoshi; Niwa, Yasuhito; Ibaraki, Kento; Kawasaki, Toru; Hamada, Daisuke; Uetsuki, Keita; Tomita, Naohide

    2014-03-01

    Vitamin E (VE) blended ultra-high molecular weight polyethylene (UHMWPE) has been developed in Japan as a material for use in total knee replacement (TKR). Various results have demonstrated that VE blended UHMWPE reduces the incidence of delamination failure and lowers the amount of wear produced during knee simulator testing. It was also found that wear particles from VE blended UHMWPE elicited a reduced biological response compared to conventional UHMWPE. A great deal of research concerning vitamin E (VE) stabilized ultrahigh molecular weight polyethylene (UHMWPE) has focused on VE's effects as an antioxidant and its ability to prevent the oxidative degradation of UHMWPE chains. However, other chemical and mechanical changes have been observed in VE blended UHMWPE that are unrelated to the oxidative protection that VE provides. This paper provides a general review of VE blended UHMWPE, with a particular focus on the non-antioxidant effects of VE. The potential application of VE blended UHMWPE in total hip replacement (THR), along with the differences in loading conditions between the knee and the hip are also discussed.

  2. An In-situ X-ray Scattering Study During Uniaxial Stretching of Ionic Liquid/Ultra-high Molecular Weight Polyethylene Blends

    Energy Technology Data Exchange (ETDEWEB)

    X Li; Y Mao; H Ma; F Zuo; B Hsiao; B Chu

    2011-12-31

    An ionic liquid (IL) 1-docosanyl-3-methylimidazolium bromide was incorporated into ultra-high molecular weight polyethylene (UHMWPE) and formed IL/UHMWPE blends by solution mixing. The structure evolution of these blends during uniaxial stretching was followed by in-situ synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. During deformation at room temperature, deformation-induced phase transformation from orthorhombic to monoclinic phase was observed in both IL/UHMWPE blends and neat UHMWPE. The elongation-to-break ratios of IL/UHMWPE blends were found to increase by 2-3 times compared with that of pure UHMWPE, while the tensile strength remained about the same. In contrast, during deformation at high temperature (120 C), no phase transformation was observed. However, the blend samples showed much better toughness, higher crystal orientation and higher tilting extent of lamellar structure at high strains.

  3. UHMWPE/HA复合关节材料的生物摩擦学研究%Biotribological Behavior of Ultra High Molecular Weight Polyethylene Composites Containing Coralline Hydroxyapatite in a Hip Joint Simulator

    Institute of Scientific and Technical Information of China (English)

    王庆良; 葛世荣; 林国明

    2007-01-01

    采用热压成型工艺制备了超高分子量聚乙烯(UHMWPE)/羟基磷灰石(HA)复合关节材料,利用人工髋关节模拟磨损试验系统(MTS),研究了该类复合材料与CoCrMo合金组合关节在人血浆润滑条件下的摩擦磨损性能.实验结果表明,添加HA能有效提高UHMWPE关节材料的表面硬度,降低其磨损率.人血浆润滑条件下,UHMWPE及其复合材料的磨损机制主要表现为研磨磨损和疲劳磨损,磨损颗粒尺寸随HA粉体添加量的增加而增大.

  4. Properties and Microstructural Characteristic of Kaolin Geopolymer Ceramics with Addition of Ultra High Molecular Weight Polyethylene

    Science.gov (United States)

    Ahmad, Romisuhani; Bakri Abdullah, Mohd Mustafa Al; Hussin, Kamarudin; Sandu, Andrei Victor; Binhussain, Mohammed; Ain Jaya, Nur

    2016-06-01

    In this paper, the mechanical properties and microstructure of kaolin geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene were studied. Inorganic polymers based on alumina and silica polysialate units were synthesized at room temperature from kaolin and sodium silicate in a highly alkaline medium, followed by curing and drying at 80 °C. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Addition of Ultra High Molecular Weight Polyethylene to the kaolin geopolymer are fabricated with Ultra High Molecular Weight Polyethylene content of 2, 4, 6 and 8 (wt. %) by using powder metallurgy method. The samples were heated at 1200 °C and the strength and morphological were tested. It was found that the flexural strength for the kaolin geopolymer ceramics with addition of UHMWPE were improved and generally increased with the increasing of UHMWPE loading. The result revealed that the optimum flexural strength was obtained at UHMWPE loading of 4 wt. % (92.1 MPa) and the flexural strength started to decrease. Microstructural analysis showed the samples appeared to have more number of pores and connected of pores increased with the increasing of UHMWPE content.

  5. In vitro studies of multiwalled carbon nanotube/ultrahigh molecular weight polyethylene nanocomposites with osteoblast-like MG63 cells

    Directory of Open Access Journals (Sweden)

    J. Reis

    2010-05-01

    Full Text Available Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE is a polymer widely used in orthopedic applications that imply wear and particle generation. We describe here the response of human osteoblast-like MG63 cells after 6 days of culture in contact with artificially generated particles from both UHMWPE polymer and multiwalled carbon nanotubes (MWCNT/UHMWPE nanocomposites. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision hip arthroplasty surgeries required by wear failure of acetabular cups and diminish particle-induced osteolysis. The results of an in vitro study of viability and proliferation and interleukin-6 (IL-6 production suggest good cytocompatibility, similar to that of conventional UHMWPE (WST-1 assay results are reported as percentage of control ± SD: UHMWPE = 96.19 ± 7.92, MWCNT/UHMWPE = 97.92 ± 8.29%; total protein: control = 139.73 ± 10.78, UHMWPE = 137.07 ± 6.17, MWCNT/UHMWPE = 163.29 ± 11.81 µg/mL; IL-6: control = 90.93 ± 10.30, UHMWPE = 92.52 ± 11.02, MWCNT/UHMWPE = 108.99 ± 9.90 pg/mL. Standard cell culture conditions were considered as control. These results, especially the absence of significant elevation in the osteolysis inductor IL-6 values, reinforce the potential of this superior wear-resistant composite for future orthopedic applications, when compared to traditional UHMWPE.

  6. Effect of surface roughness and sterilization on bacterial adherence to ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Kinnari, T J; Esteban, J; Zamora, N; Fernandez, R; López-Santos, C; Yubero, F; Mariscal, D; Puertolas, J A; Gomez-Barrena, E

    2010-07-01

    Sterilization with ethylene oxide (EO) and gas plasma (GP) are well-known methods applied to ultra-high molecular weight polyethylene (UHMWPE) surfaces in the belief that they prevent major material changes caused by gamma irradiation. However, the influence of these surface sterilization methods on bacterial adherence to UHMWPE is unknown. UHMWPE samples with various degrees of roughness (0.3, 0.8 and 2.0 μm) were sterilized with either GP or EO. The variations in hydrophobicity, surface free energy and surface functional groups were investigated before and after sterilization. Sterilized samples were incubated with either Staphylococcus aureus or Staphylococcus epidermidis in order to study bacterial adherence to these materials. Fewer bacteria adhered to UHMWPE after sterilization with EO than after sterilization with GP, especially to the smoothest surfaces. No changes in chemical composition of the UHMWPE surface due to sterilization were observed using X-ray photoemission spectroscopy analysis. The decreased bacterial adherence to UHMWPE found at the smoothest surfaces after sterilization with EO was not directly related to changes in chemical composition. Increased bacterial adherence to rougher surfaces was associated with increased polar surface energy of EO-sterilized surfaces.

  7. Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review.

    Science.gov (United States)

    Macuvele, Domingos Lusitâneo Pier; Nones, Janaína; Matsinhe, Jonas V; Lima, Marla M; Soares, Cíntia; Fiori, Márcio A; Riella, Humberto G

    2017-07-01

    Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been applied, as a bearing surface in total human joint replacements and artificial bones. UHMWPE has a superior wear resistance, low-friction surface, biological inertness, high levels of strength, creep resistance and low friction coefficient. However, the wear debris generated during the joint motions could cause problem in human implant, such as osteolysis and loosening. For this, several attempts was been made to improve UHMWPE properties and increases safety and biocompatibility in human implants. One of them, include the use of hydroxyapatite (HA), as reinforcement agent to modify the UHMWPE properties and facilitate biological fixation between the implant and the human cells. Recent studies showed that the addition of HA in polymer matrix result in enhancement of mechanical and tribological properties. In addition, it also improves the formation of the actual bond between the material and the living organism since the hydroxyapatite is the major component of the mineral part of the human bone. In this brief review the some properties and characteristic of UHMWPE and HA are described and main processing methods of UHMWPE/HA composites and biocompatibility studies were also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Ultradrawing and Ultimate Tenacity Properties of Ultrahigh Molecular Weight Polyethylene Composite Fibers Filled with Nanosilica Particles with Varying Specific Surface Areas

    Directory of Open Access Journals (Sweden)

    Jen-taut Yeh

    2015-01-01

    Full Text Available Original and/or functionalized nanosilica particles with a quoted specific surface area of 100, 300, and 600 m2/g, respectively, were used to investigate the influence of specific surface areas of nanosilica particles on ultradrawing and ultimate tensile properties of ultrahigh molecular weight polyethylene (UHMWPE, UHMWPE/nanosilica, and UHMWPE/functionalized nanosilica fibers. The specific surface areas of well-dispersed functionalized nanosilica particles in UHMWPE/functionalized nanosilica fibers can positively affect their ultradrawing, orientation, ultimate tensile properties, and “micro-fibrils” morphologies. Excellent orientation and ultimate tensile properties of UHMWPE/nanofiller fibers can be prepared by ultradrawing the UHMWPE/functionalized nanosilica as-prepared fibers with optimal contents of the best prepared functionalized nanosilica particles well dispersing in the as-prepared fibers. The ultimate tensile strength value of the best prepared UHMWPE/functionalized nanosilica drawn fiber reaches 7.6 GPa, which is about 2.3 times of those of the best prepared UHMWPE drawn fiber without addition of any nanofiller. Specific surface area, morphological and Fourier transform infrared analyses of original and functionalized nanosilica particles, and/or investigations of thermal, orientation factor, and ultimate tensile properties of as-prepared and/or drawn UHMWPE/functionalized nanosilica fibers were performed to understand the above improved ultradrawing and ultimate tensile properties of the UHMWPE/functionalized nanosilica as-prepared and/or drawn fibers.

  9. Effect of low molecular weight additives on immobilization strength, activity, and conformation of protein immobilized on PVC and UHMWPE.

    Science.gov (United States)

    Kondyurin, Alexey; Nosworthy, Neil J; Bilek, Marcela M M

    2011-05-17

    Horseradish peroxidase (HRP) was immobilized onto both plasticized and unplasticized polyvinylchloride (PVC) and ultrahigh molecular weight polyethylene (UHMWPE). Plasma immersion ion implantation (PIII) in a nitrogen plasma with 20 kV bias was used to facilitate covalent immobilization and to improve the wettability of the surfaces. The surfaces and immobilized protein were studied using attenuated total reflection infrared (ATR-IR) spectroscopy and water contact angle measurements. Protein elution on exposure to repeated sodium dodecyl sulfate (SDS) washing was used to assess the strength of HRP immobilization. The presence of low molecular weight components (plasticizer, additives in solvent, unreacted monomers, adsorbed molecules on surface) was found to have a major influence on the strength of immobilization and the conformation of the protein on the samples not exposed to the PIII treatment. A phenomenological model considering interactions between the low molecular weight components, the protein molecule, and the surface is developed to explain these observations.

  10. Temperature window effect and its application in extrusion of ultrahigh molecular weight polyethylene

    Directory of Open Access Journals (Sweden)

    2011-08-01

    Full Text Available Ultrahigh molecular weight polyethylene (UHMWPE was ram extruded using a temperature window effect. The extrusion pressure abruptly drops at a very narrow extrusion temperature window which is about 10°C higher than the theoretical melting point of orthorhombic polyethylene crystals under quiescent and equilibrium states. The correlation between extrusion pressure and parameters such as extrusion temperature, annealing condition, thermal history, piston velocity, L/D ratio of the die, and molecular weight of UHMWPE, was studied. The temperature window increases with molecular weight and is unaffected by thermal history and annealing. The stable extrusion pressure and the critical piston velocity decrease with the rise in the extrusion temperature. The flow resistance reversely depends on the L/D ratio of the die. This phenomenon is attributed to an extensional flow-induced chain alignment along the streamline, which results in the formation of a metastable mesophase with higher chain mobility.

  11. Study on critical-sized ultra-high molecular weight polyethylene wear particles loaded with alendronate sodium: in vitro release and cell response.

    Science.gov (United States)

    Liu, Yumei; Shi, Feng; Gong, Kemeng; Liu, Yang; Zhi, Wei; Weng, Jie; Qu, Shuxin

    2017-04-01

    The aim of this study was to investigate the in vitro release and the effect of RAW 264.7 macrophages of critical-sized wear particles of ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), one of the most effective drugs to treat osteoporosis in clinic. The critical-sized UHMWPE-ALN 0.5 wt.% wear particles were prepared by vacuum gradient filtration combined with Pluronic F-68. In vitro release of ALN from critical-sized UHMWPE-ALN wear particles was investigated in phosphate buffered saline (PBS) at 37 °C with a shaker. Cell morphology, proliferation, lactate dehydrogenase (LDH) leakage and secretions of cytokines were evaluated after co-cultured with critical-sized UHMWPE-ALN wear particles in vitro. Results showed that ALN released from critical-sized UHMWPE-ALN wear particles included burst release and slow release in vitro. Macrophages would be chemotaxis and aggregated around the critical-sized UHMWPE-ALN or UHMWPE wear particle, which was phagocytosed with time. The proliferation of macrophages co-cultured with critical-sized UHMWPE-ALN wear particles was significantly decreased compared with that of critical-sized UHMWPE group. Meanwhile, the critical-sized UHMWPE-ALN wear particles significantly induced the LDH leakage of macrophages, which indicated the cell death. The death of macrophages induced by ALN was one of pathways to inhibit their proliferation. The secretions of cytokines (interleukin-6 and tumor necrosis factor-alpha) in critical-sized UHMWPE-ALN group were significantly lower than those in critical-sized UHMWPE group due to the released ALN. The present results suggested that UHMWPE-ALN had the potential application in clinic to treat osteolysis induced by wear particles.

  12. Electron microscopy investigation of interface between carbon fiber and ultra high molecular weight polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Stepashkin, A.A.; Chukov, D.I., E-mail: dil_chukov@yahoo.com; Gorshenkov, M.V.; Tcherdyntsev, V.V.; Kaloshkin, S.D.

    2014-02-15

    Highlights: • Effect of the carbon fibers surface treatments on the adhesive interactions in UHMWPE composites was studied. • Air oxidation of carbon filler ensures most significant increase in adhesion interaction in UHMWPE based composites. • Nanosized UHMWPE fibers with 20–40 nm in diameter and with 6–10 μm in length, was observed on the surface of carbon fibers. -- Abstract: Scanning electron microscopy was used to investigate the surface of initial and modified high-strength and high-modulus carbon fibers as well as interfaces in the ultra high molecular weight polyethylene, filled with above-mentioned fibers. Effect of the fibers surface modifying method on the adhesive interactions in composites was studied. It was observed that interaction of matrix with a modified surface of fibers results in a formation of bonds with strength higher than the yield strength of the polymer. It results in a formation of long nanosized polymer wires at tensile fracture of composites.

  13. Study on biotribological properties of UHMWPE grafted with MPDSAH

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yaling; Xiong, Dangsheng, E-mail: xiongds@163.com; Shao, Silong

    2013-04-01

    In order to prolong the service life of artificial joints, a zwitterion monomer of MPDSAH ((3-(methacryloylamino)propyl)dimethyl (3-sulfopropyl)ammonium hydroxide) was grafted onto ultra-high molecular weight polyethylene (UHMWPE) powders to construct a brush-like structure by UV irradiation, and then the grafted UHMWPE powders were hot pressed as the bulk materials. The wettability of bulk materials surface with different monomer concentrations was analyzed. The tribological properties of modified UHMWPE bulk materials were investigated under distilled water and saline by sliding against stainless steel ball. The measurement of Fourier-transform infrared (FT-IR) spectroscopy indicates that MPDSAH is successfully grafted onto the surface of UHMWPE powders by UV irradiation. The contact angles of modified UHMWPE are decreased and the surface wettability is effectively improved. The friction coefficient of the modified sample is lower than that of untreated UHMWPE in aqueous lubricants during a long-term friction. With the increase of monomer concentration, the wear rate of grafted UHMWPE decreases gradually in distilled water. The grafting hydrophilic macromolecule polymer is helpful to form a lubricating film of water, which leads to the improvement of the lubricity of UHMWPE. - Highlights: ► PMPDSAH brushes were grafted onto UHMWPE powders by UV radiation. ► Wettability of PMPDSAH-grafted UHMWPE bulk material is improved. ► UHMWPE grafted with PMPDSAH brushes shows lower friction coefficient and wear rate.

  14. Compression Molded Ultra High Molecular Weight Polyethylene-Hydroxyapatite-Aluminum Oxide-Carbon Nanotube Hybrid Composites for Hard Tissue Replacement

    Institute of Scientific and Technical Information of China (English)

    Ankur Gupta; Garima Tripathi; Debrupa Lahiri; Kantesh Balani

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is widely used for articulating surfaces in total hip and knee replacements.In the present work,UHMWPE based polymer composites were synthesized by synergistic reinforcing of bioactive hydroxyapatite (HA),bioinert aluminum oxide (Al2O3),and carbon nanotubes (CNTs) using compression molding.Phase and microstructural analysis suggests retention of UHMWPE and reinforcing phases in the compression molded composites.Microstructural analysis elicited variation in densification due to the size effect of the reinforcing particles.The hybrid composites exhibited hardness,elastic modulus and toughness comparable to that of UHMWPE.The interfacial effect of reinforcement phases has evinced the effectiveness of Al2O3 over HA and CNT reinforcements,depicting synergistic enhancement in hardness and elastic modulus.Weak interfacial bonding of polymer matrix with HA and CNT requires utilization of coupling agents to achieve enhanced mechanical properties without deteriorating cytocompatible properties.

  15. The influence of Co-Cr and UHMWPE particles on infection persistence : An in vivo study in mice

    NARCIS (Netherlands)

    Hosman, Anton H.; Bulstra, Sjoerd K.; Sjollema, Jelmer; van der Mei, Henny C.; Busscher, Henk J.; Neut, Danielle

    2012-01-01

    Wear of metal-on-metal (cobaltchromium, CoCr particles) and metal-on-polyethylene (ultra-high-molecular-weight polyethylene, UHMWPE particles) bearing surfaces in hip prostheses is a major problem in orthopedics. This study aimed to compare the influence of CoCr and UHMWPE particles on the persisten

  16. INFLUENCE OF CHEMICAL CROSS-LINKING ON THE CREEP-BEHAVIOR OF ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    PENNING, JP; PRAS, HE; PENNINGS, AJ

    1994-01-01

    In this study, the effect of chemical crosslinking on the creep behavior of high-strength fibers, obtained by gel-spinning and subsequent hot-drawing of ultra-high molecular weight polyethylene (UHMWPE), is examined. In the first part of the paper, the general aspects of the creep behavior of these

  17. Temperature-dependent fracture mechanisms in gel-spun hot-drawn ultra-high molecular weight polyethylene fibres

    NARCIS (Netherlands)

    Pras, E; Pennings, AJ

    1998-01-01

    Tensile testing of gel-spun hot-drawn ultra-high molecular weight polyethylene (UHMWPE) fibres reveal a ductile-brittle transition temperature. Ductile fracture above the transition temperature is believed to be initiated by a stress-induced orthorhombic-hexagonal phase transition, whereas at lower

  18. The relative effects of radiation crosslinking and type of counterface on the wear resistance of ultrahigh-molecular-weight polyethylene.

    Science.gov (United States)

    Bistolfi, Alessandro; Bellare, Anuj

    2011-09-01

    The lifetime of total joint replacement prostheses utilizing ultrahigh-molecular-weight polyethylene (UHMWPE) components has historically been determined by their wear resistance. It has been discovered that radiation crosslinking of UHMWPE can substantially increase its wear resistance. However, it is also well recognized that there is a radiation-dose-dependent decrease in several important mechanical properties of UHMWPE, such as fracture toughness and resistance to fatigue crack propagation. In this study, the effect of radiation crosslinking (followed by remelting) on the morphology, tensile properties and wear resistance of UHMWPE was investigated. Wear tests were conducted against both the commonly used cobalt-chromium counterface polished to implant grade smoothness as well as a smoother ceramic (alumina) counterface. The results showed that 50kGy dose radiation crosslinking increased the wear resistance of UHMWPE against the cobalt-chromium counterface 7-fold, but the coupling of remelted, crosslinked UHMWPE against the smoother alumina counterface led to a 20-fold increase in wear resistance. This study shows that the use of an alumina counterface would circumvent the need to use a high radiation dose in crosslinking UHMWPE, associated with poor mechanical properties, without compromising wear resistance.

  19. A new technique to improve the mechanical and biological performance of ultra high molecular weight polyethylene using a nylon coating.

    Science.gov (United States)

    Firouzi, Dariush; Youssef, Aya; Amer, Momen; Srouji, Rami; Amleh, Asma; Foucher, Daniel A; Bougherara, Habiba

    2014-04-01

    A new patent pending technique is proposed in this study to improve the mechanical and biological performance of ultra high molecular weight polyethylene (UHMWPE), i.e., to uniformly coat nylon onto the UHMWPE fiber (Firouzi et al., 2012). Mechanical tests were performed on neat and new nylon coated UHMWPE fibers to examine the tensile strength and creep resistance of the samples at different temperatures. Cytotoxicity and osteolysis induced by wear debris of the materials were investigated using (MTT) assay, and RT-PCR for tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) osteolysis markers. Mechanical test results showed substantial improvement in maximum creep time, maximum breaking force, and toughness values of Nylon 6,6 and Nylon 6,12 coated UHMWPE fibers between average 15% and 60% at 25, 50, and 70°C. Furthermore, cytotoxicity studies have demonstrated significant improvement in cell viability using the nylon coated UHMWPE over the neat one (72.4% vs 54.8%) for 48h and (80.7 vs 5%) for 72h (PNylon 6,6 coated UHMWPE (2.5 fold increase for TNFα at 48h, and three fold increase for IL-6 at 72h (Pnylon could be used as a novel material in clinical applications with lower cytotoxicity, less wear debris-induced osteolysis, and superior mechanical properties compared to neat UHMWPE.

  20. Surface modification of ultra-high molecular weight polyethylene for joint prosthesis and sports applications

    Institute of Scientific and Technical Information of China (English)

    H.Dong

    2004-01-01

    The recent progresses in the surfaee modification of ultra high molecular weight polyethylene (UHMWPE) using such advanced surface modification technologies as conventional ion implantation (CⅡ), new plasma immersion ion implantation (PⅢ) and novel active screen plasma (ASP), were all reported. Significantly improved wear resistance was achieved, which has great potential for extending the life-span of joint replacement prostheses and enhancing the performance of such sports equipment as skis and snowboards.

  1. Effect of oxidation on delamination of ultrahigh-molecular-weight polyethylene tibial components.

    Science.gov (United States)

    Bell, C J; Walker, P S; Abeysundera, M R; Simmons, J M; King, P M; Blunn, G W

    1998-04-01

    Whether oxidation of ultrahigh-molecular-weight polyethylene (UHMWPE) causes delamination of the plastic in total knee arthroplasties (TKAs) was investigated. Examination of retrieved TKAs has shown that oxidation of UHMWPE can be caused by postirradiation damage leading to a subsurface band or, to a lesser extent, by mechanical forces during use leading to surface oxidation. Delamination cracks propagated through the subsurface oxidized band. In wear tests, delamination occurred in artificially aged UHMWPE where only subsurface oxidized bands had formed. Increased surface wear predominated where oxidation was associated with the surface of the plastic. Similarly, in tensile and fatigue tests of oxidized UHMWPE, there was a significant reduction in the ultimate tensile strength and in the fatigue resistance of specimens that had developed a subsurface band. Oxidation increased fatigue crack growth rate. It was observed that UHMWPE from different manufacturers varied in its resistance to oxidation. This study demonstrates that the effect of oxidation, which results in the development of a subsurface white band, combined with high subsurface shear forces observed in TKAs, is to enhance delamination wear.

  2. Peak stress intensity factor governs crack propagation velocity in crosslinked ultrahigh-molecular-weight polyethylene.

    Science.gov (United States)

    Sirimamilla, Abhiram; Furmanski, Jevan; Rimnac, Clare

    2013-04-01

    Ultrahigh-molecular-weight polyethylene (UHMWPE) has been successfully used as a bearing material in total joint replacement components. However, these bearing materials can fail as a result of in vivo static and cyclic loads. Crack propagation behavior in this material has been considered using the Paris relationship which relates fatigue crack growth rate, da/dN (mm/cycle) versus the stress intensity factor range, ΔK (Kmax - Kmin , MPa√m). However, recent work suggests that the crack propagation velocity of conventional UHMWPE is driven by the peak stress intensity (Kmax ), not ΔK. The hypothesis of this study is that the crack propagation velocity of highly crosslinked and remelted UHMWPE is also driven by the peak stress intensity, Kmax , during cyclic loading. To test this hypothesis, two highly crosslinked (65 kGy and 100 kGy) and remelted UHMWPE materials were examined. Frequency, waveform, and R-ratio were varied between test conditions to determine the governing factor for fatigue crack propagation. It was found that the crack propagation velocity in crosslinked UHMWPE is also driven by Kmax and not ΔK, and is dependent on loading waveform and frequency in a predictable quasistatic manner. This study supports that crack growth in crosslinked UHMWPE materials, even under cyclic loading conditions, can be described by a relationship between the velocity of crack growth, da/dt and the peak stress intensity, Kmax . The findings suggest that stable crack propagation can occur as a result of static loading only and this should be taken into consideration in design of UHMWPE total joint replacement components.

  3. Biocompatibility of modified ultra-high-molecular-weight polyethylene

    Science.gov (United States)

    Novotná, Z.; Lacmanová, V.; Rimpelová, S.; Juřik, P.; Polívková, M.; Å vorčik, V.

    2016-09-01

    Ultra-high-molecular-weight polyethylene (UHMWPE, PE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore this material is being used in human orthopedic implants such as total joint replacements. Surface modification of this material relates to changes of its surface hydrophilicity, energy, microstructure, roughness, and morphology, all influencing its biological response. In our recent work, PE was treated by an Ar+ plasma discharge and then grafted with biologically active polyethylene glycol in order to enhance adhesion and proliferation of mouse fibroblast (L929). The surface properties of pristine PE and its grafted counterparts were studied by goniometry (surface wettability). Furthermore, Atomic Force Microscopy was used to determine the surface morphology and roughness. The biological response of the L929 cell lines seeded on untreated and plasma treated PE matrices was quantified in terms of the cell adhesion, density, and metabolic activity. Plasma treatment leads to the ablation of the polymer surface layers. Plasma treatment and subsequent poly(ethylene glycol) grafting lead to dramatic changes in the polymer surface morphology and roughness. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with poly(ethylene glycol) increases cell proliferation compared to plasma treatment.

  4. Enhancement of Compatibility between Ultrahigh-Molecular-Weight Polyethylene Particles and Butadiene.Nitrile Rubber Matrix with Nanoscale Ceramic Particles and Characterization of Evolving Layer

    Energy Technology Data Exchange (ETDEWEB)

    Shadrinov, Nikolay V.; Sokolova, Marina D.; Cho, Jinho [Institute of Oil and Gas Issues, Yakutsk (Russian Federation); Okhlopkova, A. A. [North-Eastern Federal Univ., Yakutsk (Russian Federation); Lee, Jungkeun; Jeong, Daeyong [Myongji Univ., Seoul (Korea, Republic of)

    2013-12-15

    This article examines the modification of surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) with nanoscale ceramic particles to fabricate an improved composite with butadiene.nitrile rubber (BNR). Adhesion force data showed that ceramic zeolite particles on the surface of UHMWPE modulated the surface state of the polymer and increased its compatibility with BNR. Atomic force microscopy phase images showed that UHMWPE made up the microphase around the zeolite particles and formed the evolving layer with a complex interface. The complex interface resulted in improvements in the mechanical properties of the composite, especially its low-temperature resistance coefficients, thereby improving its performance in low-temperature applications.

  5. Desenvolvimento e caracterização de suportes porosos de polietileno de ultra alto peso molecular (PEUAPM para utilização como biomaterial para reposição e regeneração óssea Development of ultra high molecular weight polyethylene (UHMWPE porous supports for use as biomaterial in osseous replacement and regeneration

    Directory of Open Access Journals (Sweden)

    Anahi H. Aparecida

    2008-01-01

    Full Text Available O uso de polímeros como biomateriais tem crescido nos últimos anos, principalmente como suportes poliméricos para regeneração tridimensional e substituição de tecidos. Embora o polietileno de ultra alto peso molecular (PEUAPM apresente vantagens na sua utilização como biomaterial, principalmente como implante ortopédico, sua baixa reatividade química constitui-se como fator limitante para sua interação com o tecido ósseo. Neste contexto, a modificação morfológica deste polímero, tornando-o um material poroso, e sua associação com um material bioativo pode proporcionar a obtenção de um biomaterial adequado para a regeneração e reposição do tecido ósseo. Neste trabalho, foram preparados e caracterizados suportes porosos de PEUAPM, pela combinação das técnicas de lixiviação de sal e moldagem por compressão com a aplicação de diferentes pressões de compactação, visando a sua utilização como biomaterial para reposição e regeneração óssea. Os suportes poliméricos apresentaram porosidade interconectada com diâmetro médio de poros entre 34 e 49 mm e porosidade entre 39 e 53%, podendo ser classificados adequados para a utilização como biomaterial poroso.The use of polymer as biomaterials has increased in recent years, mainly as polymeric supports in the three-dimensional regeneration and substitution of tissues. Although the ultra high molecular weight polyethylene (UHMWPE shows advantages in its use as biomaterial, particularly as orthopedic implants, its low chemical reactivity constitutes a limiting factor for interaction with the osseous tissue. The morphological modification of this polymer, leading to a porous material, and its association with a bioactive material can provide tailored biomaterials for the regeneration and replacement of osseous tissue. In this work, polymeric porous supports have been prepared by combining the techniques of salt leaching and compression molding with the application

  6. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    Science.gov (United States)

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements.

  7. Reciprocating sliding wear behavior of alendronate sodium-loaded UHMWPE under different tribological conditions.

    Science.gov (United States)

    Huang, Jie; Qu, Shuxin; Wang, Jing; Yang, Dan; Duan, Ke; Weng, Jie

    2013-07-01

    The aim of this study is to investigate the tribological behaviors and wear mechanisms of ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), a potential drug to treat osteolysis, under different normal loads and lubrication conditions. A mixture of UHMWPE powder and ALN (1.0 wt.%) solution was dried and hot pressed. The static and dynamic friction coefficients of UHMWPE-ALN were slightly higher than those of UHMWPE except under normal load as 10 N and in 25 v/v % calf serum. The specific wear rates of UHMWPE-ALN and UHMWPE were the lowest in 25 v/v % calf serum compared to those in deionized water or physiological saline. In particular, the specific wear rate of UHMWPE-ALN was lower than that of UHMWPE at 50 N in 25 v/v % calf serum. The main wear mechanisms of UHMWPE and UHMWPE-ALN in deionized water and UHMWPE in physiological saline were abrasive. The main wear mechanism of UHMWPE-ALN in physiological saline was micro-fatigue. In 25 v/v % calf serum, the main wear mechanism of UHMWPE and UHMWPE-ALN was abrasive wear accompanied with plastic deformation. The results of Micro-XRD indicated that the molecular deformation of UHMWPE-ALN and UHMWPE under the lower stress were in the amorphous region but in the crystalline region at the higher stress. These results showed that the wear of UHMWPE-ALN would be reduced under calf serum lubricated, which would be potentially applied to treat osteolysis.

  8. Hypervelocity Impact Experiments on Epoxy/Ultra-High Molecular Weight Polyethylene Composite Panels Reinforced with Nanotubes

    Science.gov (United States)

    Khatiwada, Suman; Laughman, Jay W.; Armada, Carlos A.; Christiansen, Eric L.; Barrera, Enrique V.

    2012-01-01

    Advanced composites with multi-functional capabilities are of great interest to the designers of aerospace structures. Polymer matrix composites (PMCs) reinforced with high strength fibers provide a lightweight and high strength alternative to metals and metal alloys conventionally used in aerospace architectures. Novel reinforcements such as nanofillers offer potential to improve the mechanical properties and add multi-functionality such as radiation resistance and sensing capabilities to the PMCs. This paper reports the hypervelocity impact (HVI) test results on ultra-high molecular weight polyethylene (UHMWPE) fiber composites reinforced with single-walled carbon nanotubes (SWCNT) and boron nitride nanotubes (BNNT). Woven UHMWPE fabrics, in addition to providing excellent impact properties and high strength, also offer radiation resistance due to inherent high hydrogen content. SWCNT have exceptional mechanical and electrical properties. BNNT (figure 1) have high neutron cross section and good mechanical properties that add multi-functionality to this system. In this project, epoxy based UHMWPE composites containing SWCNT and BNNT are assessed for their use as bumper shields and as intermediate plates in a Whipple Shield for HVI resistance. Three composite systems are prepared to compare against one another: (I) Epoxy/UHMWPE, (II) Epoxy/UHMWPE/SWCNT and (III) Epoxy/UHMWPE/SWCNT/BNNT. Each composite is a 10.0 by 10.0 by 0.11 cm3 panel, consisting of 4 layers of fabrics arranged in cross-ply orientation. Both SWCNT and BNNT are 0.5 weight % of the fabric preform. Hypervelocity impact tests are performed using a two-stage light gas gun at Rice University

  9. Biotribological properties of UHMWPE grafted with AA under lubrication as artificial joint.

    Science.gov (United States)

    Deng, Yaling; Xiong, Dangsheng; Wang, Kun

    2013-09-01

    Osteolysis caused by wear particles from polyethylene in the artificial hip joints is a serious issue. In order to endow the low friction and wear of the bearing surface of ultra-high molecular weight polyethylene (UHMWPE) artificial joint for a longer term, hydrophilic acrylic acid (AA) was grafted on UHMWPE powders with the method of ultraviolet irradiation and then the modified powders were hot pressed. The tribological properties of modified UHMWPE sliding against CoCrMo metallic plate on reciprocating tribometer under calf serum, saline and distilled water lubrication during a long-term friction were investigated. The measurement of Fourier-transform infrared spectroscopy indicates that AA is successfully grafted on the surface of UHMWPE powders by photo-induced graft polymerization. Contact angles of UHMWPE are decreased from 83° to 35° by grafting and the surface wettability is effectively improved. The tensile strength of modified sample decreases. The friction coefficient and wear rate of UHMWPE-g-PAA under calf serum, saline and distilled water lubrication are lower than that of untreated UHMWPE. With the increase of grafting ratio, the wear rate of UHMWPE-g-PAA decreases firstly and then increases. The modified UHMWPE with grafting ratio of 3.5 % has the lowest wear rate, which is just quarter of the untreated UHMWPE. The hydrated PAA polymer brushes enclosed in the UHMWPE bulk material provide continuous lubrication during long term sliding.

  10. Strontium-doped calcium polyphosphate/ultrahigh molecular weight polyethylene composites: A new class of artificial joint components with enhanced biological efficacy to aseptic loosening

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Zhipeng [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu 610041 (China); Huang, Bingxue; Li, Yiwen [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Tian, Meng [Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu 610041 (China); Li, Li [Department of Oncology, the 452 Hospital of Chinese PLA, Chengdu 610021 (China); Yu, Xixun, E-mail: yuxixun@163.com [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2016-04-01

    To enhance implant stability and prolong the service life of artificial joint component, a new approach was proposed to improve the wear resistance of artificial joint component and endow artificial joint component with the biological efficacy of resistance to aseptic loosening. Strontium calcium polyphosphate (SCPP) were interfused in ultrahigh molecular weight polyethylene (UHMWPE) by a combination of liquid nitrogen ball-milling and flat-panel curing process to prepare the SCPP/UHMWPE composites. The micro-structure, mechanical characterization, tribological characterization and bioactivities of various SCPP/UHMWPE composites were investigated. The results suggested that this method could statistically improve the wear resistance of UHMWPE resulting from a good SCPP particle dispersion. Moreover, it is also observed that the SCPP/UHMWPE composites-wear particles could promote the production of OPG by osteoblasts and decrease the production of RANKL by osteoblasts, and then increase the OPG/RANKL ratio. This indicated that the SCPP/UHMWPE composites had potential efficacy to prevent and treat aseptic loosening. Above all, the SCPP/UHMWPE composites with a suitable SCPP content would be the promising materials for fabricating artificial joint component with ability to resist aseptic loosening. - Highlights: • SCPP/UHMWPE composites could enhance biological efficacy of resistance to aseptic loosening. • SCPP would improve biological efficacy with a few sacrifice of wear resistance. • The results might provide a promising wear-resistant material for fabricating acetabular cup.

  11. Analysis of degradation in UHMWPE a comparative study among the various commercial and laboratory grades UHMWPE

    Science.gov (United States)

    Azam, A. M.; Ali, A.; Khan, H.; Yasin, T.; Mehmood, M. S.

    2016-08-01

    Oxidative degradation of the ultra-high molecular weight polyethylene (UHMWPE) limits the life of implants. This degradation can be monitored to estimate the service life of UHMWPE following the standard protocols as defined by American Standards for Testing Materials (ASTM). In this work, a comparative study has been carried on two commercially available UHMWPE grades i.e. GUR 1020 and GUR 1050 and one laboratory grade UHMWPE which was purchased from Sigma Aldrich. These powder samples were pressed while using hot press with controlled heating and cooling setup in open air under 200 bar of external pressure. These sheets were then subjected to accelerated aging in an oven at 80 °C for three weeks. The degradation of the UHMWPE was monitored by ATR-FTIR techniquefor three weeks. The oxidation index (OI) measurement showed that the commercial grade UHMWPE i.e. GUR-1020 and GUR-1050 degrade more as compared to laboratory grade UHMWPE. The values of OI after three weeks of accelerating aging were found 0.18, 0.14, and 0.09 for GUR-1020, GUR-1050, and Sigma Aldrich, respectively. In addition to this, it was found that commercial grades of UHMWPE suffer more structural alterations as compared to laboratory grade one. We hope that these results will be of particular and fundamental importance for the researchers and orthopaedic industry.

  12. New titanium and titanium/hydroxyapatite coatings on ultra-high-molecular-weight polyethylene-in vitro osteoblastic performance

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M A; Lopes, M A; Santos, J D; Fernandes, M H [Department of Metallurgical and Materials Engineering, Materials Section-Faculty of Engineering, University of Porto (Portugal); Gomes, P S [Laboratory of Pharmacology and Cellular Biocompatibility-Faculty of Dental Medicine, University of Porto (Portugal); Vila, M; Silva, R F, E-mail: mhfernandes@fmd.up.p [Department of Ceramics and Glass Engineering, University of Aveiro, CICECO (Portugal)

    2010-06-15

    The development of optimized hip joint materials is one of the most challenging opportunities in prosthetic technologies. In current approaches, ultra-high-molecular-weight polyethylene (UHMWPE) has been a favorite material for the acetabular component and, regarding the cementless technique, several coating options may be considered to contain and stabilize bearing surfaces and establish an improved interface with bone. In this work, newly developed constructs of UHMWPE coated with either commercially pure titanium (cpTi-UHMWPE), by DC magnetron sputtering, or with commercially pure titanium and hydroxyapatite (cpTi/HA-UHMWPE), by DC/RF magnetron co-sputtering, have been prepared and biologically characterized with human bone marrow-derived osteoblastic cultures. The cpTi-UHMWPE samples allowed a high cell growth and the expression of the complete osteoblastic phenotype, with high alkaline phosphatase activity, expression of osteogenic-associated genes and evident cell-mediated mineralization of the extracellular matrix. In comparison, the cpTi/HA-UHMWPE samples reported lower cell proliferation but earlier cell-mediated matrix mineralization. Accordingly, these newly developed systems may be suitable candidates to improve the osteointegration process in arthroplastic devices; nevertheless, further biological evaluation should be conducted.

  13. Highly hydrophilic ultra-high molecular weight polyethylene powder and film prepared by radiation grafting of acrylic acid

    Science.gov (United States)

    Wang, Honglong.; Xu, Lu.; Li, Rong.; Pang, Lijuan.; Hu, Jiangtao.; Wang, Mouhua.; Wu, Guozhong.

    2016-09-01

    The surface properties of ultra-high molecular weight polyethylene (UHMWPE) are very important for its use in engineering or composites. In this work, hydrophilic UHMWPE powder and film were prepared by γ-ray pre-irradiation grafting of acrylic acid (AA) and further neutralization with sodium hydroxide solution. Variations in the chemical structure, grafting yield and hydrophilicity were investigated and compared. FT-IR and XPS analysis results showed that AA was successfully grafted onto UHMWPE powder and film; the powder was more suitable for the grafting reaction in 1 wt% AA solution than the film. Given a dose of 300 kGy, the grafting yield of AA was ∼5.7% for the powder but ∼0.8% for the film under identical conditions. Radiation grafting of a small amount of AA significantly improved the hydrophilicity of UHMWPE. The water contact angle of the UHMWPE-g-PAA powder with a grafting yield of AA at ∼5.7% decreased from 110.2° to 68.2°. Moreover, the grafting powder (UHMWPE-g-PAA) exhibited good dispersion ability in water.

  14. Impact of lipid-induced degradation on the mechanical properties of ultra-high molecular weight polyethylene for joint replacements.

    Science.gov (United States)

    Sakoda, Hideyuki; Niimi, Shingo

    2016-01-01

    Gamma or electron beam irradiation of ultra-high molecular weight polyethylene (UHMWPE) used in artificial joints for sterilization and/or crosslinking purposes generates free radicals in the material, which causes long-term oxidative degradation of UHMWPE. Recently, another mechanism for the degradation of UHMWPE by the absorption of lipids during in vivo clinical use was proposed. However, knowledge on lipid-induced degradation is quite limited, compared with that on radical-induced degradation. In this study, lipid-induced degradation was simulated using squalene absorption and subsequent accelerated aging, and its impact on the mechanical properties of UHMWPE was evaluated. The simulated lipid-induced degradation caused an increased elastic modulus and decreased elongation with maximum degradation at the surfaces. These results imply that degradation of UHMWPE may occur during in vivo long-term use, even if free radicals are completely eliminated. Therefore, further investigation is required to clarify the impact of lipid-induced degradation on clinical outcomes, such as the wear and fatigue characteristics of UHMWPE components.

  15. Structure, mechanical and tribological properties of radiation cross-linked ultrahigh molecular weight polyethylene and composite materials based on it

    Energy Technology Data Exchange (ETDEWEB)

    Tcherdyntsev, V.V., E-mail: vvch@misis.ru [National University of Science and Technology «MISiS», Leninsky Prospect, 4, Moscow, 119049 (Russian Federation); Kaloshkin, S.D.; Lunkova, A.A.; Musalitin, A.M. [National University of Science and Technology «MISiS», Leninsky Prospect, 4, Moscow, 119049 (Russian Federation); Danilov, V.D. [A.A. Blagonravov Institute of Mechanical Engineering RAS, ul. Bardina 4, Moscow, 117334 (Russian Federation); Borisova, Yu.V.; Boykov, A.A.; Sudarchikov, V.A. [National University of Science and Technology «MISiS», Leninsky Prospect, 4, Moscow, 119049 (Russian Federation)

    2014-02-15

    Highlights: • Effect of irradiation, oriented drawing, and filling on the structure and properties of UHMWPE was studied. • Radiation cross-linking leads to an increase in the melting temperature of UHMWPE. • The optimal irradiation dose is found to be 20 Mrad. • Strength of UHMWPE can be improved by a combination of irradiation, orientation, and filling with nanotubes. -- Abstract: The effect of irradiation with electrons, oriented drawing, and reinforcement with multi-walled carbon nanotubes (MWCNT) on the structure, physico-mechanical and tribological properties of ultrahigh molecular weight polyethylene (UHMWPE) is studied. It is shown that the radiation cross-linking leads to the melting temperature of UHMWPE nearly linear increases with the dose of radiation. The optimal irradiation dose with respect to the mechanical characteristics is found to be 20 Mrad. It is shown that the strength characteristics of UHMWPE can be improved most efficiently by a combination of irradiation, oriented drawing, and reinforcement with nanotubes, and the second and the third factors have a stronger effect than the first one. A combined effect of three factors enabled us to enhance the yield strength of material by almost four times without a detrimental effect on its plasticity.

  16. Fatigue crack propagation resistance of virgin and highly crosslinked, thermally treated ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Gencur, Sara J; Rimnac, Clare M; Kurtz, Steven M

    2006-03-01

    To prolong the life of total joint replacements, highly crosslinked ultra-high molecular weight polyethylenes (UHMWPEs) have been introduced to improve the wear resistance of the articulating surfaces. However, there are concerns regarding the loss of ductility and potential loss in fatigue crack propagation (FCP) resistance. The objective of this study was to evaluate the effects of gamma radiation-induced crosslinking with two different post-irradiation thermal treatments on the FCP resistance of UHMWPE. Two highly crosslinked and one virgin UHMWPE treatment groups (ram-extruded, orthopedic grade, GUR 1050) were examined. For the two highly crosslinked treatment groups, UHMWPE rods were exposed to 100 kGy and then underwent post-irradiation thermal processing either above the melt temperature or below the melt temperature (2 h-150 degrees C, 110 degrees C). Compact tension specimens were cyclically loaded to failure and the fatigue crack growth rate, da/dN, vs. cyclic stress intensity factor, DeltaK, behavior was determined and compared between groups. Scanning electron microscopy was used to examine fracture surface characteristics. Crosslinking was found to decrease the ability of UHMWPE to resist crack inception and propagation under cyclic loading. The findings also suggested that annealing as a post-irradiation treatment may be somewhat less detrimental to FCP resistance of UHMWPE than remelting. Scanning electron microscopy examination of the fracture surfaces demonstrated that the virgin treatment group failed in a more ductile manner than the two highly crosslinked treatment groups.

  17. Mechanical, rheological, and bioactivity properties of ultra high-molecular-weight polyethylene bioactive composites containing polyethylene glycol and hydroxyapatite.

    Science.gov (United States)

    Ahmad, Mazatusziha; Uzir Wahit, Mat; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

    2012-01-01

    Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis.

  18. Mechanical, Rheological, and Bioactivity Properties of Ultra High-Molecular-Weight Polyethylene Bioactive Composites Containing Polyethylene Glycol and Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Mazatusziha Ahmad

    2012-01-01

    Full Text Available Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P precipitates on the composite surface as proven from SEM and XRD analysis.

  19. Application of a Neural Network Model for Prediction of Wear Properties of Ultrahigh Molecular Weight Polyethylene Composites

    Directory of Open Access Journals (Sweden)

    Halil Ibrahim Kurt

    2015-01-01

    Full Text Available In the current study, the effect of applied load, sliding speed, and type and weight percentages of reinforcements on the wear properties of ultrahigh molecular weight polyethylene (UHMWPE was theoretically studied. The extensive experimental results were taken from literature and modeled with artificial neural network (ANN. The feed forward (FF back-propagation (BP neural network (NN was used to predict the dry sliding wear behavior of UHMWPE composites. Eleven input vectors were used in the construction of the proposed NN. The carbon nanotube (CNT, carbon fiber (CF, graphene oxide (GO, and wollastonite additives are the main input parameters and the volume loss is the output parameter for the developed NN. It was observed that the sliding speed and applied load have a stronger effect on the volume loss of UHMWPE composites in comparison to other input parameters. The proper condition for achieving the desired wear behaviors of UHMWPE by tailoring the weight percentage and reinforcement particle size and composition was presented. The proposed NN model and the derived explicit form of mathematical formulation show good agreement with test results and can be used to predict the volume loss of UHMWPE composites.

  20. Surface modification of ultrahigh molecular weight polyethylene by the poly(ethylene glycol)-grafted method and its effect on the adsorption of proteins and the adhesion of blood platelets.

    Science.gov (United States)

    Xia, Bing; Xie, Meiju; Yang, Bangcheng

    2013-01-01

    With the help of a silane coupling agent, poly(ethylene glycol) (PEG), a well-biocompatable agent, was grafted onto the surface of ultrahigh molecular weight polyethylene (UHMWPE) by ultraviolet initiation. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis proved the success of PEG grafting. Water contact angle measurement showed that the modified UHMWPE was obviously improved in surface hydrophilicity and thermogravimetric analysis result showed that its thermostability did not decline even it was pretreated by strong acids. Then, the protein adsorption of the modified UHMWPE was investigated using three model proteins including bovine serum albumin, lysozyme, and fibrinogen. Rabbit blood was used to study the platelet adhesion on the surface of modified UHMWPE. The results indicated that the quantity of protein adsorption on the modified UHMWPE grafted PEG reduced apparently for all the model proteins while there was some specific differences or exceptions among them. It was ascribed to the changed surface chemical composition, surface hydrophilicity and surface topography after modification. The adhesive ability of blood platelets on the modified surface of UHMWPE decreased after PEG grafting. Owing to the improved resistance to fibrinogen adsorption and platelet adhesion, the surface modification might endow the UHWMPE surface better anticoagulation ability according to clotting mechanism.

  1. Investigation of MWCNT Reinforcement on the Strain Hardening Behavior of Ultrahigh Molecular Weight Polyethylene

    Directory of Open Access Journals (Sweden)

    Hassan Mahfuz

    2011-01-01

    Full Text Available We have investigated strain hardening behavior of ultrahigh molecular weight polyethylene (UHMWPE reinforced with 2.0 wt% loading of multiwalled carbon nanotubes (MWCNTs. A solution spinning process was used to produce neat and MWCNT-reinforced filaments of UHMWPE. Tensile tests of filaments showed 62% and 114% improvement in strength and modulus, respectively. Strain hardening tests on filaments revealed spectacular contribution by MWCNTs in enhancing strength and modulus by more than one order of magnitude. SEM micrographs showed sufficient coating of nanotube surface with the polymer that promoted interface adhesion. This intimate interfacial interaction enforced alignment of nanotubes during repeated loading-unloading sequences and allowed effective load transfer to nanotubes. Close interaction between UHMWPE and nanotubes was further evidenced by Raman spectral distribution as a positive shift in the D-band suggesting compressive stress on nanotubes by lateral compression of polymer. Nanotubes thus deformed induced the desired strain hardening ability in the UHMWPE filament. Differential scanning calorimetry (DSC tests indicated around 15% increase in crystallinity after strain hardening—which together with nanotube alignment resulted in such dramatic improvement in properties.

  2. Wear-Resistant Ultrahigh-Molecular-Weight Polyethylene-Based Nano- and Microcomposites for Implants

    Directory of Open Access Journals (Sweden)

    S. V. Panin

    2012-01-01

    Full Text Available The influence of modification by hydroxyapatite (HA nano- and microparticles on tribotechnical properties of ultrahigh-molecular-weight polyethylene (UHMWPE was investigated to develop polymer implants for endoprosthesis. It was shown that modification of UHMWPE by hydroxyapatite nanoparticles within range of 0.1–0.5 wt.% results in increase of wear resistance at dry sliding by 3 times. On the other hand adding of 20 wt.% of micron size HA gives rise to the same effect. The effect of increasing wear resistance is not substantially changed at surface treatment of the nano- and microcomposites by N+ ion beams as compared with nonirradiated blends. Preliminary joint mechanical activation of UHMWPE powder and fillers results in more uniform distribution of nanofillers in the matrix and, as a result, formation of more ordered structure. Structure within bulk material and surface layers was studied by means of optical profilometry, scanning electron microscopy, infrared spectroscopy, and differential scanning calorimetry. It is shown that adding of hydroxyapatite nanoparticles and high-energy surface treatment of the composite by N+ ion implantation improve tribotechnical properties of UHMWPE due to formation of chemical bonds in the composite (crosslinking and ordering of permolecular structure.

  3. A comparison of the wear and physical properties of silane cross-linked polyethylene and ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Sakoda, H; Voice, A M; McEwen, H M; Isaac, G H; Hardaker, C; Wroblewski, B M; Fisher, J

    2001-12-01

    Cross-linked polyethylenes are being introduced widely in acetabular cups in hip prostheses as a strategy to reduce the incidence of wear debris-induced osteolysis. It will be many years before substantial clinical data can be collected on the wear of these new materials. Silane cross-linked polyethylene (XLPE) was introduced into clinical practice in a limited series of acetabular cups in 1986 articulating against 22.225-mm alumina ceramic femoral heads and showed reduced wear rates compared with conventionally sterilized (gamma irradiation in air) ultra-high molecular weight polyethylene (UHMWPE). We compared the wear of XLPE manufactured in 1986 with the wear of UHMWPE manufactured in 1986 in nonirradiated and irradiated forms. In the nonirradiated forms, the wear of XLPE was 3 times less than UHWMPE when articulating against smooth counterfaces. The nonirradiated materials did not show signs of oxidation. In the irradiated forms, only UHMWPE showed high levels of oxidation, and this caused a substantial increase in wear. Antioxidants added to XLPE during processing gave resistance to oxidative degradation. When sliding against scratched counterfaces, the wear of UHMWPE increased by a factor of 2 to 3 times. Against the same scratched counterfaces, the wear of XLPE increased dramatically by 30 to 200 times. This difference may be attributed to the reduction in toughness of XLPE. Clinically, XLPE has been articulated against damage-resistant ceramic heads, and this probably has been an important factor in contributing to reduced wear. New cross-linked polyethylenes differ considerably from XLPE. This study indicates that it is prudent to examine the wear of new polyethylenes under a range of conditions that may occur in vivo.

  4. Evaluation of the wear performance of a polycarbonate-urethane acetabular component in a hip joint simulator and comparison with UHMWPE and cross-linked UHMWPE.

    Science.gov (United States)

    St John, Kenneth; Gupta, Minakshi

    2012-07-01

    Acetabular hip joint components manufactured from gamma-sterilized ultra high molecular weight polyethylene (UHMWPE), gamma cross-linked UHMWPE, or polycarbonate-urethane (PCU) polymers were evaluated in a hip joint simulator, using cobalt alloy femoral components, for at least 5 million cycles. The volume of material losses due to wear was calculated for each type of sample, based upon mass loss measurements, every 500,000 cycles. The loss of material for the conventional UHMWPE was much higher than for the cross-linked UHMWPE, showing about a 70% reduction in wear due to cross-linking. The material loss for the PCU samples appears to have been at least 24% lower than for the cross-linked UHMWPE. Based upon these results, the PCU material seems to have potential for use as an alternative bearing material to UHMWPE for total hip replacement surgeries.

  5. Surface modification of ultra high molecular weight polyethylene fibers via the sequential photoinduced graft polymerization

    Science.gov (United States)

    Li, Zhi; Zhang, Wei; Wang, Xinwei; Mai, Yongyi; Zhang, Yumei

    2011-06-01

    In this study, a sequential photoinduced graft polymerization process was proposed to improve the poor interfacial bonding property of ultra high molecular weight polyethylene (UHMWPE) fibers. The polymerization was initiated by dormant semipinacol (SP) groups and carried out in a thin liquid layer. Methacrylic acid (MAA) and acryl amide (AM) were grafted stepwise onto the surface of UHMWPE fibers. Attenuated total reflectance infrared spectroscopy (ATR-IR) and thermo gravimetric analysis (TGA) confirmed the grafting. The analysis result of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) indicated the structure of grafted chains. Scanning electron microscopy (SEM) images and atomic force microscopy (AFM) images revealed the apparent morphology changing, and the grafted layers were observed. Interfacial shear stress (IFSS) test of the modified fibers showed an extensively improved interfacial bonding property. The active groups grafted onto the fibers would supply enough anchor points for the chemical bonding with various resins or further reactions.

  6. Surface modification of ultra high molecular weight polyethylene fibers via the sequential photoinduced graft polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhi; Zhang Wei; Wang Xinwei [Research and Development Center of Shanghai Research Institute of Chemical Industry, 345 YunLing Road (East), Shanghai 200062 (China); Mai Yongyi, E-mail: SRICIshanghai@163.com [Research and Development Center of Shanghai Research Institute of Chemical Industry, 345 YunLing Road (East), Shanghai 200062 (China); Zhang Yumei [Research and Development Center of Shanghai Research Institute of Chemical Industry, 345 YunLing Road (East), Shanghai 200062 (China)

    2011-06-15

    In this study, a sequential photoinduced graft polymerization process was proposed to improve the poor interfacial bonding property of ultra high molecular weight polyethylene (UHMWPE) fibers. The polymerization was initiated by dormant semipinacol (SP) groups and carried out in a thin liquid layer. Methacrylic acid (MAA) and acryl amide (AM) were grafted stepwise onto the surface of UHMWPE fibers. Attenuated total reflectance infrared spectroscopy (ATR-IR) and thermo gravimetric analysis (TGA) confirmed the grafting. The analysis result of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) indicated the structure of grafted chains. Scanning electron microscopy (SEM) images and atomic force microscopy (AFM) images revealed the apparent morphology changing, and the grafted layers were observed. Interfacial shear stress (IFSS) test of the modified fibers showed an extensively improved interfacial bonding property. The active groups grafted onto the fibers would supply enough anchor points for the chemical bonding with various resins or further reactions.

  7. Characterization of alendronate sodium-loaded UHMWPE for anti-osteolysis in orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang Dan [Key Lab of Advanced Technologies of Materials, Ministry of Education, Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Qu Shuxin, E-mail: qushuxin@swjtu.edu.cn [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Huang Jie [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Cai Zhenbing; Zhou Zhongrong [Key Lab of Advanced Technologies of Materials, Ministry of Education, Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2012-02-01

    Ultra-high molecule weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), a potential drug to prevent debris-induced osteolysis, was developed in our previous study. This study aims to investigate the wear performance of UHMWPE-ALNs. In this study, wear test, mechanical test, differential scanning calorimetry (DSC) and contact angle test were applied to characterize the wear performance, mechanical behavior and physical properties of UHMWPE-ALNs. The effect of ALN on the wear performance of UHMWPE-ALNs was investigated by scanning electron microscope (SEM), back scattering electrons (BSE) and energy dispersive X-ray spectrum (EDX). The results of wear test showed that the friction coefficient and volumetric loss of UHMWPE-ALN 0.5 wt.% were comparable with those of UHMWPE. The result of SEM-BSE-EDX revealed that the wear debris detached easily from the ALN-agglomerated regions, which was mainly responsible for the decrease of wear resistance of UHMWPE-ALN 1.0 wt.%. The loaded ALN resulted in the increase of hydrophilicity of UHMWPE-ALNs. The decrease of toughness and crystallinity of UHMWPE-ALN 1.0 wt.% attributed to the non-uniform distribution of ALN. The UHMWPE-ALN 0.5 wt.%, in which no ALN agglomeration was observed, possessed approving mechanical properties and wear performance, might have potential clinical application to prevent the debris-induced osteolysis in prosthetic joints. - Highlights: Black-Right-Pointing-Pointer The wear resistance, mechanical and physical properties UHMWPE-ALN 0.5 wt.% are not significantly different with those of UHMWPE. Black-Right-Pointing-Pointer The hydrophilicity of UHMWPE increased after loaded ALN. Black-Right-Pointing-Pointer The decrease of wear performance of UHMWPE-ALN 1.0 wt.% attributed to the non uniform distribution of ALN. Black-Right-Pointing-Pointer The ALN-agglomerated region of UHMWPE-ALN 1.0 wt.% was most easily worn out during wear processing.

  8. Wear Performance of UHMWPE and Reinforced UHMWPE Composites in Arthroplasty Applications: A Review

    Directory of Open Access Journals (Sweden)

    Juan C. Baena

    2015-05-01

    Full Text Available As the gold standard material for artificial joints, ultra-high-molecular-weight polyethylene (UHMWPE generates wear debris when the material is used in arthroplasty applications. Due to the adverse reactions of UHMWPE wear debris with surrounding tissues, the life time of UHMWPE joints is often limited to 15–20 years. To improve the wear resistance and performance of the material, various attempts have been made in the past decades. This paper reviews existing improvements made to enhance its mechanical properties and wear resistance. They include using gamma irradiation to promote the cross-linked structure and to improve the wear resistance, blending vitamin E to protect the UHMWPE, filler incorporation to improve the mechanical and wear performance, and surface texturing to improve the lubrication condition and to reduce wear. Limitations of existing work and future studies are also identified.

  9. Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder. Part II: Thermal, FTIR and morphological characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, Bahattin; Tincer, Teoman E-mail: teotin@metu.edu.tr

    2001-10-01

    Radiation induced grafted polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylamide (PAAm), poly N,N-dimethyl acrylamide (PNDAAm) and poly 1-vinyl-2 pyrrolidone (PVP) on ultra-high molecular weight polyethylene (UHMWPE) were characterised by DSC, FTIR and SEM analysis. While the effect of irradiation on pure UHMWPE was found to increase crystallinity and cause higher enthalpy of crystallisation, grafted UHMWPE powders showed lower crystallinity and enthalpy of crystallisation. In all grafted UHMWPE there existed secondary transitions corresponding to grafting polymers in the first run of DSC above 60 deg. C and they became clearer at a higher grafting level. In the second run of DSC some T{sub g} values appeared to shift to higher temperatures while some were not detected. FTIR analysis indicated the presence of water-soluble polymers in the grafted UHMWPE. The characteristic peaks of water-soluble polymers became sharper in the grafted UHMWPE. SEM analysis revealed that the grafting occurs both on fiber and microparticles of UHMWPE while flowing characteristic of powder is retained.

  10. Strontium-doped calcium polyphosphate/ultrahigh molecular weight polyethylene composites: A new class of artificial joint components with enhanced biological efficacy to aseptic loosening.

    Science.gov (United States)

    Gu, Zhipeng; Huang, Bingxue; Li, Yiwen; Tian, Meng; Li, Li; Yu, Xixun

    2016-04-01

    To enhance implant stability and prolong the service life of artificial joint component, a new approach was proposed to improve the wear resistance of artificial joint component and endow artificial joint component with the biological efficacy of resistance to aseptic loosening. Strontium calcium polyphosphate (SCPP) were interfused in ultrahigh molecular weight polyethylene (UHMWPE) by a combination of liquid nitrogen ball-milling and flat-panel curing process to prepare the SCPP/UHMWPE composites. The micro-structure, mechanical characterization, tribological characterization and bioactivities of various SCPP/UHMWPE composites were investigated. The results suggested that this method could statistically improve the wear resistance of UHMWPE resulting from a good SCPP particle dispersion. Moreover, it is also observed that the SCPP/UHMWPE composites-wear particles could promote the production of OPG by osteoblasts and decrease the production of RANKL by osteoblasts, and then increase the OPG/RANKL ratio. This indicated that the SCPP/UHMWPE composites had potential efficacy to prevent and treat aseptic loosening. Above all, the SCPP/UHMWPE composites with a suitable SCPP content would be the promising materials for fabricating artificial joint component with ability to resist aseptic loosening.

  11. Mechanical and tribological properties of short discontinuous UHMWPE fiber reinforced UHMWPE

    NARCIS (Netherlands)

    Hofste, JM; vanVoorn, B; Pennings, AJ

    1997-01-01

    The tribological properties of Ultra-High Molecular Weight Polyethylene have generated new concern regarding the long-term clinical performance of total joint replacements. To extend the lifetime of artificial joints, it is necessary to decrease the wear rate of UHMWPE. One possible solution is the

  12. ADVANCE IN THE RESEARCH OF ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE-MATRIX COMPOSITES WITH HIGH WEARRESISTANCE%高耐磨超高分子量聚乙烯改性研究进展

    Institute of Scientific and Technical Information of China (English)

    伍学诚; 解孝林

    2001-01-01

    从超高分子量聚乙烯的特点和探讨高聚物磨损机理出发,综述了高耐磨超高分子量聚乙烯的改性方法。%The modification methods of high wear-resistant ultrahigh molecular weight polyethylene (UHMWPE) are reviewed on the basis of abrasion mechanisms of polymer and the characters of UHMWPE.

  13. Interplay between surface properties of standard, vitamin E blended and oxidised ultra high molecular weight polyethylene used in total joint replacement and adhesion of Staphylococcus aureus and Escherichia coli.

    Science.gov (United States)

    Banche, G; Allizond, V; Bracco, P; Bistolfi, A; Boffano, M; Cimino, A; Brach del Prever, E M; Cuffini, A M

    2014-04-01

    We have assessed the different adhesive properties of some of the most common bacteria associated with periprosthetic joint infection on various types of ultra high molecular Weight Polyethylene (UHMWPE). Quantitative in vitro analysis of the adhesion of biofilm producing strains of Staphylococcus aureus and Escherichia coli to physically and chemically characterised standard UHMWPE (PE), vitamin E blended UHMWPE (VE-PE) and oxidised UHMWPE (OX-PE) was performed using a sonication protocol. A significant decreased bacterial adhesion was registered for both strains on VE-PE, in comparison with that observed on PE, within 48 hours of observation (S. aureus p = 0.024 and E. coli p = 0.008). Since Vitamin E reduces bacterial adhesive ability, VE-stabilised UHMWPE could be valuable in joint replacement by presenting excellent mechanical properties, while reducing bacterial adhesiveness.

  14. Study on biotribological properties of UHMWPE grafted with MPDSAH.

    Science.gov (United States)

    Deng, Yaling; Xiong, Dangsheng; Shao, Silong

    2013-04-01

    In order to prolong the service life of artificial joints, a zwitterion monomer of MPDSAH ((3-(methacryloylamino)propyl)dimethyl (3-sulfopropyl)ammonium hydroxide) was grafted onto ultra-high molecular weight polyethylene (UHMWPE) powders to construct a brush-like structure by UV irradiation, and then the grafted UHMWPE powders were hot pressed as the bulk materials. The wettability of bulk materials surface with different monomer concentrations was analyzed. The tribological properties of modified UHMWPE bulk materials were investigated under distilled water and saline by sliding against stainless steel ball. The measurement of Fourier-transform infrared (FT-IR) spectroscopy indicates that MPDSAH is successfully grafted onto the surface of UHMWPE powders by UV irradiation. The contact angles of modified UHMWPE are decreased and the surface wettability is effectively improved. The friction coefficient of the modified sample is lower than that of untreated UHMWPE in aqueous lubricants during a long-term friction. With the increase of monomer concentration, the wear rate of grafted UHMWPE decreases gradually in distilled water. The grafting hydrophilic macromolecule polymer is helpful to form a lubricating film of water, which leads to the improvement of the lubricity of UHMWPE.

  15. Research progress in UHMWPE/CNTs composite system and fibers%UHMWPE/CNTs复合体系及其纤维的研究进展

    Institute of Scientific and Technical Information of China (English)

    韩亚刚; 赵国樑

    2013-01-01

    The research progress in ultrahigh molecular weight polyethylene (UHMWPE) , carbon nanotubes (CNTs) and UHMWPE/CNTs composite system and fibers was reviewed. The effect of the addition of CNTs on the properties of UHMWPE/CNTs composite system and fibers was described. The addition of CNTs can efficiently improve the wear resistance, electrical properties and mechanical properties of UHMWPE and the creep resistance and thermal stability of UHMWPE fibers. It was pointed out that the dominant problem of UHMWPE modification with CNTs was the poor dispersion and high production cost of CNTs and we should further study the modification mechanism of UHMWPE/CNTs and develop the application fields of UHMWPE/CNTs composite system and fiber.%综述了超高分子量聚乙烯(UHMWPE)、碳纳米管(CNTs)、UHMWPE/CNTs复合体系及其纤维的研究现状,以及CNTs的添加对UHMWPE/CNTs复合体系及其纤维性能的影响;添加CNTs可有效提高UHM-WPE的耐磨性、电学性能、力学性能以及UHMWPE纤维的抗蠕变性能和热稳定性能;指出CNTs对UHM-WPE改性过程中存在的主要问题是CNTs分散性差,CNTs的生产成本高,UHMWPE/CNTs的改性机理有待进一步深入,并进一步拓宽UHMWPE/CNTs复合体系及其纤维的应用领域.

  16. Macroradical reaction in ultra-high molecular weight polyethylene in the presence of vitamin E

    Energy Technology Data Exchange (ETDEWEB)

    Jahan, M.S., E-mail: mjahan@memphis.ed [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States); Walters, B.M. [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States)

    2011-02-15

    Free radical measurements in compression molded ultra-high molecular weight polyethylene (UHMWPE), which contained vitamin E ({alpha}-tocopherol ({alpha}-T)), was performed using electron spin resonance (ESR) technique in air at room temperature following gamma irradiation (25-32 kGy) in N{sub 2}. The vitamin E was incorporated into one set of samples by blending UHMWPE resin with vitamin E (1 and 10 wt%), then compression molded into a solid and then irradiated. Another set of samples had vitamin E incorporated into them by diffusing vitamin E at 100 {sup o}C for 2 h after irradiation. Compared to a control (with no vitamin E), the vitamin E-containing UHMWPE ({alpha}-TPE) samples suffered a partial loss of PE radicals, but this loss only occurred during or immediately after irradiation (before exposure to air). Subsequently, when all blended samples were exposed to air, the remaining radicals in each sample decayed to the well-known OIR, R1 (-{sup {center_dot}C}H-[CH=CH-]{sub m}-) and R2 ({sup {center_dot}O}CH-[CH=CH-]{sub m}-) radicals. However, because of the initial loss or partial quenching, {alpha}-TPE produced a lower concentration of OIR (measured over a four-year period), but no difference was found between 1% and 10% {alpha}-TPEs. In the diffused {alpha}-TPE, similar OIR was also found when tested after four months of post-treatment exposure to air.

  17. Influence of microscopic surface asperities on the wear of ultra-high molecular weight polyethylene in a knee prosthesis.

    Science.gov (United States)

    Cho, C-H; Murakami, T; Sawae, Y

    2010-01-01

    The wear of ultra-high molecular weight polyethylene (UHMWPE) in knee and hip prostheses is one of the major factors restricting the longevity of these implants. A number of microscopic scratches caused by various factors were observed on the metallic femoral components of the retrieved knee prostheses with an anatomical design. It appears that microscopic surface asperities caused by this surface damage contribute to increasing and/or accelerating the wear of the UHMWPE tibial insert. In this study, in the first step, microscopic observations and surface roughness measurements of several retrieved metallic femoral components were performed in order to produce simplified two-dimensional (2D) finite-element method (FEM) models of a microscopic surface asperity using roughness parameters. Next, a three-dimensional (3D) microscopic surface profile measurement of the damaged surface of a retrieved metallic femoral component and the reproduction of the femoral component surface were performed in order to produce 3D FEM models of a microscopic surface asperity based on actual measurement data. 2D and 3D elastoplastic contact analyses between a metallic microscopic surface asperity and UHMWPE were also performed in order to investigate the mechanical state and microscopic wear of UHMWPE caused by a metallic microscopic surface asperity. The analytical findings of this study suggest that the aspect ratio, shape ratio, and indentation depth of the microscopic surface asperity have significant influence on increasing and/or accelerating the wear of UHMWPE. Higher aspect ratios, shape ratios, and indentation depths cause higher contact stresses and plastic strains in UHMWPE.

  18. Analysis of released products from oxidized ultra-high molecular weight polyethylene incubated with hydrogen peroxide and salt solutions.

    Science.gov (United States)

    Lee, A W; Santerre, J P; Boynton, E

    2000-04-01

    The wear of ultra-high molecular weight polyethylene (UHMWPE) implants generates polymeric and metallic particulate, which can be phagocytosed by human macrophages. The generation of these UHMWPE particles has been attributed to wear mechanisms and oxidation of the material. Many cell/particle studies have focused specifically on investigating particles of virgin materials themselves (i.e. virgin UHMWPE), while in fact, there is a strong likelihood that the oxidation processes encountered by the materials will yield particles with very different surface chemistries. Therefore, it is conceivable that chemical changes in the material would lead to altered cellular responses, as measured in the various cell study models. This paper has focused on the characterization of UHMWPE particulates that have been exposed to various conditions simulating processing steps and some of the oxidative and hydrolytic agents related to inflammatory responses. These include gamma-irradiation, thermal treatment and chemical oxidation by H2O2 and saline solutions. Oxidation of the particles was measured using Fourier transform infrared spectroscopy (FTIR). Degradation products were isolated from the incubation solutions using high-performance liquid chromatography (HPLC). UHMWPE particulates underwent extensive oxidation after gamma-irradiation and thermal treatments. There were marked differences following treatments of film samples taken from bar stock and the virgin particle samples. Polymer-related products, containing alkenes, alkanes and hydroxyl groups, were found in the incubation solutions. The study concluded that future work must consider both the particulates' surface chemistry and the possibility of soluble degradation products when assessing UHMWPE/cellular interactions.

  19. Ultradrawing novel ultra-high molecular weight polyethylene fibers filled with bacterial cellulose nanofibers.

    Science.gov (United States)

    Yeh, Jen-Taut; Tsai, Chih-Chen; Wang, Chuen-Kai; Shao, Jhih-Wun; Xiao, Ming-Zheng; Chen, Su-Chen

    2014-01-30

    Novel ultrahigh molecular weight polyethylene (UHMWPE)/bacterial cellulose (BC) (F100BCy) and UHMWPE/modified bacterial cellulose (MBC) (F100MBCx-y) as-prepared fibers were prepared and ultra-drawn. The achievable draw ratio (Dra) values of each F100MBCx-y as-prepared fiber series specimens approached a maximum value as their MBC contents reached the optimal value at 0.0625phr. In which, the maximum Dra value obtained for F100MBCx-0.0625 as-prepared fiber specimen prepared at the optimal MBC content reached another maximum value at 347 as the weight ratio of maleic anhydride grafted polyethylene to BC approach an optimal value at 10. In contrast, no significant improvement in Dra values was found for F100BCy as-prepared fiber specimens. To understand these interesting ultradrawing properties described above, Fourier transform infra-red, specific surface areas, and transmission electron microcopic analyses of original and modified BC nanofibers together with the thermal, orientation and tensile properties of F100BCy and F100MBCx-y fiber specimens were performed.

  20. Surface charges in blending short fibres with polyethylene powder

    NARCIS (Netherlands)

    Hofste, JM; Kersten, MJE; van Turnhout, J; Pennings, AJ

    1998-01-01

    Short fibres and ultra-high molecular weight polyethylene (UHMWPE) powder were mixed by swirling in a glass jar with compressed nitrogen. It was found that a kind of attraction between the fibres and UHMWPE particles is crucial for making a composite with a proper fibre distribution. If aramid and U

  1. Anti-oxidation treatment of ultra high molecular weight polyethylene components to decrease periprosthetic osteolysis: evaluation of osteolytic and osteogenic properties of wear debris particles in a murine calvaria model.

    Science.gov (United States)

    Green, Justin M; Hallab, Nadim J; Liao, Yen-Shuo; Narayan, Venkat; Schwarz, Edward M; Xie, Chao

    2013-05-01

    Wear debris-induced osteolysis remains the greatest limitation of long-term success for total joint replacements with ultra-high molecular weight polyethylene (UHMWPE) bearings. To address oxidative degradation post-gamma irradiation, manufacturers are investigating the incorporation of antioxidants into PE resins. Similarly, larger molecular weight monomers have been developed to increase crosslinking and decrease wear debris, and ultimately osteolysis. However, the effects of modifying monomer size, crosslink density, and antioxidant incorporation on UHMWPE particle-induced osteoclastic bone resorption and coupled osteoblastic bone formation have never been tested. Here, we review the field of antioxidant-containing UHMWPE, and present an illustrative pilot study evaluating the osteolytic and osteogenic potential of wear debris generated from three chemically distinct particles (MARATHON®, XLK, and AOX™) as determined by a novel 3D micro-CT algorithm designed for the murine calvaria model. The results demonstrate an approach by which the potential osteoprotective effects of antioxidants in UHMWPE can be evaluated.

  2. Oxidative-induction time as a measure of vitamin E concentration in ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Heuer, Emily G; Braithwaite, Gavin J C; Miller, Bayen L; Spiegelberg, Stephen H; Gsell, Ray A; Rufner, Alicia S; Stark, Norman

    2015-01-01

    A novel, sensitive method for quantifying an equivalent antioxidant concentration, specifically vitamin E (VE), in postprocessed ultra-high molecular weight polyethylene (UHMWPE) for orthopedic implants is presented. This method correlates oxidative-induction time (OIT) determined from differential scanning calorimetry with starting VE weight percent in solvent blended samples using a nonlinear power law fit. The generated calibration curve reliably determined the equivalent VE concentration down to blended concentrations lower than 0.007 wt %, with a measurement uncertainty of 0.0009 wt %. This measurement uncertainty implies a detection limit that is significantly lower than currently achievable with the established method using Fourier transform infrared spectroscopy to calculate a VE index. However, exact processes that are influencing the OIT in irradiated materials are unclear at this time. UHMWPE blended with VE in powder, consolidated and irradiated form were investigated. In addition, intralaboratory results give support that this technique may lend itself to standardization in quality control and verification.

  3. Peroxide cross-linked UHMWPE blended with vitamin E.

    Science.gov (United States)

    Oral, Ebru; Doshi, Brinda N; Gul, Rizwan M; Neils, Andrew L; Kayandan, Sanem; Muratoglu, Orhun K

    2016-04-15

    Radiation crosslinked ultrahigh molecular weight polyethylene (UHMWPE) is the bearing surface material most commonly used in total joint arthroplasty because of its excellent wear resistance. Crosslinking agents such as peroxides can also effectively increase wear resistance but peroxide crosslinked UHMWPE has low oxidative stability. We hypothesized that the addition of an antioxidant to peroxide crosslinked UHMWPE could improve its oxidation resistance and result in mechanical, tribological, and oxidative properties equivalent to currently utilized radiation crosslinked UHMWPEs. Various vitamin E (0.1-1.0 wt % and peroxide concentration (0.5-1.5 wt %) combinations were studied to investigate changes in crosslink density, wear rate, mechanical properties, and oxidative stability in comparison to radiation crosslinked UHMWPE. Peroxide crosslinking was more efficient as compared to radiation crosslinking in the presence of vitamin E with the former resulting in lower wear rate with vitamin E concentrations above 0.3 wt %. The tensile mechanical properties were comparable to and the impact strength was higher than those of the clinically relevant radiation crosslinked controls. We also determined that gamma sterilization of peroxide crosslinked vitamin E blends improved wear resistance further. In summary, peroxide crosslinking of vitamin E-blended UHMWPE may provide a feasible and economical alternative to radiation for achieving clinically relevant properties for total joint implants using UHMWPE. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  4. Characterization of silane coated hollow sphere alumina-reinforced ultra high molecular weight polyethylene composite as a possible bone substitute material

    Indian Academy of Sciences (India)

    S Roy; S Pal

    2002-12-01

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites were characterized for mechanical properties using destructive and non-destructive ultrasonic testing methods. The physical properties of the composite were determined and compared with those of cortical bone.

  5. Impact of UHMWPE texture on friction and wear resistance of hip prosthesis

    Directory of Open Access Journals (Sweden)

    Eddoumy Fatima

    2013-11-01

    Full Text Available Ultra High Molecular Weight PolyEthylene (UHMWPE is a polymer widely used in hip implants (prostheses as a bearing surface against metal, because of its good mechanical properties and biocompatibility [1]. Nevertheless, the durability of such implants is limited because of failure resulting from osteolysis and aseptic loosening. These two phenomenons are due to the immune response of human body consecutive to the apparition of wear particles of UHMWPE with time.

  6. UHMWPE-based nanocomposite as a material for damaged cartilage replacement

    Energy Technology Data Exchange (ETDEWEB)

    Senatov, F.S., E-mail: Senatov@misis.ru [National University of Science and Technology “MISIS”, 119049, Leninskiy pr. 4, Moscow (Russian Federation); Kopylov, A.N.; Anisimova, N.Yu.; Kiselevsky, M.V. [N.N. Blokhin Russian Cancer Research Center, 115478, Kashirskoye sh. 23, Moscow (Russian Federation); Maksimkin, A.V. [National University of Science and Technology “MISIS”, 119049, Leninskiy pr. 4, Moscow (Russian Federation)

    2015-03-01

    In the present work dispersion-strengthened nanocomposites based on ultra-high molecular weight polyethylene (UHMWPE) after mechanical activation were studied. Mechanical activation was performed for hardening of the boundaries between the polymer particles, reducing the fusion defects and increasing of wear-resistance. Three types of samples were prepared: UHMWPE, UHMWPE/Al{sub 2}O{sub 3} nanocomposite and UHMWPE/Al{sub 2}O{sub 3} nanocomposite after mechanical activation. UHMWPE/Al{sub 2}O{sub 3} nanocomposites prepared with mechanical activation show the best mechanical properties in compression and higher wear-resistance. UHMWPE/Al{sub 2}O{sub 3} nanocomposites prepared with mechanical activation were chosen for in vivo study by orthotopical transplantation in rats. Animals' activity has been being monitored for 60 days after surgery. No signs of inflammation, cellular infiltration, destruction of material or bone–cartilage defect were found. Implanted sample has not changed its position of implantation, there were no any shifts. Obtained data shows that UHMWPE-based nanocomposite is a promising material for creating bioimplants for cartilage defect replacement. - Highlights: • Mechanical activation of UHMWPE composite leads to changing of fracture mechanism. • Mechanical activation leads to increasing of wear-resistance of UHMWPE composite. • The presence of Al{sub 2}O{sub 3} in grain boundaries of UHMWPE inhibits crack growth. • Complete integration of UHMWPE-based implant in cartilage defect of rat was shown. • UHMWPE/Al{sub 2}O{sub 3} nanocomposite may be recommended for use in cartilage replacement.

  7. Photons transport through ultra-high molecular weight polyethylene based composite containing tungsten and boron carbide fillers

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, S.M. [National Research Center “Kurchatov Institute”, Moscow 123182 (Russian Federation); Kuznetsov, S.A. [Russian State Technological University “MATI”, Moscow 121552 (Russian Federation); Volkov, A.E.; Terekhin, P.N.; Dmitriev, S.V. [National Research Center “Kurchatov Institute”, Moscow 123182 (Russian Federation); Tcherdyntsev, V.V.; Gorshenkov, M.V. [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Boykov, A.A., E-mail: kink03@gmail.com [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation)

    2014-02-15

    Highlights: • The developed method for predicting X-ray properties of the polymer. • Higher content of the fillers results in an increase of mechanical properties. • X-ray defensive properties of the samples were investigated experimentally. -- Abstract: Polymers are a base for creating of composite materials with high mechanical and chemical properties. Using the heavy metals as filler in these composites can give them X-ray protective properties. These materials have high deactivation rates and can be used to create Personal Protective Equipment (PPE) used in aggressive environments. It was proposed a model for calculation of X-ray protection properties of the polymer-based nanocomposite materials with ultra-high molecular weight polyethylene (UHMWPE) matrix, filled with tungsten and boron carbide particles. X-ray protective properties were calculated in a wide range of filler content using the developed model. Results of calculations allow selecting most effective compounds of X-ray protective UHMWPE based composites.

  8. Studies on electron-beam irradiation and plastic deformation of medical-grade ultra-high molecular weight polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Krystyna, E-mail: krystyna.czaja@uni.opole.p [Opole University, Faculty of Chemistry, Oleska 48, 45-052 Opole (Poland); SudoL, Marek [Opole University, Faculty of Chemistry, Oleska 48, 45-052 Opole (Poland)

    2011-03-15

    Separated and combined electron-beam irradiation and plastic deformation effects on the structures of ultra-high molecular weight polyethylene (UHMWPE) were studied. It was found that the concentration of carbonyl (ketones, esters and peresters), hydroxyl and vinyl groups increases with the growing dose of adsorbed electrons. It also tends to exhibit a slight increase in the melting point and crystallinity of the samples. A mechanical stress in the polymer was found to accelerate radiation-induced degradation. It was concluded that each of the factors studied (i.e. electron beam sterilization and plastic deformation) had a different impact on the polymer structure. The change in the sequence of action of these factors can dramatically influence the process of UHMWPE destruction. Some effects may be limited or enhanced by the action of other factors. Therefore, the resulting effects of destructive factors depend qualitatively and quantitatively on their intensity and order.

  9. Synthesis of ultra high molecular weight polyethylene: A differentiate material for specialty applications

    Energy Technology Data Exchange (ETDEWEB)

    Padmanabhan, Sudhakar, E-mail: sudhakar.padmanabhan@ril.co [Research Centre, Vadodara Manufacturing Division, Reliance Industries Limited, Vadodara, 391 346, Gujarat (India); Sarma, Krishna R.; Rupak, Kishor; Sharma, Shashikant [Research Centre, Vadodara Manufacturing Division, Reliance Industries Limited, Vadodara, 391 346, Gujarat (India)

    2010-04-15

    Tailoring the synthesis of a suitable Ziegler-Natta (ZN) catalyst coupled with optimized polymerization conditions using a suitable activator holds the key for an array of differentiated polymers with diverse and unique properties. Ultra high molecular weight polyethylene (UHMWPE) is one such polymer which we have synthesized using TiCl{sub 4} anchored on MgCl{sub 2} as the support and activated using AlRR'{sub 2} (where R, R' = iso-prenyl or isobutyl) under specific conditions. Here in we have accomplished a process for synthesizing UHMWPE in hydrocarbon as the medium with molecular weights ranging from 5 to 10 million g/mole. The differentiated polymers exhibited the desired properties such as particle size distribution (PSD), average particle size (APS), bulk density (BD) and molecular weight (MW) with controlled amount of fine and coarse particles. Scanning electron micrographs (SEM) reflected the material to have uniform particle size distribution with a spherical morphology. The extent of entanglement was determined from thermal studies and it was found to be highly entangled.

  10. Processing, Characterization and Fretting Wear of Zinc Oxide and Silver Nanoparticles Reinforced Ultra High Molecular Weight Polyethylene Biopolymer Nanocomposite

    Science.gov (United States)

    Alam, Fahad; Kumar, Anil; Patel, Anup Kumar; Sharma, Rajeev K.; Balani, Kantesh

    2015-04-01

    Ultra-high molecular weight polyethylene (UHMWPE) is the most widely used biopolymer for articulating surfaces, such as an acetabular cup liner interfacing with a metal/ceramic femoral head. However, the formation of wear debris leads to the aseptic loosening of implants. Thus, in order to improve the life span via enhancing the fretting wear resistance, UHMWPE is reinforced with ZnO/Ag nanoparticles. It is envisaged that the ZnO/Ag addition will also exhibit antibacterial properties. In the current study, the synergetic effect of the reinforcement of ZnO/Ag nanoparticles (0-3 wt.% combinations) on the fretting wear behavior of a UHMWPE matrix is assessed. The phase characterization of compression- molded UHMWPE-Ag-ZnO biopolymer nanocomposites has elicited the retention of starting phases. All samples were processed at >98% density using compression molding. Silver and ZnO reinforcement showed enhanced hardness ~20.4% for U3A and 42.0% for U3Z. Fretting wear performance was evaluated at varying loads (5-15 N), keeping in mind the weight at different joints, with constant frequency (5 Hz) as well as amplitude of oscillation (100 µm). Laser surface profilometry showed change of wear volume from 8.6 × 10-5 mm3 for neat polymer to 5.8 × 10-5 mm3 with 1 wt.% Ag + 1 wt.% ZnO reinforcement (at 15 N load). Consequently, the mechanics of resistance offered by Ag and ZnO is delineated in the UHMWPE matrix. Further, S. aureus viability reduction is ~28.7% in cases with 1 wt.% Ag addition, ~42.5% with 1 wt.% ZnO addition, but synergistically increase to ~58.6% and 47.1% when each of Ag and ZnO is added with 1 wt.% and 3 wt.%, respectively (when compared to that of the UHMWPE control sample). Increased wear resistance and superior bioactivity and enhanced anti-bacterial properties of 1 wt.% Ag + 1 wt.% ZnO and 3 wt.% Ag + 3 wt.% ZnO shows the potential use of ZnO-Ag-UHMWPE biopolymer composites as an articulating surface.

  11. Mechanics of ZnO micro-rod and ZnO nanoparticle reinforcement in ultra-high molecular weight polyethylene biocomposite

    Science.gov (United States)

    Sharma, Rajeev K.; Balani, Kantesh

    2014-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) is one of the most promising materials for cartilage replacement as an acetabular cup liner. Implant failure due to infection is a serious issue and ZnO is a well-known antibacterial agent. In the current work, the effect of the morphology of ZnO on the mechanical properties of UHMWPE is studied, where ZnO is incorporated both as nanoparticles (ZnO(NP)) and micro-rods (ZnO(R)) at 5, 10, 15 and 20 wt%. Uniaxial tensile testing of compression-moulded composites elicited a decrease of 8.8% in the Young's modulus in UHMWPE-ZnO(R) (named ZnO(R)-PE), whereas an increase of 21.1% in the Young's modulus was observed for UHMWPE-ZnO(NP) (named ZnO(NP)-PE). This contrasting effect on the Young's modulus arising due to differences in ZnO morphology is discussed and analysed using the rule of mixture and the Halpin-Tsai equation. Even when accounting for inherent porosity, and with similar crystallinity to that of base UHMWPE, these models fail to explain the decrease in the Young's modulus of compression-moulded ZnO-PE composites. Estimation of Young's modulus via a modified geometric factor is followed by proposing an empirical relation to account for interfacial strength and narrow the bounds of the predicted elastic modulus, thus making the Halpin-Tsai estimations reach the actual experimental values.

  12. The mechanical properties of the ultra high molecular weight polyethylene grafted with 3-dimethy (3-(N-methacryamido) propyl) ammonium propane sulfonate.

    Science.gov (United States)

    Deng, Yaling; Xiong, Dangsheng; Wang, Kun

    2014-07-01

    Ultra-high molecular weight polyethylene (UHMWPE) powder was modified with a zwitterion monomer with good biocompatibility of MPDSAH (3-dimethy (3-(N-methacryamido) propyl) ammonium propane sulfonate) by UV irradiation and then hot pressed. The microstructure and mechanical properties of modified UHMWPE are investigated. The results show that the structure of powder and bulk materials has been changed. The modified powders have more filaments than that of untreated. The surface of modified bulk materials is more rough and displays the granular protuberances which have the random loose arrangement compared with untreated UHMWPE. The crystallinity, uniaxial tensile and compressive properties decreased after grafting. Ultimate elongations decrease with the increase of the monomer concentration and are higher than 300% which is recommended by ASTM and ISO except the sample with 0.45mol/L MPDSAH. The friction coefficient of modified UHMWPE is lower than that of the untreated UHMWPE and it decreases gradually with the increase of monomer concentration. The wear rates have been decreased and the wear resistance has been improved under saline and distilled water lubrication.

  13. The Influence of Irradiation and Accelerated Aging on the Mechanical and Tribological Properties of the Graphene Oxide/Ultra-High-Molecular-Weight Polyethylene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Guodong Huang

    2016-01-01

    Full Text Available Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE nanocomposite is a potential and promising candidate for artificial joint applications. However, after irradiation and accelerated aging, the mechanical and tribological behaviors of the nanocomposites are still unclear and require further investigation. GO/UHMWPE nanocomposites were successfully fabricated using ultrasonication dispersion, ball-milling, and hot-pressing process. Then, the nanocomposites were irradiated by gamma ray at doses of 100 kGy. Finally, GO/UHMWPE nanocomposites underwent accelerated aging at 80°C for 21 days in air. The mechanical and tribological properties of GO/UHMWPE nanocomposites have been evaluated after irradiation and accelerated aging. The results indicated that the incorporation of GO could enhance the mechanical, wear, and antiscratch properties of UHMWPE. After irradiation, these properties could be further enhanced, compared to unirradiated ones. After accelerated aging, however, these properties have been significantly reduced when compared to unirradiated ones. Moreover, GO and irradiation can synergistically enhance these properties.

  14. EFFECT OF CROSSLINK DENSITY ON THE HIGH PRESSURE CRYSTALLIZATION OF UHMWPE

    Science.gov (United States)

    Oral, Ebru; Beckos, Christine Godleski; Ghali, Bassem W.; Lozynsky, Andrew J.; Muratoglu, Orhun K.

    2010-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is a bearing surface material for total joint implants. It is radiation cross-linked for high wear resistance and is melted or treated with vitamin E for oxidative stability. We investigated high pressure crystallization (HPC) of irradiated UHMWPE as an alternative method to improve the mechanical strength while stabilizing the residual free radicals from radiation crosslinking. HPC of uncross-linked UHMWPE has resulted in the formation of extended chain crystals and increased crystallinity, leading to improved strength. We hypothesized that increased cross-link density would hinder crystallization during HPC due to decreased chain mobility. Therefore, we investigated the crystalline structure and tensile mechanical properties of high pressure crystallized 25-, 65- and 100-kGy irradiated UHMWPE. We also determined free radical content and wear. The strength of 25- and 65-kGy irradiated UHMWPEs was improved by HPC with increased crystallinity and crystal size. 100-kGy irradiated UHMWPE did not show improved strength, supporting our hypothesis that decreased chain mobility would hinder crystal formation and strength improvement. None of the HPC irradiated UHMWPEs contained detectable free radicals and their wear properties were maintained, suggesting oxidative and mechanical stability in the long term. Therefore, HPC can be used effectively for imparting oxidative stability while strength improvement can be achieved for irradiated UHMWPE with low to moderate crosslink density. PMID:19213055

  15. Effect of radiation on the microstructure and mechanical property of ultrahigh molecular weight polyethylene used in orthopedic prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Nho, Young Chang [KAERI, Daejon (Korea, Republic of)

    2004-07-01

    The effect of radiation on the microstructure and mechanical property of ultra high molecular weight ployethylene (UHMWPE) used in orthopedic implants was investigated. The raw material used in this study was GUR 4150 ram extruded UHMWPE bar. The UHMWPE specimen was irradiated at 140{open_square} in oil and room temperature under nitrogen with different dosages of an electron beam (EB) for the purposes of enhancing the crosslinking extent of the polymer. Following irradiation at room temperature, the UHMWPE specimens were thermally treated at various temperature to eliminate all the remaining free radicals. Surface oxidation of the UHMWPE samples according to the irradiation and thermal treating conditions were verified by FTIR-ATR. An electron spin resonance (ESR) spectroscopic study was Undertaken to investigate the remaining radicals in UHMWPE. The crystalline structure and mechanical properties of the irradiated UHMWPE were compared after the crosslinking of the EB. The crystalline structure and degree of crystallinity of irradiated UHMWPE were investigated using DSC, SAXS and WAXD. Mechanical properties such as the tensile strength were measured. The polymer pin on a metal plate type testing apparatus was used to test the wear property. The melt-irradiated samples had a higher crosslinking extent compared with the room temperature-irradiated and the UHMWPE control. The crystallinity and lamellar thickness of UHMWPE irradiated at room temperature increased much more comparing with specimens irradiated at 140{open_square}. The melt-irradiated UHMWPE had a better wear resistance than the room temperature-irradiated and the UHMWPE control.

  16. Graphene reinforced ultra high molecular weight polyethylene with improved tensile strength and creep resistance properties

    Directory of Open Access Journals (Sweden)

    A. Bhattacharyya

    2014-02-01

    Full Text Available Reduced graphene oxide or graphene was dispersed in ultra high molecular weight polyethylene (UHMWPE using two methods to prepare nanocomposite films. In pre-reduction method, graphite oxide (GO was exfoliated and dispersed in organic solvents and reduced to graphene before polymer was added, while reduction of graphene oxide was carried out after polymer addition for in situ reduction method. Raman spectroscopic study reveals that the second method results in better exfoliation of graphene but it has more amorphous content as evident from selected area electron diffraction (SAED pattern, wide angle X-ray and differential scanning calorimetry (DSC. The nanocomposite film produced by prereduction method possesses higher crystallinity (almost the same as that of the pure film as compared to the in situ method. It shows better modulus (increased from 864 to 1236 MPa, better strength (increased from 12.6 to 22.2 MPa, network hardening and creep resistance (creep strain reduced to 9% from 50% when 40% of maximum load was applied for 72 h than the pure film. These findings show that graphene can be used for reinforcement of UHMWPE to improve its tensile and creep resistance properties.

  17. J-integral fracture toughness, Tearing modulus and tensile properties of Vitamin E stabilized radiation crosslinked UHMWPE.

    Science.gov (United States)

    Bellare, Anuj; Dorfman, Robert; Samuel, Ashwanth; Thornhill, Thomas S

    2016-08-01

    Radiation crosslinking of ultra-high molecular weight polyethylene (UHMWPE) increases its wear resistance in total joint replacement prostheses. Unfortunately, it is accompanied by a dose-dependent decrease in several mechanical properties. In this study, the tensile properties and fracture behavior of radiation crosslinked, Vitamin E stabilized UHMWPE was studied as a function of radiation dose. The Rice and Sorensen model, applicable to elastic-plastic materials, was utilized to obtain the initial crack driving force, J1c, steady state J-integral fracture toughness, Jss and the Tearing modulus. Tensile tests showed the dependence of tensile properties on radiation dose. Jss of non-crosslinked UHMWPE was higher than for crosslinked UHMWPE׳s but there was no dose dependent change in Jss whereas there was almost no change in J1c over the entire dose range. Finally, a monotonic decrease in Tearing modulus was observed with radiation dose.

  18. Confocal Raman spectroscopic analysis of cross-linked ultra-high molecular weight polyethylene for application in artificial hip joints.

    Science.gov (United States)

    Pezzotti, Giuseppe; Kumakura, Tsuyoshi; Yamada, Kiyotaka; Tateiwa, Toshiyuki; Puppulin, Leonardo; Zhu, Wenliang; Yamamoto, Kengo

    2007-01-01

    Confocal spectroscopic techniques are applied to selected Raman bands to study the microscopic features of acetabular cups made of ultra-high molecular weight polyethylene (UHMWPE) before and after implantation in vivo. The micrometric lateral resolution of a laser beam focused on the polymeric surface (or subsurface) enables a highly resolved visualization of 2-D conformational population patterns, including crystalline, amorphous, orthorhombic phase fractions, and oxidation index. An optimized confocal probe configuration, aided by a computational deconvolution of the optical probe, allows minimization of the probe size along the in-depth direction and a nondestructive evaluation of microstructural properties along the material subsurface. Computational deconvolution is also attempted, based on an experimental assessment of the probe response function of the polyethylene Raman spectrum, according to a defocusing technique. A statistical set of high-resolution microstructural data are collected on a fully 3-D level on gamma-ray irradiated UHMWPE acetabular cups both as-received from the maker and after retrieval from a human body. Microstructural properties reveal significant gradients along the immediate material subsurface and distinct differences are found due to the loading history in vivo, which cannot be revealed by conventional optical spectroscopy. The applicability of the confocal spectroscopic technique is valid beyond the particular retrieval cases examined in this study, and can be easily extended to evaluate in-vitro tested components or to quality control of new polyethylene brands. Confocal Raman spectroscopy may also contribute to rationalize the complex effects of gamma-ray irradiation on the surface of medical grade UHMWPE for total joint replacement and, ultimately, to predict their actual lifetime in vivo.

  19. Radiation crosslinking of ultra high molecular weigh polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Nho, Young Chang [KAERI, Taejon (Korea, Republic of)

    2000-05-01

    The effect of {gamma}-irradiation on the thermal and mechanical properties of ultra high molecular weight polyethylene (UHMWPE) used in orthopedic implants was investigated. UHMWPE was recrystallized with different cooling conditions for the purpose of enhancing the crosslinking extent of the polymer after {gamma}-irradiation. UHMWPE was irradiated with gamma ray to a dosage of 10 kGy to 500 kGy in air and nitrogen atmosphere. Differential scanning calorimetry, tensile characterization, creep deformity and wear were examined to determine the mechanical properties of the irradiated UHMWPE specimens. The crystallinity of the irradiated samples was increased with irradiation dose. The irradiated UHMWPE after recrystallization in a quenching condition had a higher crosslinking extent compared with the irradiated UHMWPE after slowly cooling. The irradiated UHMWPE after quenching had a lower wear rate than the irradiated UHMWPE after recrystallization in a slowly cooling condition, and the wear rate of UHMWPE decreased with irradiation dose up to 250kGy, which showed about 40% of the wear rate of nonirradiated UHMWPE.

  20. Submicron sized ultra-high molecular weight polyethylene wear particle analysis from revised SB Charité III total disc replacements.

    Science.gov (United States)

    Punt, Ilona; Baxter, Ryan; van Ooij, André; Willems, Paul; van Rhijn, Lodewijk; Kurtz, Steven; Steinbeck, Marla

    2011-09-01

    Submicron sized particles are frequently observed in retrieved total hip and knee periprosthetic tissues and appear to be critical in the activation of the phagocytic inflammatory response. In this paper the concentration, size and shape of ultra-high molecular weight polyethylene (UHMWPE) wear particles between 0.05 and 2.00μm were determined after isolation from periprosthetic tissues from retrieved lumbar SB Charité III total disc replacements (TDR) using scanning electron microscopy (SEM). For comparison, UHMWPE wear particles were isolated from γ-radiation-air sterilized total hip arthroplasty (THA) revision tissues. The mean concentration of UHMWPE particles in TDR tissues was 1.6×10(9)g(-1)tissue (range 1.3-2.0), which was significantly lower than the concentration of 2.3×10(9)g(-1) THA revision tissue (range 1.8-3.2) (P=0.03). The mean particle size (equivalent circular diameter: TDR, 0.46μm; THA 0.53μm, P=0.60) and mean shape were comparable between TDR and THA (aspect ratio: TDR, 1.89; THA, 1.99, P=0.35; roundness: TDR, 0.58; THA, 0.56, P=0.35). However, the TDR particles tended to be smaller and more round. Although no correlations were found between visible damage to the UHMWPE core and the concentration or shape of the UHMWPE particles, a positive correlation was found between increasing particle size and increasing rim penetration of the TDR core (P=0.04). The presence of UHMWPE particles of similar size and shape in TDR tissue, albeit lower in concentration, might explain why, unlike THA, pain rather than osteolysis is the major reason for revision surgery. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Clinical trade-offs in cross-linked ultrahigh-molecular-weight polyethylene used in total joint arthroplasty.

    Science.gov (United States)

    Pruitt, Lisa A; Ansari, Farzana; Kury, Matt; Mehdizah, Amir; Patten, Elias W; Huddlestein, James; Mickelson, Dayne; Chang, Jennifer; Hubert, Kim; Ries, Michael D

    2013-04-01

    Highly cross-linked formulations of ultrahigh-molecular-weight polyethylene (XLPE) offer exceptional wear resistance for total joint arthroplasty but are offset with a reduction in postyield and fatigue fracture properties in comparison to conventional ultrahigh-molecular-weight polyethylene (UHMWPE). Oxidation resistance is also an important property for the longevity of total joint replacements (TJRs) as formulations of UHMWPE or XLPE utilizing radiation methods are susceptible to free radical generation and subsequent embrittlement. The balance of oxidation, wear, and fracture properties is an enduring concern for orthopedic polymers used as the bearing surface in total joint arthroplasty. Optimization of material properties is further challenged in designs that make use of locking mechanisms, notches, or other stress concentrations that can render the polymer susceptible to fracture due to elevated local stresses. Clinical complications involving impingements, dislocations, or other biomechanical overloads can exacerbate stresses and negate benefits of improved wear resistance provided by XLPE. This work examines trade-offs that factor into the use of XLPE in TJR implants.

  2. Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anup Kumar; Balani, Kantesh, E-mail: kbalani@iitk.ac.in

    2015-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al{sub 2}O{sub 3}) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al{sub 2}O{sub 3} has shown to alter the wettability (from contact angle of ∼ 88° ± 2° to ∼ 118° ± 4°) and surface energy (from ∼ 23.20 to ∼ 17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT–Al{sub 2}O{sub 3} reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT–Al{sub 2}O{sub 3} reinforced UHMWPE biopolymer composites. - Highlights: • The cellular response of UHMWPE upon MWCNT and Al{sub 2}O{sub 3} reinforcement is highlighted. • Wettability decreases with Al{sub 2}O{sub 3} and

  3. Effect of ZnO morphology on affecting bactericidal property of ultra high molecular weight polyethylene biocomposite.

    Science.gov (United States)

    Sharma, Rajeev Kumar; Agarwal, Meenakshi; Balani, Kantesh

    2016-05-01

    Bacterial infection of implants can be controlled by selective trapping of bacteria, followed with consequent killing by targeted antibacterial agents. Herein, the role of various ZnO morphologies, viz. micro-rods (R), nanoparticles (NP), and micro-disks (D) on antibacterial efficacy of ZnO via release of Zn(2+) and H2O2 is assessed, both as isolated powders and via incorporating them in cytocompatible ultra high molecular weight polyethylene (UHMWPE). Though ZnO is antibacterial, interestingly, all ZnO morphologies elicited a supportive growth of gram-negative bacteria (Escherichia coli) in culture medium (until 28-35 μg/ml). But, all ZnO morphologies did elicit bactericidal effect on gram positive bacteria (Staphylococcus aureus or Staphylococcus epidermidis) both in culture medium (for 0-2.5 μg/ml) or when incorporated (5-20 wt.%) into UHMWPE. The bactericidal mechanisms were quantified for various ZnO morphologies via: (i) H2O2 production, (ii) Zn(2+) release, and (iii) the presence of surface oxygen vacancies. On one hand, where only ZnO(NP) elicited release of H2O2 in the absence of light, maximum Zn(2+) release was elicited by ZnO(D). Interestingly, when ZnO is incorporated as reinforcement (5-20 wt.%), its antibacterial action against E. coli was vividly observed due to selective proliferation of bacteria only on friendly UHMWPE matrix. Hence, luring bacteria on affable UHMWPE surface can be complemented with their targeted killing by ZnO present in composite.

  4. Thermal Conductivity of Ultrahigh Molecular Weight Polyethylene Crystal: Defect Effect Uncovered by 0 K Limit Phonon Diffusion.

    Science.gov (United States)

    Liu, Jing; Xu, Zaoli; Cheng, Zhe; Xu, Shen; Wang, Xinwei

    2015-12-16

    Crystalline ultrahigh molecular weight polyethylene (UHMWPE) has the highest reported thermal conductivity at room temperature: 104 W/(m·K), while theoretical predictions proposed an even higher value of 300 W/(m·K). Defects and amorphous fraction in practical UHMWPE fibers significantly reduces the thermal conductivity from the ideal value. Although the amorphous effect can be readily analyzed based on the effective medium theory, the defect effects are poorly understood. This work reports on the temperature-dependent behavior (down to 22 K) of thermal diffusivity and conductivity of UHMWPE fibers in anticipation of observing the reduction in phonon density and scattering rate against temperature and of freezing out high-momentum phonons to clearly observe the defect effects. By studying the temperature-dependent behavior of thermal reffusivity (Θ, inverse of thermal diffusivity) of UHMWPE fibers, we are able to quantify the defect effects on thermal conductivity. After taking out the amorphous region's effect, the residual thermal reffusivities (Θ0) for the studied two samples at the 0 K limit are determined as 3.45 × 10(4) and 2.95 × 10(4) s/m(2), respectively. For rare-/no-defects crystalline materials, Θ0 should be close to zero at the 0 K limit. The defect-induced low-momentum phonon mean free paths are determined as 8.06 and 9.42 nm for the two samples. They are smaller than the crystallite size in the (002) direction (19.7 nm) determined by X-ray diffraction. This strongly demonstrates the diffuse phonon scattering at the grain boundaries. The grain boundary thermal conductance (G) can be evaluated as G ≈ βρc(p)v with sound accuracy. At room temperature, G is around 3.73 GW/(m(2)·K) for S2, comparable to that of interfaces with tight atomic bonding.

  5. Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder:. Part I. Grafting conditions and grafting yield

    Science.gov (United States)

    Aydinli, Bahattin; Tinçer, Teoman

    2001-02-01

    Monomers of some water-soluble polymers; acrylic acid, methacrylic acid, acrylamide, N, N -dimethyl acrylamide and 1-vinyl-2 pyrrolidone, were grafted on ultra-high molecular weight polyethylene (UHMWPE) powders by a direct grafting method in an aqueous medium in air. Inhibition of homopolymerisation was achieved by adding various concentrations of Fe 2+ or Cu 2+ ions. It was found that the degree of grafting increases linearly with dose till a gelation state is reached, and varies between 40 and 12% depending on the monomer. Four million molecular weight UHMWPE gave a higher per cent grafting than a 6 million counterpart for the monomers used, with the exception of acrylic acid monomer grafting.

  6. Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder: Part I. Grafting conditions and grafting yield

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, Bahattin; Tincer, Teoman E-mail: teotin@metu.edu.tr

    2001-02-01

    Monomers of some water-soluble polymers; acrylic acid, methacrylic acid, acrylamide, N, N-dimethyl acrylamide and 1-vinyl-2 pyrrolidone, were grafted on ultra-high molecular weight polyethylene (UHMWPE) powders by a direct grafting method in an aqueous medium in air. Inhibition of homopolymerisation was achieved by adding various concentrations of Fe{sup 2+} or Cu{sup 2+} ions. It was found that the degree of grafting increases linearly with dose till a gelation state is reached, and varies between 40 and 12% depending on the monomer. Four million molecular weight UHMWPE gave a higher per cent grafting than a 6 million counterpart for the monomers used, with the exception of acrylic acid monomer grafting. (author)

  7. Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review

    Directory of Open Access Journals (Sweden)

    Pierangiola Bracco

    2017-07-01

    Full Text Available Ultra-high molecular weight polyethylene (UHMWPE is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From “historical”, gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure–properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature.

  8. Wear tests in a hip joint simulator of different CoCrMo counterfaces on UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Mora, V.A.; Hoffmann, M.; Stroosnijder, R. [Institute for Health and Consumer Protection, Joint Research Centre, European Commission, Ispra (Italy); Gil, F.J. [CREB, Dept. Ciencia de Materiales e Ingenieria Metalurgica, ETSEIB, Universidad Politecnica de Cataluna, Av. Diagonal 647, 08028-Barcelona (Spain)], E-mail: francesc.xavier.gil@upc.edu

    2009-01-01

    The objective in this work was to study the effect of different material counterfaces on the Ultra High Molecular Weight Polyethylene (UHMWPE) wear behavior. The materials used as counterfaces were based on CoCrMo: forged with hand polished and mass finished, CoCrMo coating applied on the forged CoCrMo alloy obtained by Physical Vapour Deposition (PVD). A hip joint simulator was designed and built for these studies. The worn surfaces were observed by optical and scanning electron microscopy. The results showed that the hand polished CoCrMo alloy caused the higher UHMWPE wear of the acetabular cups. The CoCrMo coating caused the least UHMWPE wear, while the mass finished CoCrMo alloy caused an intermediate UHMWPE wear. It is shown that the wear rates obtained in this work are closer to clinical studies than to similar hip joints simulator studies.

  9. Strain-induced microstructural rearrangement in ultra-high molecular weight polyethylene for hip joints: A comparison between conventional and vitamin E-infused highly-crosslinked liners.

    Science.gov (United States)

    Takahashi, Yasuhito; Yamamoto, Kengo; Shishido, Takaaki; Masaoka, Toshinori; Tateiwa, Toshiyuki; Puppulin, Leonardo; Pezzotti, Giuseppe

    2014-03-01

    Infusion of vitamin E (α-tocopherol) in highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) liners has been conceived to achieve superior oxidation stability while preserving enhanced mechanical properties as compared to post-irradiation remelted liners. However, the presence of an antioxidant in the material microstructure brings an issue of concern in whether a "foreign substance" might reduce radiation crosslinking efficiency and/or change microstructural characteristics by diffusing into UHMWPE. The key to clarify this fundamental issue resides in performing a quantitative evaluation of the obtained material structure and its polymeric chain mobility on the molecular scale. In this paper, a Raman spectroscopic examination is presented of molecular orientation and phase fractions in as-processed vitamin E-infused UHMWPE acetabular liners in comparison with a model (undoped and unirradiated/uncrosslinked) and a conventional (undoped and 33kGy-sterilized by gamma-irradiation) UHMWPE liners. The microstructural responses of structurally different liners to externally applied compressive strain were also monitored. The main results of the spectroscopic analyses can be summarized as follows: (i) preliminary gamma irradiation reduced the fraction of amorphous phase and increased the degree of molecular alignment, the vitamin E-infused liner preserving the crystallinity level achieved by the 100-kGy irradiation injected before infusion; (ii) the presence of vitamin E significantly promoted orientational randomness, which increased with increasing compressive strain magnitude, a phenomenon beneficial to minimize strain-softening-assisted wear phenomena.

  10. Examination of the suitability of alpha-tocopherol as a stabilizer for ultra-high molecular weight polyethylene used for articulating surfaces in joint endoprostheses.

    Science.gov (United States)

    Wolf, C; Krivec, T; Blassnig, J; Lederer, K; Schneider, W

    2002-02-01

    The lifetime of articulating surfaces in joint endoprostheses made of ultra-high molecular weight polyethylene (UHMW-PE), especially of UHMW-PE-cups of hip-endoprostheses, is usually limited to 10-15 years due to material failure as a result of oxidation of the UHMW-PE in vivo. In this study the suitability of the natural antioxidant alpha-tocopherol (vitamin E) as a stabilizer for UHMW-PE in these applications was investigated. Specimens with 0.1%, 0.2%, 0.4% and 0.8% w/w alpha-tocopherol as well as unstabilized samples were sintered and sterilized with gamma-rays at 25 kGy in accordance with standard processing methods of cups for total hip-endoprostheses. These specimens were aged in pure oxygen at 70 degrees C and 5 bar as well as in aqueous H2O2 at 50 degrees C. The degree of oxidation was observed by means of FTIR-spectroscopy, DSC analysis and mechanical testing. The FTIR-measurements showed that alpha-tocopherol can prolong the lifetime of UHMW-PE in an oxidative environment by a factor of more than 2.5. In the mechanical tests no embrittlement could be observed with the stabilized samples. A comparison with the standard antioxidant system Irganox 1010/Irgafos 168 (Ciba-Geigy, Switzerland) was carried out and revealed that alpha-tocopherol can even exceed the stabilization effect of this widely-used antioxidant system.

  11. Multiaxial fatigue behavior of conventional and highly crosslinked UHMWPE during cyclic small punch testing.

    Science.gov (United States)

    Villarraga, M L; Kurtz, S M; Herr, M P; Edidin, A A

    2003-08-01

    Previous observations of reduced uniaxial elongation, fracture resistance, and crack propagation resistance of highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) have contributed to concern that the technology may not be appropriate for systems undergoing cyclic fatigue loading. Using a "total life" approach, we examined the influence of radiation crosslinking on the fatigue response of UHMWPE under cyclic loading via the small punch test. Our goal in this study was to evaluate the suitability of the small punch test for conducting miniature-specimen, cyclic loading, and fatigue experiments of conventional and highly crosslinked UHMWPE. We subjected four types of conventional and highly crosslinked UHMWPE to cyclic loading at 200 N/s and at body temperature in a small punch test apparatus. After failure, the fracture surfaces were characterized with the use of field emission scanning electron microscopy to evaluate the fatigue mechanisms. Cyclic small punch testing under load control was found to be an effective and repeatable method for relative assessment of the fatigue resistance of conventional and highly crosslinked UHMWPE specimens under multiaxial loading conditions. For each of the four conventional and highly crosslinked UHMWPE materials evaluated in this study, fatigue failures were consistently produced according to a power law relationship in the low cycle regimen, corresponding to failures below 10000 cycles. The fatigue failures were all found to be consistent with a single source of initiation and propagation to failure. Our long-term goal in this research is to develop miniature-specimen fatigue testing techniques for characterization of retrieved UHMWPE inserts.

  12. Adhesive forces and surface properties of cold gas plasma treated UHMWPE.

    Science.gov (United States)

    Preedy, Emily Callard; Brousseau, Emmanuel; Evans, Sam L; Perni, Stefano; Prokopovich, Polina

    2014-10-20

    Cold atmospheric plasma (CAP) treatment was used on ultra-high molecular weight polyethylene (UHMWPE), a common articulating counter material employed in hip and knee replacements. UHMWPE is a biocompatible polymer with low friction coefficient, yet does not have robust wear characteristics. CAP effectively cross-links the polymer chains of the UHMWPE improving wear performance (Perni et al., Acta Biomater. 8(3) (2012) 1357). In this work, interactions between CAP treated UHMWPE and spherical borosilicate sphere (representing model material for bone) were considered employing AFM technique. Adhesive forces increased, in the presence of PBS, after treatment with helium and helium/oxygen cold gas plasmas. Furthermore, a more hydrophilic surface of UHMWPE was observed after both treatments, determined through a reduction of up to a third in the contact angles of water. On the other hand, the asperity density also decreased by half, yet the asperity height had a three-fold decrease. This work shows that CAP treatment can be a very effective technique at enhancing the adhesion between bone and UHMWPE implant material as aided by the increased adhesion forces. Moreover, the hydrophilicity of the CAP treated UHMWPE can lead to proteins and cells adhesion to the surface of the implant stimulating osseointegration process.

  13. Macrophage Response to UHMWPE Submitted to Accelerated Ageing in Hydrogen Peroxide

    Science.gov (United States)

    Rocha, Magda F.G.; Mansur, Alexandra A.P.; Martins, Camila P.S.; Barbosa-Stancioli, Edel F.; Mansur, Herman S.

    2010-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important properties to extend the longevity of knee prostheses. The present study investigated the accelerated ageing of UHMWPE in hydrogen peroxide highly oxidative chemical environment. The sliced samples of UHMWPE were oxidized in a hydrogen peroxide solution for 120 days with their total level of oxidation (Iox) characterized by Fourier Transformed Infrared Spectroscopy (FTIR). The potential inflammatory response, cell viability and biocompatibility of such oxidized UHMWPE systems were assessed by a novel biological in vitro assay based on the secretion of nitric oxide (NO) by activated murine macrophages with gamma interferon (IFN-γ) cytokine and lipopolysaccharide (LPS). Furthermore, macrophage morphologies in contact with UHMWPE oxidized surfaces were analyzed by cell spreading-adhesion procedure using scanning electron microscopy (SEM). The results have given significant evidence that the longer the period of accelerated aging of UHMWPE the higher was the macrophage inflammatory equivalent response based on NO secretion analysis. PMID:20721321

  14. UHMWPE-based nanocomposite as a material for damaged cartilage replacement.

    Science.gov (United States)

    Senatov, F S; Kopylov, A N; Anisimova, N Yu; Kiselevsky, M V; Maksimkin, A V

    2015-03-01

    In the present work dispersion-strengthened nanocomposites based on ultra-high molecular weight polyethylene (UHMWPE) after mechanical activation were studied. Mechanical activation was performed for hardening of the boundaries between the polymer particles, reducing the fusion defects and increasing of wear-resistance. Three types of samples were prepared: UHMWPE, UHMWPE/Al2O3 nanocomposite and UHMWPE/Al2O3 nanocomposite after mechanical activation. UHMWPE/Al2O3 nanocomposites prepared with mechanical activation show the best mechanical properties in compression and higher wear-resistance. UHMWPE/Al2O3 nanocomposites prepared with mechanical activation were chosen for in vivo study by orthotopical transplantation in rats. Animals' activity has been being monitored for 60days after surgery. No signs of inflammation, cellular infiltration, destruction of material or bone-cartilage defect were found. Implanted sample has not changed its position of implantation, there were no any shifts. Obtained data shows that UHMWPE-based nanocomposite is a promising material for creating bioimplants for cartilage defect replacement.

  15. Dendritic cells enhance UHMWPE wear particle-induced osteoclast differentiation of macrophages.

    Science.gov (United States)

    Cang, Dingwei; Guo, Kaijin; Zhao, Fengchao

    2015-10-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been widely used in large joint replacement. Osteolysis induced by the UHMWPE wear particles is one of the main causes of replacement failure. This study aims to elucidate whether dendritic cells play a role in UHMWPE particle-induced osteolysis. An in vitro Raw 264.7 and DC 2.4 coculture system was employed to examine the effects of dendritic cells on the inflammatory and osteoclastogenic responses of Raw 264.7 toward UHMWPE particles. The expression of cytokines, NF-κB, and osteoclast marker genes was analyzed by ELISA, western blot, or quantitative PCR. The osteoclast differentiation was measured by TRAP staining and flow cytometry. UHMWPE particles induced Raw 264.7 cells to differentiate into osteoclasts, which was enhanced by coculturing with DC 2.4 cells. DC 2.4 cells augmented UHMWPE particle-elicited activation of NF-κB signaling, higher levels of TNF-α and MCP-1, and an increased expression of MMP-9, Calcr, and Ctsk, though DC 2.4 coculture alone did not significantly cause the aforementioned changes. These results suggest that dendritic cells, among other immune cells recruited by UHMWPE particle induced inflammation, could further exacerbate inflammation and osteolysis.

  16. Thermally Sprayable Anti-corrosion Marine Coatings Based on MAH-g-LDPE/UHMWPE Nanocomposites

    Science.gov (United States)

    Jeeva Jothi, K.; Santhoskumar, A. U.; Amanulla, Syed; Palanivelu, K.

    2014-12-01

    Polymer composite coatings based on low-density polyethylene (LDPE) and ultra-high-molecular-weight polyethylene (UHMWPE) blends were prepared for marine coatings. The incorporation of carboxyl moiety in the polymer blends of LDPE/UHMWPE was carried out by grafting with maleic anhydride (MAH) at varying concentrations of 1-8 wt.% using reactive extrusion process. An optimum percentage of grafting of 2.1% was achieved with 5 wt.% of maleic anhydride. Further, the nanocomposites of MAH-grafted-LDPE/UHMWPE blends were prepared by incorporating cloisite 15A nanoclay at varying concentrations of 1-4 wt.%. The polymer nanocomposites were converted into fine powders suitable for thermal spray having ≤200 μ particle size using cryogenic grinding. The effect of the intact coatings applied on grit-blasted mild steel by thermal spray technique was evaluated for abrasion resistance, adhesion strength, and corrosion resistance. The corrosion resistance of the polymer nanocomposites was studied by salt spray technique and Electrochemical Impedance Spectroscopy The abrasion resistance of coatings increases with increasing UHMWPE content in the blends. However, blends with higher concentration of UHMWPE resulted in coarse coatings with poor adhesion. The coatings with 90:10 MAH-grafted-LDPE/UHMWPE having 3 wt.% of nanoclay showed good abrasion resistance, adhesion strength, and better corrosion resistance.

  17. Improvement in the Tribological Properties of UHMWPE Sliding against Ti6Al4V by Surface Modification

    Institute of Scientific and Technical Information of China (English)

    施雯; 董汉山

    2005-01-01

    Surface engineering has been emerging as one of the most promising technologies to improve the tribological properties of biomaterials with a view to extending the life span of medical implants. For example, some novel surface engineering techniques including ion implantation of ultra-high molecular weight polyethylene (UHMWPE) and thermal oxidation (TO) treatment of titanium alloy have been developed. However, the full potential of improving the wear resistance of orthopaedic implants based on the UHMWPE/ Ti6A14V system will not be realized until the tribological performance of this surface engineered tribo-system is fully characterized and the acting wear mechanisms are well understood. In this paper, a pin-on-disc tribometer was employed to evaluate the tribological response of the following three tribo-systems: (1) untreated UHMWPE/untreated Ti6A14V. (2) untreated UHMWPE/TO-treated Ti6A14V and (3) ion implanted UHMWPE/TO treated Ti6A14V under water lubricated conditions. Experimental results show that the tribological properties of UHMWPE can be significantly increased by surface enghmering its surface and/or the counterface. Tiffs can be attributed to the hardened surface of UHMWPE via molecular structure modification induced by ion bean bombardment coupled with the surface oxide layer on Ti6A14V formed during TO treatment, which has favorable tribological compatibility with UHMWPE.

  18. Highly antibacterial UHMWPE surfaces by implantation of titanium ions

    Energy Technology Data Exchange (ETDEWEB)

    Delle Side, D., E-mail: domenico.delleside@le.infn.it [LEAS, Dipartimento di Matematica e Fisica “Ennio de Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare – Sezione di Lecce, Lecce (Italy); Nassisi, V.; Giuffreda, E.; Velardi, L. [LEAS, Dipartimento di Matematica e Fisica “Ennio de Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare – Sezione di Lecce, Lecce (Italy); Alifano, P.; Talà, A.; Tredici, S.M. [Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Lecce (Italy)

    2014-07-15

    The spreading of pathogens represents a serious threat for human beings. Consequently, efficient antimicrobial surfaces are needed in order to reduce risks of contracting severe diseases. In this work we present the first evidences of a new technique to obtain a highly antibacterial Ultra High Molecular Weight Polyethylene (UHMWPE) based on a non-stoichiometric titanium oxide coating, visible-light responsive, obtained through ion implantation.

  19. Fatigue toughness of irradiated vitamin E/UHMWPE blends.

    Science.gov (United States)

    Doshi, Brinda; Ward, Jerel S; Oral, Ebru; Muratoglu, Orhun K

    2016-09-01

    Radiation cross-linked ultrahigh molecular weight polyethylenes (UHMWPEs) have become the standard-of-care in total joint replacements (TJR) in the last decade because of their superior wear resistance in comparison with previously used "conventional" gamma sterilized UHMWPE. Some first generation radiation cross-linked UHMWPEs were stabilized against oxidation by post-irradiation melting, which significantly reduced their fatigue crack propagation resistance or fatigue toughness. Second generation cross-linked UHMWPEs incorporated instead an antioxidant such as vitamin E, eliminating the need for melting. In this study, we investigated the fatigue crack propagation resistance and the impact toughness of vitamin E-blended and radiation cross-linked UHMWPEs as a function of vitamin E concentration and radiation dose. Both properties were strongly dependent on the cross-link density and they showed a good correlation with each other (R(2)  = 0.89). © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1514-1520, 2016.

  20. In vivo degradation in modern orthopaedic UHMWPE bearings and structural characterization of a novel alternative UHMWPE material

    Science.gov (United States)

    Reinitz, Steven D.

    Ultra-high molecular weight polyethylene (UHMWPE) remains the most common bearing material for total joint arthroplasty. Advances in radiation cross-linking and other post-consolidation treatments have led to a rapid differentiation of polyethylene products on the market, with more than twenty unique materials currently being sold by the five largest orthopaedic manufacturers alone. Through oxidation, cross-link density, and free radical measurements, this work demonstrates for the first time that in vivo material degradation is occurring in cross-linked UHMWPE materials. Based on the rate of the reaction in certain materials, it is concluded that oxidative degradation may compromise the mechanical properties of the bearings in as few as ten years, potentially leading to early clinical failure of the devices. Using the knowledge gained from this work as well as previously published observations about UHMWPE oxidation, a two-mechanism model of oxidation is proposed that offers an explanation for the observed in vivo changes. From this model it is concluded that oxidative degradation is in part the result of in vivo chemical species. The two-mechanism model of oxidation suggests that different processing techniques for UHMWPE may reduce the risk of oxidative degradation. It is concluded that by avoiding any radiation cross-linking step, Equal Channel Angular Processing (ECAP) can produce UHMWPE materials with a reduced risk for in vivo oxidation while at the same time offering superior mechanical properties compared to commercially available UHMWPE materials, as well as similar wear behavior. Using dynamic mechanical analysis, the entanglement density in ECAP materials is quantified, and is related back to the ECAP processing parameters. The relationship between entanglement density and resultant material properties is established. The results will allow informed processing parameter selection for producing optimized materials for orthopaedics and other applications.

  1. Ionizing radiation effect study by electron beam on ultra high molecular weight polyethylene virgin and recycled industrial; Estudo do efeito da radiacao ionizante por feixe de eletrons sobre o polietileno de ultra alto peso molecular virgem e reciclado industrial

    Energy Technology Data Exchange (ETDEWEB)

    Rosario, Salmo Cordeiro do

    2006-07-01

    Ultra High Molecular Weight Polyethylene (UHMWPE) is an engineering plastic which has several applications, chiefly, in specific areas of the industry and medicine. UHMWPE can be even for other applications such as: port fenders, current guide, bucket coating, silos and gutters, plugs, pulleys and surgical prosthesis. This range of applications is due to the excellent technical characteristics that this material owns, such as; high resistance to wear, high resistance to impact, anti-adherence, non toxic, excellent chemical resistance, low specific weight, easy mill processing, and high resistance to fatigue. The UHMWPE type used in this work were UTEC 3041 and UTEC 6541 of the Braskem. The recycling process of UHMWPE raised much interest, because the utilization of this raw material grew over 600% in the last decade, becoming one of the most used engineering plastics for attainment of mill processed parts after polyamide. As the utilization of this polymer in the manufacturing of parts for machinery has grown, its waste is very big, because the rest of this material is thrown out, usually not being reused. The goal of this work is to recycle the UHMWPE UTEC 3041 and study the properties of this recycled and virgin material and compare the results between both with these materials submitted to different radiation dose. (author)

  2. The role of hydroperoxides as a precursor in the radiation-induced graft polymerization of methyl methacrylate to ultra-high molecular weight polyethylene

    Science.gov (United States)

    Enomoto, Ichiro; Katsumura, Yosuke; Kudo, Hisaaki; Sekiguchi, Masayuki

    2010-06-01

    A graft polymerization of methyl methacrylate (MMA) to ultra-high molecular weight polyethylene (UHMWPE) with Co-60 γ-ray irradiation in air at room temperature has been carried out. The grafting yields were measured as a function of the storage time (elapsed time from the end of irradiation to the start of grafting), and it was found that the yields reach at the maximum values at around several days since the end of irradiation. In order to clarify the precursor of the graft polymerization, changes of the radical yields and the carbonyl groups were measured as a function of storage time with ESR and microscopic FT-IR, respectively. From the similarities between the depth profiles of the hydroperoxide formation and the grafting products, it was concluded that the hydroperoxides can be main precursors of the grafting of the radiation-induced polymerization of MMA to UHMWPE under the given conditions.

  3. The role of hydroperoxides as a precursor in the radiation-induced graft polymerization of methyl methacrylate to ultra-high molecular weight polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Ichiro, E-mail: enomoto.ichiro@iri-tokyo.j [Tokyo Metropolitan Industrial Technology Research Institute, KFC bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan); School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Katsumura, Yosuke [School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kudo, Hisaaki [School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Sekiguchi, Masayuki [Tokyo Metropolitan Industrial Technology Research Institute, KFC bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan)

    2010-06-15

    A graft polymerization of methyl methacrylate (MMA) to ultra-high molecular weight polyethylene (UHMWPE) with Co-60 gamma-ray irradiation in air at room temperature has been carried out. The grafting yields were measured as a function of the storage time (elapsed time from the end of irradiation to the start of grafting), and it was found that the yields reach at the maximum values at around several days since the end of irradiation. In order to clarify the precursor of the graft polymerization, changes of the radical yields and the carbonyl groups were measured as a function of storage time with ESR and microscopic FT-IR, respectively. From the similarities between the depth profiles of the hydroperoxide formation and the grafting products, it was concluded that the hydroperoxides can be main precursors of the grafting of the radiation-induced polymerization of MMA to UHMWPE under the given conditions.

  4. 超高分子量聚乙烯纤维的液相氧化改性及其环氧树脂基复合材料的力学和摩擦性能∗%Liquid-phase Oxidation Modification of Ultra-high Molecular Weight Polyethylene Fiber and Mechanical/Tribological Properties of the Corresponding Fiber-reinforced Epoxy Resin Composites

    Institute of Scientific and Technical Information of China (English)

    李瑞培; 李微微; 孟立; 李春阳

    2016-01-01

    为增强超高分子量聚乙烯(UHMWPE)纤维与环氧树脂(EP)基体之间的界面粘结强度,采用重铬酸钾溶液对 UHMWPE 纤维进行表面改性并制备 UHMWPE 纤维/EP 复合材料。结果表明,UHMWPE 纤维经液相氧化后表面刻蚀痕迹明显,表面粗糙度明显增加,结晶度增加了11.3%,与乙二醇的接触角减小了14.12°。与纯环氧树脂相比,纤维含量为0.4%的未改性 UHMWPE 纤维/EP 复合材料的拉伸强度降低18.04%,纤维含量为0.6%的液相氧化改性 UHMWPE 纤维/EP 复合材料的拉伸强度降低51.55%,未改性 UHMWPE(纤维含量0.5%)和液相氧化改性 UHMWPE(纤维含量0.4%)纤维/EP 复合材料的冲击强度分别提升了3.29%和4.39%。当纤维含量为0.3%时,液相氧化改性 UHMWPE 纤维/EP 复合材料的弯曲强度比纯环氧树脂增加6.55%,比未改性 UHMWPE纤维/EP 复合材料增加19%。当纤维含量由0增大到0.5%时,改性和未改性 UHMWPE 纤维/EP 复合材料的摩擦系数先增加后减小。%The effects of chromic acid liquid-phase oxidation treatment on ultra-high molecular weight polyethy-lene (UHMWPE)fibers were investigated to improve the interfacial adhesion between UHMWPE fibers and epoxy resin (EP).The UHMWPE fibers/EP composites were prepared with chromic acid-treated UHMWPE fibers.The results showed that the liquid-phase oxidation could effectively increase the fiber′s surface roughness,increase its crys-tallinity by 1 1.3% and reduce the contact angle with glycol by 14.12°.Compared with pure EP,the tensile strength of unmodified UHMWPE fibers/EP composite with a fiber content of 0.4wt% decreased by 18.04%,the tensile strength of liquid-phase oxidated UHMWPE fibers/EP composite with a fiber content of 0.6wt% decreased by 5 1.55%,the impact strength of unmodified UHMWPE (0.5wt% fiber content)and liquid-phase oxidated UHMWPE (0.4wt% fiber content)fibers/EP composite increased by 3.29% and 4.39%,respectively.Compared with the pure EP and

  5. The influence of molecular weight, crosslinking and counterface roughness on TNF-alpha production by macrophages in response to ultra high molecular weight polyethylene particles.

    Science.gov (United States)

    Ingram, Joanne Helen; Stone, Martin; Fisher, John; Ingham, Eileen

    2004-08-01

    The response of murine macrophages to clinically relevant polyethylene wear particles generated from different polyethylenes at various time points and volumetric doses in vitro was evaluated. Clinically relevant ultra high molecular weight polyethylene (UHMWPE) wear debris was generated in vitro in a lubricant of RPMI 1640 supplemented with 25% (v/v) foetal calf serum using a multi-directional pin-on-plate wear rig under sterile conditions. Wear debris was cultured with C3H murine peritoneal macrophages at various particle volume (microm(3)): cell number ratios. The secretion of TNF-alpha was determined by ELISA. Initially the effect of molecular weight of UHMWPE was considered. Higher molecular weight GUR415HP was shown to have a lower wear rate than the lower molecular weight GUR1120, however a greater volume of the wear debris produced by the high molecular weight GUR415HP was in the 0.1-1.0 microm size range. Wear debris from GUR415HP produced significant levels of TNF-alpha at a concentration of 1 microm(3)/cell while at least 10 microm(3)/cell of GUR1120 wear debris per cell was needed to produce significant levels of TNF-alpha. Secondly the effects of crosslinking GUR1050 was examined when worn against a scratched counterface. The wear rate of the material was shown to decrease as the level of crosslinking increased. However the materials crosslinked with 5 and 10 Mrad of gamma irradiation produced higher percentages of 0.1-1.0 microm size wear particles than the non-crosslinked material. While the crosslinked material was able to stimulate cells to produce significantly elevated TNF-alpha levels at a particle concentration of just 0.1 microm(3)/cell only concentrations of 10 microm(3)/cell and above of the non-crosslinked wear debris were stimulatory. When the counterface was changed from scratched to smooth the wear rate for all three GUR1050 materials was further reduced. For the first time nanometre size wear particles were observed from polyethylene

  6. Study on drug release of and biological response to UHMWPE wear debris carrying estradiol

    Energy Technology Data Exchange (ETDEWEB)

    Qu Shuxin, E-mail: qushuxin@swjtu.edu.cn [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Liu Aiqin; Liu Xiaomin; Bai Yinlong; Weng Jie [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer We prepared ultra-high molecular weight polyethylene (UHMWPE) loaded with 17{beta}-estradiol (E2) to treat osteolysis after artificial joint replacement. Black-Right-Pointing-Pointer We investigate the in vitro release of E2 and the cell biological response to UHMWPE-E2 wear debris. Black-Right-Pointing-Pointer The in vitro E2 release included three stages during the release process: initial burst release, celerity release and steady release. Black-Right-Pointing-Pointer The UHMWPE-E2 wear debris could promote the proliferation and ALP activity of osteoblasts and inhibit the expression of IL-6 of osteoblasts. Black-Right-Pointing-Pointer The E2 in UHMWPE-E2 would play a role in the treatment of the osteolysis after artificial hip joint replacement. - Abstract: The aim of this study is to investigate in vitro release of 17{beta}-estradiol (E2), the potential drug to treat osteolysis, and the biological response to ultra-high molecular weight polyethylene loaded with E2 (UHMWPE-E2) wear debris. The osteoblasts (MC3T3-E1) and macrophages (RAW264.7) were co-cultured with UHMWPE-E2 wear debris via inversion culture technique, respectively. MTT, ALP and ELISA assay were employed to evaluate the cell proliferation, ALP activity and the expression of interleukin-6 (IL-6). In vitro E2 release included: initial burst release, celerity release and steady release. The E2 released steadily after 40 d and lasted more than 60 d. The E2 in UHMWPE-E2 wear debris promoted the proliferation and ALP activity of MC3T3-E1 cells at the high debris dosages of 8-10 mg. In particular, the UHMWPE-E2 wear debris inhibited the expression of IL-6 of osteoblasts at all dosages in the present study. RAW264.7 cells cultured with UHMWPE-E2 and UHMWPE wear debris exhibited large sizes about 100 {mu}m in diameter. The small size wear debris presented inside of cells indicated that the wear debris activated the phagocytosis of macrophages. The results indicated

  7. Macrophage reactivity to different polymers demonstrates particle size- and material-specific reactivity: PEEK-OPTIMA(®) particles versus UHMWPE particles in the submicron, micron, and 10 micron size ranges.

    Science.gov (United States)

    Hallab, Nadim James; McAllister, Kyron; Brady, Mark; Jarman-Smith, Marcus

    2012-02-01

    Biologic reactivity to orthopedic implant debris is generally the main determinant of long-term clinical performance where released polymeric particles of Ultra-high molecular weight polyethylene (UHMWPE) remain the most prevalent debris generated from metal-on-polymer bearing total joint arthroplasties. Polymeric alternatives to UHMWPE such as polyetherether-ketone (PEEK) may have increased wear resistance but the bioreactivity of PEEK-OPTIMA particles on peri-implant inflammation remains largely uncharacterized. We evaluated human monocyte/macrophage responses (THP-1s and primary human) when challenged by PEEK-OPTIMA, UHMWPE, and X-UHMWPE particles of three particle sizes (0.7 um, 2 um, and 10 um) at a dose of 20 particles-per-cell at 24- and 48-h time points. Macrophage responses were measured using cytotoxicity assays, viability assays, proliferation assays and cytokine analysis (IL-1b, IL-6, IL-8, MCP-1, and TNF-α). In general, there were no significant differences between PEEK-OPTIMA, UHMWPE, and X-UHMWPE particles on macrophage viability or proliferation. However, macrophages demonstrated greater cytotoxicity responses to UHMWPE and X-UHMWPE than to PEEK-OPTIMA at 24 and 48 h, where 0.7 μm-UHMWPE particles produced the highest amount of cytotoxicity. Particles of X-UHMWPE more than PEEK-OPTIMA and UHMWPE induced IL-1β, IL-6, MCP-1, and TNF-α at 24 h, p UHMWPE particles, in that they induced less inflammatory cytokine responses and thus, in part, demonstrates that PEEK-OPTIMA implant debris does not represent an increased inflammatory risk over that of UHMWPE.

  8. Ultra high molecular weight polyethylene as a base material for shielding cosmic radiation in aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Marlon A., E-mail: marlon@ieav.cta.br [Instituto de Estudos Avancados (IEAv), Sao Jose dos Campos, SP (Brazil). Divisao de Fisica Aplicada; Goncalez, Odair L. [Instituto Tecnologico de Aeronautica (PG/CTE/ITA), Sao Jose dos Campos, SP (Brazil). Programa de Pos-Graduacao em Ciencias e Tecnologias Espaciais

    2013-07-01

    Materials with high content of hydrogen have good properties of shielding against the effects of cosmic rays (CR) because are less effective than materials with high nuclear masses in the generation of secondary radiation. Beside the Aluminum, Polyethylene has been used as a reference and as a base material for composites applied in structures and in shielding of ionizing radiation for aerospace applications. Ultra high molecular weight polyethylene (UHMWPE), pure and doped 10% by mass with cadmium chloride, had its shielding properties for CR evaluated in this paper. Methodology used was based in conventional radioactive sources employed on simple geometries experiments and then computational simulation for isotropic fluxes of cosmic-ray high energy particles. Transmission experiments were performed with a3.7GBq (100 mCi){sup 241}Am-Be neutron source and a set of conventional calibration gamma radiation sources. Samples were characterized according to their gamma total attenuation coefficients from 59 to 1,408 keV, dose deposition curve for {sup 60}Co gamma-rays, fast neutron transmission coefficient, generation and self-absorption of thermal neutrons as well as their generation of internal cascades of secondary electrons and gamma-rays by nuclear interactions of fast neutrons with shielding material. Main effects of the additive in the polyethylene base were the most effective removal of gamma radiation and of secondary electrons with energies below 200 keV, the reduction of the albedo as well as the thermal neutrons transmission. Dose reduction due to primary CR were not significant, since the largest contribution to the doses due to high energy ionizing particles transmitted and, also, due to secondary radiation with energy above 1 MeV produced in shielding. (author)

  9. Wear-testing of a temporomandibular joint prosthesis : UHMWPE and PTFE against a metal ball, in water and in serum

    NARCIS (Netherlands)

    Van Loon, JP; Verkerke, GJ; de Bont, LGM; Liem, RSB

    1999-01-01

    For a temporomandibular joint prosthesis, an estimation of the wear rate was needed, prior to patient application. Therefore, we determined the in vitro wear rate of the ball-socket articulation of this prosthesis, consisting of a metal head and an ultra-high molecular weight polyethylene (UHMWPE) c

  10. The effects of proton radiation on UHMWPE material properties for space flight and medical applications

    Science.gov (United States)

    Cummings, Chad S.; Lucas, Eric M.; Marro, Justin A.; Kieu, Tri M.; DesJardins, John D.

    2011-11-01

    Ultra High Molecular Weight Polyethylene (UHMWPE) is a polymer widely used as a radiation shielding material in space flight applications and as a bearing material in total joint replacements. As a long chain hydrocarbon based polymer, UHMWPE's material properties are influenced by radiation exposure, and prior studies show that gamma irradiation is effective for both medical sterilization and increased wear resistance in total joint replacement applications. However, the effects of space flight radiation types and doses on UHMWPE material properties are poorly understood. In this study, three clinically relevant grades of UHMWPE (GUR 1020, GUR 1050, and GUR 1020 blended with Vitamin E) were proton irradiated and tested for differences in material properties. Each of the three types of UHMWPE was irradiated at nominal doses of 0 Gy (control), 5 Gy, 10 Gy, 20 Gy, and 35 Gy. Following irradiation, uniaxial tensile testing and thermal testing using Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were performed. Results show small but significant changes in several material properties between the control (0 Gy) and 35 Gy samples, indicating that proton irradiation could have a effect on the long term performance of UHMWPE in both medical and space flight applications.

  11. Novel active stabilization technology in highly crosslinked UHMWPEs for superior stability

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew L.; Wannomae, Keith K.; Muratoglu, Orhun K.

    2014-12-01

    Radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is the bearing of choice in joint arthroplasty. The demands on the longevity of this polymer are likely to increase with the recently advancing deterioration of the performance of alternative metal-on-metal implants. Vitamin E-stabilized, cross-linked UHMWPEs are considered the next generation of improved UHMWPE bearing surfaces for improving the oxidation resistance of the polymer. It was recently discovered that in the absence of radiation-induced free radicals, lipids absorbed into UHMWPE from the synovial fluid can initiate oxidation and result in new free radical-mediated oxidation mechanisms. In the presence of radiation-induced free radicals, it is possible for the polymer to oxidize through both existing free radicals at the time of implantation and through newly formed free radicals in vivo. Thus, we showed that reducing the radiation-induced free radicals in vitamin E-stabilized UHMWPE would increase its oxidative stability and presumably lead to improved longevity. We describe mechanical annealing and warm irradiation of irradiated vitamin E blends as novel methods to eliminate 99% of radiation-induced free radicals without sacrificing crystallinity. These are significant improvements in the processing of highly cross-linked UHMWPE for joint implants with improved longevity.

  12. Characterization and Accelerated Ageing of UHMWPE Used in Orthopedic Prosthesis by Peroxide

    Directory of Open Access Journals (Sweden)

    Herman Mansur

    2009-05-01

    Full Text Available Ultra-high molecular weight polyethylene (UHMWPE has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important mechanical properties to extend the longevity of knee prostheses. Though accelerated in vitro protocols have been developed to test the relative oxidation resistance of various types of UHMWPE, its mechanism is not accurately understood yet. Thus, in the present study an accelerated ageing of UHMWPE in hydrogen peroxide solution was performed and relative oxidation was extensively characterized by Fourier Transformed Infrared Spectroscopy (FTIR spectroscopy and the morphological changes were analyzed by Scanning Electron Microscopy (SEM. Different chemical groups of UHMWPE associated with the degradation reaction were monitored for over 120 days in order to evaluate the possible oxidation mechanism(s which may have occurred. The results have provided strong evidence that the oxidation mechanism is rather complex, and two stages with their own particular first-order kinetics reaction patterns have been clearly identified. Furthermore, hydrogen peroxide has proven to be an efficient oxidative medium to accelerate ageing of UHMWPE.

  13. Characterization and Accelerated Ageing of UHMWPE Used in Orthopedic Prosthesis by Peroxide

    Science.gov (United States)

    Rocha, Magda; Mansur, Alexandra; Mansur, Herman

    2009-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important mechanical properties to extend the longevity of knee prostheses. Though accelerated in vitro protocols have been developed to test the relative oxidation resistance of various types of UHMWPE, its mechanism is not accurately understood yet. Thus, in the present study an accelerated ageing of UHMWPE in hydrogen peroxide solution was performed and relative oxidation was extensively characterized by Fourier Transformed Infrared Spectroscopy (FTIR) spectroscopy and the morphological changes were analyzed by Scanning Electron Microscopy (SEM). Different chemical groups of UHMWPE associated with the degradation reaction were monitored for over 120 days in order to evaluate the possible oxidation mechanism(s) which may have occurred. The results have provided strong evidence that the oxidation mechanism is rather complex, and two stages with their own particular first-order kinetics reaction patterns have been clearly identified. Furthermore, hydrogen peroxide has proven to be an efficient oxidative medium to accelerate ageing of UHMWPE.

  14. DLC coatings for UHMWPE: relationship between bacterial adherence and surface properties.

    Science.gov (United States)

    Del Prado, G; Terriza, A; Ortiz-Pérez, A; Molina-Manso, D; Mahillo, I; Yubero, F; Puértolas, J A; Manrubia-Cobo, M; Gómez Barrena, E; Esteban, J

    2012-10-01

    Development of intrinsically antibacterial surfaces is of key importance in the context of prostheses used in orthopedic surgery. This work presents a thorough study of several plasma-based coatings that may be used with this functionality: diamond-like carbon (DLC), fluorine-doped DLC (F-DLC), and a high-fluorine-content-carbon-fluor polymer (CF(X)). The coatings were obtained by a radio-frequency plasma-assisted deposition on ultra high molecular weight polyethylene (UHMWPE) samples and physicochemical properties of the coated surfaces were correlated with their antibacterial performance against collection and clinical Staphylococcus aureus and Staphylococcus epidermidis strains. The fluorine content and the relative amount of C-C and C-F bonds were controlled by X-ray photoelectron spectroscopy, and hydrophobicity and surface tension by contact angle measurements. Surface roughness was studied by Atomic Force Microscopy. Additional nanoidentation studies were performed for DLC and F-DLC coatings. Unpaired t test and regression linear models evaluated the adherence of S. aureus and S. epidermidis on raw and coated UHMWPE samples. Comparing with UHMWPE, DLC/UHMWPE was the least adherent surface with independence of the bacterial species, finding significant reductions (p ≤ 0.001) for nine staphylococci strains. Bacterial adherence was also significantly reduced in F-DLC/ UHMWPE and CFx/UHMWPE for six strains.

  15. An Environmentally Friendly Process for the Preparation of UHMWPE As-Spun Fibres

    Directory of Open Access Journals (Sweden)

    Abdul Waqar Rajput

    2014-01-01

    Full Text Available The extrusion of ultra high molecular weight polyethylene (UHMWPE fibres cannot be achieved by conventional extrusion processes due to its very high melt viscosity. To overcome this limitation, UHMWPE is first dissolved in a petrochemical to form a gel before extrusion. The petrochemicals used to dissolve the polymer then need to be removed using other chemicals making the process unfriendly to the environment. This article is focused on finding an environmentally friendly, natural solution to replace these chemicals and altering the process to potentially reduce the process cost.

  16. Effect of Different Bearing Ratios on the Friction between Ultrahigh Molecular Weight Polyethylene Ski Bases and Snow.

    Science.gov (United States)

    Rohm, Sebastian; Knoflach, Christoph; Nachbauer, Werner; Hasler, Michael; Kaserer, Lukas; van Putten, Joost; Unterberger, Seraphin H; Lackner, Roman

    2016-05-18

    The purpose of this study was to analyze the effect of surfaces with different bearing ratios, but similar roughness heights, on the friction between ultrahigh molecular weight polyethylene (UHMWPE) and snow. On a linear tribometer positioned inside a cold chamber, the different samples were tested over a wide range of velocities and snow temperatures. The surface roughness was measured with a focus variation microscope and analyzed using the bearing ratio curve and its parameters. The surface energy was investigated by measuring the contact angles of a polar (water) and nonpolar (diiodmethane) liquid. The friction tests showed that the bearing ratio had a major effect on the friction between UHMWPE and snow. For temperatures close to the melting point a surface with wide grooves and narrow plateaus (nonbearing surface) performed well. For cold conditions, the friction was less for a surface with narrow grooves and wide plateaus (bearing surface). Interpretations of the results are given on the basis of mixed friction, with lubricated friction being dominant at higher snow temperatures and solid-solid interaction at lower ones.

  17. A two-dimensional model of cyclic strain accumulation in ultra-high molecular weight polyethylene knee replacements.

    Science.gov (United States)

    Reeves, E A; Barton, D C; FitzPatrick, D P; Fisher, J

    1998-01-01

    As new methods of sterilization of the ultra-high molecular weight polyethylene (UHMWPE) component in knee replacements are introduced, reported incidents of delamination will decrease. The prediction of plastic strain accumulation and associated failure mechanisms will then become more important in knee replacement design. The finite element analysis reported in this paper aims to advance the modelling of strain accumulation in UHMWPE over repeated gait cycles and seeks to determine the effects of the knee replacement design variables of geometry and kinematics. Material testing was performed under cyclic and creep conditions to generate the elastic, viscoplastic material model that has been used in this time-dependent analysis. Non-conforming geometries were found to accumulate plastic strains at higher rates than conforming geometries. The anatomical motion known as rollback initially produced lower strain rates, but predictions of the long-term response indicated that designs which allow rollback may produce higher strains than static designs after only about a week of loading for a knee replacement patient.

  18. Influence of surface PMPC brushes on tribological and biocompatibility properties of UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Dangsheng, E-mail: xiongds@163.com; Deng, Yaling; Wang, Nan; Yang, Yuanyuan

    2014-04-01

    Graphical abstract: - Highlights: • Wettability and blood compatibility of PMPC-grafted UHMWPE were improved. • The friction properties including the short and long term under high contact stress were investigated. • The PMPC brushes were sheared off from the surface with the increase of sliding cycles. - Abstract: Extremely efficient lubrication has been observed between natural joint surfaces and the friction coefficients can reach as low as 0.001. However, attaining the ultra-low friction coefficients between articulating cartilage surfaces in any artificial joints remains a challenge for bio-tribologists. In order to obtain the ultra-low friction coefficients as in natural joints, a biomimetic zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted on the ultra high molecular weight polyethylene (UHMWPE) by UV radiation and self-polymerized to form brush-like structure. The results of total reflection (FT-IR/ATR) spectra and X-ray photoelectron spectroscopy (XPS) spectra indicated successful grafting of PMPC on to the UHMWPE surface (Polymerization of 2-methacryloyloxyethyl phosphorylcholine). The water contact angle of UHMWPE decreased from 80° to 15° after grafting PMPC for 45 min. Tribological properties were tested under high contact stress for a longer duration of time. The friction coefficient of the sample grafted with PMPC was found to be much lower than that of untreated UHMWPE at initial stage which increased gradually with the increase of the cycle till it attained the same level as that observed for untreated UHMWPE. The wear rate of modified samples was decreased by 37% and 46% in distilled water and saline, respectively. The highly hydrated PMPC layer provided efficient lubrication at the interface between the sliding couple leading to wear reduction of UHMWPE. Furthermore, blood compatibility of modified artificial joint materials was improved significantly, which has been attributed to the properties and

  19. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    Science.gov (United States)

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A

    1999-08-01

    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene.

  20. Tensile behaviour of polyethylene and poly(p-xylylene) fibres

    NARCIS (Netherlands)

    van der Werff, Harm

    1991-01-01

    This thesis deals with the tensile behaviour of fibres prepared from high molecular weight polymers.The tensile strength of a polymeric fibre is in general much lower than the corresponding theoretical value. In case of ultra-high molecular weight polyethylene (UHMWPE), fibres can be prepared by gel

  1. Radiation synthesis of a new amidoximated UHMWPE fibrous adsorbent with high adsorption selectivity for uranium over vanadium in simulated seawater

    Science.gov (United States)

    Gao, Qianhong; Hu, Jiangtao; Li, Rong; Xing, Zhe; Xu, Lu; Wang, Mouhua; Guo, Xiaojing; Wu, Guozhong

    2016-05-01

    A new kind of highly efficient adsorbent material has been fabricated in this study for the purpose of extracting uranium from seawater. Ultra-high molecular weight polyethylene (UHMWPE) fiber was used as a trunk material for the adsorbent, which was prepared by a series of modification reactions, as follows: (1) grafting of glycidyl methacrylate (GMA) and methyl acrylate (MA) onto UHMWPE fibers via 60Co γ-ray pre-irradiation; (2) aminolyzation of UHMWPE fiber by the ring-opening reaction between of epoxy groups PGMA and ethylene diamine (EDA); (3) Michael addition of amino groups with acrylonitrile (AN) to yield nitrile groups; (4) amidoximation of the attached nitrile moieties by hydroxylamine in dimethyl sulfoxide-water mixture. Modified UHMWPE fibers were characterized by means of attenuated total reflectance-Fourier transformed infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to confirm the attachment of amidoxime (AO) groups onto the UHMWPE fibers. The results of X-ray diffraction (XRD) and single fiber tensile strength verified that the modified UHMWPE fiber retained excellent mechanical properties at a low absorbed radiation dose. The adsorption performance of the UHMWPE fibrous adsorbent was evaluated by subjecting it to an adsorption test in simulated seawater using a continuous-flow mode. The amount of uranium adsorbed by this AO-based UHMWPE fibrous adsorbent was 1.97 mg-U/g after 42 days. This new adsorbent also showed high selectivity for the uranyl ion, and its selectivity for metal ions was found to decrease in the following order: U>Cu>Fe>Ca>Mg>Ni>Zn>Pb>V>Co. The adsorption selectivity for uranium is significantly higher than that for vanadium. In addition, preparation of this modified adsorbent consumes much smaller amounts of the toxic acrylonitrile monomer than the conventional preparation methods of AO-based polyethylene fibers.

  2. Influence of heat treatment on structural, mechanical and wear properties of crosslinked UHMWPE.

    Science.gov (United States)

    Chiesa, R; Moscatelli, M; Giordano, C; Siccardi, F; Cigada, A

    2004-01-01

    New crosslinked ultra high molecular weight polyethylenes (UHMWPEs) have recently been developed, characterized and introduced in clinical applications. UHMWPE cross-linking treatments are very promising for reducing osteolysis induced by wear debris. The irradiation type, gamma or beta, the dosage and the thermal treatment performed during or following the irradiation process are all factors affecting polyethylene wear resistance. Thermal stabilization treatments performed after or during the irradiation process at a temperature above melting point (i.e. >130 degrees C) have been proven to effectively remove the free radicals generated during irradiation from UHMWPE, but their effect on the mechanical properties of UHMWPE are not completely clear. In addition to wear rate reduction, maintaining good mechanical properties is fundamental aspect in designing the new generation of crosslinked UHMWPE for artificial load bearing materials, especially considering the application in total knee replacements. In this study, we investigated the influence of different stabilization treatments, performed after gamma irradiation, on structural, wear and mechanical properties of UHMWPE. We performed four different stabilization treatments, with different temperatures and cooling rates, on 100 kGy gamma irradiated UHMWPE. Structural properties of UHMWPE were assessed by differential scanning calorimetry (DSC). To assess the mechanical performance of the materials, uni-axial tensile tests were performed according to the ASTM D638 standard, bi-axial tension performance was evaluated by small punch tests (ASTM F2183-02), toughness resistance was evaluated by the Izod method (ASTM F648), and cold flow resistance was analysed by a dynamic compressive test. Evaluation of wear resistance was by a multidirectional pin-on-disk screening machine. Materials considered were in "aged" and "non-aged" conditions. Results confirmed that cross-linking greatly enhances UHMWPE wear resistance, but

  3. Effect of ZnO morphology on affecting bactericidal property of ultra high molecular weight polyethylene biocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Rajeev Kumar [Biomaterials Processing and Characterization Laboratory, Indian Institute of Technology Kanpur, Kanpur -208016 (India); Agarwal, Meenakshi [Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh - 201303 (India); Balani, Kantesh, E-mail: kbalani@iitk.ac.in [Biomaterials Processing and Characterization Laboratory, Indian Institute of Technology Kanpur, Kanpur -208016 (India)

    2016-05-01

    Bacterial infection of implants can be controlled by selective trapping of bacteria, followed with consequent killing by targeted antibacterial agents. Herein, the role of various ZnO morphologies, viz. micro-rods (R), nanoparticles (NP), and micro-disks (D) on antibacterial efficacy of ZnO via release of Zn{sup 2+} and H{sub 2}O{sub 2} is assessed, both as isolated powders and via incorporating them in cytocompatible ultra high molecular weight polyethylene (UHMWPE). Though ZnO is antibacterial, interestingly, all ZnO morphologies elicited a supportive growth of gram-negative bacteria (Escherichia coli) in culture medium (until 28–35 μg/ml). But, all ZnO morphologies did elicit bactericidal effect on gram positive bacteria (Staphylococcus aureus or Staphylococcus epidermidis) both in culture medium (for 0–2.5 μg/ml) or when incorporated (5–20 wt.%) into UHMWPE. The bactericidal mechanisms were quantified for various ZnO morphologies via: (i) H{sub 2}O{sub 2} production, (ii) Zn{sup 2+} release, and (iii) the presence of surface oxygen vacancies. On one hand, where only ZnO(NP) elicited release of H{sub 2}O{sub 2} in the absence of light, maximum Zn{sup 2+} release was elicited by ZnO(D). Interestingly, when ZnO is incorporated as reinforcement (5–20 wt.%), its antibacterial action against E. coli was vividly observed due to selective proliferation of bacteria only on friendly UHMWPE matrix. Hence, luring bacteria on affable UHMWPE surface can be complemented with their targeted killing by ZnO present in composite. - Highlights: • The role of ZnO morphology in affecting bactericidal mechanisms • Quantification of Zn{sup 2+} release, H{sub 2}O{sub 2} production and surface oxygen vacancy defects • Inherent resistance by gram negative bacteria at lower ZnO concentrations • Containment of bacteria on polymeric surface and consequent targeted killing by ZnO.

  4. 纤维级超高分子量聚乙烯的制备及性能研究%Preparation and properties of fiber-grade ultrahigh-molecular weight polyethylene

    Institute of Scientific and Technical Information of China (English)

    李晓庆; 周建勇; 毕晓龙; 李留忠; 李文义; 裴小静

    2012-01-01

    采用自制新型高效负载型QTE-1催化剂,合成了用于纺丝的纤维级超高分子量聚乙烯(UHMWPE),进行了中试以及工业化生产;考察了反应温度、反应压力等工艺条件对UHMWPE性能的影响,并考察了其纺丝性能.结果表明:QTE-1催化剂体系聚合活性较高,可达5×104g/(g·h)以上,反应动力学平稳,UHMWPE黏均分子量可达4×106以上;UHMWPE黏均分子量随反应温度的升高而降低,随反应压力的增大而增高;UHMWPE堆密度随反应温度和反应压力升高而增高;UHMWPE中试和工业化生产工艺平稳,产品性能优异,能够较好地满足纺丝要求.UHMWPE纤维断裂强度达28.44 cN/dtex,模量达1 400 cN/dtex.%A fiber-grade ultrahigh-molecular weight polyethylene (UHMWPE) was synthesized using self-made novel high-efficiency supported catalyst QTE-1. The pilot and commercial production were carried out. The effects of process conditions, including reaction temperature and pressure, on the properties of UHMWPE were investigated. The spinning performance of UHMWPE was also studied. The results showed that QTE-1 catalyst system had relatively high polymerization activity above 5 x 104 g/( g o h) and provided steady reaction kinetics, and UHMWPE had the viscous average molecular weight over 4 x 106; the viscous average molecular weight of UHMWPE dropped with the increase of reaction temperature and rose with the increase of reaction pressure when the bulk density increased with the increase of reaction temperature and pressure; the pilot and commercial production of UHMWPE proceeded stably and the product satisfied the spinning requirement due to its excellent properties. UHMWPE fiber had the breaking strength of 28.44 cN/dtex and modulus of 1 400 cN/dtex.

  5. Micro X-Ray Computed Tomography Mass Loss Assessment of Different UHMWPE: A Hip Joint Simulator Study on Standard vs. Cross-Linked Polyethylene

    Science.gov (United States)

    Zanini, Filippo; Carmignato, Simone

    2017-01-01

    More than 60.000 hip arthroplasty are performed every year in Italy. Although Ultra-High-Molecular-Weight-Polyethylene remains the most used material as acetabular cup, wear of this material induces over time in vivo a foreign-body response and consequently osteolysis, pain, and the need of implant revision. Furthermore, oxidative wear of the polyethylene provoke several and severe failures. To solve these problems, highly cross-linked polyethylene and Vitamin-E-stabilized polyethylene were introduced in the last years. In in vitro experiments, various efforts have been made to compare the wear behavior of standard PE and vitamin-E infused liners. In this study we compared the in vitro wear behavior of two different configurations of cross-linked polyethylene (with and without the add of Vitamin E) vs. the standard polyethylene acetabular cups. The aim of the present study was to validate a micro X-ray computed tomography technique to assess the wear of different commercially available, polyethylene’s acetabular cups after wear simulation; in particular, the gravimetric method was used to provide reference wear values. The agreement between the two methods is documented in this paper. PMID:28107468

  6. Characteristics of metal and ceramic total hip bearing surfaces and their effect on long-term ultra high molecular weight polyethylene wear.

    Science.gov (United States)

    Davidson, J A

    1993-09-01

    The micromechanics of ultra high molecular weight polyethylene (UHMWPE) wear in total hip replacement are very complex. Polyethylene wear from the metal head and debris formation are two common types of wear. There are additional wear-related processes occurring at the metal-bearing surfaces that are not well-known, however. This study outlines these processes, including (1) surface wettability changes, (2) oxidative wear of metal surfaces, (3) microabrasion of metal surfaces from oxide film damage, and (4) surface abrasion from three-body polymethylmethacrylate and bone debris. These processes can contribute to metal ion release and a gradual increase in the roughness of the metal surfaces. This can lead to increased long-term UHMWPE wear. Of the metal alloys currently used in total hip replacements, Co-Cr-Mo alloy is significantly more resistant to roughening processes. Hard, stable, oxide: ceramic surfaces articulating against UHMWPE are essentially immune to these surface-roughening processes, however. In addition, they provide a more wettable surface, further minimizing polyethylene wear relative to metal surfaces. By analyzing metal release rates from metal-polyethylene wear tests, it is shown here that Co-Cr-Mo is gradually removed at a rate of about 0.1 micron per year (10(6) cycles), whereas 316L stainless steel is removed on the order of 0.2 microns per year and Ti-6Al-4V on the order of 1 micron per year. The wear rate of Co-Cr-Mo articulating against itself is reported to be still greater, at about 2-4 microns per year after an initial wear-in period. Because metal is gradually removed with articulation time, surface-hardening methods such as nitrogen ion implantation can be expected to provide only temporary resistance to these metal removal and surface-roughening processes. Hard, stable ceramic surfaces such as Al2O3 and ZrO2, however, can be expected to maintain their initial surface finish and thus minimize UHMWPE wear in the long term.

  7. MA-SEBS对超高分子量聚乙烯/碳纳米管复合材料结晶和熔融行为的影响%Effect of MA-SEBS on crystallization and melting behavior of ultra high molecular weight polyethylene/carbon nanotube composites

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    以马来酸酐接枝SEBS (MA-SEBS)作相容剂,采用溶液共混的方法制备超高分子量聚乙烯(UHMWPE)/碳纳米管(CNTs)复合材料.熔融结晶的UHMWPE/CNT复合材料是将其熔体以20℃/分的速率降温结晶而成.采用差示扫描量热法(DSC)研究了以不同方式结晶制备的UHMWPE/CNT复合材料的结晶和熔融行为.结果表明UHMWPE/CNT复合材料中UHMWPE相在溶液态结晶比在熔融态结晶形成的晶片厚,因而表现出更高的熔点(Tm)和结晶度(Xc).随着CNTs含量增加,UHMWPE/CNT复合材料中UHMWPE相的结晶温度(Tc)趋于提高.而且MA-SEBS的加入降低了UHMWPE/CNT复合材料中UHMWPE相的Tm 和 Tc. 此外UHMWPE/CNT复合材料中UHMWPE相的结晶速率随CNTs的引入而提高; MA-SEBS起相容剂的作用,改善了CNTs在UHMWPE基体中的分散性,使UHMWPE相的结晶速率进一步提高.%Ultra-high molecular weight polyethylene (UHMWPE) is filled with carbon nano-tubes (CNTs) by solution in the presence of maleic anhydride grafted styrene-(ethylene-co-butylene)-styrene copolymer (MA-SEBS) as a compatibilizer. The UHMWPE/CNT composites crystallized in melting state were prepared at a cooling rate of 20 ℃ min-1. The melting and crystallization behaviors of UHMWPE/CNT composites were investigated by differential scanning calorimetry. The results showed that Tm and Xc of UHMWPE/CNT composites crystallized in solution state are higher than those in melting state due to the larger crystalline lamellar thickness. Tc of UHMWPE/CNT composites tends to shift to higher temperature region with increasing CNTs content in the composites. Tm and Tc of UHMWPE phase in UHMWPE/CNT composites decrease with the addition of MA-SEBS. Moreover, the crystallization rate of UHMWPE phase in UHMWPE/CNT composite is accelerated due to the introduction of CNTs. MA-SEBS acts as compatilizer, enhances the dispersion of CNTs in the UHMWPE matrix. Thereby, the crystallization rate of UHMWPE phase in UHMWPE

  8. Modeling Ballistic Response of Ultra-High-Molecular-Weight Polyethylene (UHMWPE)

    Science.gov (United States)

    2016-07-01

    materials in front of the projectile deform and fail, which can absorb a lot of the energy. Fast energy drop occurs for this stage. The second stage is...in evaluating behind helmet blunt trauma , which results when the deformed helmet contacts the head. Of course, the set of parameters is not

  9. Study on the rheological behavior of ultra-high molecular weight polyethylene/liner low density polyethylene/hyper-branched polyester-amide blends%UHMWPE/LLDPE/HBP共混体系流变行为研究

    Institute of Scientific and Technical Information of China (English)

    王亓超; 于俊荣; 张天; 陈蕾; 胡祖明; 诸静

    2012-01-01

    In order to improve the processing properties of ultra-high molecular weight polyethylene, blends of ultra-high molecular weight polyethylene/liner low density polyethylene/hyper-branched polyester-amide were prepared. The rheological behavior of UHMWPE/LLDPE/HBP blends was researched in this paper. The results indicated the apparent viscosity of the blends first deceases and then increases with increasing of HBP content. The blends are shear-thinning fluid and the non-Newtonian index less than 1. The viscous flow activation energy of the blends is lowest when the shear rate is 10 s~. The structural viscosity index of blends was decreased with the HBP content increased and increase with the viscosity average relative molecular weight of UHMWPE increased.%为改善超高相对分子质量聚乙烯(UHMWPE)的加工流变性,将超支化聚酯酰胺(HBP)和线性低密度聚乙烯(LLDPE)与UHMWPE共混,研究了不同比例UHMwPE/LLDPE/HBP共混体系的流变行为。结果表明:UHMWPE/LLDPE/HBP共混体系熔体表观粘度随HBP质量分数的增加而减小;共混体系非牛顿指数〈1,为典型的切力变稀流体;当剪切速率为10s。时,共混体系的粘流活化能较小;结构粘度指数随HBP质量分数增加而下降,随UHMWPE粘均相对分子质量增加而增大。

  10. Static and Dynamic Properties of Semi-Crystalline Polyethylene

    Directory of Open Access Journals (Sweden)

    Ming-ming Xu

    2016-03-01

    Full Text Available Properties of extruded polymers are strongly affected by molecular structure. For two different semi-crystalline polymers, low-density polyethylene (LDPE and ultra-high molecular weight polyethylene (UHMWPE, this investigation measures the elastic modulus, plastic flow stress and strain-rate dependence of yield stress. Also, it examines the effect of molecular structure on post-necking tensile fracture. The static and dynamic material tests reveal that extruded UHMWPE has a somewhat larger yield stress and much larger strain to failure than LDPE. For both types of polyethylene, the strain at tensile failure decreases with increasing strain-rate. For strain-rates 0.001–3400 s−1, the yield stress variation is accurately represented by the Cowper–Symonds equation. These results indicate that, at high strain rates, UHMWPE is more energy absorbent than LDPE as a result of its long chain molecular structure with few branches.

  11. Influence of DBD plasma pretreatment on the deposition of chitosan onto UHMWPE fiber surfaces for improvement of adhesion and dyeing properties

    Science.gov (United States)

    Ren, Yu; Ding, Zhirong; Wang, Chunxia; Zang, Chuanfeng; Zhang, Yin; Xu, Lin

    2017-02-01

    The combination treatment of dielectric barrier discharge (DBD) plasma and chitosan coatings was performed on ultrahigh molecular weight polyethylene (UHMWPE) fibers in order to improve the wettability, dyeability and adhesion properties. The properties of UHMWPE fibers coated with chitosan, after being pretreated by DBD plasma, were evaluated through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The interfacial shear strength (IFSS) between the fiber and the epoxy resin was determined using the single fiber pull-out test technique. The modified UHMWPE fibers were dyed with reactive dyes after the combined treatment. Surface wettability and dyeability were investigated by water contact angle and K/S measurement, respectively. SEM images confirmed that the chitosan was induced onto the surfaces of the UHMWPE fibers after the combined treatment. The XPS analysis showed that the oxygen and nitrogen contents of the UHMWPE fiber surfaces after the combined treatment were higher than that of the fiber modified by chitosan without DBD plasma pretreatment. Meanwhile, the UHMWPE fibers treated with combination of DBD plasma and chitosan treatment had better wettability, dyeability and adhesion property than those of the non-plasma pretreated surfaces, indicating that DBD plasma pretreatment facilitated the deposition of chitosan onto the UHMWPE surfaces.

  12. Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sherazi, Tauqir A. [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Guiver, Michael D.; Kingston, David; Xue, Xinzhong [Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Ahmad, Shujaat [PIEAS/PINSTECH, P O Nilore, Islamabad 45650 (Pakistan); Kashmiri, M. Akram [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Board of Intermediate and Secondary Education, Lahore 54000 (Pakistan)

    2010-01-01

    Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a {sup 60}Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by X-ray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion {sup registered} 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acid-type membranes for DMFC. (author)

  13. Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

    Science.gov (United States)

    Sherazi, Tauqir A.; Guiver, Michael D.; Kingston, David; Ahmad, Shujaat; Kashmiri, M. Akram; Xue, Xinzhong

    Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a 60Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by X-ray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion ® 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acid-type membranes for DMFC.

  14. Effects of simulated oxidation on the in vitro wear and mechanical properties of irradiated and melted highly crosslinked UHMWPE.

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew L; Doshi, Brinda N; Fu, Jun; Muratoglu, Orhun K

    2016-02-01

    Radiation crosslinked ultrahigh molecular weight polyethylene (UHMWPE) have reduced the wear rate of the bearing surface in total joint arthroplasty and the incidence of peri-prosthetic bone loss due to wear particles. The oxidation potential afforded to the material by the trapped residual free radicals after irradiation was addressed in first generation crosslinked UHMWPEs by using thermal treatments such as annealing or melting after irradiation. Postirradiation melted crosslinked UHMWPE did not contain detectable free radicals at the time of implantation and was expected to be resistant against oxidation for the lifetime of the implants. Recent analyses of long-term retrievals showed it was possible for irradiated and melted UHMWPEs to oxidize in vivo but studies on the effects of oxidation on these materials have been limited. In this study, we determined the effects of in vitro aging on the wear and mechanical properties of irradiated and melted UHMWPE as a function of radiation dose and found that even small amount of oxidation (oxidation index of 0.1) can have detrimental effects on its mechanical properties. There was a gradual increase in the wear rate below an oxidation index of 1 and a drastic increase thereafter. Therefore, it was shown in a simulated environment that oxidation can have detrimental effects to the clinically relevant properties of irradiated and melted UHMWPEs.

  15. 表面改性提高与Ti6A14V对磨材料UHMWPE摩擦学性能%Improvement in the Tribological Properties of UHMWPE Sliding against Ti6Al4V by Surface Modification

    Institute of Scientific and Technical Information of China (English)

    施雯; 董汉山

    2005-01-01

    Surface engineering has been emerging as one of the most promising technologies to improve the tribological properties of biomaterials with a view to extending the life span of medical implants. For example, some novel surface engineering techniques including ion implantation of ultra-high molecular weight polyethylene (UHMWPE) and thermal oxidation (TO) treatment of titanium alloy have been developed. However, the full potential of improving the wear resistance of orthopaedic implants based on the UHMWPE/ Ti6Al4V system will not be realized until the tribological performance of this surface engineered tribo-system is fully characterized and the acting wear mechanisms are well understood. In this paper, a pin-on-disc tribometer was employed to evaluate the tribological response of the following three tribo-systems: (1) untreated UHMWPE/untreated Ti6Al4V, (2) untreated UHMWPE/TO-treated Ti6Al4V and (3) ion implanted UHMWPE/TO treated Ti6Al4V under water lubricated conditions. Experimental results show that the tribological properties of UHMWPE can be significantly increased by surface engineering its surface and/or the counterface. This can be attributed to the hardened surface of UHMWPE via molecular structure modification induced by ion bean bombardment coupled with the surface oxide layer on Ti6Al4V formed during TO treatment, which has favorable tribological compatibility with UHMWPE.

  16. EFFECTS OF TRITIUM ON UHMW-PE, PTFE, AND VESPEL POLYIMIDE

    Energy Technology Data Exchange (ETDEWEB)

    Clark, E; Kirk Shanahan, K

    2006-11-01

    Samples of ultrahigh molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE), and the polyimide Vespel{reg_sign} were exposed to tritium gas in closed containers initially at 101 kPa (1 atmosphere) pressure and ambient temperature for various times up to 2.3 years. Tritium exposure effects on the samples were characterized by dynamic mechanical analysis (DMA) and radiolysis products were characterized by measuring the total final pressure and composition in the exposure containers at the end of exposure period.

  17. Oxidation resistant peroxide cross-linked UHMWPE produced by blending and surface diffusion

    Science.gov (United States)

    Gul, Rizwan M.; Oral, Ebru; Muratoglu, Orhun K.

    2014-06-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been widely used as acetabular cup in total hip replacement (THR) and tibial component in total knee replacement (TKR). Crosslinking of UHMWPE has been successful used to improve its wear performance leading to longer life of orthopedic implants. Crosslinking can be performed by radiation or organic peroxides. Peroxide crosslinking is a convenient process as it does not require specialized equipment and the level of crosslinking can be manipulated by changing the amount of peroxide added. However, there is concern about the long-term stability of these materials due to possible presence of by-products. Vitamin E has been successfully used to promote long-term oxidative stability of UHMWPE. In this study, UHMWPE has been crosslinked using organic peroxide in the presence of Vitamin E to produce an oxidation resistant peroxide crosslinked material. Crosslinking was performed both in bulk by mixing peroxide and resin, and only on the surface using diffusion of peroxides.The results show that UHMWPE can be crosslinked using organic peroxides in the presence of vitamin E by both methods. However, the level of crosslinking decreases with the increase in vitamin E content. The wear resistance increases with the increase in crosslink density, and oxidation resistance significantly increases due to the presence of vitamin E.

  18. A surface crosslinked UHMWPE stabilized by vitamin E with low wear and high fatigue strength.

    Science.gov (United States)

    Oral, Ebru; Ghali, Bassem W; Rowell, Shannon L; Micheli, Brad R; Lozynsky, Andrew J; Muratoglu, Orhun K

    2010-09-01

    Wear particle-induced periprosthetic osteolysis has been a clinical problem driving the development of wear resistant ultrahigh molecular weight polyethylene (UHMWPE) for total joint replacement. Radiation crosslinking has been used to decrease wear through decreased plastic deformation; but crosslinking also reduces mechanical properties including fatigue resistance, a major factor limiting the longevity of joint implants. Reducing UHMWPE wear with minimal detriment to mechanical properties is an unaddressed need for articular bearing surface development. Here we report a novel approach to achieve this by limiting crosslinking to the articular surface. The antioxidant vitamin E reduces crosslinking efficiency in UHMWPE during irradiation with increasing concentration, thus we propose to spatially control the crosslink density distribution by controlling the vitamin E concentration profile. Surface crosslinking UHMWPE prepared using this approach had high wear resistance and decreased crosslinking in the bulk resulting in high fatigue crack propagation resistance. The interface region did not represent a weakness in the material due to the gradual change in the crosslink density. Such an implant has the potential of decreasing risk of fatigue fracture of total joint implants as well as expanding the use of UHMWPE to younger and more active patients.

  19. Molecular chain stretch is a multiaxial failure criterion for conventional and highly crosslinked UHMWPE.

    Science.gov (United States)

    Bergström, J S; Rimnac, C M; Kurtz, S M

    2005-03-01

    The development of accurate theoretical failure, fatigue, and wear models for ultra-high molecular weight polyethylene (UHMWPE) is an important step towards better understanding the micromechanisms of the surface damage that occur in load bearing orthopaedic components and improving the lifetime of joint arthoplasties. Previous attempts to analytically predict the clinically observed damage, wear, and fatigue failure modes have met with limited success due to the complicated interaction between microstructural deformations and continuum level stresses. In this work, we examined monotonic uniaxial and multiaxial loading to failure of UHMWPE using eight failure criteria (maximum principal stress, Mises stress, Tresca stress, hydrostatic stress, Coulomb stress, maximum principal strain, Mises strain, and chain stretch). The quality of the predictions of the different models was assessed by comparing uniaxial tension and small punch test data at different rates with the failure model predictions. The experimental data were obtained for two conventional (unirradiated and gamma radiation sterilized in nitrogen) and two highly crosslinked (150kGy, remelted and annealed) UHMWPE materials. Of the different failures models examined, the chain stretch failure model was found to capture uniaxial and multiaxial failure data most accurately for all of the UHMWPE materials. In addition, the chain stretch failure criterion can readily be calculated for contemporary UHMWPE materials based on available uniaxial tension data. These results lay the foundation for future developments of damage and wear models capable of predicting multiaxial failure under cyclic loading conditions.

  20. The Biomechanical Effect of Loading Speed on Metal-on-UHMWPE Contact Mechanics.

    Science.gov (United States)

    Zdero, Radovan; Bagheri, Zahra S; Rezaey, Mojtaba; Schemitsch, Emil H; Bougherara, Habiba

    2014-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is a material commonly used in total hip and knee joint replacements. Numerous studies have assessed the effect of its viscoelastic properties on phenomena such as creep, stress relaxation, and tensile stress. However, these investigations either use the complex 3D geometries of total hip and knee replacements or UHMWPE test objects on their own. No studies have directly measured the effect of vertical load application speed on the contact mechanics of a metal sphere indenting UHMWPE. To this end, a metal ball was used to apply vertical force to a series of UHMWPE flat plate specimens over a wide range of loading speeds, namely, 1, 20, 40, 60, 80, 100, and 120 mm/min. Pressure sensitive Fujifilm was placed at the interface to measure contact area. Experimental results showed that maximum contact force ranged from 3596 to 4520 N and was logarithmically related (R(2)=0.96) to loading speed. Average contact area ranged from 76.5 to 79.9 mm(2) and was linearly related (R(2)=0.56) to loading speed. Average contact stress ranged from 45.1 to 58.2 MPa and was logarithmically related (R(2)=0.95) to loading speed. All UHMWPE specimens displayed a circular area of permanent surface damage, which did not disappear with time. This study has practical implications for understanding the contact mechanics of hip and knee replacements for a variety of activities of daily living.

  1. Texturing of UHMWPE surface via NIL for low friction and wear properties

    Energy Technology Data Exchange (ETDEWEB)

    Kustandi, Tanu Suryadi; Low, Hong Yee [Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Choo, Jian Huei; Sinha, Sujeet K, E-mail: hy-low@imre.a-star.edu.s, E-mail: mpesks@nus.edu.s [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2010-01-13

    Wear is a major obstacle limiting the useful life of implanted ultra-high molecular weight polyethylene (UHMWPE) components in total joint arthroplasty. It has been a continuous effort in the implant industry to reduce the frictional wear problem of UHMWPE by improving the structure, morphology and mechanical properties of the polymer. In this paper, a new paradigm that utilizes nanoimprint lithography (NIL) in producing textures on the surface of UHMWPE is proposed to efficiently improve the tribological properties of the polymer. Friction and wear experiments were conducted on patterned and controlled (non-patterned) UHMWPE surfaces using a commercial tribometer, mounted with a silicon nitride ball, under a dry-sliding condition with normal loads ranging from 60 to 200 mN. It has been shown that the patterned UHMWPE surface showed a reduction in the coefficient of friction between 8% and 35% as compared with the controlled (non-patterned) surface, depending on the magnitude of the normal load. Reciprocating wear experiments also showed that the presence of surface textures on the polymer resulted in lower wear depth and width, with minimal material transfer to the sliding surface.

  2. Restricting the ageing degradation of the mechanical properties of gamma irradiated UHMWPE using MWCNTs.

    Science.gov (United States)

    Rama Sreekanth, P S; Kanagaraj, S

    2013-05-01

    Property degradation of the medical grade polymers after gamma irradiation is the primary concern that limits longevity of them. Though the conventional antioxidant material helps to reduce the degradation but it limits the degree of crosslinking of the polymer. The objective of the present work is to study the influence of multi walled carbon nanotubes (MWCNTs) on restricting the degradation of mechanical properties of medical grade ultra high molecular weight polyethylene (UHMWPE) after its irradiation. UHMWPE was reinforced by chemically treated MWCNTs at different concentrations such as 0.5, 1.0, 1.5, and 2.0 wt%. The test samples were then subjected to Co⁶⁰ gamma irradiation with an integral dose of 25, 50, 75 and 100 kGy in air. The mechanical properties of irradiated samples were evaluated within 10 days, 60 and 120 days after irradiation. It was observed that the mechanical properties of virgin UHMWPE and nanocomposites were enhanced immediately after irradiation but they were found to be reduced at later stages. It was also observed that the presence of MWCNTs limited the ageing degradation of the mechanical properties of UHMWPE. Raman spectroscopic and TEM studies confirmed the formation of irradiation induced defects on the MWCNTs. Electron spin resonance studies showed that the relative radical intensity of virgin UHWMPE was reduced significantly with an increase of MWCNTs concentration confirming the radical scavenging ability of them. It is concluded that MWCNTs restricted the ageing degradation of irradiated UHMWPE.

  3. High vitamin E content, impact resistant UHMWPE blend without loss of wear resistance.

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew; Muratoglu, Orhun K

    2015-05-01

    Antioxidant stabilization of radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) has been introduced to improve the oxidative stability of total joint implant bearing surfaces. Blending of antioxidants (most commonly vitamin E) with UHMWPE resin powder followed by consolidation and uniform radiation cross-linking is currently available for use in both total hips and total knees. It was previously shown that the fatigue resistance of vitamin E-blended and irradiated UHMWPEs could be further improved by spatially manipulating the vitamin E concentration throughout the implant and limiting cross-linking to the surface of the implant where it is necessary for wear resistance. This was possible by designing a low concentration of vitamin E on the surface and higher concentration in the bulk of the implant because cross-linking is hindered in UHMWPE as a function of increasing vitamin E concentration. In this study, we hypothesized that such a surface cross-linked UHMWPE with low wear rate and high fatigue strength could be obtained by limiting the penetration of radiation into UHMWPE with uniform vitamin E concentration. Our hypothesis tested positive; we were able to obtain control of the surface cross-linked region by manipulating the energy of the irradiation, resulting in extremely low wear, and high impact strength. In addition, we discussed alternatives of improving the oxidation resistance of such a material by using additional vitamin E reservoirs. These results are significant because this material may allow increased use of antioxidant-stabilized, cross-linked UHMWPEs in high stress applications and in more active patients.

  4. Peak Stress Intensity Factor Governs Crack Propagation Velocity In Crosslinked UHMWPE

    Science.gov (United States)

    Sirimamilla, P. Abhiram; Furmanski, Jevan; Rimnac, Clare

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) has been successfully used as a bearing material in total joint replacement components. However, these bearing materials can fail as a result of in vivo static and cyclic loads. Crack propagation behavior in this material has been considered using the Paris relationship which relates fatigue crack growth rate, da/dN (mm/cycle) versus the stress intensity factor range, ΔK (Kmax-Kmin, MPa√m). However, recent work suggests that the crack propagation velocity of conventional UHMWPE is driven by the peak stress intensity (Kmax), not ΔK. The hypothesis of this study is that the crack propagation velocity of highly crosslinked and remelted UHMWPE is also driven by the peak stress intensity, Kmax, during cyclic loading, rather than by ΔK. To test this hypothesis, two highly crosslinked (65 kGy and 100 kGy) and remelted UHMWPE materials were examined. Frequency, waveform and R-ratio were varied between test conditions to determine the governing factor for fatigue crack propagation. It was found that the crack propagation velocity in crosslinked UHMWPE is also driven by Kmax and not ΔK, and is dependent on loading waveform and frequency in a predictable quasi-static manner. The current study supports that crack growth in crosslinked UHMWPE materials, even under cyclic loading conditions, can be described by a relationship between the velocity of crack growth, da/dt and the peak stress intensity, Kmax. The findings suggest that stable crack propagation can occur as a result of static loading only and this should be taken into consideration in design of UHMWPE total joint replacement components. PMID:23165898

  5. Study on Tribological Properties of Irradiated Crosslinking UHMWPE Nano-Composite

    Institute of Scientific and Technical Information of China (English)

    Lei Xiong; Dang-sheng Xiong; Jia-bo Jin

    2009-01-01

    Ultra High Molecular Weight Polyethylene (UHMWPE) has been widely used as a bearing material for artificial joint replacement over forty years. It is usually crosslinked by gamma rays irradiation before its implantation into human body. In this study, UHMWPE and UHMWPE/nano-hydroxyapatite (n-HA) composite were prepared by vacuum hot-pressing method. The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation. The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine (model MM-200) under deionized water lubrication. Micro-morphology of wom surface was observed by metallographic microscope. Contact angle and hardness of the materials were also measured. The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation. Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA. While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation. The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear, and that of n-HA filled material is mainly characterized as abrasive wear. After gamma irradiation, the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced. Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear. The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

  6. Enhanced Thermal Performance and Impact Strength of UHMWPE/Recycled-PA6 Blends Synthesized via a Melting Extrusion Route

    Directory of Open Access Journals (Sweden)

    Xiuying Yang

    2016-01-01

    Full Text Available The blends of ultra-high molecular weight polyethylene (UHMWPE and recycled-polyamide 6 (R-PA6 were prepared via a melting extrusion route using high-density polyethylene-graft-maleic anhydride (HDPE-g-MAH as the compatibilizer. The morphologies and distributions of the chemical components of the blends were characterized by scanning electron microscopy and synchrotron Fourier transform infrared microspectroscopy. The effects of R-PA6 content on the Vicat softening temperature (VST, heat distortion temperature (HDT, and impact strength of the blends were studied. Remarkably, in comparison with those of UHMWPE, the VST and HDT of UHMWPE/R-PA6 blends with 44 wt% R-PA6 were increased to 165.1 and 98.4°C, respectively, and the Charpy impact strength and Izod impact strength of the blends were enhanced to 33.9 and 16.2 kJ/m2, respectively. In addition, it was found that the blending system containing 44 wt% R-PA6 and 48 wt% UHMWPE exhibited the best compatibility when it was prepared using 8 wt% HDPE-g-MAH. The distribution of the phases of UHMWPE and R-PA6 was uniform, and no obvious phase separation was observed in the blends.

  7. Regulation of UHMWPE biomaterials in total hip arthroplasty.

    Science.gov (United States)

    Kasser, Michael J

    2013-04-01

    This manuscript provides a brief history of the development of ultrahigh molecular weight polyethylene (UHWMPE) biomaterials and how the U.S. Food and Drug Administration (FDA) regulates medical devices. The flowchart used to decide whether a device is medium or high risk, known as the 510(k) flowchart, is illustrated by taking several examples through the flowchart. In order to demonstrate how changes to UHWMPE material used in the acetabular liners of total hips have been regulated, two major modifications to UHMWPE, highly crosslinked polyethylene and Vitamin E polyethylene, are taken through the flowchart. This manuscript describes the testing that has been provided to demonstrate safety and effectiveness of these modifications, as well as an explanation why the testing was supplied to the FDA.

  8. 超高分子量聚乙烯纤维的生产技术和市场分析%Production technology and market analysis of ultrahigh-molecular weight polyethylene fiber

    Institute of Scientific and Technical Information of China (English)

    武红艳

    2012-01-01

    介绍了超高分子量聚乙烯(UHMWPE)纤维的主要生产方法,对干法纺丝和湿法纺丝工艺路线进行了比较;分析了国内外UHMWPE纤维的生产现状、市场需求及预测;从工艺路线、生产规模及产品质量方面比较了国内外UHMWPE纤维产品之间的差距;指出干法纺丝工艺路线是今后UHMWPE纤维的主要生产技术,我国应加大干法纺丝工艺的研发力度,尤其是十氢萘的回收技术,提高单机产量,实现规模化生产.%The dominant production technologies for ultrahigh-molecular weight polyethylene ( UHMWPE) fiber were introduced. The dry spinning process and wet spinning process were compared. The production status, market demand and forecast of UHMWPE fiber were analyzed in China and abroad. The gap between China and international UHMWPE fibers was analyzed from the aspects of process technologies, production scale and product quality. It was pointed out that dry spinning process should be the dominant production technology for UHMWPE fiber in the future, and China should enhance the research of dry spinning process, particularly decalin recovery technology, increase the single line output and realize the scale production.

  9. 21 CFR 178.3750 - Polyethylene glycol (mean molecular weight 200-9,500).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyethylene glycol (mean molecular weight 200-9..., PRODUCTION AIDS, AND SANITIZERS Certain Adjuvants and Production Aids § 178.3750 Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol identified in this section may be safely used as...

  10. 21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyethylene glycol (mean molecular weight 200-9... ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.820 Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol identified in this section may be safely used in food...

  11. Effect of processing, sterilization and crosslinking on UHMWPE fatigue fracture and fatigue wear mechanisms in joint arthroplasty.

    Science.gov (United States)

    Ansari, Farzana; Ries, Michael D; Pruitt, Lisa

    2016-01-01

    Ultra high molecular weight polyethylene (UHMWPE) has been used as a bearing surface in total joint replacements (TJR) for nearly five decades. This semi-crystalline polymer has extraordinary energetic toughness owing to its high molecular weight and entanglement density. However, it is challenged by a need to offer a combined resistance to fatigue, wear and oxidation in vivo. The processing, sterilization treatment, and microstructural tailoring of UHMWPE has evolved considerably in the past 50 years but an optimized microstructure remains elusive. This review seeks to provide an overview of this processing history to address two primary questions: First, how does microstructure affect fatigue fracture and fatigue wear mechanisms in UHMWPE? And second, can microstructure be optimized to provide resistance to fatigue, oxidation and wear in vivo? Previous literature demonstrates that while crosslinking improves resistance to adhesive/abrasive wear, it also reduces resistance to fatigue crack propagation and fatigue wear by restricting molecular mobility and rendering the polymer more brittle. Crystallinity improves fatigue resistance but generally increases elastic modulus and concomitant contact stresses in vivo. The presence of fusion defects or oxidation reduces further fatigue resistance and enhances fatigue wear. Thus, UHMWPE microstructural evolution comes with trade-offs. Currently there is no singular formulation of UHMWPE that is ideal for all TJR applications.

  12. Improving Tensile Properties of Ultrahigh Molecular Weight Polyethylene Fibers%超高分子量聚乙烯纤维拉伸性能改进

    Institute of Scientific and Technical Information of China (English)

    喻文; 叶正涛

    2015-01-01

    超高分子量聚乙烯(UHMWPE)添加纳米氧化铝(NAL),酸蚀纳米氧化铝(ATNAL)及功能化纳米氧化铝(FNAL)可制得拉伸性质更优异的复合纤维。正如傅里叶红外光谱分析中所述,在功能化过程中马来酸酐接枝聚乙烯(PEg-MAH)分子成功接枝在ATNAL表面,使得FNAL样品比表面积数值明显增大。当添加极少量的FNAL时, UHMWPE/FNAL (F100Aax%-81PEg-MAHzy)初丝拉伸性能得到明显增强。本文对UHMWPE/NAL, UHMWPE/ATNAL及UHMWPE/FNAL初丝热学性质及拉伸性质进行分析,并研究纳米氧化铝对纤维拉伸性质的影响。%By the addition of nanoalumina (NAL), acid treated nanoalumina (ATNAL) or functionalized nanoalumina (FNAL), we can obtain composite fibers with more excellent tensile properties. As evidenced by FTIR analyses, maleic anhydride grafted polyethylene (PEg-MAH) molecules were successfully grafted onto ATNAL fillers, which made the specific surface areas of FNAL fillers increase significantly. The tensile properties of UHMWPE/FNAL (F100Aax%-81PEg-MAHzy) was improved significantly after adding a few of FNAL fillers. In this paper, the thermal properties and tensile properties of UHMWPE/NAL, UHMWPE/ATNAL and UHMWPE/FNAL as-prepared fibers were analyzed and we studied the effect of nanoalumina on the tensile properties of UHMWPE.

  13. UHMWPE wear debris and tissue reactions are reduced for contemporary designs of lumbar total disc replacements.

    Science.gov (United States)

    Veruva, Sai Y; Lanman, Todd H; Isaza, Jorge E; MacDonald, Daniel W; Kurtz, Steven M; Steinbeck, Marla J

    2015-03-01

    Lumbar total disc replacement (L-TDR) is a procedure used to relieve back pain and maintain mobility. Contemporary metal-on-polyethylene (MoP) L-TDRs were developed to address wear performance concerns about historical designs, but wear debris generation and periprosthetic tissue reactions for these newer implants have not been determined. The purpose of this study was to determine (1) whether periprosthetic ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris and biological responses were present in tissues from revised contemporary MoP L-TDRs that contain conventional cores fabricated from γ-inert-sterilized UHMWPE; (2) how fixed- versus mobile-bearing design affected UHMWPE wear particle number, shape, and size; and (3) how these wear particle characteristics compare with historical MoP L-TDRs that contain cores fabricated from γ-air-sterilized UHMWPE. We evaluated periprosthetic tissues from 11 patients who received eight fixed-bearing ProDisc-L and four mobile-bearing CHARITÉ contemporary L-TDRs with a mean implantation time of 4.1 and 2.7 years, respectively. Histologic analysis of tissues was performed to assess biological responses and polarized light microscopy was used to quantify number and size/shape characteristics of UHMWPE wear particles from the fixed- and mobile-bearing devices. Comparisons were made to previously reported particle data for historical L-TDRs. Five of seven (71%) fixed-bearing and one of four mobile-bearing L-TDR patient tissues contained at least 4 particles/mm(2) wear with associated macrophage infiltration. Tissues with wear debris were highly vascularized, whereas those without debris were more necrotic. Given the samples available, the tissue around mobile-bearing L-TDR was observed to contain 87% more, 11% rounder, and 11% less-elongated wear debris compared with tissues around fixed-bearing devices; however, there were no significant differences. Compared with historical L-TDRs, UHMWPE particle number and

  14. Mesoporous silica supported multiple single-site catalysts and polyethylene reactor blends with tailor-made trimodal and ultra-broad molecular weight distributions.

    Science.gov (United States)

    Kurek, Alexander; Mark, Stefan; Enders, Markus; Kristen, Marc O; Mülhaupt, Rolf

    2010-08-03

    A ternary blend of the bisiminopyridine chromium (III) (Cr-1) with the bisiminopyridine iron (II) (Fe-2) post-metallocenes with the quinolylsilylcyclopentadienyl chromium (III) halfsandwich complex (Cr-3) was supported on mesoporous silica to produce novel multiple single-site catalysts and polyethylene reactor blends with tailor-made molecular weight distributions (MWDs). The preferred cosupporting sequence of this ternary blend on MAO-treated silica was Fe-2 followed by Cr-1 and Cr-3. Cosupporting does not impair the single-site nature of the blend components producing polyethylene fractions with $\\overline M _{\\rm w}$ = 10(4) g · mol(-1) on Cr-1, $\\overline M _{\\rm w}$ = 3 × 10(5) g · mol(-1) on Fe-2, and $\\overline M _{\\rm w}$ = 3 × 10(6) g · mol(-1) on Cr-3. As a function of the Fe-2/Cr-1/Cr-2 mixing ratio it is possible to control the weight ratio of these three polyethylenes without affecting the individual average molecular weights and narrow polydispersities of the three polyethylene fractions. Tailor-made polyethylene reactor blends with ultra-broad MWD and polydispersities varying between 10 and 420 were obtained. When the molar ratio of Fe-2/Cr-1 was constant, the ultra-high molecular polyethylene (UHMWPE, $\\overline M _{\\rm w}$ > 10(6) g · mol(-1) ) content was varied between 8 and 16 wt.-% as a function of the Cr-3 content without impairing the blend ratio of the other two polyethylene fractions and without sacrificing melt processability. When the molar ratio Fe-2/Cr-3 was constant, it was possible to selectively increase the content of the low molecular weight fraction by additional cosupporting of Cr-1. Due to the intimate mixing of low and ultra-high molecular weight polyethylenes (UHMPEs) produced on cosupported single-site catalysts a wide range of melt processable polyethylene reactor blends was obtained.

  15. Wear behaviour of cross-linked polyethylene assessed in vitro under severe conditions.

    Science.gov (United States)

    Affatato, Saverio; Bersaglia, Gianluca; Rocchi, Mirko; Taddei, Paola; Fagnano, Concezio; Toni, Aldo

    2005-06-01

    The polyethylene (PE) for hip implants presents serious clinical problems; the production of debris may induce adverse tissue reactions that may lead to extensive bone loss around the implant and consequently osteolysis and implant loosening. Several attempts have been made to improve the wear properties of ultra-high molecular weight polyethylene (UHMWPE). More recently the attention of various researchers has been focused on cross-linked polyethylene (XLPE), due to its improved wear resistance with respect to conventional UHMWPE. This study was aimed at comparing the wear performances of clinically available acetabular liners (Zimmer Inc.) made of electron beam XLPE and conventional UHMWPE. To evaluate the influence of the material properties on wear, conventional UHMWPE and XLPE acetabular cups were tested against deliberately scratched CoCrMo femoral heads (Ra = 0.12-0.14 microm) in a hip joint wear simulator run for 3 million cycles with bovine calf serum as lubricant. Gravimetric measurements revealed significant differences between the wear behaviours of the two sets of acetabular cups: XLPE exhibited a wear rate about 40 times lower than conventional UHMWPE. Raman spectroscopy coupled to partial least-squares analysis was used to evaluate the possible crystallinity changes induced by mechanical stress (and thus the material wear resistance): only the UHMWPE cup which showed the highest weight loss displayed significant crystallinity changes. These results were correlated to the thickness of the plasticity-induced damage layer. The wear debris produced during the tests were isolated according to a validated protocol and imaged by scanning electron microscopy . The wear particles produced by XLPE were smaller than those produced by UHMWPE; the latter were observed as fibrillar and agglomerated particles. The mean equivalent circle diameter was 0.71 and 0.26 microm for UHMWPE and XLPE, respectively.

  16. Development and validation of the small punch test for UHMWPE used in total joint replacements

    Energy Technology Data Exchange (ETDEWEB)

    Edidin, A.A. [Drexel Univ., Philadelphia, PA (United States). School of Biomedical Engineering, Science and Health Systems; Howmedica Osteonics Corp., Allendale, NJ (United States); Kurtz, S.M. [Drexel Univ., Philadelphia, PA (United States). School of Biomedical Engineering, Science and Health Systems; Thomas Jefferson Univ., Philadelphia, PA (United States). Dept. of Orthopaedic Surgery; Exponent, Inc., Philadelphia, PA (United States)

    2001-07-01

    In order to better understand the mechanical effects of oxidative degradation, improved oxidative stability and crosslinking on ultra-high molecular weight polyethylene (UHMWPE), a unique miniature specimen mechanical testing technique, known as the small punch test, was developed for evaluating total joint replacement components. The small punch test involves deforming a disk-shaped specimen having a thickness of 0.5 mm and a diameter of 6.4 mm. In addition to its small specimen size, the small punch test differs from conventional testing in that deformation of the UHMWPE specimen occurs under multiaxial loading conditions. Using the small punch test, we have traced the evolution of mechanical behavior in UHMWPE after natural (shelf-storage) and accelerated aging conditions. In addition, we have determined relationships between the mechanical behavior of UHMWPE and the biologically relevant wear debris volume generated in total hip replacements. The small punch test has also been used to investigate the effects of radiation crosslinking which has been shown to improve the wear performance in an in vitro hip simulator. However, the crosslinking and subsequent thermal processes used to improve the wear behavior may compromise the native mechanical behavior by changing the ductility and toughness of the UHMWPE bearing. The primary objective of this study was to investigate which tradeoffs exist related to the mechanical behavior associated with various clinically available types of highly crosslinked and thermally treated UHMWPE. We also review the development and validation of the small punch disk bend test and highlight its application to problems of clinical relevance in both hip and knee arthroplasty. (orig.)

  17. Miniature specimen shear punch test for UHMWPE used in total joint replacements.

    Science.gov (United States)

    Kurt, S M; Jewett, C W; Bergström, J S; Foulds, J R; Edidin, A A

    2002-05-01

    Despite the critical role that shear is hypothesized to play in the damage modes that limit the performance of total hip and knee replacements, the shear behavior of ultra-high molecular weight polyethylene (UHMWPE) remains poorly understood, especially after oxidative degradation or radiation crosslinking. In the present study, we developed the miniature specimen (0.5 mm thickness x 6.4mm diameter) shear punch test to evaluate the shear behavior of UHMWPE used in total joint replacement components. We investigated the shear punch behavior of virgin and crosslinked stock materials, as well as of UHMWPE from tibial implants that were gamma-irradiated in air and shelf aged for up to 8.5 years. Finite element analysis, scanning electron microscopy, and interrupted testing were conducted to aid in the interpretation of the shear punch load-displacement curves. The shear punch load-displacement curves exhibited similar distinctive features. Following toe-in, the load-displacement curves were typically bilinear, and characterized by an initial stiffness, a transition load, a hardening stiffness, and a peak load. The finite element analysis established that the initial stiffness was proportional to the elastic modulus of the UHMWPE, and the transition load of the bilinear curve reflected the development of a plastically deforming zone traversing through the thickness of the sample. Based on our observations, we propose two interpretations of the peak load during the shear punch test: one theory is based on the initiation of crystalline plasticity, the other based on the transition from shear to tension during the tests. Due to the miniature specimen size, the shear punch test offers several potential advantages over bulk test methods, including the capability to directly measure shear behavior, and quite possibly infer ultimate uniaxial behavior as well, from shelf aged and retrieved UHMWPE components. Thus, the shear punch test represents an effective and complementary

  18. Wave transparent performance of UHMWPE laminates%UHMWPE层合板透波性能研究

    Institute of Scientific and Technical Information of China (English)

    陈昕; 朱锡; 张立军

    2011-01-01

    The dielectric parameters of ultra-high molecular weight polyethylene(UHMWPE) composites and GFRP fabricated by different technics were tested. The results show that UHMWPE molded laminates have very low dielectric constant and loss tangent. Wave transparent performance of UHMWPE laminate was computed and analyzed based on dielectric parameter tests,and transmissivity of a laminate sample with thickness of 33 mm was tested. Results show that UHMWPE laminates have high wave transparent performance. Considering high ballistic resistance and wave transparency of UHMWPE composites, the article discusses their application in ballistic resistant radomes.%对采用不同工艺制作的超高分子量聚乙烯(UHMWPE)复合材料以及玻璃钢复合材料的介电参数进行测试.结果显示,UHMWPE模压层合板具有很低的介电常数和损耗角正切.利用介电参数测试得到的数据对UHMWPE层合板透波性能进行计算和分析,并制作一块33 mm厚的层合板试样进行透波性测试.结果表明,UHMWPE层合板具有优异的透波性能.鉴于UHMWPE复合材料在防弹和透波方面所具有的优异性能,对其在防弹天线罩上的应用进行探讨.

  19. Structural and chemical changes in ultra-high-molecular-weight polyethylene due to gamma radiation-induced crosslinking and annealing in air.

    Science.gov (United States)

    Viano, A M; Spence, K E; Shanks, M A; Scott, M A; Redfearn, R D; Carlson, C W; Holm, T A; Ray, A K

    2007-01-01

    Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) is the material of choice for one of the articulating surfaces in many total joint replacements, notably hip and knee prostheses. The various methods used by the orthopaedic biomaterials industry to sterilize and anneal UHMWPE components, and the resulting oxidation and crosslinking, affect the mechanical wear resistance properties in ways still unknown at the microscopic and molecular levels. Transmission electron microscopy and chemical pyrolysis were used to quantify crosslinking induced by gamma irradiation and annealing in air. Changes in lamellar stacking and the amount of crosslinking suggest two types of crosslinking: relatively unstable crosslinks in the amorphous region initially resulting from gamma irradiation which are later replaced by more thermally stable crosslinks resulting from rearrangements at the annealing temperature. Lamellar mobility, the ability of crystalline lamellae to flow in the material, is enhanced during the transition from one type of bond to the other, and this appears to optimize near eight hours of annealing time. Results from decomposition and percent crystallinity measurements provide further support for this theory.

  20. Wear resistant performance of highly cross-linked and annealed ultra-high molecular weight polyethylene against ceramic heads in total hip arthroplasty.

    Science.gov (United States)

    Sato, Taishi; Nakashima, Yasuharu; Akiyama, Mio; Yamamoto, Takuaki; Mawatari, Taro; Itokawa, Takashi; Ohishi, Masanobu; Motomura, Goro; Hirata, Masanobu; Iwamoto, Yukihide

    2012-12-01

    The purpose of this study was to examine the effects of ceramic femoral head material, size, and implantation periods on the wear of annealed, cross-linked ultra-high molecular weight polyethylene (UHMWPE) (XLPE) in total hip arthroplasty compared to non-cross-linked conventional UHMWPE (CPE). XLPE was fabricated by cross-linking with 60 kGy irradiation and annealing. Femoral heads made from zirconia and alumina ceramics and cobalt-chrome (CoCr) of 22 or 26 mm diameter were used. In this retrospective cohort study, the femoral head penetration into the cup was measured digitally on radiographs of 367 hips with XLPE and 64 hips with CPE. The average follow-up periods were 6.3 and 11.9 years, respectively. Both XLPE creep and wear rates were significantly lower than those of CPE (0.19 mm vs. 0.44 mm, 0.0001 mm/year vs. 0.09 mm/year, respectively). Zirconia displayed increased wear rates compared to alumina in CPE; however, there was no difference among head materials in XLPE (0.0008, 0.00007, and -0.009 mm/year for zirconia, alumina, and CoCr, respectively). Neither head size or implantation period impacted XLPE wear. In contrast to CPE, XLPE displayed low wear rates surpassing the effects of varying femoral head material, size, implantation period, and patient demographics. Further follow-up is required to determine the long-term clinical performance of the annealed XLPE.

  1. A hemi-metallocene chromium catalyst with trimethylaluminum-free methylaluminoxane for the synthesis of disentangled ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Romano, Dario; Ronca, Sara; Rastogi, Sanjay

    2015-02-01

    Recently, it has been shown that by using a single-site catalytic system having titanium as a metallic center, it is possible to tailor the entanglement density in the amorphous region of a semi-crystalline ultra-high molecular weight polyethylene (UHMWPE). This route provides the possibility to make high-modulus, high-strength uniaxially and biaxially drawn tapes and films, without using any solvent during processing. In this publication, it is shown that a single-site catalyst having chromium as metallic center, proposed by Enders and co-workers, can also be tuned to provide control on the entanglement density during synthesis of the UHMWPE. However, to achieve the goal some modifications during the synthesis are required. The synthesized polymers can be processed in the solid state below the equilibrium melting temperature, resulting in uniaxially drawn tapes having tensile strength and modulus greater than 3.5 N/tex and 200 N/tex, respectively. Rheological studies have been performed to follow the increase in entanglement density in melt state with time.

  2. Surface modification of UHMWPE with infrared femtosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Pradas, J.M., E-mail: jmfernandez@ub.edu [Departament de Fisica Aplicada i Optica, Universitat de Barcelona Marti i Franques 1, E-08028 Barcelona (Spain); Naranjo-Leon, S.; Morenza, J.L.; Serra, P. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona Marti i Franques 1, E-08028 Barcelona (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Ultra High Molecular Weight Polyethylene surface was modified with femtosecond laser pulses at 1027 nm wavelength. Black-Right-Pointing-Pointer Surface roughness is increased. Black-Right-Pointing-Pointer Ablation efficiency is maximum for 6 {mu}J pulses. Black-Right-Pointing-Pointer Irradiated surfaces remain almost chemically unaltered. - Abstract: Ultra-high-molecular-weight polyethylene (UHMWPE) is a polymer with mechanical and corrosion properties, which make it appropriate for using in biomedical devices such as hip and knee prostheses. The surface morphology and chemistry of UHMWPE influence its biocompatibility. A laser with wavelength at 1027 nm delivering 450 fs pulses at a repetition rate of 1 kHz is used to modify the surface of UHMWPE samples with 0.45 {mu}m root mean square surface roughness. Micrometric resolution is achieved with the use of a focusing lens of 0.25 NA and pulse energies of few microjoules. The study focuses in the influence of different pulse energies and pulse overlaps on the laser-induced surface roughness and ablation yield. Confocal microscopy is used to characterize changes in the morphology of the irradiated surfaces, and their chemical structure is analyzed by attenuated total reflectance infrared and Raman spectroscopies. The roughness increases as the pulse energy increases until it reaches a maximum. The ablation yield increases with the pulse energy and pulse overlap. However, the ablation yield per pulse is lower for higher pulse overlap. Pulses of 6 {mu}J have the highest ablation efficiency. Infrared and Raman spectra of samples irradiated with low energy pulses are similar to those of the pristine sample. However, some C=C and C=O bonds can be detected after irradiation with the highest pulse energies.

  3. Irradiation crosslinking of ultra-high molecular weight polyethylene%超高分子质量聚乙烯辐射交联的研究现状

    Institute of Scientific and Technical Information of China (English)

    罗淑平; 陈云平; 黄嘉祐

    2016-01-01

    背景:辐射交联可显著提高超高分子质量聚乙烯人工关节的耐磨性,降低磨损率。目的:综述当前国内外超高分子质量聚乙烯辐射交联改性的研究进展。方法:以“UHMWPE,irradiation crosslinking”为检索词,应用计算机检索1995年1月至2012年4月 ISI WEB of Knowledge 系列数据库,纳入与超高分子质量聚乙烯辐射交联相关的研究。结果与结论:目前国内外超高分子质量聚乙烯辐射交联改性研究主要集中在磨擦性能、耐氧化性和机械性能方面。在高能射线辐照下,超高分子质量聚乙烯内产生自由基,自由基间相互交联。辐射交联改性极大提高了超高分子质量聚乙烯的耐磨性,但却降低了耐氧化性和机械性能。因此,如何在降低磨损率的基础上,提高耐氧化性和机械性能,获得这3种性能平衡的超高分子质量聚乙烯将是今后研究的重点。%BACKGROUND: Irradiation crosslinking can remarkably increase the abrasive performance of ultra-high molecular weight polyethylene (UHMWPE), thereby reducing its wear rate. OBJECTIVE: To review the recent progress in irradiated crosslinking UHMWPE. METHODS: A computer-based online search of ISI Web of knowledge was performed for articles related to irradiated crosslinking UHMWPE published from January1995 to April 2012 using the keywords of“irradiation crosslinking UHMWPE” in English. RESULTS AND CONCLUSION: At present, domestic studies on irradiation crosslinking of UHMWPE mainly focus on the wear resistance, oxidation resistance and mechanical properties. Under high-energy radiation, radicals generate from the UHMWPE, which are inter-crosslinked. Irradiation crosslinking dramatical y enhances the UHMWPE wear resistance, while reduces its oxidation resistance and mechanical properties. In the future, the research wil focus on how to develop new UHMWPE composite with good wear resistance, oxidation resistance and

  4. The elimination of free radicals in irradiated UHMWPEs with and without vitamin E stabilization by annealing under pressure.

    Science.gov (United States)

    Oral, Ebru; Ghali, Bassem W; Muratoglu, Orhun K

    2011-04-01

    Radiation crosslinking of ultrahigh molecular weight polyethylene (UHMWPE) has been used to decrease the wear of joint implant bearing surfaces. While radiation crosslinking has been successful in decreasing femoral head penetration into UHMWPE acetabular liners in vivo, postirradiation thermal treatment of the polymer is required to ensure the oxidative stability of joint implants in the long term. Two types of thermal treatment have been used: (i) annealing below the melting point preserves the mechanical properties but the residual free radicals trapped in the crystalline regions are not completely eliminated, leading to oxidation in the long-term and (ii) annealing above the melting point (melting) eliminates the free radicals but leads to a decrease in mechanical properties through loss of crystallinity during the melting process. In this study, we hypothesized that free radicals could be reduced by annealing below the melting point under pressure effectively without melting due to the elevation of the melting point. By avoiding the complete melting of UHMWPE, mechanical properties would be preserved. Our hypothesis tested positive in that we found the radiation-induced free radicals to be markedly reduced (below the detection limit of state-of-the-art electron spin resonance) by thermal annealing under pressure in radiation crosslinked virgin UHMWPE and UHMWPE/vitamin-E blends without loss of mechanical properties.

  5. Assessment of bulk and surface properties of medical grade UHMWPE based nanocomposites using Nanoindentation and microtensile testing.

    Science.gov (United States)

    Rama Sreekanth, P S; Kanagaraj, S

    2013-02-01

    A thrust on the enhancement of the mechanical properties of ultra high molecular weight polyethylene (UHMWPE) to enhance its longevity has taken a new direction with the advent of nanomaterials and carbon nanotubes. In the present work, UHMWPE was reinforced by chemically treated multi walled carbon nanotubes (MWCNTs) at different concentrations such as 0.5, 1.0, 1.5, 2.0, 2.5 and 5 wt%. The mechanical properties of nanocomposites were studied using a Nanoindentation technique and micro-tensile testing. It is observed that the toughness, ultimate stress, fracture strain, and yield stress of medical grade UHMWPE were enhanced by 176, 93, 70, and 44%, respectively at an optimum concentration of 2 wt% MWCNTs reinforcement. The mechanism for the enhancement of mechanical properties was confirmed by the micro-Raman and calorimetric technique. The reduction of the mechanical properties of nanocomposites beyond optimum concentration of MWCNTs was confirmed by the rheological studies. The generation of microvoids on the nanocomposites was verified by the scanning electron microscopy technique. Nanoindentation characteristics revealed that the surface hardness of UHMWPE was increased by 75% by the reinforcement of 2 wt% of MWCNTs. The Young's modulus obtained at the surface of nanocomposites was observed to be 9.8% higher than that of surface layer removed sample for 2 wt% nanocomposite. It is concluded that the presence of MWCNTs enhanced the mechanical properties and surface properties of medical grade UHMWPE.

  6. The influence of Co-Cr and UHMWPE particles on infection persistence: an in vivo study in mice.

    Science.gov (United States)

    Hosman, Anton H; Bulstra, Sjoerd K; Sjollema, Jelmer; van der Mei, Henny C; Busscher, Henk J; Neut, Daniëlle

    2012-03-01

    Wear of metal-on-metal (cobalt-chromium, Co-Cr particles) and metal-on-polyethylene (ultra-high-molecular-weight polyethylene, UHMWPE particles) bearing surfaces in hip prostheses is a major problem in orthopedics. This study aimed to compare the influence of Co-Cr and UHMWPE particles on the persistence of infection. Bioluminescent Staphylococcus aureus Xen36 were injected in air pouches prepared in subcutaneous tissue of immuno-competent BALB/c mice (control), as a model for the joint space, in the absence or presence of Co-Cr or UHMWPE particles. Bioluminescence was monitored longitudinally up to 21 days, corrected for absorption and reflection by the particles and expressed relative to the bioluminescence found in the presence of staphylococci only. After termination, air pouch fluid and air pouch membrane were cultured and histologically analyzed. Bioluminescence was initially lower in mice exposed to UHMWPE particles with staphylococci than in mice injected with staphylococci only, possibly because UHMWPE particles initially stimulated a higher macrophage presence in murine air pouch membranes. For mice exposed to Co-Cr particles with staphylococci, bioluminescence was observed to be higher in two out of six animals compared to the presence of staphylococci alone. In the majority of mice, infection risk in the absence or presence of Co-Cr and UHMWPE particles appeared similar, assuming that the longevity of an elevated bioluminescence is indicative of a higher infection risk. However, the presence of Co-Cr particles yielded a higher bioluminescence in two out of six mice, possibly because the macrophage degradative function was hampered by the presence of Co-Cr particles.

  7. Electrical and electromagnetic interference shielding characteristics of GNP/UHMWPE composites

    Science.gov (United States)

    Al-Saleh, Mohammed H.

    2016-05-01

    Conductive polymer composites (CPC) are attractive materials for a wide range of applications because of their weight, corrosion resistivity, design flexibility and low cost. In the present work, the electrical and electromagnetic interference (EMI) shielding characteristics of graphene nanoplatelets (GNP)/ultrahigh molecular weight polyethylene (UHMWPE) composites filled with up to 40 wt% GNP were investigated. In addition, the intrinsic conductivity of the GNP network was estimated based on the statistical power law and the rule of mixtures for randomly oriented filler particles in insulating matrix. Due to the formation of a segregated conductive network at the external surface of UHMWPE powder, an electrical percolation threshold of between 2 and 3 wt% GNP was obtained. At GNP loading of 15 wt%, the composite exhibited an EMI shielding effectiveness of 33 dB, corresponding to 99.95% blocking of the EMI.

  8. Behavior of Aramid Fiber/Ultrahigh Molecular Weight Polyethylene Fiber Hybrid Composites under Charpy Impact and Ballistic Impact

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The aramid fiber/UHMWPE (ultrahigh molecular weight polyethylene) fiber hybrid composites (AF/DF) were manufactured. By Charpy impact, the low velocity impact behavior of AF/DF composite was studied. And the high velocity impact behavior under ballistic impact was also investigated. The influence of hybrid ratio on the performances of low and high velocity impact was analyzed, and hybrid structures with good impact properties under low velocity impact and high velocity were optimized. For Charpy impact, the maximal impact load increased with the accretion of the AF layers for AF/DF hybrid composites. The total impact power was reduced with the decrease of DF layers and the delamination can result in the increase of total impact power. For ballistic impact, the DF ballistic performance was better than that of the AF and the hybrid ratio had a crucial influence. The failure morphology of AF/DF hybrid composite under Charpy impact and ballistic impact was analyzed. The AF/DF hybrid composites in suitable hybrid ratio could attain better performance than AF or DF composites.

  9. Significant Improvement in Thermal and UV Resistances of UHMWPE Fabric through in Situ Formation of Polysiloxane-TiO2 Hybrid Layers.

    Science.gov (United States)

    Hu, Jiangtao; Gao, Qianhong; Xu, Lu; Zhang, Mingxing; Xing, Zhe; Guo, Xiaojing; Zhang, Kuo; Wu, Guozhong

    2016-09-07

    Anatase nanocrystalline titanium dioxide coatings were produced on ultrahigh molecular weight polyethylene (UHMWPE) fabric by radiation-induced graft polymerization of γ-methacryloxypropyl trimethoxysilane (MAPS) and subsequent cohydrolysis of the graft chains (PMAPS) with tetrabutyl titanate, followed by boiling water treatment for 180 min. The resulting material was coded as UHMWPE-g-PMAPS/TiO2 and characterized by attenuated total reflection infrared spectrometry, differential scanning calorimetry, X-ray diffraction, thermal gravimetry, and ultraviolet absorption spectroscopy, among others. The predominant form of TiO2 in the thin film was anatase. The coating layer was composed of two sublayers: an inner part consisting of an organic-inorganic hybrid layer to prevent photocatalytic degradation of the matrix by TiO2 film, and an outer part consisting of anatase nanocrystalline TiO2 capable of UV absorption. This UHMWPE-g-PMAPS/TiO2 composite exhibited much better thermal resistance than conventional UHMWPE fabric, as reflected by the higher melting point, decreased maximum degradation rate, and higher char yield at 700 °C. Compared with UHMWPE fabric, UHMWPE-g-PMAPS/TiO2 exhibited significantly enhanced UV absorption and excellent duration of UV illumination. Specifically, the UV absorption intensity was 2.4-fold higher than that of UHMWPE fabric; the retention of the break strength of UHMWPE-g-PMAPS/TiO2 reached 92.3% after UV irradiation. This work provides an approach for addressing the issue of self-degradation of TiO2-coated polymeric materials due to the inherent photoactivity of TiO2.

  10. Hydrophobic composition based on mixed-molecular weight polyethylene

    Science.gov (United States)

    Gorlenko, Nikolay; Debelova, Natalya; Sarkisov, Yuriy; Volokitin, Gennadiy; Zavyalova, Elena; Lapova, Tatyana

    2016-01-01

    The paper presents investigations of compositions based on low and high molecular weight polyethylene so as to synthesize a hydrophobic composition for moisture protection of timber. X-ray phase analysis and measurements of the tear-off force of hydrophobic coating needed to apply to the timber surface and the limiting wetting angle are carried out to detect the hydrophobic, adhesive, electrophysical, and physicochemical properties of compositions. Kinetic dependencies are given for moisture absorption of timber specimens. It is shown that the preliminary formation of the texture by the surface patterning or its treatment with low-temperature plasma with the following protective coating results in the improvement of hydrophobic properties of the suggested compositions. These compositions can be used in the capacity of water repellents to protect building materials from moisture including restoration works.

  11. FABRICATION AND CHARACTERIZATION OF UHMWPE REINFORCED BY FORSTERITE NANO CRYSTALLITES AS AN IMPLANT BIOCOMPOSITE

    Directory of Open Access Journals (Sweden)

    Mehran Jaberzadeh

    2016-05-01

    Full Text Available Forsterite nano crystallite was synthesized by mixing talc and MgCO₃ in a ball mill for ten hours and then heating at 1000°C for ten minutes. Using twin-screw extrusion and then compression molding, an ultra high molecular weight polyethylene (UHMWPE reinforced by forsterite nano crystallites with volume fraction of 0/5 was produced as a composite sheet. Scanning electron microscopy images showed homogeneous distribution of forsterite particles in the UHMWPE matrix with size scale of less than 1 μm. In vitro evaluation test in simulated body fluid (SBF solution revealed the bioactivity of this composite. Mechanical properties of the produced composite were then evaluated using standard tensile test. Results showed that this composite has a strong Young modulus which is ten times higher than that of pure UHMWPE. In addition, the excellent toughness of pure UHMWPE was approximately maintained using 0/5 volume fraction of forsterite nano crystallite which is gained by over 300% fracture strain.

  12. The effect of roughness on the tribological behavior of the prosthetic pair UHMWPE/TiN-coated stainless steel.

    Science.gov (United States)

    Gispert, M P; Serro, A P; Colaço, R; Pires, E; Saramago, B

    2008-01-01

    The effect of roughness on the tribological behavior of the prosthetic pair ultra high molecular weight polyethylene (UHMWPE)/TiN coated stainless steel was investigated. Standard and polished TiN coated stainless steel pins were tested against either standard or smooth UHMWPE disks. Hanks' Balanced Salt Solution (HBSS) and bovine serum albumin (BSA) solution in HBSS were used as lubricants. Friction and wear were determined using a pin-on-disk apparatus and the wear mechanisms were investigated through optical microscopy, scanning electron microscopy, and atomic force microscopy. The results showed that the decrease in the roughness led to a reduction of the friction coefficient and of the wear rate of UHMWPE. However, the most important effect was achieved through the decrease in the roughness of the hard TiN counterface while keeping the standard UHMWPE surface. If BSA was added to HBSS, a strong decrease of both the friction coefficient and the polymeric wear was observed independently of the roughness of both the TiN and the polyethylene surfaces. Abrasive and fatigue wear mechanisms are proposed to interpret the experimental results.

  13. In Vitro Wear Testing of a CoCr-UHMWPE Finger Prosthesis with Hydroxyapatite Coated CoCr Stems

    Directory of Open Access Journals (Sweden)

    Andrew Naylor

    2015-04-01

    Full Text Available A finger prosthesis consisting of a Cobalt-chromium (CoCr proximal component and an Ultra-high-molecular-weight-polyethylene (UHMWPE medial component (both mounted on hydroxyapatite coated stems was evaluated to 5,000,000 cycles in an in vitro finger simulator. One “test” prosthesis was cycled through flexion-extension (90°–30° with a dynamic load of 10 N, whilst immersed in a lubricant of dilute bovine serum. Additionally, a static load of 100 N was applied for 45 s every 3000 cycles to simulate a static gripping force. A second “control” prosthesis was immersed in the same lubricant to account for absorption. Gravimetric and Sa (3D roughness measurements were taken at 1,000,000 cycle intervals. Micrographs and Sa values revealed negligible change to the CoCr surfaces after 5,000,000 cycles. The UHMWPE also exhibited no distinctive Sa trend, however the micrographs indicate that polishing occurred. Both the CoCr and UHMWPE test components progressively decreased in weight. The CoCr control component did not change in weight, whilst the UHMWPE component gained weight through absorption. To account for the disparity between surface and gravimetric results, the hydroxyapatite coatings were examined. Micrographs of the test stems revealed that the hydroxyapatite coating was partially removed, whilst the micrographs of the control stems exhibited a uniform coating.

  14. Macrophage response to cross-linked and conventional UHMWPE.

    Science.gov (United States)

    Sethi, Rajiv K; Neavyn, Mark J; Rubash, Harry E; Shanbhag, Arun S

    2003-07-01

    To prevent wear debris-induced osteolysis and aseptic loosening, cross-linked ultra-high molecular weight polyethylene's (UHMWPE) with improved wear resistance have been developed. Hip simulator studies have demonstrated very low wear rates with these new materials leading to their widespread clinical use. However, the biocompatibility of this material is not known. We studied the macrophage response to cross-linked UHMWPE (XLPE) and compared it to conventional UHMWPE (CPE) as well as other clinically used orthopaedic materials such as titanium-alloy (TiAlV) and cobalt-chrome alloy (CoCr). Human peripheral blood monocytes and murine macrophages, as surrogates for cells mediating peri-implant inflammation, were cultured onto custom designed lipped disks fabricated from the test materials to isolate cells. Culture supernatants were collected at 24 and 48h and analyzed for cytokines such as IL-1alpha, IL-1beta, TNF-alpha and IL-6. Total RNA was extracted from adherent cells and gene expression was analyzed using qualitative RT-PCR. In both in vitro models, macrophages cultured on cross-linked and conventional polyethylene released similar levels of cytokines, which were also similar to levels on control tissue culture dishes. Macrophages cultured on TiAlV and CoCr-alloy released significantly higher levels of cytokines. Human monocytes from all donors varied in the magnitude of cytokines released when cultured on identical surfaces. The variability in individual donor responses to TiAlV and CoCr surfaces may reflect how individuals respond differently to similar stimuli and perhaps reveal a predisposed sensitivity to particular materials.

  15. In vitro analysis of the cytotoxic and anti-inflammatory effects of antioxidant compounds used as additives in ultra high-molecular weight polyethylene in total joint replacement components.

    Science.gov (United States)

    Bladen, C L; Tzu-Yin, L; Fisher, J; Tipper, J L

    2013-04-01

    Ultra high-molecular weight polyethylene (UHMWPE) remains the most commonly used material in modern joint replacement prostheses. However, UHMWPE wear particles, formed as the bearing articulates, are one of the main factors leading to joint replacement failure via the induction of osteolysis and subsequent aseptic loosening. Previous studies have shown that the addition of antioxidants such as vitamin E to UHMWPE can improve wear resistance of the polymer and reduce oxidative fatigue. However, little is known regarding the biological consequences of such antioxidant chemicals. This study investigated the cytotoxic and anti-inflammatory effects of a variety of antioxidant compounds currently being tested experimentally for use in hip and knee prostheses, including nitroxides, hindered phenols, and lanthanides on U937 human histocyte cells and human peripheral blood mononuclear cells (PBMNCs) in vitro. After addition of the compounds, cell viability was determined by dose response cytotoxicity studies. Anti-inflammatory effects were determined by quantitation of TNF-α release in lipopolysaccharide (LPS)-stimulated cells. This study has shown that many of these compounds were cytotoxic to U937 cells and PBMNCs, at relatively low concentrations (micromolar), specifically the hindered phenol 3,5-di-tert-butyl-4-hydroxyhydrocinnamate (HPAO1), and the nitroxide 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO). Lanthanides were only cytotoxic at very high concentrations and were well tolerated by the cells at lower concentrations. Cytotoxic compounds also showed reduced anti-inflammatory effects, particularly in PBMNCs. Careful consideration should therefore be given to the use of any of these compounds as potential additives to UHMWPE.

  16. Influence of carbon nano- and micron-sized fibers on structure, mechanical and tribotechnical properties of polymer composites with UHMWPE matrix

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Aleksenko, V. O.; Ivanova, L. R.; Shilko, S. V.

    2016-11-01

    To compare the efficiency of the solid lubricating and enforcing properties of carbon nano-and microfibers in ultra-high molecular weight polyethylene (UHMWPE) composites their mechanical and tribotechnical characteristics under dry sliding friction and abrasion have been studied. It is shown that under dry sliding friction the wear resistance of the polymer composite "UHMWPE + 0.5 wt % C (nano)" has increased up to 6.6 times, while in the composite "UHMWPE + 5 wt % C (micro)"—by 2.5 times only. At the same time abrasive wear resistance of these composites has increased approximately 2-fold for both types of fillers. The mechanisms of the observed effects are discussed and interpreted.

  17. HA/UHMWPE Nanocomposite Produced by Twin-screw Extrusion

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The HA/UHMWPE nanocomposite is compounded by twin-screw extrusion of the HA and UHMWPE powder mixture in paraffin oil and then compression molded to a sheet form. TGA measurement shows the HA weight loss after processing is about 1%-2% . FTIR spectra indicate the paraffin oil residue is trivial and UHMWPE is not oxidized. SEM reveals the HA nano particles are homogeneously dispersed by twin- screw extrusion and the inter-particle spaces are penetrated with UHMWPE fibrils by swelling treatment. HRTEM image indicates the HA particles and UHMWPE are intimately contacted by mechanical interlocking. Compared with the unfilled UHMWPE, stiffness of the composite with the HA volume fraction 0.23 was significantly enhanced to 9 times without detriment of the yield strength and the ductility.

  18. Radiation effects of UHMW-PE fibre on gel fraction and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yanning [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); College of Chemistry, Jilin Normal University, Jilin 136000 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wang Mouhua [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); Tang Zhongfeng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wu Guozhong, E-mail: wuguozhong@sinap.ac.c [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China)

    2011-02-15

    The effect of gamma ray irradiation on ultra-high molecular weight polyethylene (UHMW-PE) fibre was investigated for the change of gel fraction, mechanical properties, and morphology of crystallites. In the case of irradiation in air, the oxidation was limited to the fibre surface where the gel fraction decreased by chain scission, and the depth of the oxidation area from the surface was estimated to be 2 {mu}m. Tensile tests showed similar stress-strain curves for irradiation in vacuum or in air, but the elongation at break decreased more obviously for irradiation in air. The oxidation products, such as carboxylic acids, were detected by FTIR measurement. However, the DSC and XRD analyses indicated little change of crystallinity on irradiation in vacuum or in air. The oxidation was limited to a thin surface area on irradiation in air due to a low migration rate of the radicals trapped in the crystallite in the UHMW-PE fibre.

  19. Surface Treatment of UHMWPE Fibers for Adhesion Promotion in Epoxy Polymers

    Institute of Scientific and Technical Information of China (English)

    SONG Jun; XIAO Chang-fa; AN Shu-lin; JIA Guang-xia

    2007-01-01

    Surface of Ultra-high molecular weight polyethylene (UHMWPE) fiber were treated by chromic acid chemical etching, pyrrole chemical vapour phase deposition and the complex of these two methods, respectively. The change of surface properties and structure of fibers were discussed by Fiour Transform Insfrared Spectroscope (FTIR), Dynamic Mechanical Analysis (DMA) and Scanning Electron Microscope (SEM). The results show that some new oxygenous groups could he found on surface of UHMWPE fiber after chromic acid chemical etching, which enhanced intermolecular interaction with polypyrrole. The adhesion of the fibet and resin matrix increased after pyrrole chemical vapour deposition. When chromic acid etching combined with pyrrole clinical vapor deposition, the treated fiber not only has the same properties as original fiber but also outstanding adhesion to epoxy resin matrix, and its composites have better mechanic properties (shear strength), resulting from intermolecular interaction between treated fiber and polypyrrole.

  20. ESR study of free radicals in UHMW-PE fiber irradiated by gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yanning [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); College of Chemistry, Jilin Normal University, Jilin 136000 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wang Mouhua [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); Tang Zhongfeng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wu Guozhong, E-mail: wuguozhong@sinap.ac.c [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800 (China)

    2010-04-15

    ESR spectra of the trapped radicals in an ultra-high molecular weight polyethylene (UHMW-PE) fiber irradiated by gamma rays showed well-resolved hyperfine splitting at room temperature since the c-axis of the crystallites is aligned with the fiber direction and the radicals are trapped in crystallites. The alkyl radical (-CH{sub 2}-{sup c}entre dotCH-CH{sub 2}-) was the major product after irradiation in vacuum and in air at room temperature. Some of the alkyl radicals converted to allyl radicals (-CH{sub 2}-{sup c}entre dotCH-CH=CH-) and polyenyl radicals (-CH{sub 2}-{sup c}entre dotCH-(CH=CH){sub n}-CH{sub 2}-) during storage in vacuum. Upon storage in air atmosphere, the alkyl radicals decayed by reaction with oxygen. Of particular interest is the very slow decay rate of the alkyl radical trapped in UHMW-PE fiber, the half-life is 26 days in vacuum, and 13 days in air at room temperature, which is about 1/30 and 1/100 of that reported for high density polyethylene (HDPE), respectively. The extremely long lifetime of the alkyl radical is supposed to be caused by the large size of crystallites in UHMW-PE fiber. The rate of radical decay was accelerated by annealing at elevated temperature.

  1. Effect of Argon Plasma Treatment on Tribological Properties of UHMWPE/MWCNT Nanocomposites

    Directory of Open Access Journals (Sweden)

    Nitturi Naresh Kumar

    2016-08-01

    Full Text Available Ultra-high molecular weight polyethylene (UHMWPE is widely used in artificial joints in the replacement of knee, hip and shoulder that has been impaired as a result of arthritis or other degenerative joint diseases. The UHMWPE made plastic cup is placed in the joint socket in contact with a metal or ceramic ball affixed to a metal stem. Effective reinforcement of multi-walled carbon nanotubes (MWCNTs in UHMWPE results in improved mechanical and tribological properties. The hydrophobic nature of the nanocomposites surface results in lesser contact with biological fluids during the physiological interaction. In this project, we investigate the UHMWPE/MWCNTs nanocomposites reinforced with MWCNTs at different concentrations. The samples were treated with cold argon plasma at different exposure times. The water contact angles for 60 min plasma-treated nanocomposites with 0.0, 0.5, 1.0, 1.5, and 2.0 wt % MWCNTs were found to be 55.65°, 52.51°, 48.01°, 43.72°, and 37.18° respectively. Increasing the treatment time of nanocomposites has shown transformation from a hydrophobic to a hydrophilic nature due to carboxyl groups being bonded on the surface for treated nanocomposites. Wear analysis was performed under dry, and also under biological lubrication, conditions of all treated samples. The wear factor of untreated pure UHMWPE sample was reduced by 68% and 80%, under dry and lubricated conditions, respectively, as compared to 2 wt % 60 min-treated sample. The kinetic friction co-efficient was also noted under both conditions. The hardness of nanocomposites increased with both MWCNTs loading and plasma treatment time. Similarly, the surface roughness of the nanocomposites was reduced.

  2. Wear measurement of highly cross-linked UHMWPE using a 7Be tracer implantation technique.

    Science.gov (United States)

    Wimmer, Markus A; Laurent, Michel P; Dwiwedi, Yasha; Gallardo, Luis A; Chipps, Kelly A; Blackmon, Jeffery C; Kozub, Raymond L; Bardayan, Daniel W; Gross, Carl J; Stracener, Daniel W; Smith, Michael S; Nesaraja, Caroline D; Erikson, Luke; Patel, Nidhi; Rehm, Karl E; Ahmad, Irshad; Greene, John P; Greife, Uwe

    2013-04-01

    The very low wear rates achieved with the current highly cross-linked ultrahigh molecular weight polyethylenes (UHMWPE) used in joint prostheses have proven to be difficult to measure accurately by gravimetry. Tracer methods are therefore being explored. The purpose of this study was to perform a proof-of-concept experiment on the use of the radioactive tracer beryllium-7 ((7)Be) for the determination of in vitro wear in a highly cross-linked orthopedic UHMWPE. Three cross-linked and four conventional UHMWPE pins made from compression-molded GUR 1050, were activated with 10(9) to 10(10) (7)Be nuclei using a new implantation setup that produced a homogenous distribution of implanted nuclei up to 8.5 μm below the surface. The pins were tested for wear in a six-station pin-on-flat apparatus for up to 7.1 million cycles (178 km). A Germanium gamma detector was employed to determine activity loss of the UHMWPE pins at preset intervals during the wear test. The wear of the cross-linked UHMWPE pins was readily detected and estimated to be 17 ± 3 μg per million cycles. The conventional-to-cross-linked ratio of the wear rates was 13.1 ± 0.8, in the expected range for these materials. Oxidative degradation damage from implantation was negligible; however, a weak dependence of wear on implantation dose was observed limiting the number of radioactive tracer atoms that can be introduced. Future applications of this tracer technology may include the analysis of location-specific wear, such as loss of material in the post or backside of a tibial insert.

  3. Thermal, Mechanical and Rheological Behaviors of Nanocomposites Based on UHMWPE/Paraffin Oil/Carbon Nanofiller Obtained by Using Different Dispersion Techniques

    Science.gov (United States)

    Visco, Annamaria; Yousef, Samy; Galtieri, Giovanna; Nocita, Davide; Pistone, Alessandro; Njuguna, James

    2016-04-01

    Ultra-high molecular weight polyethylene (UHMWPE) is a very attractive polymer employed as a high performance material. For its high viscosity, dispersion of fillers is considered a critical point in UHMWPE nanocomposites preparation process. Currently, paraffin oil (PO) is used extensively to overcome this issue in an assisted melt-mixing process. In this work, we have prepared nanocomposites based on UHMWPE, carbon nanofiller (CNF) and PO mixed by different mixing methods: magnetic stirring, ball milling (BM), ultrasonic and Mini-Lab extruder (EX). The aim of this work was to check the effect of the dispersion method on the mechanical and thermal features of UHMWPE/CNF nano composites in order to obtain a material with improved mechanical and physical properties. The samples were characterized by calorimetric, density, mechanical tensile and rheological analyses. Experimental results highlighted that the nanocomposites produced by EX and BM exhibits the best dispersion, good filler matrix interaction and had significantly improved mechanical properties compared to pure UHMWPE. For instance, for the BM method, the yield strength improved to 18.6 MPa (+96%), the yield strain improved by 60%, while stress at break improved by 13%. In summary, the EX improved the stiffness while the BM produced better ductility, melting temperature and the crystalline degree of the nanocomposites.

  4. A novel alginate-encapsulated system to study biological response to critical-sized wear particles of UHMWPE loaded with alendronate sodium.

    Science.gov (United States)

    Liu, Yumei; Shi, Feng; Bo, Lin; Zhi, Wei; Weng, Jie; Qu, Shuxin

    2017-10-01

    The aim of this study was to develop a novel alginate-encapsulated system (Alg beads) to investigate the cell response to critical-sized wear particles of ultra-high molecular weight polyethylene loaded with alendronate sodium (UHMWPE-ALN), one of the most effective drugs to treat bone resorption in clinic. The extrusion method was used to prepare Alg beads encapsulating rat calvarial osteoblasts (RCOs) and critical-sized UHMWPE-ALN wear particles with spherical morphology and uniform size. The morphology, permeability and stability of Alg beads were characterized. The proliferation, ALP activity, cell apoptosis and distribution of live/dead RCOs co-cultured with wear particles in Alg beads were evaluated. RCOs and critical-sized UHMWPE-ALN wear particles distributed evenly and contacted efficiently in Alg beads. Alg beads were both permeable to trypsin and BSA, while the smaller the molecular was, the larger the diffuse was. The proliferation of RCOs in Alg beads increased with time, which indicated that Alg beads provided suitable conditions for cell culture. The long-term stability of Alg beads indicated the possibility for the longer time of co-cultured cells with wear particles. Critical-sized UHMWPE-ALN and UHMWPE wear particles both inhibited the proliferation and differentiation of RCOs, and induced the apoptosis of RCOs encapsulated in Alg beads. However, these effects could be significantly alleviated by the ALN released from the critical-sized UHMWPE-ALN wear particles. The present results suggested that this novel-developed co-culture system was feasible to evaluate the cell response to critical-sized UHMWPE-ALN wear particles for a longer time. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. [Current knowledge on the effect of technology and sterilization on the structure, properties and longevity of UHMWPE in total joint replacement].

    Science.gov (United States)

    Pokorný, D; Šlouf, M; Fulín, P

    2012-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is the most frequently used bearing surface in currently used total joint replacements (TJR). According to the literature available, UHMWPE is the best polymer material, in terms of biocompatibility, mechanical properties and wear resistance, for this application. In spite of this fact, UHMWPE wear (i.e., release of microscopic particles from the polymer surface) remains one of the main reasons of TJR failures. Consequently, the wear of UHMWPE is a subject of intensive study by both materials scientists and orthopaedic surgeons. The structure and properties of UHMWPE strongly depend on the way of processing and post-processing modifications. The processing includes polymer resin preparation (microparticles about 100 ěm in size) and resin consolidation (forming bulk material). Post-processing modifications aim at increasing wear resistance and oxidation stability which are regarded as major factors involved in TJR failure. In order to maintain high purity materials for medical application, it is not allowed to use additional chemicals during the modification processes. The only exception is the use of vitamin E, a natural stabilizer and antioxidant. Considering all the above mentioned facts, the modifications can be based on (I) ionizing radiation such as gamma rays or accelerated electrons, (II) thermal modification, (III) additional stabilization with vitamin E, and (IV) sterilization. According to the modifications, we usually differentiate three generations of UHMWPE. The 1st generation UHMWPE is not modified except for obligatory sterilization. The sterilization procedures based on chemical procedures (formaldehyde vapours, hot water) have lately been forbidden, abandoned and replaced by gamma-irradiation with doses of 25-45 kGy. In the course of time, sterilization by means of gamma-irradiation showed to be unsuitable due to oxidative degradation of UHMWPE, which resulted in lower wear resistance, worse

  6. Tribology, UV degradation, and structure-property-processing relationships of detonation nanodiamond-polyethylene nanocomposites

    Science.gov (United States)

    Tipton, John

    Nanoscale reinforcements offer the possibility of coupling the already proven high strength to weight properties of polymer matrix composites with additional multifunctional properties such as electrical conductivity, thermal conductivity, unique optics, UV/IR radiation absorption, and enhanced wear resistance. This work presents materials based on detonation nanodiamonds dispersed in two types of polyethylene. The work begins with an understanding of nucleation phenomena. It was discovered through isothermal kinetics using differential scanning calorimetry that nanodiamonds act as nucleating agents during polyethylene crystallization. A processing technique to disperse nanodiamonds into very viscous ultra-high molecular weight polyethylene was developed and analyzed. These composites were further studied using dynamic mechanical analysis which showed increases in both stiffness and energy absorbing modes over unfilled UHMWPE. Exposure to UV degradation caused a failure of the polymer microstructure which was found to be caused by residual tensile stresses between the polymer particles formed during processing. These high stress regions were more prone to photo oxidation even though the nanodiamond particles were shown to decrease surface oxidation. Additionally, the tribological properties of UHMWPE/nanodiamond composites were investigated. Ultra-high molecular weight polyethylene is an already proven ultra tough and wear resistant polymer that is used in many high performance thermoplastic applications such as bearings, surfaces (skids/wheels), ropes/nets, and orthopedic implants. This work showed that UHMWPE loaded with 5.0wt% nanodiamonds might be a candidate to replace the currently used crosslinked polyethylene material used in orthopedic implants.

  7. Appearance of perfect amorphous linear bulk polyethylene under applied electric field and the analysis by radial distribution function and direct tunneling effect.

    Science.gov (United States)

    Zhang, Rong; Bin, Yuezhen; Yang, Wenxiao; Fan, Shaoyan; Matsuo, Masaru

    2014-02-27

    Without melting flow, linear ultrahigh molecular weight polyethylene (UHMWPE) provided X-ray intensity curve from only amorphous halo at 129.0 °C (surface temperature, Ts arisen by Joule heat) lower than the conventionally known melting point 145.5 °C on applying electric field to UHMWPE-nickel-coated carbon fiber (NiCF) composite. Such surprising phenomenon was analyzed by simultaneous measurements of X-ray intensity, electric current, and Ts as a function of time. The calculated radial distribution function revealed the amorphous structure with disordered chain arrangement. The appearance of such amorphous phase was arisen by the phenomenon that the transferring electrons between overlapped adjacent NiCFs by tunneling effect struck together with X-ray photons and some of the transferring electron flown out from the gap to UHMWPE matrix collided against carbon atoms of UHMWPE. The impact by the collision caused disordering chain arrangement in crystal grains.

  8. Study on Properties of Reactive Compatibilization of PA66/UHMWPE/HDPE-g-GMA Blend Alloy%HDPE-g-GMA反应性增容PA66/UHMWPE共混合金性能研究

    Institute of Scientific and Technical Information of China (English)

    赵梓年; 雷钢强

    2009-01-01

    By means of melting extrusion process, the polyamide 66(PA66)/ultra high molecular weight polyethylene(UHMWPE)/high density polyethylene graft glycidyl methacrylate(HDPE-g-GMA)blends were prepared, in which the high density polyethylene graft glycidyl methacrylate(HDPE-g-GMA)acted as reac- tive compatibilizer of PA66/UHMWPE. The HDPE-g-GMA as a compatilizer to PA66/UHMWPE blends was studied through Molau experiment, scanning electron microscopy(SEM)observation, and mechanical prop- erty test. The result showed that the grafted copolymer, which was produced by HDPE-g-GMA and PA66 be- ing in chemical reaction during melt blending had a good compatibilization on PA66/UHMWPE blends. Inter- facial morphology and mechanical property of PA66/UHMWPE blends were improved obviously, meanwhile the water absorption decreased.%以甲基丙烯酸缩水甘油酯接枝高密度聚乙烯(HDPE-g-GMA)作为聚酰胺66/超高摩尔质量聚乙烯(PA66/UHMWPE)共混合金的增容剂,采用熔融法制备了PA66/uHMwPE/HDPE-g-GMA共混合金.通过Molau试验、SEM观察和力学性能测试,研究了HDPE-g-GMA在熔融共混过程中对PA66/UHMWPE共混合金的增容作用.结果表明:HDPE-g-GMA与PA66发生了化学反应,所生成的接枝共聚物对PA66/UHMWPE共混合金有较好的增容作用;PA66/UHMWPE共混合金的界面形态和力学性能均有较大改善,吸水率也有所降低.

  9. Tribological performance of DLC coatings on UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Nogues, V; Medel, F J; Mariscal, M D; Endrino, J L; Krzanowski, J; Yubero, F; Puertolas, J A, E-mail: enav@unizar.es

    2010-11-01

    Diamond like carbon (DLC) coatings were deposited by several methods (ion beam assisted evaporation, magnetron sputtering, filter cathodic arc, and plasma enhanced chemical vapor deposition) onto medical grade ultra-high-molecular weight polyethylene (UHMWPE) discs. The chemical characteristics and mechanical properties of the deposited DLC coatings were studied by Raman spectroscopy and nanoindentation, respectively. In addition, a set of tribological tests was conducted at human body temperature and under bovine serum lubrication against alumina balls. After testing, wear tracks were both visually inspected and documented using confocal microscopy. Visual inspection of the wear tracks confirmed that the DLC coatings were completely removed in all cases, the only exception being the DLC coating prepared by magnetron sputtering with thickness about 0.5 microns. Although this type of DLC coating exhibited the highest friction coefficient, and therefore it suggested a somewhat lower resistance to abrasive/adhesive wear conditions, no evidence of cracking or delamination was observed after the high contact pressure wear testing. This fact points out a good substrate-coating adhesion, and confirms magnetron sputtered DLC as a potential coating for orthopaedic applications.

  10. Nondestructive characterization of UHMWPE armor materials

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, Chien-Ping; Margetan, Frank J.; Barnard, Daniel J.; Hsu, David K.; Jensen, Terrence; Eisenmann, David [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

    2012-05-17

    Ultra-high molecular weight polyethylene (UHMWPE) is a material increasingly used for fabricating helmet and body armor. In this work, plate specimens consolidated from thin fiber sheets in series 3124 and 3130 were examined with ultrasound, X-ray and terahertz radiation. Ultrasonic through-transmission scans using both air-coupled and immersion modes revealed that the 3130 series material generally had much lower attenuation than the 3124 series, and that certain 3124 plates had extremely high attenuation. Due to the relatively low inspection frequencies used, pulse-echo immersion ultrasonic testing could not detect distinct flaw echoes from the interior. To characterize the nature of the defective condition that was responsible for the high ultrasonic attenuation, terahertz radiation in the time-domain spectroscopy mode were used to image the flaws. Terahertz scan images obtained on the high attenuation samples clearly showed a distribution of a large number of defects, possibly small planar delaminations, throughout the volume of the interior. Their precise nature and morphology are to be verified by optical microscopy of the sectioned surface.

  11. Comportamento balístico de compósito de polietileno de altíssimo peso molecular: efeito da radiação gama Ballistic behaviour of ultra-high molecular weight polyethylene: effect of gamma radiation

    Directory of Open Access Journals (Sweden)

    Andreia L. S. Alves

    2004-06-01

    polyethylene (UHMWPE fibers are used in the production of armor materials, for personnel protection and armored vehicles. As these have been developed and commercialized more recently, there is not enough information about the action of the ionizing radiation in the ballistic performance of this armor material. In the present work the ballistic behavior of composite plates manufactured with ultrahigh molecular weight polyethylene (UHMWPE fibers were evaluated after exposure to gamma radiation. The ballistic tests results were related to the macromolecular modifications induced by the environmental degradation through mechanical (hardness, impact and flexure and physicochemical (infrared spectroscopy, differential scanning calorimetry and thermal gravimetric analysis tests. Our results indicate that gamma irradiation induces modifications in the UHMWPE macromolecular chains, altering the mechanical properties of the composite and decreasing, for higher radiation doses, its ballistic performance. These results are presented and discussed.

  12. Elevated cytokine expression of different PEEK wear particles compared to UHMWPE in vivo.

    Science.gov (United States)

    Lorber, V; Paulus, A C; Buschmann, A; Schmitt, B; Grupp, T M; Jansson, V; Utzschneider, Sandra

    2014-01-01

    Due to their mechanical properties, there has been growing interest in poly-ether-ether-ketone (PEEK) and its composites as bearing material in total and unicompartmental knee arthroplasty. The aim of this study was to analyze the biological activity of wear particles of two different (pitch and PAN) carbon-fiber-reinforced- (CFR-) PEEK varieties in comparison to ultra-high-molecular-weight-polyethylene (UHMWPE) in vivo. The authors hypothesized no difference between the used biomaterials. Wear particle suspensions of the particulate biomaterials were injected into knee joints of Balb/c mice, which were sacrificed after seven days. The cytokine expression (IL-1β, IL-6, TNF-α) was analyzed immunohistochemically in the synovial layer, the adjacent bone marrow and the articular cartilage. Especially in the bone marrow of the two CFR-PEEK varieties there were increased cytokine expressions compared to the control and UHMWPE group. Furthermore, in the articular cartilage the CFR-PEEK pitch group showed an enhanced cytokine expression, which could be a negative predictor for the use in unicondylar knee systems. As these data suggest an increased proinflammatory potential of CFR-PEEK and its composites in vivo, the initial hypothesis had to be refuted. Summarizing these results, CFR-PEEK seems not to be an attractive alternative to UHMWPE as a bearing material, especially in unicompartmental knee arthroplasty.

  13. Deformation and Stress Response of Carbon Nanotubes/UHMWPE Composites under Extensional-Shear Coupling Flow

    Science.gov (United States)

    Wang, Junxia; Cao, Changlin; Yu, Dingshan; Chen, Xudong

    2017-05-01

    In this paper, the effect of varying extensional-shear couple loading on deformation and stress response of Carbon Nanotubes/ ultra-high molecular weight polyethylene (CNTs/UHMWPE) composites was investigated using finite element numerical simulation, with expect to improve the manufacturing process of UHMWPE-based composites with reduced stress and lower distortion. When applying pure extensional loading and pure X-Y shear loading, it was found that the risk of a structural breakage greatly rises. For identifying the coupling between extensional and shear loading, distinct generations of force loading were defined by adjusting the magnitude of extensional loading and X-Y shear loading. It was shown that with the decrement of X-Y shear loading the deformation decreases obviously where the maximal Mises stress in Z-direction at 0.45 m distance is in the range from 24 to 10 MPa and the maximal shear stress at 0.61 m distance is within the range from 0.9 to 0.3 MPa. In addition, all the stresses determined were clearly below the yield strength of CNTs/UHMWPE composites under extensional-shear couple loading.

  14. UHMW-PE. A shielding material with special properties influenced by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ehe, K. von der; Jaunich, M.; Wolff, D. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany)

    2011-07-01

    Ultra high molecular weight polyethylene (UHMW-PE) - due to its high hydrogen content - is used as neutron shielding material in casks for storage and transport of radioactive materials. Besides this, UHMW-PE - as a high-performance polymer - has been used for several years in medical technology due to its excellent slip and wear properties. Due to the special properties of UHMW-PE which result basically from its extreme chain lengths and its high degree of crystallinity, it is predestinated for the aforementioned applications. In both cases, irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation exists as a by-product of inserting the radioactive material in the cask. Hence PE has to withstand any type of degradation affecting safety relevant aspects to be applicable for long term radiation shielding purposes for instance over a period of 40 years. In the second case irradiation is applied deliberately for purposes such as sterilization and crosslinking, leading to partial improvement of the mechanical properties (e.g. fracture toughness, crack propagation resistance, wear resistance) and better chemical stability. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been objects of numerous publications. It is generally accepted that two parallel and competitive processes, based on chain scission and reactions of C-centered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is an antagonist of the C-centered radicals. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystals. It is followed by folding of molecular fragments

  15. Experimental study on correlation between sound velocity and solute molecular weight in polyethylene glycol solution

    Institute of Scientific and Technical Information of China (English)

    YIN XiangYu; SONG Hao; ZHOU HuiJun

    2009-01-01

    In this study, ultrasound grating was used to measure the sound velocity in solutions of ethylene glycol and polyethylene glycol with molecular weights of 200, 600, 2000, and 10000. We found Parthasarathy empirical rule, that is, sound velocity is higher in the solution of larger molecules, is invalid in the case of polyethylene glycol solution. We tried to provide a tentative explanation using the Flory-Krigbaum's chained block cloud model.

  16. Experimental study on correlation between sound velocity and solute molecular weight in polyethylene glycol solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this study,ultrasound grating was used to measure the sound velocity in solutions of ethylene glycol and polyethylene glycol with molecular weights of 200,600,2000,and 10000.We found Parthasarathy empirical rule,that is,sound velocity is higher in the solution of larger molecules,is invalid in the case of polyethylene glycol solution. We tried to provide a tentative explanation using the Flory-Krigbaum’s chained block cloud model.

  17. Investigation of properties of (U)HMW-PE under the influence of gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ehe, K. von der; Wolff, D.; Boehning, M. [BAM Federal Institute for Materials Research and Testing, Berlin (Germany)

    2012-11-01

    High molecular weight polyethylene (HMW-PE) and ultra high molecular weight polyethylene (UHMW-PE) are high performance materials, which are predestinated for a wide range of applications due to characteristics like high chemical resistance, low wear, and high hydrogen content. In addition to the application of (U)HMW-PE as sports equipment (sliding surface of snowboards, skis) and in mechanical engineering (materials for spur gears and chain guides) these polymers are used in two other and even more demanding areas: as implant material in medical technology and as a component for neutron shielding purposes in casks for storage and transport of radioactive waste. In these two cases, gamma irradiation and its impact on the molecular structure of polyethylene play an important role. In the first case, irradiation is applied for sterilization purposes and in the second one it exists as a side-effect of inserting the radioactive material in the cask. Specifically concerning their use in the field of medical technology, different types of UHMW-PE have been intensively studied. It is generally accepted that two concurrent and competitive processes, based on initial chain scission and subsequent reactions of C-centered radicals and molecular fragments, occur in PE as a consequence of radiation: radical recombination accounts for crosslinking, together with some disproportionation, formation of low molecular weight fragments, and recrystallization. Furthermore, formation of oxygenated structures in the presence of traces of oxygen is a competitive process to those mentioned above. Radiation induced scission preferentially takes place in the amorphous phase and noncrystalline surface of the crystallites and results in shorter polymer chains, fewer entanglements, and consequently, increased molecular mobility. The latter enables folding of polymer segments and thus, crystal growth and increased perfection in the crystal lamellae. With regard to the long-term application of

  18. The effect of an additional phosphite stabilizer on the properties of radiation cross-linked vitamin E blends of UHMWPE.

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew; Yabannavar, Pooja; Muratoglu, Orhun K

    2014-06-01

    Antioxidant stabilization of radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) has been introduced to improve the oxidative stability of total joint implant bearing surfaces. Blending of an antioxidant with UHMWPE resin powder followed by consolidation and radiation cross-linking has been cleared by the FDA for use in both total hips and total knees for designs incorporating two antioxidants, namely vitamin E and Covernox™ (a medical grade version of Irganox™ 1010). The antioxidants in the polymer are expected to protect the polymer during consolidation, during radiation cross-linking, on the shelf before implantation, and in vivo after implantation. To maximize the protection of the polymer afforded by the antioxidant in vivo, a novel approach may be the use of multiple antioxidants, especially to protect the primary antioxidant for a longer period of time. We hypothesized that the addition of a phosphite stabilizer (Irgafos 168™) commonly used in conjunction with hindered phenolic antioxidants in polymer processing could improve the oxidative stability of radiation cross-linked blends of vitamin E. To test our hypothesis, we prepared UHMWPE blends with 0.05 wt% Irgafos and 0.05 wt% vitamin E and compared its cross-link density, wear resistance, tensile properties, and impact strength to control blends containing only vitamin E. Our hypothesis was not supported; the cross-link density of UHMWPE was significantly decreased by the additive without additional benefit to oxidative stability. To our knowledge, this was the first attempt at using multiple stabilizers in medical grade UHMWPE.

  19. Wear Measurement of Highly Cross-linked UHMWPE using a 7Be Tracer Implantation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Wimmer, Markus A. [Rush Uniiv. Medical Center; Laurent, Michael P. [Rush Univ. Medical Center; Dwivedi, Yasha [Rush Univ. Medical Center; Gallardo, Luis A. [Rush Univ. Medical Center; Chipps, K. [Colorado School of Mines, Golden; Blackmon, Jeffery C [Louisiana State University; Kozub, R. L. [Tennessee Technological University; Bardayan, Daniel W [ORNL; Gross, Carl J [ORNL; Stracener, Daniel W [ORNL; Smith, Michael Scott [ORNL; Nesaraja, Caroline D [ORNL; Erikson, Luke [Colorado School of Mines, Golden; Patel, Nidhi [Colorado School of Mines, Golden; Rehm, Karl E. [Argonne National Laboratory (ANL); Ahmad, Irshad [Argonne National Laboratory (ANL); Greene, John P. [Argonne National Laboratory (ANL); Greife, Uwe [Colorado School of Mines, Golden

    2013-01-01

    The very low wear rates achieved with the current highly cross-linked ultrahigh molecular weight polyethylenes (UHMWPE) used in joint prostheses have proven to be difficult to measure accurately by gravimetry. Tracer methods are there- fore being explored. The purpose of this study was to perform a proof-of-concept experiment on the use of the radioactive tracer beryllium-7 (7Be) for the determination of in vitro wear in a highly cross-linked orthopedic UHMWPE. Three cross-linked and four conventional UHMWPE pins made from compression- molded GUR 1050, were activated with 109 to 1010 7Be nuclei using a new implantation setup that produced a homogenous distribution of implanted nuclei up to 8.5 lm below the surface. The pins were tested for wear in a six-station pin-on-flat appara- tus for up to 7.1 million cycles (178 km). A Germanium gamma detector was employed to determine activity loss of the UHMWPE pins at preset intervals during the wear test. The wear of the cross-linked UHMWPE pins was readily detected and esti- mated to be 17 6 3 lg per million cycles. The conventional-to- cross-linked ratio of the wear rates was 13.1 6 0.8, in the expected range for these materials. Oxidative degradation dam- age from implantation was negligible; however, a weak depend- ence of wear on implantation dose was observed limiting the number of radioactive tracer atoms that can be introduced. Future applications of this tracer technology may include the analysis of location-specific wear, such as loss of material in the post or backside of a tibial insert.

  20. Surface Crosslinking Modification of UHMWPE Fibers%UHMWPE纤维的表面交联改性

    Institute of Scientific and Technical Information of China (English)

    徐明忠; 赵国樑

    2012-01-01

    [2,4,6-tris(2-propenyloxy)-1,3,5-triazine](TAC) was chosen as crosslinking agent for the ultra-high molecular weight polyethylene(UHMWPE) fiber surface crosslinking modification initiated by ultraviolet radiation.Influence of n-heptane soaking time,concentration of the crosslinking agent and ultraviolet radiation time on the effectiveness of the surface cross-linking as well as the improvement of the creep properties of UHMWPE were discussed.IR,SEM and creeping test were conducted to characterize the crosslinking structure and creeping properties of the UHMWPE fiber.The results show that,the best soaking time of the fiber in n-heptane is 24 h and the best time of UV irradiation is 1.5 h.After crosslinking modification,the creep resistance of UHMWPE fiber is obviously improved.%选用三聚氰酸三丙烯酯(TAC)作为交联剂对超高分子量聚乙烯(UHMWPE)纤维进行紫外辐照交联改性,探讨了正庚烷浸泡时间、交联剂浓度、紫外线辐照时间等因素对UHMWPE纤维表面交联效果及纤维蠕变性能的影响。采用红外光谱、扫描电子显微镜及力学性能测试等多种手段对交联改性前后UHMWPE纤维的结构进行表征。结果表明,UHMWPE在正庚烷中的最佳浸泡时间为24h;紫外线辐照最佳时间为1.5 h;经交联改性后UHMWPE纤维的抗蠕变性能有较明显提高。

  1. Prediction of multiaxial mechanical behavior for conventional and highly crosslinked UHMWPE using a hybrid constitutive model.

    Science.gov (United States)

    Bergström, J S; Rimnac, C M; Kurtz, S M

    2003-04-01

    The development of theoretical failure, fatigue, and wear models for ultra-high molecular weight polyethylene (UHMWPE) used in joint replacements has been hindered by the lack of a validated constitutive model that can accurately predict large deformation mechanical behavior under clinically relevant, multiaxial loading conditions. Recently, a new Hybrid constitutive model for unirradiated UHMWPE was developed Bergström et al., (Biomaterials 23 (2002) 2329) based on a physics-motivated framework which incorporates the governing micro-mechanisms of polymers into an effective and accurate continuum representation. The goal of the present study was to compare the predictive capability of the new Hybrid model with the J(2)-plasticity model for four conventional and highly crosslinked UHMWPE materials during multiaxial loading. After calibration under uniaxial loading, the predictive capabilities of the J(2)-plasticity and Hybrid model were tested by comparing the load-displacement curves from experimental multiaxial (small punch) tests with simulated load-displacement curves calculated using a finite element model of the experimental apparatus. The quality of the model predictions was quantified using the coefficient of determination (r(2)). The results of the study demonstrate that the Hybrid model outperforms the J(2)-plasticity model both for combined uniaxial tension and compression predictions and for simulating multiaxial large deformation mechanical behavior produced by the small punch test. The results further suggest that the parameters of the HM may be generalizable for a wide range of conventional, highly crosslinked, and thermally treated UHMWPE materials, based on the characterization of four material properties related to the elastic modulus, yield stress, rate of strain hardening, and locking stretch of the polymer chains. Most importantly, from a practical perspective, these four key material properties for the Hybrid constitutive model can be measured

  2. Characterization of the mechanical properties of a new grade of ultra high molecular weight polyethylene and modeling with the viscoplasticity based on overstress.

    Science.gov (United States)

    Khan, Fazeel; Yeakle, Colin; Gomaa, Said

    2012-02-01

    Enhancements to the service life and performance of orthopedic implants used in total knee and hip replacement procedures can be achieved through optimization of design and the development of superior biocompatible polymeric materials. The introduction of a new or modified polymer must, naturally, be preceded by a rigorous testing program. This paper presents the assessment of the mechanical properties of a new filled grade of ultra high molecular weight polyethylene (UHMWPE) designated AOX(TM) and developed by DePuy Orthopaedics Inc. The deformation behavior was investigated through a series of tensile and compressive tests including strain rate sensitivity, creep, relaxation, and recovery. The polymer was found to exhibit rate-reversal behavior for certain loading histories: strain rate during creep with a compressive stress can be negative, positive, or change between the two during a test. Analogous behavior occurs during relaxation as well. This behavior lies beyond the realm of most numerical models used to computationally investigate and improve part geometry through finite element analysis of components. To address this shortcoming, the viscoplasticity theory based on overstress (VBO) has been suitably modified to capture these trends. VBO is a state variable based model in a differential formulation. Numerical simulation and prediction of all of the aforementioned tests, including good reproduction of the rate reversal behavior, is presented in this study.

  3. EFFECTS OF TRITIUM EXPOSURE ON UHMW-PE, PTFE, AND VESPEL

    Energy Technology Data Exchange (ETDEWEB)

    Clark, E; Kirk Shanahan, K

    2006-05-31

    Samples of three polymers, Ultra-High Molecular Weight Polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, also known as Teflon{reg_sign}), and Vespel{reg_sign} polyimide were exposed to 1 atmosphere of tritium gas at ambient temperature for varying times up to 2.3 years in closed containers. Sample mass and size measurements (to calculate density), spectra-colorimetry, dynamic mechanical analysis (DMA), and Fourier-transform infrared spectroscopy (FT-IR) were employed to characterize the effects of tritium exposure on these samples. Changes of the tritium exposure gas itself were characterized at the end of exposure by measuring total pressure and by mass spectroscopic analysis of the gas composition. None of the polymers exhibited significant changes of density. The color of initially white UHMW-PE and PTFE dramatically darkened to the eye and the color also significantly changed as measured by colorimetry. The bulk of UHMW-PE darkened just like the external surfaces, however the fracture surface of PTFE appeared white compared to the PTFE external surfaces. The white interior could have been formed while the sample was breaking or could reflect the extra tritium dose at the surface directly from the gas. The dynamic mechanical response of UHMW-PE was typical of radiation effects on polymers- an initial stiffening (increased storage modulus) and reduction of viscous behavior after three months exposure, followed by lowering of the storage modulus after one year exposure and longer. The storage modulus of PTFE increased through about nine months tritium exposure, then the samples became too weak to handle or test using DMA. Characterization of Vespel{reg_sign} using DMA was problematic--sample-to-sample variations were significant and no systematic change with tritium exposure could be discerned. Isotopic exchange and incorporation of tritium into UHMW-PE (exchanging for protium) and into PTFE (exchanging for fluorine) was observed by FT-IR using an attenuated

  4. EFFECTS OF TRITIUM EXPOSURE ON UHMW-PE, PTFE, AND VESPEL

    Energy Technology Data Exchange (ETDEWEB)

    Clark, E; Kirk Shanahan, K

    2006-05-31

    Samples of three polymers, Ultra-High Molecular Weight Polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, also known as Teflon{reg_sign}), and Vespel{reg_sign} polyimide were exposed to 1 atmosphere of tritium gas at ambient temperature for varying times up to 2.3 years in closed containers. Sample mass and size measurements (to calculate density), spectra-colorimetry, dynamic mechanical analysis (DMA), and Fourier-transform infrared spectroscopy (FT-IR) were employed to characterize the effects of tritium exposure on these samples. Changes of the tritium exposure gas itself were characterized at the end of exposure by measuring total pressure and by mass spectroscopic analysis of the gas composition. None of the polymers exhibited significant changes of density. The color of initially white UHMW-PE and PTFE dramatically darkened to the eye and the color also significantly changed as measured by colorimetry. The bulk of UHMW-PE darkened just like the external surfaces, however the fracture surface of PTFE appeared white compared to the PTFE external surfaces. The white interior could have been formed while the sample was breaking or could reflect the extra tritium dose at the surface directly from the gas. The dynamic mechanical response of UHMW-PE was typical of radiation effects on polymers- an initial stiffening (increased storage modulus) and reduction of viscous behavior after three months exposure, followed by lowering of the storage modulus after one year exposure and longer. The storage modulus of PTFE increased through about nine months tritium exposure, then the samples became too weak to handle or test using DMA. Characterization of Vespel{reg_sign} using DMA was problematic--sample-to-sample variations were significant and no systematic change with tritium exposure could be discerned. Isotopic exchange and incorporation of tritium into UHMW-PE (exchanging for protium) and into PTFE (exchanging for fluorine) was observed by FT-IR using an attenuated

  5. Tribological characterization of a biocompatible thin film of UHMWPE on Ti6Al4V and the effects of PFPE as top lubricating layer.

    Science.gov (United States)

    Panjwani, Bharat; Satyanarayana, Nalam; Sinha, Sujeet K

    2011-10-01

    Ultra-high molecular weight polyethylene (UHMWPE) thin film was coated onto Ti6Al4V alloy specimens using dip coating method. Tribological performance of this coating (thickness of 19.6 ± 2.0 μm) was evaluated using 4 mm diameter Si(3)N(4) ball counterface in a ball-on-disk tribometer. Tests were carried out for different normal loads (0.5, 1.0, 2.0 and 4.0 N) and rotational speeds of the disk (200 and 400 rpm). UHMWPE coating formed in this study exhibits high hydrophobicity with water contact angle of 135.5 ± 3.3° and meets the requirements of cytotoxicity test using the ISO 10993-5 elution method. This coating shows low coefficient of friction (0.15) and high wear durability (>96,000 cycles) for the tested conditions. PFPE overcoat on UHMWPE has further increased the wear durability of UHMWPE coating as evaluated at even higher rotational speed of 1000 rpm.

  6. Characterization and tribology of PEG-like coatings on UHMWPE for total hip replacements.

    Science.gov (United States)

    Kane, Sheryl R; Ashby, Paul D; Pruitt, Lisa A

    2010-03-15

    A crosslinked hydrogel coating similar to poly(ethylene glycol) (PEG) was covalently bonded to the surface of ultrahigh molecular weight polyethylene (UHMWPE) to improve the lubricity and wear resistance of the UHWMPE for use in total joint replacements. The chemistry, hydrophilicity, and protein adsorption resistance of the coatings were determined, and the wear behavior of the PEG-like coating was examined by two methods: pin-on-disk tribometry to evaluate macroscale behavior, and atomic force microscopy (AFM) to simulate asperity wear. As expected, the coating was found to be highly PEG-like, with approximately 83% ether content by x-ray photoelectron spectroscopy and more hydrophilic and resistant to protein adsorption than uncoated UHMWPE. Pin-on-disk testing showed that the PEG-like coating could survive 3 MPa of contact pressure, comparable to that experienced by total hip replacements. AFM nanoscratching experiments uncovered three damage mechanisms for the coatings: adhesion/microfracture, pure adhesion, and delamination. The latter two mechanisms appear to correlate well with wear patterns induced by pin-on-disk testing and evaluated by attenuated total reflection Fourier transform infrared spectroscopy mapping. Understanding the mechanisms by which the PEG-like coatings wear is critical for improving the behavior of subsequent generations of wear-resistant hydrogel coatings.

  7. Influence of ionizing irradiation in air and nitrogen for sterilization of surgical grade polyethylene for implants

    Science.gov (United States)

    Streicher, R. M.

    The influence of the atmosphere and the applied dose during ionizing radiation treatment on selected properties of ultra high molecular weight polyethylene (UHMWPE) have been investigated. A linear correlation between extinction coefficient and applied dosis in air from 6 to 125 kGy was found, while oxidation was not linear with irradiation in nitrogen. Bacteria survival rate shows a necessary minimum dose of 15 kGy for assured sterility of the product. Post reaction of latent free radicals in UHMWPE created during irradiation, which react or recombine time- and environment dependent, has also been investigated after storage of UHMWPE-films in air and nitrogen at 21°C and in water at body temperature 37°C for up to nine months. Results show that the properties of UHMWPE after radiation-sterilization change depending on time, the absorbed dose, the atmosphere where irradiation took place and the environment of storage. UHMWPE, which mainly crosslinks during irradiation degrades by an oxidation process after sterilizing when stored in air and even more in water at body temperature. So irradiation and storage in nitrogen before implantation in the human body is beneficial.

  8. Crosslinking modification of ultra high molecular weight polyethylene during joint arthroplasty%人工关节超高分子量聚乙烯交联改性的观察

    Institute of Scientific and Technical Information of China (English)

    佟刚; 田华; 王彩梅; 王刚

    2015-01-01

    Objective To explore the optimal condition of crosslinking modification of ultra high molecular weight polyethylene (UHMWPE) by gamma ray irradiation.Methods The hip and knee joint samples of UHMWPE were tested with regards to friction and wear performance at different doses of 60Co radiation and heat treatment.And the optimal condition of crosslinking was determined by wear performance and physicochemical properties.Results Under the condition of 75 kGy irradiation and 150 ℃ heat treatment,crosslinked UHMWPE showed the best performance.Acetabular sample wear rate decreased 63.24% and knee sample wear rate decreased 59.95% compared with conventional UHMWPE.The modified material had excellent mechanical properties of impact strength 83 kJ/m2,tensile strength 50.32 MPa,yield strength 21.83 MPa and elongation at break 312%.Also the material showed excellent antifatigue and reliable chemical properties.Conclusion The optimal condition of crosslinking modification of UHMWPE is 75 kGy irradiation after 150 ℃ heat treatment.%目的 探讨人工关节超高分子量聚乙烯(UHMWPE)采用γ射线辐照交联及热处理的最佳条件.方法 将医用UHMWPE材料用不同剂量γ射线辐照并热处理,制备成髋关节内衬和膝关节垫片,进行摩擦磨损测试,并进行理化性能评估,依据测试结果筛选出最佳辐照交联改性方案.结果 以75 kGy剂量辐照,在150℃热处理后的UHMWPE样品磨损率最低,与未经处理的材料相比,改性后的髋臼磨损率平均降低了63.24%、膝关节垫片磨损率平均降低了59.95%.同时此改性后的UHMWPE材料具有良好的机械性能,冲击强度为83 kJ/m2、拉伸强度50.32 mPa、屈服强度21.83 mPa、断裂伸长率312%.此外,改性后的材料还具有较好的抗疲劳性能和可靠的化学性能.结论 以75 kGy剂量的γ射线辐照,在150℃下热处理,为人工关节超高分子聚乙烯交联改性的最佳条件.

  9. A randomized controlled trial comparing Oxinium and cobalt-chrome on standard and cross-linked polyethylene.

    Science.gov (United States)

    Morison, Zachary A; Patil, Sunit; Khan, Habeeb A; Bogoch, Earl R; Schemitsch, Emil H; Waddell, James P

    2014-09-01

    The purpose of the investigation was to assess the clinical and radiographic outcomes in four bearing surfaces. Eighty patients (91 hips) undergoing total hip arthroplasty between 2004 and 2007 were randomized to one of four bearing surfaces: (1) cobalt-chrome (CoCr) and ultra-high molecular weight polyethylene (UHMWPE); (2) CoCr and XLPE; (3) Oxinium and UHMWPE; and (4) Oxinium and XLPE. The mean follow-up for this study was 6.8 years. There were no significant differences in clinical outcomes. The linear wear rates for the four groups were 0.241 mm/year, 0.076 mm/year, 0.238 mm/year and 0.061 mm/year respectively. HXLPE results in significantly less wear than UHMWPE. However, we found no significant reduction in wear rate by using Oxinium in place of CoCr femoral heads at early follow-up.

  10. Comparison of oxidation resistance of UHMWPE and POM in H2O2 solution from ReaxFF reactive molecular dynamics simulations.

    Science.gov (United States)

    Chen, Wu; Duan, Hai-tao; Hua, Meng; Gu, Ka-li; Shang, Hong-fei; Li, Jian

    2014-08-28

    The oxidation mechanism of ultra-high-molecular-weight polyethylene (UHMWPE) and polyoxymethylene (POM) in hydrogen peroxide solution was investigated by molecular dynamics (MD) simulations via reactive force field (ReaxFF) method. MD results from ReaxFF suggested that UHMWPE provided better antioxidation activity at high temperature (>373 K) than its POM counterpart in the same concentration of hydrogen peroxide solution. Furthermore, POM was relatively more susceptible to erosion and swelling because of the infiltration of H2O2 solution. Calculations of the diffusion coefficient at different temperatures permit further understanding of the chemical phenomena involved in the level of oxidation in the course of MD simulations. Results of the simulations are generally consistent with the previous experimental available in literature. The simulations also provide new insights into understanding the mechanism resulting oxidation products among the interested polymers.

  11. Surface modification of carbon fibers and its effect on the fiber–matrix interaction of UHMWPE based composites

    Energy Technology Data Exchange (ETDEWEB)

    Chukov, D.I., E-mail: dil_chukov@yahoo.com; Stepashkin, A.A.; Gorshenkov, M.V.; Tcherdyntsev, V.V.; Kaloshkin, S.D.

    2014-02-15

    Highlights: • Both chemical and thermal treatments of UKN 5000 carbon fibers allow one to obtain well-developed surface. • The changes of structure and properties of VMN-4 fibers after both thermal and chemical oxidation are insignificant due to more perfect initial structure of these fibers. • The oxidative treatment of carbon fibers allows one to improve the interfacial interaction in the UHMWPE-based composites. • The oxidative treatment of the fibers allows one to a triple increase of Young’s modulus of the modified fibers reinforced UHMWPE composites. -- Abstract: The PAN-based carbon fibers (CF) were subjected to thermal and chemical oxidation under various conditions. The variation in the surface morphology of carbon fibers after surface treatment was analyzed by scanning electron microscopy (SEM). It was found that the tensile strength of carbon fibers changed after surface modification. The interaction between the fibers and the matrix OF ultra-high molecular weight polyethylene (UHMWPE) was characterized by the Young modulus of produced composites. It was shown that the Young modulus of composites reinforced with modified carbon fibers was significantly higher than that of composites reinforced with non-modified fibers.

  12. Contact Stress Generation on the UHMWPE Tibial Insert

    Directory of Open Access Journals (Sweden)

    S. Petrović Savić

    2014-12-01

    Full Text Available Total knee replacement (TKR is considered, during last years, as a very successful surgical technique for removing knee joint deformities and eliminating pain caused by cartilage damage. In literature, as primary causes for knee joint endoprothesis damage are cited complex movements which cause occurrences of complex stress conditions, sagital radius conformity, sliding, types of materials etc. Aim of this study is analysis of contact stresses that occur on tibial implant for 15°, 45° and 60° knee flexion and 50 kg, 75 kg, 100 kg and 125 kg weight. Knee joint prosthesis model and finite elements method (FEM analysis are done in software Catia V5. For this analysis we used ultra-high molecular weight polyethylene (UHMWPE for tibial implant material and AISI 316, AISI 317, AISI 321, 17-4PH, CoCrMo, Ti6Al4V and SAE A-286 for femoral component materials. Results show that area of maximal contact stress is identified in medial and lateral part of tibial implant. Von Mises stress values vary regarding of flexion degree and weight, but values are approximate for types of chosen materials. Contact stress location corresponds to damage that occur on tibial implant during exploitation.

  13. Background data for modulus mapping high-performance polyethylene fiber morphologies.

    Science.gov (United States)

    Strawhecker, Kenneth E; Sandoz-Rosado, Emil J; Stockdale, Taylor A; Laird, Eric D

    2017-02-01

    The data included here provides a basis for understanding "Interior morphology of high-performance polyethylene fibers revealed by modulus mapping" (K.E. Strawhecker, E.J. Sandoz-Rosado, T.A. Stockdale, E.D. Laird, 2016) [1], in specific: the multi-frequency (AMFM) atomic force microscopy technique and its application to ultra-high-molecular-weight Polyethylene (UHMWPE) fibers. Furthermore, the data suggests why the Hertzian contact mechanics model can be used within the framework of AMFM theory, simple harmonic oscillator theory, and contact mechanics. The framework is first laid out followed by data showing cantilever dynamics, force-distance spectra in AC mode, and force-distance in contact mode using Polystyrene reference and UHMWPE. Finally topography and frequency shift (stiffness) maps are presented to show the cases where elastic versus plastic deformation may have occurred.

  14. Background data for modulus mapping high-performance polyethylene fiber morphologies

    Directory of Open Access Journals (Sweden)

    Kenneth E. Strawhecker

    2017-02-01

    Full Text Available The data included here provides a basis for understanding “Interior morphology of high-performance polyethylene fibers revealed by modulus mapping” (K.E. Strawhecker, E.J. Sandoz-Rosado, T.A. Stockdale, E.D. Laird, 2016 [1], in specific: the multi-frequency (AMFM atomic force microscopy technique and its application to ultra-high-molecular-weight Polyethylene (UHMWPE fibers. Furthermore, the data suggests why the Hertzian contact mechanics model can be used within the framework of AMFM theory, simple harmonic oscillator theory, and contact mechanics. The framework is first laid out followed by data showing cantilever dynamics, force-distance spectra in AC mode, and force-distance in contact mode using Polystyrene reference and UHMWPE. Finally topography and frequency shift (stiffness maps are presented to show the cases where elastic versus plastic deformation may have occurred.

  15. Attachment of human primary osteoblast cells to modified polyethylene surfaces.

    Science.gov (United States)

    Poulsson, Alexandra H C; Mitchell, Stephen A; Davidson, Marcus R; Johnstone, Alan J; Emmison, Neil; Bradley, Robert H

    2009-04-09

    Ultra-high-molecular-weight polyethylene (UHMWPE) has a long history of use in medical devices, primarily for articulating surfaces due to its inherent low surface energy which limits tissue integration. To widen the applications of UHMWPE, the surface energy can be increased. The increase in surface energy would improve the adsorption of proteins and attachment of cells to allow tissue integration, thereby allowing UHMWPE to potentially be used for a wider range of implants. The attachment and function of human primary osteoblast-like (HOB) cells to surfaces of UHMWPE with various levels of incorporated surface oxygen have been investigated. The surface modification of the UHMWPE was produced by exposure to a UV/ozone treatment. The resulting surface chemistry was studied using X-ray photoelectron spectroscopy (XPS), and the topography and surface structure were probed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), which showed an increase in surface oxygen from 11 to 26 atom % with no significant change to the surface topography. The absolute root mean square roughness of both untreated and UV/ozone-treated surfaces was within 350-450 nm, and the water contact angles decreased with increasing oxygen incorporation, i.e., showing an increase in surface hydrophilicity. Cell attachment and functionality were assessed over a 21 day period for each cell-surface combination studied; these were performed using SEM and the alamarBlue assay to study cell attachment and proliferation and energy-dispersive X-ray (EDX) analysis to confirm extracellular mineral deposits, and total protein assay to examine the intra- and extracellular protein expressed by the cells. HOB cells cultured for 21 days on the modified UHMWPE surfaces with 19 and 26 atom % oxygen incorporated showed significantly higher cell densities compared to cells cultured on tissue culture polystyrene (TCPS) from day 3 onward. This indicated that the cells attached and proliferated more

  16. The relative influence of five variables on the in vitro wear rate of uncrosslinked UHMWPE acetabular cup liners.

    Science.gov (United States)

    Lewis, Gladius; Fencl, Robert M; Carroll, Michael; Collins, Tim

    2003-05-01

    The wear factors, k(exp)(in 10(-6)mm(3)N(-1)m(-1)), of two sets of hemispherical uncrosslinked ultra-high-molecular-weight polyethylene UHMWPE acetabular cup liners, when articulated against 28-mm-diameter Co-Cr alloy femoral heads, were determined in a hip joint wear simulator. All test conditions used were the same for both sets, with the exception that in one set (comprising six liners), the bovine serum concentration in the test lubricant (P) was 25vol%, while it was 90vol% for the other set (comprising seven liners). For each liner in each set, the values of the following independent or explanatory variables were determined: the tensile toughness (U, in MJm(-3)) of the UHMWPE; the degree of crystallinity (%C) of the UHMWPE; the mean surface roughness (R(a), in microm) of the liner; and the radial clearance between the femoral head and the liner (DeltaL, in mm). All the results in both sets were combined and correlational analyses were performed between k(exp), on the one hand, and various combinations of U, %C,R(a),DeltaL, and P, on the other hand. It was found that the strongest correlations were obtained when P was included, but that %C and U are also important variables. Within the range of values of the independent variables used, the recommended relationship isk(exp)=460U(0.72)%C(-5.29)P(-0.66)(adjustedr(2)=0.858). This relationship has many potential uses, such as for screening uncrosslinked UHMWPEs that are being considered as candidates for fabricating acetabular cup liners, and for conducting studies of the sensitivity of k(exp) to a change in a value of a specified independent variable (with the values of all the other independent variables held constant). These uses, as well as the study limitations, are discussed in detail.

  17. Anisotropy and oxidative resistance of highly crosslinked UHMWPE after deformation processing by solid-state ram extrusion.

    Science.gov (United States)

    Kurtz, Steven M; Mazzucco, Dan; Rimnac, Clare M; Schroeder, Dave

    2006-01-01

    Solid-state deformation processing is a promising technique for modifying the physical and mechanical properties of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) beyond simple thermal treatment cycles that have been employed previously. This study evaluates anisotropy and oxidative resistance in a novel, radiation crosslinked (50 kGy) UHMWPE material (ArComXL: Biomet, Inc., Warsaw, IN), incorporating solid-state, deformation processing by extrusion below the melt transition for application in total hip arthroplasty. Tensile, compression, and small punch tests were conducted to evaluate the material properties in the three principal axes of the resulting material. Furthermore, short-term oxidative resistance was evaluated using Fourier transform infrared spectroscopy and the small punch test in conjunction with accelerated shelf aging protocols. The results of this testing indicate that the material is anisotropic, with significantly enhanced strength oriented along the long axis of the rod. For certain other properties, the magnitude of the anisotropy was relatively slight, especially in the elastic regime, in which only a 20% difference was noted between the long axis of the rod and the orthogonal, radial direction. The highly crosslinked material contains detectable free radicals, at a concentration that is 90% less than control, gamma inert sterilized UHMWPE. An unexpected finding of this study was evidence of oxidative stability of the deformation-processed material, even after 4 weeks of accelerated aging in a pressure vessel containing five atmospheres of oxygen (ASTM F2003), which resulted in macroscopic embrittlement of the control material. The oxidative stability observed in ArComXL suggests that the deformation-processed material may be suitable for air-permeable packaging and gas sterilization, which has thus far been reserved for remelted highly crosslinked UHMWPE.

  18. Effects of Ti, PMMA, UHMWPE, and Co-Cr wear particles on differentiation and functions of bone marrow stromal cells.

    Science.gov (United States)

    Jiang, Yunpeng; Jia, Tanghong; Gong, Weiming; Wooley, Paul H; Yang, Shang-You

    2013-10-01

    This study investigates the roles of orthopedic biomaterial particles [Ti-alloy, poly(methyl methacrylate) (PMMA), ultrahigh-molecular-weight polyethylene (UHMWPE), Co-Cr alloy] on the differentiation and functions of bone marrow stromal cells (BMSCs). Cells were isolated from femurs of BALB/c mice and cultured in complete osteoblast-induction medium in presence of micron-sized biomaterial particles at various doses. 3-(4,5)-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and lactate dehydrogenase assay were performed for cell proliferation and cytotoxicity. Differentiation and function of osteoblasts were evaluated by alkaline phosphatase (ALP), osteocalcin, RANKL, OSX, and Runx2 expressions. Murine interleukin-1 (IL-1), IL-6, and tumor necrosis factor-α in culture media were determined by enzyme-linked immunosorbent assay. Challenge with low doses of Ti, UHMWPE, or Co-Cr particles markedly promoted the bone marrow cell proliferation while high dose of Co-Cr significantly inhibited cell growth (p UHMWPE particles (0.63 mg/mL) exhibited strong ALP activity, whereas Ti and Co-Cr groups showed minimal effects (p UHMWPE and Ti particles also promoted higher expression of proinflammatory cytokines. Real-time polymerase chain reaction data suggested that cells treated with low dose (0.5 mg/mL) particles resulted in distinctly diminished RANKL expression compared to those exposed to high concentrated (3 mg/mL) particles. In conclusion, various types of wear debris particles behaved differently in the differentiation, maturation, and functions of osteogenic cells; and the particulate debris-interacted BMSCs may play an important role in the pathogenesis and process of the debris-associated aseptic prosthetic loosening.

  19. The Interplay of Design and Materials in Orthopedics: Evaluating the Impact of Notch Geometry on Fatigue Failure of UHMWPE Joint Replacements

    OpenAIRE

    Ansari, Farzana

    2015-01-01

    Each year, roughly 750,000 patients in the US receive a total joint replacement (TJR), or a synthetic medical device that serves to replace the natural joint to restore function and relieve pain. TJRs have had a long history of use in the hip, knee and shoulder, yet still retain the same standard design of a hard-on-soft bearing coupling. Today, those bearings are primarily composed of hard cobalt chrome (CoCr) surface articulating against ultrahigh molecular weight polyethylene (UHMWPE), a p...

  20. UHM WPE-PUF复合材料结构设计与隔爆实验%Structural Design and Anti-Explosion Experiment of UHMWPE-PUF Composite

    Institute of Scientific and Technical Information of China (English)

    蔡军锋; 易建政; 赵然

    2012-01-01

    采用层状复合工艺,制备了超高分子量聚乙烯(UHMWPE)-聚氨酯泡沫材料(PUF)复合材料;设计了复合材料隔爆实验,运用定制的聚偏氟乙烯(PVDF)压电传感器,直接测量了隔爆实验中材料内部冲击波压力,研究了UHMWPE-PUF复合材料对爆炸冲击波的衰减性能。研究表明,所制备的UHMWPE-PUF复合材料隔爆能力与同厚度的纯聚氨酯材料相比提高了近50%。将UHMWPE材料与PUF材料进行复合,可以充分发挥UHMWPE材料的高强、高模以及PUF材料较高的吸能特点,同时又弥补了PUF材料强度低的缺陷,且材料对爆炸冲击波的衰减性能得到极大提升,在爆炸防护领域有着很好的应用前景。%Ultra high molecular weight polyethylene (UHMWPE)- polyurethane foam (PUF) composite was synthesized by laminated composite technology and the anti-explosion experiment of composite was designed. The pressure in material under explosion load was measured directly by custom-built polyvinylidene fluoride (PVDF) piezoelectric sensor. Shock wave attenuation properties of UHMWPE-PUF composite were studied by experimental method. The results show that UHMWPE-PUF composite can give full play to the high-strength high-model feature of UI-IMWPE material and the energy absorbing property of polyurethane foam material, and the low strength imperfection of polyurethane foam plastics was offset by UHMWPE material. The experiment shows shock wave attenuation ability of UHMWPE-PUF composite can improve by 50 % than of pure PUF material. The strength and shock wave attenuation properties of UHMWPE-PUF composites were maximally improved. The materials have a good applied outlook in the realm of anti-expbsion.

  1. The investigation of nanotribology of UHMWPE in fluid using atomic force microscopy.

    Science.gov (United States)

    Wu, Jingping; Peng, Zhongxiao

    2015-05-01

    The fundamental understanding of the nanowear behavior of ultrahigh molecular weight polyethylene (UHMWPE) at a nanometer scale needs to be achieved to provide a better understanding of the initiating wear process and the potential causes of the wear particles generation of joint replacement. A nanotribology study was performed using atomic force microscope (AFM) tips sliding against UHMWPE surfaces in both water and bovine serum lubricants. Frictional properties of the nanocontact, and the geometry and mechanical features of the resulting scratches have been quantitatively characterized using AFM lateral force and PeakForce QNM modes. The results in this work indicated that the friction force and friction coefficient were smaller in serum lubricant than that in water. A normal load of 120 nN was the transition point for the plastic deformation of the material. The plastic deformation and material accumulation evolute with the increase of applied normal loads. Material pileup formed at the edges of the scratch, but they were not symmetrical due to the asymmetrical geometry of the silicon AFM tip. The height of the material pileup on the right side was approximately 40-70% of the pileup on the left side. The information may be useful for developing strategies for surface finishing techniques, which can control and minimize the production of asymmetric asperity and the resulting pileup with particular features. Furthermore, the moduli of the pileups were much larger than that of the fresh UHMWPE, which had the moduli greater than those of the inner scratch area. This suggested that stress concentration at these points could cause the pileup to be more susceptible to further wear processes, and eventually result in detaching from the bulk material.

  2. A study of the influence of UHMWPE fiber on failure morphology and bending performance for lumber%超高分子量聚乙烯纤维增强对木材破坏形貌及承载性能影响∗

    Institute of Scientific and Technical Information of China (English)

    沈文东; 李坚

    2014-01-01

    In order to research whether ultra high molecular weight polyethylene (UHMWPE)fiber could be used in wood-based composite,three layer structure of wood composite materials from planed timber-UHM-WPE fiber-veneer was designed and prepared,PUR was selected as adhesive for this structure.The influences of UHMWPE fiber and veneer thickness composited with lumber on bending performance and ILSS of lumber were examined.The chemical constituents of deboning fibers were characterized by infrared spectroscopy (FT-IR).The mechanism of lumber heightened was discussed.The results showed that PUR could be used in UH-MWPE/lumber composite;UHMWPE fiber obviously changed the wood failure process and failure morpholo-gy,and improved the bearing capacity of wood;the effect reinforced by UHMWPE fiber was closely related to the thickness of veneer.Reinforced effect of UHMWPE fiber much affects the shear performance of bonding in-terface.%选用 PUR 木材层压胶,设计“刨光锯材-超高分子量聚乙烯(UHMWPE)纤维-单板”3层结构木质复合材,探索研究了 UHMWPE 纤维增强对木材抗弯性能、剪切性能以及单板厚度对其增强效果影响,并利用红外光谱(FT-IR)对脱粘纤维进行表征,进而对 UHMWPE 纤维增强机理进行了分析。结果表明, PUR 木材层压胶可用于 UHMWPE 纤维/木材的复合,UHMWPE纤维增强明显改变了木材破坏过程和破坏形貌,提高了木材的承载性能,同时 UHMWPE纤维增强效果与单板厚度密切相关。UHMWPE 纤维的加入降低了胶合界面的剪切性能。

  3. The biomaterials challenge: A comparison of polyethylene wear using a hip joint simulator.

    Science.gov (United States)

    Affatato, Saverio; Freccero, Nadia; Taddei, Paola

    2016-01-01

    Although hip arthroplasty is an established procedure that relieves pain and improves functions, problems remain with wear and osteolysis. Highly cross-linked polyethylene and Vitamin-E-stabilized polyethylene were introduced in the last years to solve these problems. In this study we compared the in vitro wear behaviour of cross-linked polyethylene (XLPE) versus Vitamin-E diffused XLPE (XLPE_VE) versus conventional ultra-high molecular weight polyethylene (UHMWPE) acetabular cups. The test was performed using a hip joint simulator run for two millions cycles under bovine calf serum as lubricant. Mass loss was found to decrease along the series UHMWPE>XLPE_VE>XLPE, although statistically significant differences were found only between the mass losses of XLPE and UHMWPE at 1.2 and 2 million cycles. The mass loss data were explained in relation to the crystalline morphology of the control unworn cups, as investigated by non-destructive micro-Raman spectroscopy. This technique allowed to disclose a different wear behaviour of the three sets of cups. Wear testing produced a stress-induced crystallisation in UHMWPE, with increases in both amorphous (αa) and orthorhombic (αo) phases at the expense of the third phase (αb), which decreased upon wear. Moreover, the all-trans content decreased, while the ortho-trans content increased, contrarily to the trend observed for XLPE and XLPE_VE, for which no statistically significant changes in αo, αa and αb contents were detected. The XLPE_VE specimens underwent the least significant changes in the spectroscopic markers of micromorphology upon mechanical stress, probably due to their lower starting amorphous content.

  4. Effect of crosslinking UHMWPE on its tensile and compressive creep performance.

    Science.gov (United States)

    Lewis, G; Carroll, M

    2001-01-01

    The in vitro quasi-static tensile and compressive creep properties of three sets of GUR 1050 ultra-high-molecular-weight polyethylene (UHMWPE) specimens were obtained. These sets were: control (as-received stock); "low-gamma" (specimens were crosslinked using gamma radiation, with a minimum dose of 5 Mrad); and "high-gamma" (specimens were crosslinked using gamma radiation, with a minimum dose of 15 Mrad). The % crystallinity (%C) and crosslink density (rho(x)) of the specimens in the three sets were also obtained. It was found that, in both tension and compression, crosslinking resulted in a significant depreciation in the creep properties, relative to control. The trend in the creep results is explained in terms of the impact of crosslinking on the polymer's %C and rho(x). The present results are in contrast to literature reports that show that crosslinking enhances the wear resistance of the polymer. The implications of the present results, taken together with the aforementioned literature results, are fully discussed vis-a-vis the use of crosslinked UHMWPE for fabricating articular components for arthroplasties.

  5. Influence of laser power on tensile properties and material characteristics of laser-sintered UHMWPE

    Directory of Open Access Journals (Sweden)

    Khalil Yas

    2016-01-01

    Full Text Available Ultra High Molecular Weight Polyethylene (UHMWPE has excellent properties, such as high mechanical performance, low friction, high wear and chemical resistance but so far there has been limited use in additive manufacturing (AM. Laser sintering of polymers is one of the most promising AM technologies due to its ability to produce complex geometries with accurate dimensions and good mechanical properties. Consequently, this study investigates the influence of laser power on physical and mechanical properties of UHMWPE parts produced by laser sintering. In particular mechanical properties, such as Ultimate Tensile Strength (UTS, Young’s Modulus and elongation at break were evaluated alongside relative density, dilation and shrinkage. Finally, the fracture surface of the tensile test specimens was examined by electron microscopy. Results show that within a laser power range of 6–12 W there appears to be an optimum where tensile strength and relative density reach a maximum, dilation is minimised and where elongation increases with laser power. UTS up to 2.42 MPa, modulus up to 72.6 MPa and elongation at break up to 51.4% were observed. Relative density and part dimensions are also influenced by laser power.

  6. Adsorption of albumin and sodium hyaluronate on UHMWPE: a QCM-D and AFM study.

    Science.gov (United States)

    Serro, A P; Degiampietro, K; Colaço, R; Saramago, B

    2010-06-15

    The biotribological properties of artificial joints, in particular the efficiency of the lubrication, strongly determine their lifetime. The most commonly used artificial joints combine a metallic or ceramic part articulating against a ultra high molecular weight polyethylene (UHMWPE) counterface, and are lubricated by the periprosthetic fluid. This fluid contains several macromolecules, namely albumin and sodium hyaluronate (NaHA), that are known to be involved in the lubrication process. There are several studies in the literature concerning the interaction of the referred macromolecules with ceramic or metallic prosthetic materials. However, to our knowledge, information about their binding to the polymeric surface is practically inexistent. The objective of this work is to contribute to clarify the role played by albumin and NaHA on the biolubrication process, through the investigation of their interaction with the UHMWPE surface. The study involves adsorption measurements using a quartz crystal microbalance with dissipation (QCM-D), the characterization of the adsorbed films by atomic force microscopy (AFM) and wettability determinations. Albumin was found to adsorb strongly and extensively to the polymer, while NaHA led to a very low adsorption. In both cases rigid films were obtained, but with different morphology and porosity. The high binding affinity of the protein to the polymer was demonstrated both by the results of the fittings to Langmuir and Freundlich models and by the values of the adhesion forces determined by AFM. In the simultaneous adsorption of albumin and NaHA, protein adsorption is predominant and determines the surface properties.

  7. High molecular weight poly(L-lactide) and poly(ethylene oxide) blends : Thermal characterization and physical properties

    NARCIS (Netherlands)

    Nijenhuis, AJ; Colstee, E; Grijpma, DW; Pennings, AJ

    1996-01-01

    The miscibility of high molecular weight poly(L-lactide) (PLLA) with high molecular weight poly(ethylene oxide) (PEG) was studied by differential scanning calorimetry. Ail blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were f

  8. Using a surrogate contact pair to evaluate polyethylene wear in prosthetic knee joints.

    Science.gov (United States)

    Sanders, Anthony P; Lockard, Carly A; Weisenburger, Joel N; Haider, Hani; Raeymaekers, Bart

    2016-01-01

    With recent improvements to the properties of ultra-high molecular weight polyethylene (UHMWPE) used in joint replacements, prosthetic knee and hip longevity may extend beyond two decades. However, it is difficult and costly to replicate such a long in vivo lifetime using clinically relevant in vitro wear testing approaches such as walking gait joint simulators. We advance a wear test intermediate in complexity between pin-on-disk and knee joint simulator tests. The test uses a surrogate contact pair, consisting of a surrogate femoral and tibial specimen that replicate the contact mechanics of any full-scale knee condyle contact pair. The method is implemented in a standard multi-directional pin-on-disk wear test machine, and we demonstrate its application via a two-million-cycle wear test of three different UHMWPE formulations. Further, we demonstrate the use of digital photography and image processing to accurately quantify fatigue damage based on the reduced transmission of light through a damage area in a UHMWPE specimen. The surrogate contact pairs replicate the knee condyle contact areas within -3% to +12%. The gravimetric wear test results reflect the dose of crosslinking radiation applied to the UHMWPE: 35 kGy yielded a wear rate of 7.4 mg/Mcycles, 55 kGy yielded 1.0 mg/Mcycles, and 75 kGy (applied to a 0.1% vitamin E stabilized UHMWPE) yielded 1.5 mg/Mcycles. A precursor to spalling fatigue is observed and precisely measured in the radiation-sterilized (35 kGy) and aged UHMWPE specimen. The presented techniques can be used to evaluate the high-cycle fatigue performance of arbitrary knee condyle contact pairs under design-specific contact stresses, using existing wear test machines. This makes the techniques more economical and well-suited to standardized comparative testing.

  9. Supercritical CO2 impregnation of polyethylene components for medical purposes

    Directory of Open Access Journals (Sweden)

    Gamse Thomas

    2007-01-01

    Full Text Available Modem hip and knee endoprosthesis are produced in titanium and to reduce the friction at the contact area polymer parts, mainly ultra-high molecular weight polyethylene (UHMW-PE, are installed. The polyethylene is impregnated with a-tocopherol (vitamin E before processing for remarkable decrease of oxidative degradation. Cross linked UHMW-PE offers much higher stability, but a-tocopherol cannot be added before processing, because a-tocopherol hinders the cross linking process accompanied by a heavy degradation of the vitamin. The impregnation of UHMW-PE with a-tocopherol has to be performed after the cross linking process and an accurate concentration has to be achieved over the cross section of the whole material. In the first tests UHMW-PE-cubes were stored in pure a-tocopherol under inert atmosphere at temperatures from 100 to 150 °C resulting in a high mass fraction of a-tocopherol in the edge zones and no constant concentration over the cross section. For better distribution and for regulating the mass fraction of a-tocopherol in the cross linked UHMW-PE material supercritical CO2 impregnation tests were investigated. Again UHMW-PE-cubes were impregnated in an autoclave with a-tocopherol dissolved in supercritical CO2 at different pressures and temperatures with variable impregnation times and vitamin E concentrations. Based on the excellent results of supercritical CO2 impregnation standard hip and knee cups were stabilized nearly homogeneously with varying mass fraction of a-tocopherol.

  10. Quantification of the effect of cross-shear and applied nominal contact pressure on the wear of moderately cross-linked polyethylene.

    Science.gov (United States)

    Abdelgaied, Abdellatif; Brockett, Claire L; Liu, Feng; Jennings, Louise M; Fisher, John; Jin, Zhongmin

    2013-01-01

    Polyethylene wear is a great concern in total joint replacement. It is now considered a major limiting factor to the long life of such prostheses. Cross-linking has been introduced to reduce the wear of ultra-high-molecular-weight polyethylene (UHMWPE). Computational models have been used extensively for wear prediction and optimization of artificial knee designs. However, in order to be independent and have general applicability and predictability, computational wear models should be based on inputs from independent experimentally determined wear parameters (wear factors or wear coefficients). The objective of this study was to investigate moderately cross-linked UHMWPE, using a multidirectional pin-on-plate wear test machine, under a wide range of applied nominal contact pressure (from 1 to 11 MPa) and under five different kinematic inputs, varying from a purely linear track to a maximum rotation of +/- 55 degrees. A computational model, based on a direct simulation of the multidirectional pin-on-plate wear tester, was developed to quantify the degree of cross-shear (CS) of the polyethylene pins articulating against the metallic plates. The moderately cross-linked UHMWPE showed wear factors less than half of that reported in the literature for, the conventional UHMWPE, under the same loading and kinematic inputs. In addition, under high applied nominal contact stress, the moderately crosslinked UHMWPE wear showed lower dependence on the degree of CS compared to that under low applied nominal contact stress. The calculated wear coefficients were found to be independent of the applied nominal contact stress, in contrast to the wear factors that were shown to be highly pressure dependent. This study provided independent wear data for inputs into computational models for moderately cross-linked polyethylene and supported the application of wear coefficient-based computational wear models.

  11. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate)

    DEFF Research Database (Denmark)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati

    2017-01-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough...... physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196 kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.......7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half...

  12. Modification of UHMWPE membrane with a PE/clay/PE-G-MA nano composite film to treat oily effluents; Modificacao de membrana de PEUAPM com filme nanocomposito de PEAD/argila/PE-G-MA para o tratamento de efluentes oleosos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Suelem S.L.; Silva, Caio M.B.; Leal, Tania L.; Carvalho, Laura H.; Costa, Anna R.M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)], e-mail: tanlucleal@yahoo.com.br

    2011-07-01

    Interest in techniques of surface modification is evinced by the large number of studies in recent decades. In this work the internal surfaces of polymeric membranes of ultra high molecular weight polyethylene (UHMWPE) were modified by impregnation of HDPE/organoclay/PE-g-MA nanocomposite film. The addition of PE-g-MA aims to increase polymer/clay interaction and to control and/or modify surface characteristics of UHMWPE membranes, such as permeability and pore size, so as to make the membranes more efficient and/or appropriate for effluent treatment, more specifically in the treatment of oil contaminated water. The films were analyzed by infrared spectroscopy (FTIR), the modified membranes were characterized by scanning electron microscopy (SEM) and their performance (permeate flux and selectivity) were measured using distilled water and an oil in water dispersion. (author)

  13. EFFECTS OF MATRIX MOLECULAR WEIGHT ON STRUCTURE AND REINFORCEMENT OF HIGH DENSITY POLYETHYLENE/MICA COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Li Chen; Yu-fang Xiang; Ke Wang; Qin Zhang; Rong-ni Du; Qiang Fu

    2011-01-01

    Three types of high-density polyethylene (HDPE) with different molecular weights (high, medium and Iow) were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM, 2d-WAXS, DSC, DMA and tensile testing. Various structural factors including orientation, filler dispersion, interfacial interaction between HDPE and mica, etc., which can impact the macroscopic mechanics, were compared in detail among the three HDPE/mica composites. The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence. Obvious transcrystalline structure was found in the composite with Iow molecular weight HDPE, whereas it was hard to be detected in the composites with increased HDPE molecular weight. The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interracial adhesion between matrix and mica filler, which arises from the transerystallization mechanism.

  14. Can pin-on-disk testing be used to assess the wear performance of retrieved UHMWPE components for total joint arthroplasty?

    Science.gov (United States)

    Kurtz, Steven M; MacDonald, Daniel W; Kocagöz, Sevi; Tohfafarosh, Mariya; Baykal, Doruk

    2014-01-01

    The objective of this study was to assess the suitability of using multidirectional pin-on-disk (POD) testing to characterize wear behavior of retrieved ultrahigh molecular weight polyethylene (UHMWPE). The POD wear behavior of 25 UHMWPE components, retrieved after 10 years in vivo, was compared with 25 that were shelf aged for 10-15 years in their original packaging. Components were gamma sterilized (25-40 kGy) in an air or reduced oxygen (inert) package. 9 mm diameter pins were fabricated from each component and evaluated against CoCr disks using a super-CTPOD with 100 stations under physiologically relevant, multidirectional loading conditions. Bovine serum (20 g/L protein concentration) was used as lubricant. Volumetric wear rates were found to vary based on the aging environment, as well as sterilization environment. Volumetric wear rates were the lowest for the pins in the gamma inert, shelf aged cohort. These results support the utility of using modern, multidirectional POD testing with a physiologic lubricant as a novel method for evaluating wear properties of retrieved UHMWPE components. The data also supported the hypothesis that wear rates of gamma-inert liners were lower than gamma-air liners for both retrieved and shelf aging conditions. However, this difference was not statistically significant for the retrieved condition.

  15. Can Pin-on-Disk Testing Be Used to Assess the Wear Performance of Retrieved UHMWPE Components for Total Joint Arthroplasty?

    Directory of Open Access Journals (Sweden)

    Steven M. Kurtz

    2014-01-01

    Full Text Available The objective of this study was to assess the suitability of using multidirectional pin-on-disk (POD testing to characterize wear behavior of retrieved ultrahigh molecular weight polyethylene (UHMWPE. The POD wear behavior of 25 UHMWPE components, retrieved after 10 years in vivo, was compared with 25 that were shelf aged for 10–15 years in their original packaging. Components were gamma sterilized (25–40 kGy in an air or reduced oxygen (inert package. 9 mm diameter pins were fabricated from each component and evaluated against CoCr disks using a super-CTPOD with 100 stations under physiologically relevant, multidirectional loading conditions. Bovine serum (20 g/L protein concentration was used as lubricant. Volumetric wear rates were found to vary based on the aging environment, as well as sterilization environment. Volumetric wear rates were the lowest for the pins in the gamma inert, shelf aged cohort. These results support the utility of using modern, multidirectional POD testing with a physiologic lubricant as a novel method for evaluating wear properties of retrieved UHMWPE components. The data also supported the hypothesis that wear rates of gamma-inert liners were lower than gamma-air liners for both retrieved and shelf aging conditions. However, this difference was not statistically significant for the retrieved condition.

  16. Bacterial adherence on fluorinated carbon based coatings deposited on polyethylene surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Terriza, A; Del Prado, G; Perez, A Ortiz; Martinez, M J; Puertolas, J A; Manso, D Molina; Gonzalez-Elipe, A R; Yubero, F; Barrena, E Gomez; Esteban, J, E-mail: antonia.terriza@icmse.csic.es

    2010-11-01

    Development of intrinsically antibacterial surfaces is of key importance in the context of prostheses used in orthopaedic surgery. In this work we present a thorough study of several plasma based coatings that may be used with this functionality: diamond like carbon (DLC), fluorine doped DLC (F-DLC) and a high fluorine content carbon-fluor polymer (CF{sub X}). The study correlates the surface chemistry and hydrophobicity of the coating surfaces with their antibacterial performance. The coatings were deposited by RF-plasma assisted deposition at room temperature on ultra high molecular weight polyethylene (UHMWPE) samples. Fluorine content and relative amount of C-C and C-F bond types was monitored by X-ray photoelectron spectroscopy and hydrophobicity by water contact angle measurements. Adherence of Staphylococcus aureus and Staphylococcus epidermidis to non-coated and coated UHMWPE samples was evaluated. Comparisons of the adherence performance were evaluated using a paired t test (two materials) and a Kruskall Wallis test (all the materials). S. aureus was statistically significant (p< 0.001) less adherent to DLC and F-DLC surfaces than S. epidermidis. Both bacteria showed reduction of adherence on DLC/UHMWPE. For S. aureus, reduction of bacterial adherence on F-DLC/UHMWPE was statistically significant respect to all other materials.

  17. Photodegradation of UHMWPE Compounded with Annatto and Beetroot Extracts

    Directory of Open Access Journals (Sweden)

    Alexandre Rangel de Sousa

    2016-01-01

    Full Text Available We observed the anti-UV action of beetroot extract in an ultra-high molecular weight (UHMWPE matrix. The beetroot extract and the one prepared from annatto seed also acted efficiently as pigment to the same polymeric matrix. Neat UHMWPE and UHMWPE compounded with annatto and beet extract were compression molded and tensile specimens were obtained from the molded plates and submitted to UV radiation for up to 42 days. Tensile tests were performed and it was observed that the beet extract had a stabilizing action in the polymer compared to neat polymer and the one with annatto extract. Complementary analyses showed good homogenization of the extracts through the polymer matrix indicating the possibility of use as pigment, although the annatto extract appeared to be very unstable under irradiation. Spectroscopic characterization helped to explain the stability of the extracts before and after molding.

  18. Development and Characterization of UHMWPE Fiber-Reinforced Hydrogels For Meniscal Replacement

    Science.gov (United States)

    Holloway, Julianne Leigh

    Meniscal tears are the most common orthopedic injuries to the human body. The current treatment of choice, however, is a partial meniscectomy that leads to osteoarthritis proportional to the amount of tissue removed. As a result, there is a significant clinical need to develop materials capable of restoring the biomechanical contact stress distribution to the knee after meniscectomy and preventing the onset of osteoarthritis. In this work, a fiber-reinforced hydrogel-based synthetic meniscus was developed that allows for tailoring of the mechanical properties and molding of the implant to match the size, shape, and property distribution of the native tissue. Physically cross-linked poly(vinyl alcohol) (PVA) hydrogels were reinforced with ultrahigh molecular weight polyethylene (UHMWPE) fibers and characterized in compression (0.1-0.8 MPa) and tension (0.1-250 MPa) showing fine control over mechanical properties within the range of the human meniscus. Morphology and crystallinity analysis of PVA hydrogels showed increases in crystallinity and PVA densification, or phase separation, with freeze-thaw cycles. A comparison of freeze-thawed and aged, physically cross-linked hydrogels provided insight on both crystallinity and phase separation as mechanisms for PVA gelation. Results indicated both mechanisms independently contributed to hydrogel modulus for freeze-thawed hydrogels. In vitro swelling studies were performed using osmotic solutions to replicate the swelling pressure present in the knee. Minimal swelling was observed for hydrogels with a PVA concentration of 30-35 wt%, independently of hydrogel freeze-thaw cycles. This allows for independent tailoring of hydrogel modulus and pore structure using freeze-thaw cycles and swelling behavior using polymer concentration to match a wide range of properties needed for various soft tissue applications. The UHMWPE-PVA interface was identified as a significant weakness. To improve interfacial adhesion, a novel

  19. Characteristics of precipitation-formed polyethylene glycol microgels are controlled by molecular weight of reactants.

    Science.gov (United States)

    Thompson, Susan; Stukel, Jessica; AlNiemi, Abrar; Willits, Rebecca Kuntz

    2013-12-23

    This work describes the formation of poly(ethylene glycol) (PEG) microgels via a photopolymerized precipitation reaction. Precipitation reactions offer several advantages over traditional microsphere fabrication techniques. Contrary to emulsion, suspension, and dispersion techniques, microgels formed by precipitation are of uniform shape and size, i.e. low polydispersity index, without the use of organic solvents or stabilizers. The mild conditions of the precipitation reaction, customizable properties of the microgels, and low viscosity for injections make them applicable for in vivo purposes. Unlike other fabrication techniques, microgel characteristics can be modified by changing the starting polymer molecular weight. Increasing the starting PEG molecular weight increased microgel diameter and swelling ratio. Further modifications are suggested such as encapsulating molecules during microgel crosslinking. Simple adaptations to the PEG microgel building blocks are explored for future applications of microgels as drug delivery vehicles and tissue engineering scaffolds.

  20. Effect of molecular weight on the physical properties of poly(ethylene brassylate) homopolymers.

    Science.gov (United States)

    Fernández, Jorge; Amestoy, Hegoi; Sardon, Haritz; Aguirre, Miren; Varga, Aitor Larrañaga; Sarasua, Jose-Ramon

    2016-12-01

    Poly(ethylene brassylate) (PEB) is a biodegradable polyester that nowadays is of particular interest owing to its poly(ε-caprolactone)-like properties (with a Tg at -30°C and a Tm at 70°C) and the low-cost of its monomer. However, it is not simple to achieve high molar masses with conventional catalysts. In this work, high molar mass PEBs, characterized by SEC-MALS, were successfully synthesized using triphenyl bismuth (Ph3Bi) as catalyst. Then, with the aim of evaluating the impact of the molecular weight on the physical properties, several PEBs ranging from 27 to 247kgmol(-1) were prepared. It was demonstrated that above a Mw of 90Kgmol(-1), PEB behaved in a constant manner. PEBs with lower molecular weight (20MPa.

  1. Ultra-High Molecular Weight Polyethylene Reinforced with Multiwall Carbon Nanotubes: In Vitro Biocompatibility Study Using Macrophage-Like Cells

    Directory of Open Access Journals (Sweden)

    Nayeli Camacho

    2015-07-01

    Full Text Available Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwall carbon nanotubes in biomaterials contacting with bone. This study describes the response of murine macrophage-like Raw 264.7 cells after two and six days of culture in contact with artificially generated particles from both, ultra-high molecular weight polyethylene polymer and the composite (multiwall carbon nanotubes and ultra-high molecular weight polyethylene. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision knee arthroplasty surgeries required by wear failure of tibial articulating component and diminish particle-induced osteolysis. The results of an in vitro study of viability, and interleukin-6 and tumor necrosis factor-alpha production suggest good cytocompatibility, similar to that of conventional ultra-high molecular weight polyethylene.

  2. PHASE SEPARATION IN BIMODAL MOLECULAR WEIGHT HIGH DENSITY POLYETHYLENE WITH DIFFERING BRANCH CONTENTS BY MOLECULAR DYNAMICS AND MESODYN SIMULATION

    Institute of Scientific and Technical Information of China (English)

    Zhi-jie Zhang; Zhong-yuan Lu; Ze-sheng Li

    2009-01-01

    The phase behavior of bimodal molecular weight high density polyethylene (BHDPE) in solid state was investigated. Hildebrand solubility parameters (δ) were calculated for the models of blends of higher molecular weight branch polyethylene (HBPE) with different branch contents and lower molecular weight linear polyethylene (LLPE), by using molecular dynamics (MD) simulations. These δ values were then used to calculate the corresponding Flory-Huggins interaction parameter (χ) between HBPE and LLPE models. In order to better understand the compatibility between LLPE and various HBPE, Mesodyn simulations were used to show the density profiles of the blends of LLPE with various HBPE at different compositions. The results indicated that the phase behavior of BHDPE was influenced by both the global branch content of the system and the local branch content, I.e., the branch content of HBPE.

  3. Bacterial adherence on UHMWPE doped with Vitamin E: an in vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Manso D; Gomez-Barrena E; Esteban J; Adames H; Martinez M J; Cordero J; Fernandez-Roblas R; Puertolas J A, E-mail: dmolina@fjd.es

    2010-11-01

    Biomaterials may improve its capacity to resist bacterial adherence, and subsequent infection through material changes. Our aim was to test the bacterial adherence to vitamin E (VE) doped UHMWPE with S. aureus and S. epidermidis (collection and clinical strains), compared to virgin material. Experimental UHMWPE with 3%, 0.4%, and commercial 0.1% VE concentration (1000 ppm) were tested. The biofilm-developing ability was used as a covariable. The collection strain of S. aureus showed significantly less adherence to the commercial VE UHMWPE (p=0.036) but the clinical strains did not significantly modified its adhesion to UHMWPE in presence of VE. The collection strain of S. epidermidis showed significantly less adherence to experimental UHMWPE with VE, independently of the concentration used (p=0.008). However, only 1 of the 4 clinical strains under study clearly confirmed these results in commercial VE polyethylene. Vitamin E doped UHMWPE affects the adherence of some S. aureus and S. epidermidis strains, independently of the concentration in use, but the results showed important intraspecies differences.

  4. UHMWPE球面层合板弹道侵彻性能研究%Ballistic penetration properties of a UHMWPE spherical laminate

    Institute of Scientific and Technical Information of China (English)

    陈昕; 朱锡; 梅志远; 王晓强

    2011-01-01

    进行了超高分子量聚乙烯(UHMWPE)平面层合板、平面夹芯结构以及球面夹芯结构的弹道侵彻实验研究,发现凸球面结构的抗侵彻能力低于平面结构,根据实验现象对球面结构初始曲率的不利影响作了初步分析.应用DYTRAN软件对不同曲率的UHMWPE层合板弹道侵彻进行了数值仿真,分析了层合板曲率对弹道性能的影响规律,认为曲率对层合板变形的限制作用以及由此导致的应力集中是造成抗侵彻能力下降的主要原因.%Ultra-high molecular weight polyethylene (UHMWPE) laminates, plane sandwich stuctures and spherical sandwich structures were studied with ballistic penetration tests, and lower anti-penetraion performance of convex spherical structures was found than that of plane structures.Disadvantage of initial curvature of spherical structures was elementarily analyzed based on experimental phenomena.Ballistic penetration of UHMWPE laminates with different curvatures was numerically simulated with DYTRAN FEM software, and curvature influence on ballistic properties was analyzed.The deformation restriction of curvatures and the induced stress concentration due to initial curvature were considered to be the main causes to lead to degradation of anti-penetration capacity of a UHMWPE spherical laminate.

  5. Effects of surface texturing on the performance of biocompatible UHMWPE as a bearing material during in vitro lubricated sliding/rolling motion.

    Science.gov (United States)

    López-Cervantes, Adrián; Domínguez-López, Iván; Barceinas-Sánchez, José Dolores Oscar; García-García, Adrián Luis

    2013-04-01

    The effect of surface texturing on the performance of biocompatible ultra-high molecular weight polyethylene (UHMWPE) as a bearing material has been investigated using the kinematic range of motions reported for a knee-joint replacement. An experimental apparatus consisting of a ball and a disk rotating independently from each other was used to compare the performance of UHMWPE textured versus plain surfaces, under different combinations of sliding and rolling motion, better known as sliding-to-rolling ratio (SRR). Performance was evaluated through the coefficient of traction of a tribosystem comprising a steel ball on a flat UHMWPE disk and distilled water at 36°C, acting as lubricant. A square array of cavities with diameter D=0.397mm and center-to-center spacing of 1.5D was machined on UHMWPE disks. The experimental design considered two levels for cavity depth, D and D/2, and two for the applied load, 17 and 25N. The SRR was varied from 1 to 11% and the mean speed range was set from 5 to 55mm/s, covering the kinematics and contact pressure conditions of a sauntering cycle on a knee-joint replacement. Stribeck curves of the plain and textured surfaces were obtained and compared against one another. The results demonstrate that the proposed surface pattern reduces the coefficient of traction of the tribological system for the 17N load in the entire kinematic range explored, while for the 25N load the effects were more noticeable at low mean speed and SRR, corresponding to the beginning of motion.

  6. Radiation-induced graft polymerization for the preparation of a highly efficient UHMWPE fibrous adsorbent for Cr(VI) removal

    Science.gov (United States)

    Gao, Qianhong; Hua, Jiangtao; Li, Rong; Xing, Zhe; Pang, Lijuan; Zhang, Mingxing; Xu, Lu; Wu, Guozhong

    2017-01-01

    A novel fibrous adsorbent containing amine and quaternary ammonium groups was prepared by radiation-induced graft of glycidyl methacrylate (GMA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber and further modifying with triethylenetetramine (TETA) and glycidyl trimethylammonium chloride (GTA). The ATR-IR spectra and SEM observation demonstrated that amine and quaternary ammonium groups were immobilized onto the surface of UHMWPE fiber. The principal factors affecting the adsorption of Cr(VI) ions have been investigated including pH of the aqueous solution, contact time, temperature and coexisting anions. This novel fibrous adsorbent could effectively adsorb Cr(VI) in the range of pH 1-9, and the maximum adsorption capacity reached 295 mg/g at pH 3 and 25 °C based on the Langmuir isotherm. It was found that adsorption equilibrium could be achieved within 2 h for initial Cr(VI) of 100 mg/L, following the pseudo-second order model. The effect of coexisting anions (including SO42-, H2PO4-, NO3-and Cl-) on the uptake of Cr(VI) was investigated in detail. Additionally, the adsorption saturated fiber could be regenerated by soaking in 0.5 mol/L NaOH solution, and the adsorption performance of this adsorbent could be maintained at 90% after eight cycles of adsorption-desorption. ATR-IR and XPS analysis revealed that Cr(VI) ions were adsorbed on the fiber adsorbent through ion exchange mechanism.

  7. A comparative microstructural study of vitamin-E blended and infused highly crosslinked UHMWPE for total knee arthroplasty.

    Science.gov (United States)

    Puppulin, Leonardo; Leto, Andrea; Hasegawa, Masahiro; Pezzotti, Giuseppe

    2014-11-01

    The impact of adding antioxidant vitamin-E (α-tocopherol) to the microstructure of ultrahigh molecular weight polyethylene (UHMWPE) for total knee arthroplasty has been studied in detail by means of Raman microprobe spectroscopy. Three tibial insert samples prepared by different manufacturing methods were investigated, as follows: (A) a sample manufactured without blending with vitamin E which did not receive any irradiation dose after consolidation but underwent final sterilization in ethylene oxide (EtO); (B) a sample blended with 0.3 wt% of α-tocopherol, an isomer of vitamin E, and manufactured as sample (A); and, (C) a sample in which vitamin E was diffused after being irradiated with 100 kGy dose of γ-ray. Clear microstructural differences were observed in terms of phase contents (i.e., amorphous, crystalline, and intermediate phase fraction), molecular orientation, and the degree of anisotropy between the investigated tibial plates. Vitamin E in the starting resin promoted chain mobility leading to reorganization of the molecular chains. The spectroscopic characterizations helps to rationalize the complex effect of vitamin-E on the UHMWPE microstructure and gives useful information on how significantly any single step of the manufacturing procedures might affect the mechanical properties of the final orthopedic component.

  8. MOLECULAR WEIGHT DEPENDENCE OF CRYSTAL PATTERN TRANSITIONS OF POLY(ETHYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    Guo-liang Zhang; Liu-xin Jin; Ping Zheng; Wei Wang; Xiao-jing Wen

    2013-01-01

    Crystal patterns in ultrathin films of six poly(ethylene oxide) fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃ to 60 ℃.Labyrinthine,dendritic and faceted crystal patterns were observed in different temperature ranges,and then labyrinthine-to-dendritic and dendritic-tofaceted transition temperatures TL-D and TD-F were quantitatively identified.Their molecular weight dependences are TL-D(Mw) =TL-D(∞)-KL-D/Mw,where TL-D(∞) =38.2 ℃ and KL-D =253000 ℃·g/mol and TD-F(Mw) =TD-F(∞)-KD-F/Mw,where TD-F(∞) =54.7 ℃ and KD-F =27000 ℃·g/mol.Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences.The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation (DLA) and a polymer chain with Mw ≈ 253000 g/mol within a blob can join crystals independently.The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control,and a polymer chain with a Mw ≈ 27000g/mol as an independent blob crosses to a depletion zone to join crystals.These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.

  9. CONDUCTING BLENDS OF POLY(2-VINYL PYRIDINE) AND POLYETHYLENE OXIDE WITH HIGH MOLECULAR WEIGHT

    Institute of Scientific and Technical Information of China (English)

    CUI Minhui; GUO Junshi; XIE Hongquan; CHENG Donghua

    1997-01-01

    Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinyl pyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after doped with LiClO4, TCNQ or LiClO4 and TCNQ were investigated. Effects of LiClO4 and TCNQ concentrations on the conductivity of PEO/P2VP/LiClO4 or TCNQ blend were studied.The ionic conductivity of PEO/P2VP/LiClO4 blend increases with increasing PEO content.At a Li/ethylene oxide molar ratio of 0.10 and a TCNQ/2-vinyl pyridine molar ratio of 0.5,the mixed conductivity of PEO/P2VP/LiClO4/TCNQ is higher than the total of ionic conductivity of PEO/P2VP/LiClO4 and electronic conductivity of PEO/P2VP/TCNQ when the weight ratio of PEO and P2VP is 6/4 or 5/5. Scanning electron microscopy (SEM) on the broken cross-section of the PEO/P2VP/LiClO4 blend and differential scanning calorimetry (DSC) results show that LiClO4 could act as a compatibilizer in the blend.

  10. Fabrication and anti-fouling properties of photochemically and thermally immobilized poly(ethylene oxide) and low molecular weight poly(ethylene glycol) thin films.

    Science.gov (United States)

    Wang, Hui; Ren, Jin; Hlaing, Aye; Yan, Mingdi

    2011-02-01

    Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2×10(-4)Å(-2) and an average distance between grafted chains of 33Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers.

  11. Compression Molded Ultra High Molecular Weight Polyethylene-- Hydroxyapatite-Aluminum Oxide-Carbon Nanotube Hybrid Composites for Hard Tissue Replacement

    National Research Council Canada - National Science Library

    Ankur Gupta Garima Tripathi Debrupa Lahiri Kantesh Balani

    2013-01-01

    ...), bioinert aluminum oxide (Al2O3), and carbon nanotubes (CNTs) using compression molding. Phase and microstructural analysis suggests retention of UHMWPE and reinforcing phases in the compression molded composites...

  12. Preparation of High Modulus Poly(Ethylene Terephthalate: Influence of Molecular Weight, Extrusion, and Drawing Parameters

    Directory of Open Access Journals (Sweden)

    Jian Min Zhang

    2017-01-01

    Full Text Available Poly(ethylene terephthalate (PET which is one of the most commercially important polymers, has for many years been an interesting candidate for the production of high performance fibres and tapes. In current study, we focus on investigating the effects of the various processing variables on the mechanical properties of PET produced by a distinctive process of melt spinning and uniaxial two-stage solid-state drawing (SSD. These processing variables include screw rotation speed during extrusion, fibre take-up speed, molecular weight, draw-ratio, and drawing temperature. As-spun PET production using a single-screw extrusion process was first optimized to induce an optimal polymer microstructure for subsequent drawing processes. It was found that less crystallization which occurred during this process would lead to better drawability, higher draw-ratio, and mechanical properties in the subsequent SSD process. Then the effect of drawing temperature (DT in uniaxial two-stage SSD process was studied to understand how DT (

  13. Influence of ethylene glycol pretreatment on effectiveness of atmospheric pressure plasma treatment of polyethylene fibers

    Energy Technology Data Exchange (ETDEWEB)

    Wen Ying; Li Ranxing [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education (China); Cai Fang [Key Laboratory of Eco-Textiles (Donghua University), Ministry of Education (China); Fu Kun; Peng Shujing; Jiang Qiuran; Yao Lan [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education (China); Qiu Yiping, E-mail: ypqiu@dhu.edu.cn [Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China)

    2010-03-01

    For atmospheric pressure plasma treatments, the results of plasma treatments may be influenced by liquids adsorbed into the substrate. This paper studies the influence of ethylene glycol (EG) pretreatment on the effectiveness of atmospheric plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers with 0.31% and 0.42% weight gain after soaked in EG/water solution with concentration of 0.15 and 0.3 mol/l for 24 h, respectively. Scanning electron microscopy (SEM) shows that the surface of fibers pretreated with EG/water solution does not have observable difference from that of the control group. The X-ray photoelectron spectroscopy (XPS) results show that the oxygen concentration on the surface of EG-pretreated fibers is increased less than the plasma directly treated fibers. The interfacial shear strength (IFSS) of plasma directly treated fibers to epoxy is increased almost 3 times compared with the control group while that of EG-pretreated fibers to epoxy does not change except for the fibers pretreated with lower EG concentration and longer plasma treatment time. EG pretreatment reduces the water contact angle of UHMWPE fibers. In conclusion, EG pretreatment can hamper the effect of plasma treatment of UHMWPE fibers and therefore longer plasma treatment duration is required for fibers pretreated with EG.

  14. [Intra-articular reinforcement of a partially torn anterior cruciate ligament (ACL) using newly developed UHMWPE biomaterial in combination with Hexalon ACL/PCL screws: ex-vivo mechanical testing of an animal knee model].

    Science.gov (United States)

    Fedorová, P; Srnec, R; Pěnčík, J; Dvořák, M; Krbec, M; Nečas, A

    2015-01-01

    PURPOSE OF THE STUDY Recent trends in the experimental surgical management of a partial anterior cruciate ligament (ACL) rupture in animals show repair of an ACL lesion using novel biomaterials both for biomechanical reinforcement of a partially unstable knee and as suitable scaffolds for bone marrow stem cell therapy in a partial ACL tear. The study deals with mechanical testing of the newly developed ultra-high-molecular-weight polyethylene (UHMWPE) biomaterial anchored to bone with Hexalon biodegradable ACL/PCL screws, as a new possibility of intra-articular reinforcement of a partial ACL tear. MATERIAL AND METHODS Two groups of ex vivo pig knee models were prepared and tested as follows: the model of an ACL tear stabilised with UHMWPE biomaterial using a Hexalon ACL/PCL screw (group 1; n = 10) and the model of an ACL tear stabilised with the traditional, and in veterinary medicine used, extracapsular technique involving a monofilament nylon fibre, a clamp and a Securos bone anchor (group 2; n = 11). The models were loaded at a standing angle of 100° and the maximum load (N) and shift (mm) values were recorded. RESULTS In group 1 the average maximal peak force was 167.6 ± 21.7 N and the shift was on average 19.0 ± 4.0 mm. In all 10 specimens, the maximum load made the UHMWPE implant break close to its fixation to the femur but the construct/fixation never failed at the site where the material was anchored to the bone. In group 2, the average maximal peak force was 207.3 ± 49.2 N and the shift was on average 24.1 ± 9.5 mm. The Securos stabilisation failed by pullout of the anchor from the femoral bone in nine out of 11 cases; the monofilament fibre ruptured in two cases. CONCLUSIONS It can be concluded that a UHMWPE substitute used in ex-vivo pig knee models has mechanical properties comparable with clinically used extracapsular Securos stabilisation and, because of its potential to carry stem cells and bioactive substances, it can meet the requirements for

  15. Mechanisms of plastic deformation in highly cross-linked UHMWPE for total hip components--the molecular physics viewpoint.

    Science.gov (United States)

    Takahashi, Yasuhito; Shishido, Takaaki; Yamamoto, Kengo; Masaoka, Toshinori; Kubo, Kosuke; Tateiwa, Toshiyuki; Pezzotti, Giuseppe

    2015-02-01

    Plastic deformation is an unavoidable event in biomedical polymeric implants for load-bearing application during long-term in-vivo service life, which involves a mass transfer process, irreversible chain motion, and molecular reorganization. Deformation-induced microstructural alterations greatly affect mechanical properties and durability of implant devices. The present research focused on evaluating, from a molecular physics viewpoint, the impact of externally applied strain (or stress) in ultra-high molecular weight polyethylene (UHMWPE) prostheses, subjected to radiation cross-linking and subsequent remelting for application in total hip arthroplasty (THA). Two different types of commercial acetabular liners, which belong to the first-generation highly cross-linked UHMWPE (HXLPE), were investigated by means of confocal/polarized Raman microprobe spectroscopy. The amount of crystalline region and the spatial distribution of molecular chain orientation were quantitatively analyzed according to a combined theory including Raman selection rules for the polyethylene orthorhombic structure and the orientation distribution function (ODF) statistical approach. The structurally important finding was that pronounced recrystallization and molecular reorientation increasingly appeared in the near-surface regions of HXLPE liners with increasing the amount of plastic (compressive) deformation stored in the microstructure. Such molecular rearrangements, occurred in response to external strains, locally increase surface cross-shear (CS) stresses, which in turn trigger microscopic wear processes in HXLPE acetabular liners. Thus, on the basis of the results obtained at the molecular scale, we emphasize here the importance of minimizing the development of irrecoverable deformation strain in order to retain the pristine and intrinsically high wear performance of HXLPE components.

  16. A multicenter approach evaluating the impact of vitamin e-blended polyethylene in cementless total hip replacement.

    Science.gov (United States)

    Jäger, Marcus; van Wasen, Andrea; Warwas, Sebastian; Landgraeber, Stefan; Haversath, Marcel; Group, Vitas

    2014-04-22

    Since polyethylene is one of the most frequently used biomaterials as a liner in total hip arthroplasty, strong efforts have been made to improve design and material properties over the last 50 years. Antioxidants seems to be a promising alternative to further increase durability and reduce polyethylene wear in long term. As of yet, only in vitro results are available. While they are promising, there is yet no clinical evidence that the new material shows these advantages in vivo. To answer the question if vitamin-E enhanced ultra-high molecular weight polyethylene (UHMWPE) is able to improve long-term survivorship of cementless total hip arthroplasty we initiated a randomized long-term multicenter trial. Designed as a superiority study, the oxidation index assessed in retrieval analyses of explanted liners was chosen as primary parameter. Radiographic results (wear rate, osteolysis, radiolucency) and functional outcome (Harris Hip Scores, University of California-Los Angeles, Hip Disability and Osteoarthritis Outcome Score, Visual Analogue Scale) will serve as secondary parameters. Patients with the indication for a cementless total hip arthroplasty will be asked to participate in the study and will be randomized to either receive a standard hip replacement with a highly cross-linked UHMWPE-X liner or a highly cross-linked vitamin-E supplemented UHMWPE-XE liner. The follow-up will be 15 years, with evaluation after 5, 10 and 15 years. The controlled randomized study has been designed to determine if Vitamin-E supplemented highly cross-linked polyethylene liners are superior to standard XLPE liners in cementless total hip arthroplasty. While several studies have been started to evaluate the influence of vitamin-E, most of them evaluate wear rates and functional results. The approach used for this multicenter study, to analyze the oxidation status of retrieved implants, should make it possible to directly evaluate the ageing process and development of the implant

  17. A multicenter approach evaluating the impact of vitamin E-blended polyethylene in cementless total hip replacement

    Directory of Open Access Journals (Sweden)

    Marcus Jäger

    2014-04-01

    Full Text Available Since polyethylene is one of the most frequently used biomaterials as a liner in total hip arthroplasty, strong efforts have been made to improve design and material properties over the last 50 years. Antioxidants seems to be a promising alternative to further increase durability and reduce polyethylene wear in long term. As of yet, only in vitro results are available. While they are promising, there is yet no clinical evidence that the new material shows these advantages in vivo. To answer the question if vitamin-E enhanced ultra-high molecular weight polyethylene (UHMWPE is able to improve long-term survivorship of cementless total hip arthroplasty we initiated a randomized long-term multicenter trial. Designed as a superiority study, the oxidation index assessed in retrieval analyses of explanted liners was chosen as primary parameter. Radiographic results (wear rate, osteolysis, radiolucency and functional outcome (Harris Hip Scores, University of California-Los Angeles, Hip Disability and Osteoarthritis Outcome Score, Visual Analogue Scale will serve as secondary parameters. Patients with the indication for a cementless total hip arthroplasty will be asked to participate in the study and will be randomized to either receive a standard hip replacement with a highly cross-linked UHMWPE-X liner or a highly cross-linked vitamin-E supplemented UHMWPE-XE liner. The follow-up will be 15 years, with evaluation after 5, 10 and 15 years. The controlled randomized study has been designed to determine if Vitamin-E supplemented highly cross-linked polyethylene liners are superior to standard XLPE liners in cementless total hip arthroplasty. While several studies have been started to evaluate the influence of vitamin-E, most of them evaluate wear rates and functional results. The approach used for this multicenter study, to analyze the oxidation status of retrieved implants, should make it possible to directly evaluate the ageing process and development

  18. Moldagem por compressão a frio do polietileno de ultra alto peso molecular. Parte 1: influência do tamanho, distribuição e morfologia da partícula na densidade a verde Cold compression molding of ultra high molecular weight polyethylene. Part 1: influence of the size, distribution and morphology of particles on the green density

    Directory of Open Access Journals (Sweden)

    Bernadete A. Bittencourt

    2009-01-01

    Full Text Available Neste trabalho foram investigadas as características de amostras de pó de polietileno de ultra alto peso molecular (PEUAPM, tais como porosidade, morfologia, tamanho médio e distribuição de partícula, que são importantes na moldagem por compressão a frio. Também foi avaliada a influência dessas características na densidade a verde de pré-formas. As amostras dos pós foram caracterizadas por calorimetria diferencial de varredura (DSC, análise granulométrica, absorção de óleo, área superficial, porosimetria de mercúrio, fluidez do pó, densidade de compactação, densidade aparente e microscopia eletrônica de varredura (MEV. Através das técnicas de caracterização estudadas ficou evidenciado que as características da partícula citadas anteriormente, assim como o parâmetro de densificação (DP, que é função direta da porosidade interparticular, favorecem a densidade a verde relativa (DVR e consequentemente a tensão de resistência à flexão (TRF.In this paper an investigation was made of the characteristics of Ultra High Molecular Weight Polyethylene (UHMWPE powder samples, including porosity, particles average size, size distribution and morphology, which are important in cold compression molding. The influence of these characteristics on the green density of molded pre-shapes was also investigated. The UHMWPE powder samples were characterized by Differential Scanning Calorimetry (DSC, granulometric analysis, oil absorption, surface area, mercury porosity, density compaction, apparent density and Scanning Electron Microscopy (SEM. The characterization techniques used demonstrate that the UHMWPE particles characteristics cited above as well as the densification parameter (DP, which is a direct function of the interparticles porosity, affect the relative green density (RGD and hence, the flexural tensile strength (FTS.

  19. THE EFFECT OF FIBER DIAMETER ON THE DRAWING BEHAVIOR OF GEL-SPUN ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    PENNING, JP; DEVRIES, AA; PENNINGS, AJ

    1993-01-01

    In the continuous drawing of gel-spun UHMWPE fibres, the diameter of the undrawn fibre appears to have a pronounced effect on its drawing behaviour and on the mechanical properties of the resulting hot-drawn fibres. A highly oriented structure is developed more efficiently upon drawing of thinner fi

  20. Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Bistolfi, Alessandro; Turell, Mary Beth; Lee, Ying-Lung; Bellare, Anuj; (BWH)

    2009-09-02

    Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

  1. Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE.

    Science.gov (United States)

    Bistolfi, Alessandro; Turell, Mary Beth; Lee, Ying-Lung; Bellare, Anuj

    2009-07-01

    Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

  2. A Multidirectional Tribo-System: Wear of UHMWPE under Sliding, Rolling, and Rotation

    Science.gov (United States)

    Patten, Elias Wolfgang

    Total knee replacements (TKR) have become a successful surgical procedure for addressing end-stage osteoarthritis, with ultra-high molecular weight polyethylene and cobalt chrome alloy (UHMWPE/Co-Cr) serving as the bearing materials of choice for decades. However, more than 10% of TKRs fail and require revision surgery. The predominant challenge with UHMWPE is the particulate debris generated through wear-mediated processes; wear debris from the UHMWPE tibial bearing surface leading to loosening is still the main cause for post-fifth-year revisions. UHMWPE wear in hip arthroplasty has been linked to microstructural evolution at the surface from multidirectional sliding in the hip joint but little is known about how the microstructure responds to clinically relevant sliding conditions in the knee. This is likely because wear tests are typically performed under basic motion parameters with simplified geometry (pin-on-disk tests) while the knee has more complex kinematics: it is neither a ball-and-socket joint nor a simple hinge joint, but has 2D sliding, rolling/slip motion, and rotation. There is also disagreement over how to best quantify cross-shear and how to model how much wear it will cause. A custom multidirectional tribo-system was used to investigate the individual and combined effects of the different motions in TKR: 2D sliding, rolling, and rotation, for a total of eight separate kinematic conditions. The trends in wear rates and wear factors for these different motions were compared with many different definitions for magnitudes and ratios of cross-shear. Additionally, the wear surfaces were examined for wear mechanism and the microstructural changes in lamellae orientation for the different motions were analyzed. To mimic the tribological conditions of a condyle in a TKR, polished Co-Cr spheres were articulated against flat, smooth UHMWPE disks with physiologically relevant loading, speed, and lubrication conditions. The motion parameters were selected

  3. Enhanced adherence of mouse fibroblast and vascular cells to plasma modified polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Reznickova, Alena, E-mail: alena.reznickova@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic); Novotna, Zdenka, E-mail: zdenka1.novotna@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic); Kolska, Zdenka [Faculty of Science, J.E. Purkyně University, 400 96 Usti nad Labem (Czech Republic); Kasalkova, Nikola Slepickova [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic); Rimpelova, Silvie [Department of Biochemistry and Microbiology, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic); Svorcik, Vaclav [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic)

    2015-07-01

    Since the last decade, tissue engineering has shown a sensational promise in providing more viable alternatives to surgical procedures for harvested tissues, implants and prostheses. Biomedical polymers, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE), were activated by Ar plasma discharge. Degradation of polymer chains was examined by determination of the thickness of ablated layer. The amount of an ablated polymer layer was measured by gravimetry. Contact angle, measured by goniometry, was studied as a function of plasma exposure and post-exposure aging times. Chemical structure of modified polymers was characterized by angle resolved X-ray photoelectron spectroscopy. Surface chemistry and polarity of the samples were investigated by electrokinetic analysis. Changes in surface morphology were followed using atomic force microscopy. Cytocompatibility of plasma activated polyethylene foils was studied using two distinct model cell lines; VSMCs (vascular smooth muscle cells) as a model for vascular graft testing and connective tissue cells L929 (mouse fibroblasts) approved for standardized material cytotoxicity testing. Specifically, the cell number, morphology, and metabolic activity of the adhered and proliferated cells on the polyethylene matrices were studied in vitro. It was found that the plasma treatment caused ablation of the polymers, resulting in dramatic changes in their surface morphology and roughness. ARXPS and electrokinetic measurements revealed oxidation of the polymer surface. It was found that plasma activation has a positive effect on the adhesion and proliferation of VSMCs and L929 cells. - Highlights: • Plasma activation of LDPE, HDPE and UHMWPE • Study of surface properties by several techniques: ARXPS, AFM, zeta-potential, and goniometry • Investigation of adhesion and spreading of vascular smooth muscle cells (VSMCs) and mouse fibroblasts (L929)

  4. Biotribological behavior of Ag-ZrCxN1-x coatings against UHMWPE for joint prostheses devices.

    Science.gov (United States)

    Calderon V, S; Sánchez-López, J C; Cavaleiro, A; Carvalho, S

    2015-01-01

    This study aims to evaluate the structural, mechanical and tribological properties of zirconium carbonitrides (ZrCxN1-x) coatings with embedded silver nanoparticles, produced with the intention of achieving a material with enhanced multi-functional properties, including mechanical strength, corrosion resistance, tribological performance and antibacterial behavior suitable for their use in joint prostheses. The coatings were deposited by direct current (DC) reactive magnetron sputtering onto 316 L stainless steel, changing the silver content from 0 to 20 at% by modifying the current density applied to the targets. Different nitrogen and acetylene gas fluxes were used as reactive gases. The coatings revealed different mixtures of crystalline ZrCxN1-x, silver nanoparticles and amorphous carbon phases. The hardness of the films was found to be mainly controlled by the ratio between the hard (ZrCxN1-x) and soft (Ag and amorphous carbon) phases in the films, fluctuating between 7.4 and 20.4 GPa. The coefficient of friction, measured against ultra-high molecular weight polyethylene (UHMWPE) in Hank's balanced salt solution with 10 gL(-1) albumin, is governed by the surface roughness and hardness. The UHMWPE wear rates were in the same order of magnitude (between 1.4 and 2.0 × 10(-6)mm(3)N(-1)m(-1)), justified by the effect of the protective layer of albumin formed during the tests. The small differences were due to the hydrophobic/hydrophilic character of the surface, as well as to the silver content.

  5. 分子量1050万超高分子量聚乙烯管材制品挤出%Extrusion products of UHMWPE Pipe with 10.5 mil-lion molecular weight

    Institute of Scientific and Technical Information of China (English)

    陈勇; 钱晓宇; 周亚俊; 王猛; 高坤光; 严为群; 王德禧

    2010-01-01

    概述超高分子量聚乙烯(UHMWPE)的特性和加工难点,介绍了张家港联冠新材料有限公司采用近熔点挤出理念挤出了分子量高达1050万的UHMWPE管材及Ticona公司及美国十方国际公司对联冠UHMWPE管材的检测结果,其结果预示着随着UHMWPE管材加工技术的进步必将促进UHMWPE上下游产业的发展.

  6. Screening of stabilized crosslinked polyethylene using a novel wear tester.

    Science.gov (United States)

    Hoffmann, M; Gonzalez-Mora, V; Chiesa, R; Cigada, A; Stroosnijder, M F

    2002-01-01

    A novel pin-on-disk type wear tester is described allowing a rapid screening of different types of polyethylene under both unidirectional and multidirectional sliding motion. The wear of four polyethylene materials sliding against a roughened CoCrMo alloy was evaluated: a non-irradiated UHMWPE, a UHMWPE irradiated with a dose of 25 kGy in air, and two types of crosslinked UHMWPE (100 kGy, air), which were subjected to a stabilization heat treatment in nitrogen at 155 degrees C for 72 hours (XLPE I) and in water at 130 degrees C for 72 hours (XLPE II), respectively.Under multidirectional sliding conditions both types of XLPE exhibited significantly less wear with respect to the 25 kGy irradiated UHMWPE and the non-irradiated UHMWPE, even under the rough counterface conditions applied. Under unidirectional sliding motion both types of XLPE exhibited the highest wear of all materials tested, because the orientation hardening effect acting under linear lubricated condition is less pronounced for crosslinked polyethylene.

  7. Amphiphilic, low molecular weight poly(ethylene imine) derivatives with enhanced stability for efficient pulmonary gene delivery.

    Science.gov (United States)

    Roesler, Susanne; Koch, Felix P V; Schmehl, Thomas; Weissmann, Norbert; Seeger, Werner; Gessler, Tobias; Kissel, Thomas

    2011-02-01

    Poly(ethylene imine) (PEI) is a widely used transfection reagent for mammalian cells, but in vivo application of PEI 25 kDa is restricted by its toxicity. Low molecular weight (LMW) PEI is less toxic, but also less efficient than its high molecular weight equivalent, and prone to aggregation. A set of polymers was synthesized by coupling poly(ethylene glycol) (PEG) that contained either C(16/18) -chains (Cx-EO) or butyl-poly(propylene oxide)-co-poly(ethylene glycol) (ButPP). Critical micelle concentration (CMC) was determined for copolymers. Polyplexes were characterized by DNA binding ability, polyplex size and aggregation, hemolysis, and cytotoxicity. Transfection efficiency was tested in vitro and in vivo in mouse lungs. Copolymers formed stable complexes with DNA, and showed enhanced complex stability in isotonic solution for at least 1 h. CMC was determined for Cx-EO-PEI 4.7 and 8.3 at 0.0019 and 0.0037 mM, respectively; membrane activity in a haemolysis assay was demonstrated for ButPP-PEI: both factors possibly enhance endosomal escape effect after PEGylation. IC(50) values of all synthesized polymers were in the range 6-33 ng/ml. Transfection efficiency of unmodified LMW-PEIs was equivalent or better than that of PEI 25 as a result of aggregation in vitro. Cells treated with polyplexes of amphiphilic polymers showed reduced transfection compared to PEI 25. After instillation in mouse lungs, highest transfection efficiency was demonstrated with Cx-EO copolymer of lowest molecular weight PEI. A new set of polymers with low toxicity and high stability was synthesized, which contains promising candidates for pulmonary gene transfer, as documented by in vivo experiments in mice. Copyright © 2011 John Wiley & Sons, Ltd.

  8. Mechanical Properties of UHMWPE Composites Filled with Three Kinds of Fibers%三种纤维改性超高分子量聚乙烯复合材料的力学性能

    Institute of Scientific and Technical Information of China (English)

    吴贺贺; 何春霞; 刘军恒

    2012-01-01

    以未处理和偶联剂KH550处理的C纤维、SiC纤维和Al2O3纤维为填充材料,以超高分子量聚乙烯(UHMWPE)为基体,用模压成型法制备了三种纤维改性UHMWPE复合材料,对复合材料的硬度、弯曲强度、拉伸强度和断裂伸长率进行了实验研究,用光学显微镜观察分析了拉伸断面形貌。结果表明,未处理的C纤维、SiC纤维和Al2O3纤维改性UHMWPE复合材料硬度较纯UHMWPE分别提高了11.76%、21%和6%。经KH550处理的三种纤维改性UHMWPE复合材料弯曲强度和拉伸强度均优于未处理纤维的复合材料,已处理的SiC纤维/UHMWPE复合材料弯曲强度和拉伸强度提高较大。KH550处理的三种纤维与UHMWPE基体界面粘接紧密,未处理纤维与UHMWPE基体粘接较差。%Ultra-high molecular-weight polyethylene(UHMWPE) composites filled with untreated and treated C fiber, SiC fiber and Al2O3 fiber were prepared by molding method. The hardness, bending strength, tensile strength and wear performances of the composites were studied. The tensile fractore-surface morphology of composities were studied too. The results show that the hardness of composite filled with untreated C fiber, SiC fiber, Al2O3 fiber is 11.76 %, 21% and 6 % higher than that of pure UHMWPE respectively. The bending strength and tensile strength of UHMWPE composites filled with 3 kinds of fiber treated by coupling agent are better than those of the untreated fibers composites, and SiC fiber/UHMWPE is the best composite. The treated fibers show good interfacile adhesion UHMWPE which untreated fibers do not.

  9. Evaluation of the effect of vitamin E doped UHMWPE on biofilm development and infection using an in vivo experimental model

    Science.gov (United States)

    Molina-Manso, D.; Gómez-Barrena, E.; Alonso-Rodríguez, N.; Sandoval, E.; Cordero, J.; Fernández-Roblas, R.; Puértolas, J. A.; Esteban, J.

    2010-11-01

    The aim of our study was the evaluation of an in vivo experimental model of implant-related septic arthritis. 5 × 10 mm strips out of a polyethylene sheet 500 microns thick were incubated with a 0.5 McFarland bacterial suspension of collection strains S. aureus and S. epidermidis. A surgical experimental model was prepared, implanting the samples in the subquadricipital articular space of the rabbit's knee. After 7 days of survival, the knee joint was opened wide through the previous surgical approach and the polyethylene sample was retrieved. The UHMWPE samples were processed following a sonication and quantification protocol. Ten rabbits for each species were studied, five with each material. Negative controls (UHMWPE strips without attached bacteria) were also implanted in contralateral knees. S. aureus colonies were detected only in three rabbits with non-treated UHMWPE and in two with vitamin E-doped UHMWPE. No differences in colony counts were observed for S. aureus. No growth was detected for S. epidermidis, although clinical signs of infection were detected in all animals with inoculated samples. The model was useful to evaluate the effect of modifications in biomaterials, although highly pathogenic bacteria are needed to obtain quantifiable data.

  10. Evaluation of the effect of vitamin E doped UHMWPE on biofilm development and infection using an in vivo experimental model

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Manso D; Gomez-Barrena E; Alonso-Rodriguez N; Sandoval E; Cordero J; Fernandez-Roblas R; Puertolas J A; Esteban J, E-mail: dmolina@fjd.es

    2010-11-01

    The aim of our study was the evaluation of an in vivo experimental model of implant-related septic arthritis. 5 x 10 mm strips out of a polyethylene sheet 500 microns thick were incubated with a 0.5 McFarland bacterial suspension of collection strains S. aureus and S. epidermidis. A surgical experimental model was prepared, implanting the samples in the subquadricipital articular space of the rabbit's knee. After 7 days of survival, the knee joint was opened wide through the previous surgical approach and the polyethylene sample was retrieved. The UHMWPE samples were processed following a sonication and quantification protocol. Ten rabbits for each species were studied, five with each material. Negative controls (UHMWPE strips without attached bacteria) were also implanted in contralateral knees. S. aureus colonies were detected only in three rabbits with non-treated UHMWPE and in two with vitamin E-doped UHMWPE. No differences in colony counts were observed for S. aureus. No growth was detected for S. epidermidis, although clinical signs of infection were detected in all animals with inoculated samples. The model was useful to evaluate the effect of modifications in biomaterials, although highly pathogenic bacteria are needed to obtain quantifiable data.

  11. A Tribological Assessment of Ultra High Molecular Weight Polyethylene Types GUR 1020 and GUR 1050 for Orthopedic Applications

    Directory of Open Access Journals (Sweden)

    Benjamin J. Hunt

    2016-06-01

    Full Text Available The wear properties of biomaterials have been demonstrated to have a high importance within orthopedic bearing surfaces. This study performed a comparison of the wear between the two main grades of Ultra High Molecular Weight Polyethylene types GUR 1020 and GUR 1050 articulating against Cobalt Chromium. Such a high capacity wear comparison has not been reported elsewhere in the scientific literature. Under an identical testing protocol it was found that GUR 1020 had a wear factor of 3.92 ± 0.55 × 10 − 6 ( mm 3 / Nm and GUR 1050 had a wear factor of 3.64 ± 0.39 × 10 − 6 ( mm 3 / Nm , with a non-statistical significant difference of p = 0.052. These wear factors correlate closely with those observed from other screening wear studies and explant analysis.

  12. Structural Evolution of Low-Molecular-Weight Poly(ethylene oxide)-block-polystyrene Diblock Copolymer Thin Film

    Science.gov (United States)

    Huang, Xiaohua

    2013-01-01

    The structural evolution of low-molecular-weight poly(ethylene oxide)-block-polystyrene (PEO-b-PS) diblock copolymer thin film with various initial film thicknesses on silicon substrate under thermal annealing was investigated by atomic force microscopy, optical microscopy, and contact angle measurement. At film thickness below half of the interlamellar spacing of the diblock copolymer (6.2 nm), the entire silicon is covered by a polymer brush with PEO blocks anchored on the Si substrate due to the substrate-induced effect. When the film is thicker than 6.2 nm, a dense polymer brush which is equal to half of an interlamellar layer was formed on the silicon, while the excess material dewet this layer to form droplets. The droplet surface was rich with PS block and the PEO block crystallized inside the bigger droplet to form spherulite. PMID:24302862

  13. Wear predictions for UHMWPE material with various surface properties used on the femoral component in total knee arthroplasty: a computational simulation study.

    Science.gov (United States)

    Kang, Kyoung-Tak; Son, Juhyun; Kim, Ho-Joong; Baek, Changhyun; Kwon, Oh-Ryong; Koh, Yong-Gon

    2017-07-01

    The wear of ultrahigh-molecular weight polyethylene (UHMWPE) tibial inserts in total knee arthroplasty (TKA) remains a major limitation that hinders the longevity of clinically successful devices. Surface properties significantly affect the overall performance of TKA, and surface modification with mechanically and chemically stable materials is an effective method for overcoming the wear of TKA. However, wear tests are not cost-efficient or time-efficient; thus, the effects of geometric, loading, and alignment perturbations are often evaluated via parametric studies. Computational wear prediction using a finite element (FE) model followed by validation through comparison with experimental data is effective for assessing new prosthetic designs or surface change methods prior to functional testing and surgical implementation. The aim of this study was to evaluate the weight loss, wear depth, and kinematics for different surface properties, including nanostructured diamond (NSD), diamond-like carbon (DLC), titanium-nitride (TiN), and oxidized zirconium (OxZr) on femoral components in TKA using FE analysis under gait-cycle loading conditions. Weight loss and wear depth were lowest with OxZr followed by TiN, NSD, and DLC. However, the DLC femoral component did not show any improvement in wear rate compared to an uncoated cobalt-chromium (Co-Cr) femoral component. Not all surface changes applied in this study did lead to improvement in wear performance. However, this study demonstrates the potential of OxZr and TiN for reducing UHMWPE wear and offers new insights into the effects of wear on TKA.

  14. Hydrogel fibers for ACL prosthesis: design and mechanical evaluation of PVA and PVA/UHMWPE fiber constructs.

    Science.gov (United States)

    Bach, Jason S; Detrez, Fabrice; Cherkaoui, Mohammed; Cantournet, Sabine; Ku, David N; Corté, Laurent

    2013-05-31

    Prosthetic devices for anterior cruciate ligament (ACL) reconstruction have been unsuccessful due to mechanical failure or chronic inflammation. Polymer hydrogels combine biocompatibility and unique low friction properties; however, their prior use for ligament reconstruction has been restricted to coatings due to insufficient tensile mechanics. Here, we investigate new constructs of polyvinyl alcohol (PVA) hydrogel fibers. In water, these fibers swell to an equilibrium water content of 50% by weight, retaining a tensile modulus greater than 40 MPa along the fiber axis at low strain. Rope constructs were assembled for ACL replacement and mechanical properties were compared with data from the literature. Pure PVA hydrogel constructs closely reproduce the non-linear tensile stiffness of the native ACL with an ultimate strength of about 2000 N. An additional safety factor in tensile strength was achieved with composite braids by adding ultrahigh molecular weight polyethylene (UHMWPE) fibers around a core of PVA cords. Composition and braiding angle are adjusted to produce a non-linear tensile behavior within the range of the native ligament that can be predicted by a simple rope model. This design was found to sustain over one million cycles between 50 and 450 N with limited damage and less than 20% creep. The promising mechanical performances of these systems provide justification for more extensive in vivo evaluation.

  15. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate)

    DEFF Research Database (Denmark)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati

    2017-01-01

    .7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half-lives...... physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264...... correlated well with the observed in vitro half-times of drug delivery (R2=0.96). Here, the PEC of the highest molecular weight resulted in the fastest degradation/drug release. When incubated with macrophages or implanted in animals, the degradation rate of PEC films superimposed the results of in vitro...

  16. 超高分子量聚乙烯/Al2O3人工关节副磨合期磨损颗粒的形态特征%Morphological characteristics of prosthetic wear particles generated in Al2O3-ultrahigh molecular weight polyethylene during running-in period

    Institute of Scientific and Technical Information of China (English)

    黄传辉; 杨根喜

    2008-01-01

    BACKGROUND: Wear particles factually serve as a medium carrying extensive information on the wear process involved in hip implants. Moreover, it has been demonstrated that wear particles contribute to the failure of Charnley total hip replacement.OBJECTIVE: To investigate the morphological characteristics of wear particles generated by couples of ultrahigh molecular weight polyethylene (UHMWPE) cups and Al2O3 femoral heads, mounted in a simulator in the presence of distilled water and explore the wear mechanism of UHMWPE cup.DESIGN: Wear tests were performed on a ball-in-socket hip simulator.SETTING: Department of Mechanical Engineering, Xuzhou Institute of Technology.MATERIALS: The molecular weight of UHMWPE selected as cup was 3 000 000. Its density was 0.935 g/cm3, hardness 30 HB, fracture strength 35 MPa, and water absorption 450 MPa, and tenacity 7 MPaM1/2.METHODS: The experiment was performed in the laboratory of tribology, China University of Mining and Technology from December 2003 to July 2005. Hip simulator was used to assess the tribological performance of Al2O3-UHMWPE at room temperature, 100 r/min, 784 N load for 1.5×106 cycles. Distilled water was used as the lubricant. Wear of UHMWPE acetabulum was measured every 3×105 cycles by taking out the acetabulum from simulator, cleaning in distilled water for 3 minutes in an ultrasonic bath, putting in an oven for 40 minutes at 80 ℃, and cooling off in a desiccator. A BT211D electronic balance (reciprocal sensibility, 0.01 mg) was used to measure the weight loss of UHMWPE acetabula according to the reference sample method to calculate the wear. A sample (20 mL) of distilled water lubricant used in test was obtained when the simulator was stopped for gravimetric analysis. Morphology of wear particles in samples and surface of worn UHMWPE acetabula were observed by using scanning electron microscope (SEM). The components of wear particles were determined by X-ray. Detailed measurements of the wear

  17. Application of atmospheric pressure plasma on polyethylene for increased prosthesis adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Van Vrekhem, S., E-mail: stijn.vanvrekhem@ugent.be [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Cools, P. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Declercq, H. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); Van Tongel, A. [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185 13K12, 9000 Ghent (Belgium); Vercruysse, C.; Cornelissen, M. [Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); De Geyter, N.; Morent, R. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium)

    2015-12-01

    Biopolymers are often subjected to surface modification in order to improve their surface characteristics. The goal of this study is to show the use of plasma technology to enhance the adhesion of ultra-high molecular weight polyethylene (UHMWPE) shoulder prostheses. Two different plasma techniques (low pressure plasma activation and atmospheric pressure plasma polymerization) are performed on UHMWPE to increase the adhesion between (1) the polymer and polymethylmethacrylate (PMMA) bone cement and (2) the polymer and osteoblast cells. Both techniques are performed using a dielectric barrier discharge (DBD). A previous paper showed that low pressure plasma activation of UHMWPE results in the incorporation of oxygen-containing functional groups, which leads to an increased surface wettability. Atmospheric pressure plasma polymerization of methylmethacrylate (MMA) on UHMWPE results in a PMMA-like coating, which could be deposited with a high degree of control of chemical composition and layer thickness. The thin film also proved to be relatively stable upon incubation in a phosphate buffer solution (PBS). This paper discusses the next stage of the study, which includes testing the adhesion of the plasma-activated and plasma-polymerized samples to bone cement through pull-out tests and testing the cell adhesion and proliferation on the samples. In order to perform the pull-out tests, all samples were cut to standard dimensions and fixed in bone cement in a reproducible way with a sample holder specially designed for this purpose. The cell adhesion and proliferation were tested by means of an MTS assay and live/dead staining after culturing MC3T3 osteoblast cells on UHMWPE samples. The results show that both plasma activation and plasma polymerization significantly improve the adhesion to bone cement and enhance cell adhesion and proliferation. In conclusion, it can be stated that the use of plasma technology can lead to an implant with improved quality and a subsequent

  18. Ultrahigh molecular weight polyethylene particles have direct effects on proliferation, differentiation, and local factor production of MG63 osteoblast-like cells.

    Science.gov (United States)

    Dean, D D; Schwartz, Z; Blanchard, C R; Liu, Y; Agrawal, C M; Lohmann, C H; Sylvia, V L; Boyan, B D

    1999-01-01

    Small particles of ultrahigh molecular weight polyethylene stimulate formation of foreign-body granulomas and bone resorption. Bone formation may also be affected by wear debris. To determine if wear debris directly affects osteoblasts, we characterized a commercial preparation of ultrahigh molecular weight polyethylene (GUR4150) particles and examined their effect on MG63 osteoblast-like cells. In aliquots of the culture medium containing ultrahigh molecular weight polyethylene, 79% of the particles were less than 1 microm in diameter, indicating that the cells were exposed to particles of less than 1 microm. MG63 cell response to the particles was measured by assaying cell number, [3H]thymidine incorporation, alkaline phosphatase specific activity, osteocalcin production, [35S]sulfate incorporation, and production of prostaglandin E2 and transforming growth factor-beta. Cell number and [3H]thymidine incorporation were increased in a dose-dependent manner. Alkaline phosphatase specific activity, a marker of cell differentiation for the cultures, was significantly decreased, but osteocalcin production was not affected. [35S]sulfate incorporation, a measure of extracellular matrix production, was reduced. Prostaglandin E2 release was increased, but transforming growth factor-beta production was decreased in a dose-dependent manner. This shows that ultrahigh molecular weight polyethylene particles affect MG63 proliferation, differentiation, extracellular matrix synthesis, and local factor production. These effects were direct and dose dependent. The findings suggest that ultrahigh molecular weight polyethylene wear debris particles with an average size of approximately 1 microm may inhibit bone formation by inhibiting cell differentiation and reducing transforming growth factor-beta production and matrix synthesis. In addition, increases in prostaglandin E2 production may not only affect osteoblasts by an autocrine pathway but may also stimulate the proliferation and

  19. Microstructure, thermooxidation and mechanical behavior of a novel highly linear, vitamin E stabilized, UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Medel, F.J., E-mail: fjmedel@unizar.es [Department of Mechanical Engineering. Engineering and Architecture School, Universidad de Zaragoza, E-50018, Zaragoza (Spain); Instituto Ciencia de Materiales de Aragon, ICMA, Universidad de Zaragoza-CSIC, E-50018, Zaragoza (Spain); Martinez-Morlanes, M.J. [Department of Materials Science and Technology, Instituto de Investigaciones en Ingenieria de Aragon, I3A, Universidad de Zaragoza, E-50018, Zaragoza (Spain); Alonso, P.J.; Rubin, J. [Instituto Ciencia de Materiales de Aragon, ICMA, Universidad de Zaragoza-CSIC, E-50018, Zaragoza (Spain); Pascual, F.J. [Department of Materials Science and Technology, Instituto de Investigaciones en Ingenieria de Aragon, I3A, Universidad de Zaragoza, E-50018, Zaragoza (Spain); Puertolas, J.A. [Instituto Ciencia de Materiales de Aragon, ICMA, Universidad de Zaragoza-CSIC, E-50018, Zaragoza (Spain); Department of Materials Science and Technology, Instituto de Investigaciones en Ingenieria de Aragon, I3A, Universidad de Zaragoza, E-50018, Zaragoza (Spain)

    2013-01-01

    A novel, vitamin E-stabilized, medical grade ultra-high molecular polyethylene, MG003 (DSM Biomedical; The Netherlands), has been very recently introduced for use in total joint replacements. This homopolymer resin features average molecular weight similar to that of conventional GUR 1050 resin (5.5-6*10{sup 6} g/mol), but a higher degree of linearity. The aim of this study was to characterize the microstructure, thermal and thermooxidation properties as well as the mechanical behavior of this novel MG003 resin before and after gamma irradiation in air to 90 kGy. For this purpose, a combination of experimental techniques were performed including differential scanning calorimetry (DSC), thermogravimetry (TG), transmission electron microscopy (TEM), X-Ray Diffraction, electron paramagnetic resonance (EPR), and uniaxial tensile tests. As-consolidated MG003 materials exhibited higher crystalline contents ({approx} 62%), transition temperatures ({approx} 140 Degree-Sign C), crystal thickness ({approx} 36 nm), yield stress ({approx} 25 MPa) and elastic modulus ({approx} 400 MPa) than GUR 1050 controls (55%, 136 Degree-Sign C, 27 nm, 19 MPa, and 353 MPa, respectively). Irradiation produced similar changes in both MG003 and GUR 1050 materials, specifically increased crystallinity (63% and 60%, respectively), crystal thickness (39 nm and 30 nm), yield stress (27 MPa and 21 MPa), but, above of all, loss of elongation to breakage (down to 442 and 469%, respectively). Thermogravimetric and EPR results suggest comparable susceptibilities to oxidation for both MG003 and GUR 1050 polyethylenes. Based on the present findings, MG003 appears as a promising alternative medical grade polyethylene and it may satisfactorily contribute to the performance of total joint replacements. - Highlights: Black-Right-Pointing-Pointer MG003 UHMWPE materials exhibited higher crystallinity, and melting temperatures than conventional GUR resins. Black-Right-Pointing-Pointer MG003 materials had higher

  20. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    Science.gov (United States)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-06-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints.

  1. Tribo-biological deposits on the articulating surfaces of metal-on-polyethylene total hip implants retrieved from patients

    Science.gov (United States)

    Cui, Zhiwei; Tian, Yi-Xing; Yue, Wen; Yang, Lei; Li, Qunyang

    2016-01-01

    Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to explore the composition and formation mechanism of the tribo-layer on the articulating surfaces of metal-on-polyethylene (MoPE) implants retrieved from patients. Results showed that, in contrast to conventional understanding, the attached tribo-layer contained not only denatured proteins but also a fraction of polymer particles. The formation of the tribo-layer was believed to relate to lubrication regime, which was supposed to be largely affected by the nature of the ultra-high-molecule-weight-polyethylene (UHMWPE). Wear and formation of tribo-layer could be minimized in elasto-hydrodynamic lubrication (EHL) regime when the UHMWPE was less stiff and have a morphology containing micro-pits; whereas the wear was more severe and tribo-layer formed in boundary lubrication. Our results and analyses suggest that enhancing interface lubrication may be more effective on reducing wear than increasing the hardness of material. This finding may shed light on the design strategy of artificial hip joints. PMID:27345704

  2. Microphase structures and 13C NMR relaxation parameters in ultrahigh molecular weight polyethylene

    Institute of Scientific and Technical Information of China (English)

    朱清仁; 洪昆仑; 鲁非; 戚嵘嵘; 庞文民; 周贵恩; 宋名实

    1995-01-01

    The phase transformations in ultrahigh molecular weight polyethylene(UHMWPE)gel-filmsupon superdrawing have been studied by X-ray diffraction and high resolution solid state 13C NMR.Themorphological change and molecular motions in the crystalline phase,amorphous phase and interphase are dis-cussed according to the 13C nuclear relaxation time(T1c,T2cresults.A brief interpretation to the three orfour T1cvalues in the crystalline phase is presented.It is found that the component with the highest T1c(T1cα)plays a key role in the forming of ’Shish-Kebab’ microfibril which determines the sample strength andmodulus,namely,the greater the T1cα,the higher the modulus and strength of the drawn UHMWPEgel-film.These results support the ’Shish-Kebabs’ model in crystalline polymers.

  3. CR TKA UHMWPE Wear Tested after Artificial Aging of the Vitamin E Treated Gliding Component by Simulating Daily Patient Activities

    Directory of Open Access Journals (Sweden)

    Jens Schwiesau

    2014-01-01

    Full Text Available The wear behaviour of total knee arthroplasty (TKA is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE cruciate retaining (CR total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62±0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

  4. The role of the amorphous phase in melting of linear UHMW-PE; implications for chain dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Sanjay [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Lippits, Dirk R [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Hoehne, Guenther W H [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Mezari, Brahim [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Magusin, Pieter C M M [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands)

    2007-05-23

    In ultra-high molecular weight polyethylene (UHMW-PE), it is possible to obtain single chain forming single crystals, where chains are adjacently re-entrant. Depending on the heating rate, it is feasible to melt these crystals either by simple consecutive detachment of chain stems from the crystalline substrate or by cluster melting, where several chain stems are involved. The consecutive detachment of chain stems occurs at the melting point predicted from the Gibbs-Thomson equation, whereas the cluster melting at much higher temperatures. Melting by the consecutive detachment of chain stems from the crystal substrate and their diffusion in the melt ultimately result in a new melt state having a heterogeneous distribution of physical entanglements, which invokes differences in local mobility. With combined DSC, rheology and solid-state NMR studies, it is concluded that the disentangled domains present within the entangled matrix possess higher local mobility than the entangled domains, ultimately causing lower elastic modulus. The fraction of the entangled and disentangled domains is maintained at higher temperatures, leading to a thermodynamically non-equilibrium melt state. In contrast, in cluster melting, where several chain stems (initially disentangled) can simultaneously adopt the random coil state, entanglements that are formed are homogeneously distributed in the melt. The paper invokes the influence of the topological differences present in the amorphous phase of the semi-crystalline polymer on the melting kinetics of crystals. The reported findings have implications for the melting behaviour and the resulting melt state of polymers in general.

  5. CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

    Science.gov (United States)

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

  6. Wear of cross-linked polyethylene against itself: a material suitable for surface replacement of the finger joint.

    Science.gov (United States)

    Sibly, T F; Unsworth, A

    1991-05-01

    Cross-linking of polyethylene (XLPE) has dramatically improved its properties in industrial applications, and it may also have some application in the field of human joint replacement. Additionally it has the advantage of permitting a lower molecular weight base material to be used, so that components may be injection moulded rather than machined. This study therefore investigates the wear resistance of medical grade cross-linked polyethylene (XLPE), cross-linked by a silane-grafting process, with a molecular weight between cross links of 5430 g mol(-1). This first report investigates the wear resistance of XLPE against itself, because for certain joints, such as the metacarpo-phalangeal joint, the material may have a high enough wear resistance to allow both bearing surfaces to be made from it. Tests were carried out both on a reciprocating pin and plate machine with pins loaded at 10 and 40 N and also on a new finger joint simulator, which simulates the loads applied to and the movements of, the metacarpo-phalangeal joint. An average wear rate of 1.8 x 10(-6) mm3 N-1 m-1 was found (range 0.9-2.75 x 10(-6) mm3 N-1 m-1). This is about six times greater than the wear rate of non-cross-linked ultra high molecular weight polyethylene (UHMWPE) against stainless steel, but for applications with low loading, such as the metacarpo-phalangeal joint, this material is shown to have adequate wear resistance. The coefficient of friction was 0.1, which is similar to that of UHMWPE on stainless steel.

  7. The interplay of plasma treatment and gold coating and ultra-high molecular weight polyethylene: On the cytocompatibility.

    Science.gov (United States)

    Novotná, Zdenka; Rimpelová, Silvie; Juřík, Petr; Veselý, Martin; Kolská, Zdenka; Hubáček, Tomáš; Ruml, Tomáš; Švorčík, Václav

    2017-02-01

    We have investigated the application of Ar plasma for creation of nanostructured ultra high molecular weight polyethylene (PE) surface in order to enhance adhesion of mouse embryonic fibroblasts (L929). The aim of this study was to investigate the effect of the interface between plasma-treated and gold-coated PE on adhesion and spreading of cells. The surface properties of pristine samples and its modified counterparts were studied by different experimental techniques (gravimetry, goniometry and X-ray photoelectron spectroscopy (XPS), electrokinetic analysis), which were used for characterization of treated and sputtered layers, polarity and surface chemical structure, respectively. Further, atomic force microscopy (AFM) was employed to study the surface morphology and roughness. Biological responses of cells seeded on PE samples were evaluated in terms of cell adhesion, spreading, morphology and proliferation. Detailed cell morphology and intercellular connections were followed by scanning electron microscopy (SEM). As it was expected the thickness of a deposited gold film was an increasing function of the sputtering time. Despite the fact that plasma treatment proceeded in inert plasma, oxidized degradation products were formed on the PE surface which would contribute to increased hydrophilicity (wettability) of the plasma treated polymer. The XPS method showed a decrease in carbon concentration with increasing plasma treatment. Cell adhesion measured on the interface between plasma treated and gold coated PE was inversely proportional to the thickness of a gold layer on a sample. Copyright © 2016. Published by Elsevier B.V.

  8. Higher molecular weight polyethylene glycol increases cell proliferation while improving barrier function in an in vitro colon cancer model.

    Science.gov (United States)

    Bharadwaj, Shruthi; Vishnubhotla, Ramana; Shan, Sun; Chauhan, Chinmay; Cho, Michael; Glover, Sarah C

    2011-01-01

    Polyethylene glycol (PEG) has been previously shown to protect against enteric pathogens and prevent colon cancer invasion. To determine if PEG could indeed protect against previously observed pro-invasive effects of commensal E. coli and EPEC, Caco-2 cells grown in an in vitro model of colon cancer were infected with strains of human commensal E. coli or EPEC and treated with 10% PEG 3350, PEG 8000, and PEG 20,000, respectively. At 24 hours after infection, MMP-1 and MMP-13 activities, cell cluster thickness, depth of invasion, and proliferation were determined using standard molecular biology techniques and advanced imaging. We found that higher molecular weight PEG, especially PEG 8000 and 20,000, regardless of bacterial infection, increased proliferation and depth of invasion although a decrease in cellular density and MMP-1 activity was also noted. Maximum proliferation and depth of invasion of Caco-2 cells was observed in scaffolds treated with a combination of commensal E. coli strain, HS4 and PEG 8000. In conclusion, we found that PEG 8000 increased cell proliferation and led to the preservation of cell density in cells treated with commensal bacteria. This is important, because the preservation of a proliferative response in colon cancer results in a more chemo-responsive tumor.

  9. Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

    Directory of Open Access Journals (Sweden)

    Leonardo A. Baldenegro-Perez

    2014-02-01

    Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

  10. Higher Molecular Weight Polyethylene Glycol Increases Cell Proliferation While Improving Barrier Function in an In Vitro Colon Cancer Model

    Directory of Open Access Journals (Sweden)

    Shruthi Bharadwaj

    2011-01-01

    Full Text Available Polyethylene glycol (PEG has been previously shown to protect against enteric pathogens and prevent colon cancer invasion. To determine if PEG could indeed protect against previously observed pro-invasive effects of commensal E. coli and EPEC, Caco-2 cells grown in an in vitro model of colon cancer were infected with strains of human commensal E. coli or EPEC and treated with 10% PEG 3350, PEG 8000, and PEG 20,000, respectively. At 24 hours after infection, MMP-1 and MMP-13 activities, cell cluster thickness, depth of invasion, and proliferation were determined using standard molecular biology techniques and advanced imaging. We found that higher molecular weight PEG, especially PEG 8000 and 20,000, regardless of bacterial infection, increased proliferation and depth of invasion although a decrease in cellular density and MMP-1 activity was also noted. Maximum proliferation and depth of invasion of Caco-2 cells was observed in scaffolds treated with a combination of commensal E. coli strain, HS4 and PEG 8000. In conclusion, we found that PEG 8000 increased cell proliferation and led to the preservation of cell density in cells treated with commensal bacteria. This is important, because the preservation of a proliferative response in colon cancer results in a more chemo-responsive tumor.

  11. α, ω-Cholesterol-functionalized low molecular weight polyethylene glycol as a novel modifier of cationic liposomes for gene delivery.

    Science.gov (United States)

    Ma, Cui-Cui; He, Zhi-Yao; Xia, Shan; Ren, Ke; Hui, Li-Wei; Qin, Han-Xiao; Tang, Ming-Hai; Zeng, Jun; Song, Xiang-Rong

    2014-11-06

    Here, three novel cholesterol (Ch)/low molecular weight polyethylene glycol (PEG) conjugates, termed α, ω-cholesterol-functionalized PEG (Ch2-PEGn), were successfully synthesized using three kinds of PEG with different average molecular weight (PEG600, PEG1000 and PEG2000). The purpose of the study was to investigate the potential application of novel cationic liposomes (Ch2-PEGn-CLs) containing Ch2-PEGn in gene delivery. The introduction of Ch2-PEGn affected both the particle size and zeta potential of cationic liposomes. Ch2-PEG2000 effectively compressed liposomal particles and Ch2-PEG2000-CLs were of the smallest size. Ch2-PEG1000 and Ch2-PEG2000 significantly decreased zeta potentials of Ch2-PEGn-CLs, while Ch2-PEG600 did not alter the zeta potential due to the short PEG chain. Moreover, the in vitro gene transfection efficiencies mediated by different Ch2-PEGn-CLs also differed, in which Ch2-PEG600-CLs achieved the strongest GFP expression than Ch2-PEG1000-CLs and Ch2-PEG2000-CLs in SKOV-3 cells. The gene delivery efficacy of Ch2-PEGn-CLs was further examined by addition of a targeting moiety (folate ligand) in both folate-receptor (FR) overexpressing SKOV-3 cells and A549 cells with low expression of FR. For Ch2-PEG1000-CLs and Ch2-PEG2000-CLs, higher molar ratios of folate ligand resulted in enhanced transfection efficacies, but Ch2-PEG600-CLs had no similar in contrast. Additionally, MTT assay proved the reduced cytotoxicities of cationic liposomes after modification by Ch2-PEGn. These findings provide important insights into the effects of Ch2-PEGn on cationic liposomes for delivering genes, which would be beneficial for the development of Ch2-PEGn-CLs-based gene delivery system.

  12. Investigation of the Influence of Shapes-Texture on Surface Deformation of UHMWPE as a Bearing Material in Static Normal Load and Rolling Contact

    Science.gov (United States)

    Lestari, W. D.; Ismail, R.; Jamari, J.; Bayuseno, A. P.

    2017-05-01

    Surface texture is a common method for improving wear properties of a tribo-pair of soft and hard bearing material. The reduction of wear rates on the contacting surface material is becoming important issues. In the present study, analysis of the contact pressure on the flat surface of UHMWPE (Ultra High Molecular Weight Polyethylene) under the static- and rolling motion with the surface of steel ball used the 3D finite element method (FEM) (the ABAQUS software version 6.12). Five shaped-texture models (square, circle, ellipse, triangle, and chevron) were presented on the flat surface for analysis. The normal load of 17, 30 and 50 N was deliberately set-up for static and rolling contact analysis. The contact pressure was determined to predict the wear behavior of the shaped-texture on the flat surface of UHMWPE. The results have shown that the static normal load yielded the lowest von-Mises stress distribution on the shaped-texture of the ellipse for all values applied a load, while the square shape experienced the highest stress distribution. Under rolling contact, however, the increasing load yielded the increasing von Mises stress distribution for the texture with a triangle shape. Moreover, the texture shapes for circle, ellipse, and chevron respectively, may undergo the lowest stress distribution for all load. The wear calculation provided that the circle and square shape may undergo the highest wear rates. Obviously, the surface texture of circle, ellipse, and chevron may experience the lowest wear rates and is potential for use in the surface engineering of bearing materials.

  13. Alpha-Calcitonin Gene-Related Peptide Can Reverse The Catabolic Influence Of UHMWPE Particles On RANKL Expression In Primary Human Osteoblasts

    Directory of Open Access Journals (Sweden)

    Max D. Kauther, Jie Xu, Christian Wedemeyer

    2010-01-01

    Full Text Available Background and purpose: A linkage between the neurotransmitter alpha-calcitonin gene-related peptide (alpha-CGRP and particle-induced osteolysis has been shown previously. The suggested osteoprotective influence of alpha-CGRP on the catabolic effects of ultra-high molecular weight polyethylene (UHMWPE particles is analyzed in this study in primary human osteoblasts. Methods: Primary human osteoblasts were stimulated by UHMWPE particles (cell/particle ratios 1:100 and 1:500 and different doses of alpha-CGRP (10-7 M, 10-9 M, 10-11 M. Receptor activator of nuclear factor-κB ligand (RANKL and osteoprotegerin (OPG mRNA expression and protein levels were measured by RT-PCR and Western blot. Results: Particle stimulation leads to a significant dose-dependent increase of RANKL mRNA in both cell-particle ratios and a significant down-regulation of OPG mRNA in cell-particle concentrations of 1:500. A significant depression of alkaline phosphatase was found due to particle stimulation. Alpha-CGRP in all tested concentrations showed a significant depressive effect on the expression of RANKL mRNA in primary human osteoblasts under particle stimulation. Comparable reactions of RANKL protein levels due to particles and alpha-CGRP were found by Western blot analysis. In cell-particle ratios of 1:100 after 24 hours the osteoprotective influence of alpha-CGRP reversed the catabolic effects of particles on the RANKL expression. Interpretation: The in-vivo use of alpha-CGRP, which leads to down-regulated RANKL in-vitro, might inhibit the catabolic effect of particles in conditions of particle induced osteolysis.

  14. Surface modification of UHMWPE for use in total joint replacements.

    Science.gov (United States)

    Zhang, Min; James, Susan P; King, Richard; Beauregard, Guy

    2004-01-01

    To create a hydrophilic, lubricious, more wear-resistant UHMWPE bearing, a novel hyaluronan (HA) derivative and novel UHMWPE-hyaluronan composite were developed. HA was silylated to increase its hydrophobicity and compatibility with UHMWPE. The sily1 HA rapidly diffused into the connected pores of UHMWPE preforms in xylenes solution, and fixed within UHMWPE and on its surface after crosslinking. A micro-composite was obtained after hot-pressing the porous preform. The presence of HA film on the composite surface has been demonstrated through X-Ray photoelectron spectroscopy (XPS) analysis and Toluidine Blue O (TBO) dye assay. The aqueous contact angles of micro-composite samples were significantly lower compared with UHMWPE control samples, and the samples processed with hydrolysis prior to final molding were superior to those processed with hydrolysis after molding.

  15. Nanomechanical and tribological characterization of the MPC phospholipid polymer photografted onto rough polyethylene implants.

    Science.gov (United States)

    Wang, Na; Trunfio-Sfarghiu, Ana-Maria; Portinha, Daniel; Descartes, Sylvie; Fleury, Etienne; Berthier, Yves; Rieu, Jean-Paul

    2013-08-01

    Grafting biomimetic polymers onto biomaterials such as implants is one of the promising approaches to increase their tribological performance and biocompatibility and to reduce wear. In this paper, poly(2-methacryloyloxyethyl phosphorylcholine) (p(MPC)) brushes were obtained by photografting MPC from the rough surface of ultra high molecular weight polyethylene (UHMWPE) joint implants. Such substrates have a high roughness (Ra∼650nm) which often has the same order of magnitude as the brush thickness, so it is very difficult to estimate the vertical density profile of the grafted content. The quality of the p(MPC) grafting was evaluated through a wide range of characterization techniques to reveal the effectiveness of the grafting: atomic force microcopy (AFM) imaging and force spectroscopy, contact angle, SEM/EDX, and confocal microscopy. After testing the methods on smooth glass substrate as reference, AFM nano-indentation proves to be a reliable non destructive method to characterize the thickness and the mechanical properties of the p(MPC) layer in liquid physiological medium. Tribological measurements using a homemade biotribometer confirm that, despite heterogeneity thickness (h=0.5-6μm), the p(MPC) layer covers the roughness of the UHMWPE substrate and acts as an efficient lubricant with low friction coefficient and no wear for 9h of friction.

  16. Nitric oxide and prostaglandin E2 production in response to ultra-high molecular weight polyethylene particles depends on osteoblast maturation state.

    Science.gov (United States)

    Lohmann, Christoph H; Dean, David D; Bonewald, Lynda F; Schwartz, Zvi; Boyan, Barbara D

    2002-03-01

    Recent studies have shown that osteoblast-like cells respond directly to ultra-high molecular weight polyethylene particles in culture, suggesting that they may be involved in aseptic loosening of endoprostheses. We tested the hypothesis that the state of cell maturation plays a role in the response of osteogenic cells to ultra-high molecular weight polyethylene particles. MG63 cells (immature osteoblast-like cells), OCT-1 cells (mature secretory osteoblast-like cells), and MLO-Y4 cells (osteocyte-like cells) were treated for twenty-four hours with commercial ultra-high molecular weight polyethylene particles with an average diameter of 1 mm. The effect of particle treatment on cell proliferation was assessed by measuring the number of cells, whereas the effects on differentiation and local factor production were assessed by measuring the production of osteocalcin, prostaglandin E2, and nitric oxide. The effect of particles on apoptosis was also evaluated. The addition of ultra-high molecular weight polyethylene particles increased the number of MG63 cells, did not affect the number of OCT-1 cells, and led to a decrease in the number of MLO-Y4 cells. The observed changes in cell number were not due to programmed cell death, as no more than 3% of the cells in cultures treated with the highest concentration of particles were undergoing apoptosis. Osteocalcin production was not affected by the addition of particles. Prostaglandin E2 production was increased in all three types of cultures, but the effect was greatest in OCT-1 cell cultures, as was the absolute amount of prostaglandin E2 produced. Nitric oxide production was unaffected in MG63 cell cultures, but it was stimulated in OCT-1 and MLO-Y4 cell cultures. The results of the present study support the hypothesis that osteoblast cell maturation state plays an important role in the response to ultra-high molecular weight polyethylene particles and that the terminally differentiated osteocyte may be involved in the

  17. SILANE CROSSLINKED ULTRA HIGH MOLECULA WEIGHT POLYETHYLENE%硅烷交联超高分子量聚乙烯

    Institute of Scientific and Technical Information of China (English)

    解孝林; 伍学诚; 邓泽贤

    2003-01-01

    采用硅烷对超高分子量聚乙烯(UHMWPE)进行交联改性,系统地研究了交联UHMWPE的凝胶率、熔点、结晶度、力学性能与耐磨性.结果表明,硅烷偶联剂导致了UHMWPE的交联,使UHMWPE的凝胶率提高.当硅烷含量较低时,UHMWPE的熔点增高、结晶度增大;当硅烷含量较高时,UHMWPE的熔点、结晶度呈下降的趋势;硅烷交联导致了UHMWPE材料的模量和强度提高,磨耗率降低;当硅烷含量较高时,交联UHMWPE材料的力学性能和磨耗率均变差;当硅烷含量为0.2份~0.4份时,交联UHMWPE材料的综合性能最佳.

  18. Radiation Shielding of Lunar Regolith/Polyethylene Composites and Lunar Regolith/Water Mixtures

    Science.gov (United States)

    Johnson, Quincy F.; Gersey, Brad; Wilkins, Richard; Zhou, Jianren

    2011-01-01

    Space radiation is a complex mixed field of ionizing radiation that can pose hazardous risks to sophisticated electronics and humans. Mission planning for lunar exploration and long duration habitat construction will face tremendous challenges of shielding against various types of space radiation in an attempt to minimize the detrimental effects it may have on materials, electronics, and humans. In late 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) discovered that water content in lunar regolith found in certain areas on the moon can be up to 5.6 +/-2.8 weight percent (wt%) [A. Colaprete, et. al., Science, Vol. 330, 463 (2010). ]. In this work, shielding studies were performed utilizing ultra high molecular weight polyethylene (UHMWPE) and aluminum, both being standard space shielding materials, simulated lunar regolith/ polyethylene composites, and simulated lunar regolith mixed with UHMWPE particles and water. Based on the LCROSS findings, radiation shielding experiments were conducted to test for shielding efficiency of regolith/UHMWPE/water mixtures with various percentages of water to compare relative shielding characteristics of these materials. One set of radiation studies were performed using the proton synchrotron at the Loma Linda Medical University where high energy protons similar to those found on the surface of the moon can be generated. A similar experimental protocol was also used at a high energy spalation neutron source at Los Alamos Neutron Science Center (LANSCE). These experiments studied the shielding efficiency against secondary neutrons, another major component of space radiation field. In both the proton and neutron studies, shielding efficiency was determined by utilizing a tissue equivalent proportional counter (TEPC) behind various thicknesses of shielding composite panels or mixture materials. Preliminary results from these studies indicated that adding 2 wt% water to regolith particles could increase shielding of

  19. The wear of cross-linked polyethylene against itself.

    Science.gov (United States)

    Joyce, T J; Ash, H E; Unsworth, A

    1996-01-01

    Cross-linked polyethylene (XLPE) may have an application as a material for an all-plastic surface replacement finger joint. It is inexpensive, biocompatible and can be injection-moulded into the complex shapes that are found on the ends of the finger bones. Further, the cross-linking of polyethylene has significantly improved its mechanical properties. Therefore, the opportunity exists for an all-XLPE joint, and so the wear characteristics of XLPE sliding against itself have been investigated. Wear tests were carried out on both reciprocating pin-on-plate machines and a finger function simulator. The reciprocating pin-on-plate machines had pins loaded at 10 N and 40 N. All pin-on-plate tests show wear factors from the plates very much greater than those of the pins. After 349 km of sliding, a mean wear factor of 0.46 x 10(-6) mm3/N m was found for the plates compared with 0.021 x 10(-6) mm3/N m for the pins. A fatigue mechanism may be causing this phenomenon of greater plate wear. Tests using the finger function simulator give an average wear rate of 0.22 x 10(-6) mm3/N m after 368 km. This sliding distance is equivalent to 12.5 years of use in vivo. The wear factors found were comparable with those of ultra-high molecular weight polyethylene (UHMWPE) against a metallic counterface and, therefore, as the loads across the finger joint are much less than those across the knee or the hip, it is probable that an all-XLPE finger joint will be viable from a wear point of view.

  20. Synthesis by High-Efficiency Liquid-Phase (HELP Method of Oligonucleotides Conjugated with High-Molecular Weight Polyethylene Glycols (PEGs

    Directory of Open Access Journals (Sweden)

    Bonora GM

    1998-01-01

    Full Text Available The chemical modification of synthetic oligonucleotides has recently been investigated to improve their pharmacological utilization. In addition to chemical alterations of the backbone and of the heterocyclic bases, their conjugation with amphiphylic moieties, such as the polyethylene glycol has been proposed. The large scale production of these molecules as demanded for commercial purposes is hampered by the heterogeneity of the solid-phase processes and by the low reactivity of high-molecular weight PEGs in solution. A new synthetic procedure based on the recently developed liquid-phase method (HELP, has been set up to overcome these limitations.

  1. Periprosthetic UHMWPE Wear Debris Induces Inflammation, Vascularization, and Innervation After Total Disc Replacement in the Lumbar Spine.

    Science.gov (United States)

    Veruva, Sai Y; Lanman, Todd H; Isaza, Jorge E; Freeman, Theresa A; Kurtz, Steven M; Steinbeck, Marla J

    2017-05-01

    The pathophysiology and mechanisms driving the generation of unintended pain after total disc replacement (TDR) remain unexplored. Ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris from TDRs is known to induce inflammation, which may result in pain. The purpose of this study was to determine whether (1) periprosthetic UHMWPE wear debris induces immune responses that lead to the production of tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, the vascularization factors, vascular endothelial growth factor (VEGF) and platelet-derived growth factor-bb (PDGFbb), and the innervation/pain factors, nerve growth factor (NGF) and substance P; (2) the number of macrophages is associated with the production of the aforementioned factors; (3) the wear debris-induced inflammatory pathogenesis involves an increase in vascularization and associated innervation. Periprosthetic tissues from our collection of 11 patients with contemporary TDRs were evaluated using polarized light microscopy to quantify UHMWPE wear particles. The major reason for revision (mean implantation time of 3 years [range, 1-6 years]) was pain. For control subjects, biopsy samples from four patients with degenerative disc disease with severe pain and autopsy samples from three normal patients with no history of back pain were also investigated. Immunohistochemistry and histology were used to identify secretory factors, macrophages, and blood vessels. Immunostained serial sections were imaged at ×200 magnification and using MATLAB and NIH ImageJ, a threshold was determined for each factor and used to quantify positive staining normalized to tissue sectional area. The Mann-Whitney U test was used to compare results from different patient groups, whereas the Spearman Rho test was used to determine correlations. Significance was based on p < 0.05. The mean percent area of all six inflammatory, vascularization, and innervation factors was higher in TDR tissues when compared with normal disc

  2. 低温等离子体与马来酸酐对 UHMWPE 纤维表面改性%Low Temperature Plasma/Grafting Treatment of Maleic Anhydride on UHMWPE

    Institute of Scientific and Technical Information of China (English)

    赵艳凝; 赵丹丹; 侯金国; 王春莲

    2014-01-01

    Low temperature plasma technology and grafting treatment were used on surface modification on the ultra high molecular weight polyethylene fiber ( UHMWPE) surface.The optimum process of the grafted Maleic anhydride on the fiber surface was aqueous solution as a solvent and 1.0 mol/L of Maleic anhydride concentration at 80 ℃for 1.5 h.After the treated polar groups were grafted in the side chain of the fiber , so the chemical bonding ability with other matrix materials increased and the occlusion ability between the fiber surface and other materials enhanced but the mechanical properties and surface morphology of the fiber were kept unchanged.As a result, the surface properties were improved.%用低温等离子体技术和接枝反应对超高分子量聚乙烯( UHMWPE)纤维进行表面处理.纤维进行低温等离子体后接枝处理的最佳工艺条件是:在80℃的1.0 mol/L的马来酸酐水溶液中加热1.5 h在维持整体形貌的前提下,在纤维长链表面引入了活性基团,增大了纤维与其他基质材料之间的化学键合能力和咬合能力,提高纤维的表面性能,从而达到表面改性的目的。

  3. A study of the oriented composites with the conductive segregated structure obtained via solid-phase processing of the UHMWPE reactor powder mixed with the carbon nanofillers

    Science.gov (United States)

    Lebedev, Oleg V.; Kechek'yan, Alexander S.; Shevchenko, Vitaly G.; Kurkin, Tikhon S.; Golubev, Evgeny K.; Karpushkin, Evgeny A.; Sergeev, Vladimir G.; Ozerin, Alexander N.

    2016-05-01

    Electrically conductive oriented polymer nano-composites of different compositions, based on the reactor powder of ultra-high-molecular-weight polyethylene (UHMWPE) with a special morphology, filled with particles of nanostructured graphite (NG), multi-walled carbon nanotubes (MWCNTs), and electrically conductive carbon black (CB), were investigated. Polymer composites were obtained via compaction of the mechanical mixture of the polymer and filler powder, followed by uniaxial deformation of the material under homogeneous shear (HS) conditions (all of the processing stages were conducted at room temperature). Resulted composites possess a high tensile strength, high level of the electrical conductivity and low percolation threshold, owing it to the formation of the segregated conductive structure, The influence of the type of nanosized carbon filler, degree of the deformation under HS condition, temperature and etc. on the electrical conductivity and mechanical properties of strengthened conductive composites oriented under homogeneous shear conditions was investigated. Changes in the electrical conductivity of oriented composite materials during reversible "tension-shrinkage" cycles along the orientation axis direction were studied. A theoretical approach, describing the process of transformation of the conductive system as a response on polymer phase deformation and volume change, was proposed, based on the data received from the analysis of the conductivity behavior during the uniaxial deformation and thermal treatment of composites.

  4. A study of the oriented composites with the conductive segregated structure obtained via solid-phase processing of the UHMWPE reactor powder mixed with the carbon nanofillers

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Oleg V. [Moscow Institute of Physics and Technology (State University,) Institutskiy per., Dolgoprudny, Moscow Region, 141700 (Russian Federation); N.S. Enikolopov Institute of Synthetic Polymer Materials of RAS, Profsoyuznaya st., Moscow, 117393 (Russian Federation); Kechek’yan, Alexander S.; Shevchenko, Vitaly G.; Kurkin, Tikhon S.; Golubev, Evgeny K.; Ozerin, Alexander N. [N.S. Enikolopov Institute of Synthetic Polymer Materials of RAS, Profsoyuznaya st., Moscow, 117393 (Russian Federation); Karpushkin, Evgeny A.; Sergeev, Vladimir G. [Moscow State University, Chemical Department, Leninskie Gori, Moscow, 119234 (Russian Federation)

    2016-05-18

    Electrically conductive oriented polymer nano-composites of different compositions, based on the reactor powder of ultra-high-molecular-weight polyethylene (UHMWPE) with a special morphology, filled with particles of nanostructured graphite (NG), multi-walled carbon nanotubes (MWCNTs), and electrically conductive carbon black (CB), were investigated. Polymer composites were obtained via compaction of the mechanical mixture of the polymer and filler powder, followed by uniaxial deformation of the material under homogeneous shear (HS) conditions (all of the processing stages were conducted at room temperature). Resulted composites possess a high tensile strength, high level of the electrical conductivity and low percolation threshold, owing it to the formation of the segregated conductive structure, The influence of the type of nanosized carbon filler, degree of the deformation under HS condition, temperature and etc. on the electrical conductivity and mechanical properties of strengthened conductive composites oriented under homogeneous shear conditions was investigated. Changes in the electrical conductivity of oriented composite materials during reversible “tension–shrinkage” cycles along the orientation axis direction were studied. A theoretical approach, describing the process of transformation of the conductive system as a response on polymer phase deformation and volume change, was proposed, based on the data received from the analysis of the conductivity behavior during the uniaxial deformation and thermal treatment of composites.

  5. Effects of Environment on Strengths of UHMWPE and Aramid Fiber

    Institute of Scientific and Technical Information of China (English)

    曹涛; 李显波

    2013-01-01

    This paper is devoted on influences of acid-base,high and low temperature on strength of UHMWPE and aramid fiber, characterized by fracture strength, SEM’s effects on fiber strength and surface morphology. It turns out to be that UHMWPE fiber has a superior acid-base, low temperature and light aging resistance property,with strength keeping above 90% in acid-base environment. Comparing with UHMWPE fiber, aramid fiber does well in mechanical properties, temperature resistant performances and alkali resistances at room temperature, with strength losing less than 10%in alkaline environment.

  6. Statistical analysis of the effects of polyethylene glycol concentration and molecular weight on the sedimentation and resuspendability behavior of model aqueous dispersions.

    Science.gov (United States)

    Zhu, Wuxin; Vermeir, Lien; Govoreanu, Ruxandra; Verbruggen, Katrien; Ariën, Tina; Van der Meeren, Paul

    2013-09-10

    This work investigates the flocculation effect of polyethylene glycol (PEG) on typical aqueous dispersions, such as O/W emulsions and solid/liquid suspensions. Hereby, sunflower oil and flubendazole were selected as model ingredients, whereas microfluidization at variable driving air pressure was used to enable particle size distribution variations for both systems. The molecular weight of PEG varied from 2000 to 12,000g/mol while its concentration ranged from 50 to 100mg/ml. Statistical analysis revealed that both PEG concentration and molecular weight showed a flocculation enhancing effect. Hereby the inhibiting effect of particle size toward the formation of voluminous and easily resuspendable sediment could at least partially be overcome by selecting appropriate PEG characteristics.

  7. The use of DBD plasma treatment and polymerization for the enhancement of biomedical UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Cools, Pieter, E-mail: Pieter.cools@ugent.be; Van Vrekhem, Stijn; De Geyter, Nathalie; Morent, Rino

    2014-12-01

    Surface modification of polymers for biomedical applications is a thoroughly studied area. The goal of this paper is to show the use of atmospheric pressure plasma technology for the treatment of polyethylene shoulder implants. Atmospheric pressure plasma polymerization of methyl methacrylate will be performed on PE samples to increase the adhesion between the polymer and a PMMA bone cement. For the plasma polymerization, a dielectric barrier discharge is used, operating in a helium atmosphere at an ambient pressure. Parameters such as treatment time, monomer gas flow and discharge power are varied one at a time. Chemical and physical changes at the sample surface are studied making use of X-ray photoelectron spectroscopy and atomic force microscopy measurements. Coating thicknesses are determined by making use of optical reflectance spectroscopy. After characterization, the coated samples are incubated into a phosphate buffered saline solution for a minimum of one week at 37 °C, testing the coating stability when exposed to implant conditions. The results show that PMMA coatings can be deposited with a high degree of control in terms of chemical composition and layer thickness. - Highlights: • Medium pressure DBD successfully activates UHMWPE substrates. • Deposition of PMMA like film via atmospheric pressure DBD on activated UHMWPE • Fast deposition rate is confirmed via optical reflectance spectroscopy. • Relative stable coating found after tests in PBS solution and analysed via FT-IR.

  8. Segregated ultrahigh molecular weight polyethylene composites filled with graphene sheets and hybrid multi-walled carbon nanotubes%石墨烯-多壁碳纳米管/超高分子量聚乙烯导电复合材料的制备及性能

    Institute of Scientific and Technical Information of China (English)

    狄莹莹; 任鹏刚; 张倩

    2012-01-01

    为了比较超高分子量聚乙烯(UHMWPE)在单一填充和混合填充时,复合材料导电性的差别。在超声和肼的作用下,通过对氧化石墨烯(GO)、多壁碳纳米管(MWCNTs)和超高分子量聚乙烯水/乙醇分散液减压蒸馏及热压制备了隔离型MWCNTs/UHMWPE、石墨烯(GNS)/UHMWPE和MWCNTs-GNS/UHMWPE导电复合材料。经SEM、TEM测试发现,导电填料分散于UHMWPE颗粒表面,热压后形成隔离结构。隔离型的MWCNTs/UHMWPE和GNS/UHMWPE复合材料均表现出较低的导电逾渗(0.148%和0.059%,体积分数,下同),但MWCNTs/UHMWPE复合材料的电导率(2.0×10-2 S/m,1.0%,质量分数,下同)明显高于相同填料含量下的GNS/UHMWPE复合材料。MWCNTs-GNS/UHMWPE复合材料表现出了更低的逾渗(0.039%)和较高导电性能(1.0×10-2 S/m,1.0%),其拉伸强度和断裂伸长率随填充剂含量的增加呈现出先上升后下降的趋势。%For the sake of comparing the different electricity conductivities of composite materials when the UHMWPE filled singleness and mixed,graphene nanosheets(GNS)-multi-walled carbon nanotubes(MWCNTs)/ultrahigh molecular weight polyethylene(UHMWPE) composites with a segregated network structure were prepared by alcohol-assisted dispersion,ultrasound and hydrazine.SEM and TEM results show that MWCNTs or GNS homogeneously disperse around UHMWPE particle,and from a segregated conductive network during the hot-pressing.It is found that the percolation threshold of GNS/UHMWPE composites(0.059%,volume fraction)is much lower than that of MWCNTs/UHMWPE composites(0.148%,volume fraction).At the same filler content,the electrical conductivity of GNS/UHMWPE composites is much lower than that of the MWCNTs/UHMWPE composites(2.0×10-2 S/m,1.0%,mass fraction).The percolation threshold of GNS-MWCNTs/UHMWPE hybrid composites(0.039%,volume fraction) is lower than that of composites filled with GNS and MWCNTs alone

  9. 网络结构对多层聚乙烯共混物界面扩散行为的影响%INFLUENCE OF NETWORK ON THE INTERFACIAL DIFFUSION OF MULTILAYER POLYETHYLENE BLENDS

    Institute of Scientific and Technical Information of China (English)

    李文林; 牛艳华; 王志刚; 张军

    2012-01-01

    通过溶液法制备超高分子量聚乙烯(UHMWPE)/乙烯-己烯共聚物(PEH)共混物,采用动态流变学方法研究了UHMWPE/PEH共混物多层膜在熔点以上的界面扩散行为,结合Double-Reptation理论计算得到了UHMWPE/PEH共混物多层膜的自扩散系数.研究表明UHMWPE在浓度c=1.0 wt%以上可以在PEH基体中形成网络结构.UHMWPE/PEH共混物多层膜界面扩散不符合严格的菲克扩散定律,扩散系数具有时间依赖性.扩散曲线显示扩散过程在到达平台值之前分为2个区域,区域Ⅰ接近于菲克扩散;然而由于引入UHMWPE,区域Ⅱ扩散显著偏离菲克扩散行为,特别是当UHMWPE在PEH基体中形成网络结构以后,偏离菲克扩散行为更加显著.%Ultrahigh molecular mass polyethylene ( UHMWPE ) and statistical copolymer of ethylene and 1 -hexene (PEH) were used to prepare UHMWPE/PEH blends with relatively low UHMWPE concentrations. UHMWPE forms network structure in the blends with UHMWPE concentrations above a critical value of c = 1 wt% . The influence of the formed UHMWPE network on the interfacial diffusion behaviors of multilayer UHMWPE/PEH blends was investigated by applying small oscillatory shear rheology. The interfacial diffusion coefficients of multilayer UHMWPE/PEH blends were obtained from the rheological data. It is found that the diffusion coefficients are time-dependent and two diffusion regions are distinct before the diffusion reaches the plateaus according to the changes of diffusion exponent n in the relation of D-t n, which implies an approximate Fickian diffusion behavior in region I (c 1.0 wt% ) . With the formation of UHMWPE network in the UHMWPE/PEH blends, deviation from the Fickian behavior for diffusion of multilayer UHMWPE/PEH blends becomes significant. The above results help facilitate the industrial processing of multilayer polyolefins, which is related to the interfacial diffusion.

  10. Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

    Directory of Open Access Journals (Sweden)

    Stuart Leigh Phoenix

    2017-03-01

    Full Text Available Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex, twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i a reverse-fired, fragment simulating projectile (FSP where the flat rear face impacted the yarn rather than the beveled nose; and (ii a ‘saddle-nosed projectile’ having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young’s modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre

  11. Reinforced Modified UHMWPE/PP Blend System Composition (Ⅱ)%UHMWPE/PP共混改性体系研究(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    张炜; 麦永懿; 唐颂超; 吴向阳; 张玉梅; 洪尉

    2008-01-01

    制备了UHMWPE/PP合金材料,研究了UHMWPE/PP共混体系的流动性和力学性能及相容剂对共混体系的增容作用,研究表明:PP能有效地改善UHMWPE流动性,但与UHMWPE为不相容体系,相容剂D能够有效提高UHMWPE/PP体系的相容性,提高了材料的拉伸强度和冲击强度,达到一定的增强和增韧效果.

  12. Development and Validation of a Wear Model to Predict Polyethylene Wear in a Total Knee Arthroplasty: A Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Bernardo Innocenti

    2014-11-01

    Full Text Available Ultra-high molecular weight polyethylene (UHMWPE wear in total knee arthroplasty (TKA components is one of the main reasons of the failure of implants and the consequent necessity of a revision procedure. Experimental wear tests are commonly used to quantify polyethylene wear in an implant, but these procedures are quite expensive and time consuming. On the other hand, numerical models could be used to predict the results of a wear test in less time with less cost. This requires, however, that such a model is not only available, but also validated. Therefore, the aim of this study is to develop and validate a finite element methodology to be used for predicting polyethylene wear in TKAs. Initially, the wear model was calibrated using the results of an experimental roll-on-plane wear test. Afterwards, the developed wear model was applied to predict patello-femoral wear. Finally, the numerical model was validated by comparing the numerically-predicted wear, with experimental results achieving good agreement.

  13. Chemical modification of high molecular weight polyethylene through gamma radiation for biomaterials applications; Modificacao quimica de polietileno de alto peso molecular atraves de radiacao gama para aplicacao em biomateriais

    Energy Technology Data Exchange (ETDEWEB)

    Raposo, Matheus P.; Rocha, Marisa C.G., E-mail: matheusmerlim@hotmail.com [Universidade Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico

    2015-07-01

    Ultra high molecular weight polyethylene has been used in the medical field due to its high mechanical properties compared to the other polymers. Its main application is in the development of orthopedic implants, which requires high resistance to abrasion. One of the most used methods is the introduction of crosslinks in the polymer through gamma irradiation. In order to prevent oxidation reactions, studies have been developed using tacoferol (vitamin E) as an antioxidant for the material. The ascorbic acid (vitamin C), however, has been appointed as a viable alternative for vitamin E. In this work, a high molecular weight polyethylene grade (HMWPE) and polyethylene samples formulated with vitamin C were submitted to gamma radiation. Thermodynamic-mechanical methods and gel content determinations were used to characterize the samples obtained. The sample containing 1% of vitamin C and irradiated with 50 KGy of gamma radiation presented the highest content of crosslinks. (author)

  14. Surface modifications induced by in-vitro wear and oxidation on γ-irradiated UHMWPE hip liners belonging to different commercial generations.

    Science.gov (United States)

    Puppulin, Leonardo; Negra, Sara Della; Sugano, Nobuhiko; Sbaizero, Orfeo; Pezzotti, Giuseppe

    2016-01-01

    Single-step and three-step irradiated and annealed ultra-high molecular weight polyethylene (UHMWPE) hip liners have been studied by means of Raman spectroscopy (RS) and Fourier transform infrared spectroscopy (FT-IR), in order to clarify the microstructural modifications induced by in vitro oxidative degradation and wear. These spectroscopic techniques enabled us to measure profiles of oxidation index (OI), crystalline (αc), amorphous (αa), and third phase (αb) fractions along the subsurface of the acetabular cups as a function of in vitro oxidation time or after standard testing in hip simulator. Microtomed sections of the liners after accelerated aging (ASTM F2003-02) showed that oxidation profiles developed differently during the first two weeks, while all samples aged longer than 2 weeks revealed OI increasing with lower rates. The initial oxidation of the single-step-annealed material was higher than the one retrieved from the 3-step-annealed material and showed a peak of OI located at a depth of ~1mm below the exposed surface. The profiles of αc, calculated from the same sample cross-sections, followed trends similar to the respective OI profiles, which enabled a phenomenological (but quantitative) correlation between oxidation and crystallization processes to be obtained. Wear simulation under edge loading conditions was conducted on series of four samples of the above two types of irradiated and annealed materials, and for two different liner thicknesses (5.9 and 7.9 mm). The wear rates calculated at the end of the test were very low for all samples (max 2.08 mm(3)/mc for the thinner liners of the single-step irradiated and annealed material). The results indicated that there was a statistically significant increase in both wear rate and volume loss only for the thinner single-step irradiated and annealed liners. Surface analyses by Raman spectroscopy revealed distinct gradients of crystallinity, amorphous, and third phase fractions along the in

  15. The stabbing-resistance of Ultrahigh molecular weight polyethylene%超高分子量聚乙烯织物的防刺穿性

    Institute of Scientific and Technical Information of China (English)

    王颖; 徐伯俊; 徐耀林; 俞萍

    2012-01-01

    探讨了超高分子量聚乙烯(UHMWPE)纤维织物的防剌穿性能.采用单层UHMWPE机织布、双层UHMWPE机织布复合粘胶非织造布、4层UHMWPE机织布复合粘胶非织造布作实验材料,对上述3种织物进行刺穿试验,得到了织物被刺破所需力的大小.

  16. High molecular weight poly(ethylene-2,5-furanoate); critical aspects in synthesis and mechanical property determination

    NARCIS (Netherlands)

    Knoop, J.R.I.; Vogelzang, W.; Haveren, van J.; Es, van D.S.

    2013-01-01

    Furan-2,5-dicarboxylic acid (FDCA) is a widely advocated renewable substitute for terephthalic acid (TA). Preparation of high molecular weight FDCA based polyesters by an industrially common combination of melt polymerization and subsequent solid state post condensation is described. Ultimately, pol

  17. Comparison of Biotribology of Swine Compact Bone Against UHMWPE

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-liang; GE Shi-rong

    2007-01-01

    A pin-on-disk tribometer was used, in a comparative test to observe the tribological behavior of the swine femoral bone against UHMWPE with dry friction, physiological water and human plasma lubrication. The wear mechanisms of swine bones and UHMWPE were investigated by SEM. The experimental results of these wear tests demonstrated that both the friction coefficient and wear rate of UHMWPE were the lowest when human plasma lubrication was used. The wear mechanism of the compact bone was mainly fatigue wear with dry friction, corrosive wear under physiological water lubrication and abrasive wear with human plasma lubrication. For UHMWPE, the wear mechanism was adhesive wear and plastic deformation with dry friction, serious ploughing and fatigue fracture wear under physiological water lubrication, fine ploughing and plastic deformation with human plasma lubrication. An analysis of.nitrogen elements on the wear surface of UHMWPE indicated that the content of nitrogen in worn areas was 16 times higher than that in unworn areas, which proved that serum protein deposition occurred on worn areas.

  18. Modifications by {gamma} irradiation of polyethylene at very high molecular weight. Tribological behaviour for orthopedic applications; Modifications par irradiation {gamma} du polyethylene a tres haut poids moleculaire. Comportement tribologique pour des applications orthopediques

    Energy Technology Data Exchange (ETDEWEB)

    Chaix, N

    2001-07-01

    A new mode of sterilization by vacuum gamma irradiation is studied. This new mode improves significantly the polyethylene behaviour during the study in friction-corrosion against a stainless steel-316L sphere. (N.C.)

  19. Research on the Ballistic Performance of UHMWPE Fiber Fabric Composite Targets%UHMWPE纤维织物复合靶板抗弹性能研究

    Institute of Scientific and Technical Information of China (English)

    高恒; 杨宏伟; 杜建华

    2014-01-01

    To study the ballistic performance of the composite of different high-performance fiber fabric structure,the ballistic performance of UD cloth/2D woven fabric composite targets made of UHMWPE (Ultra-High Molecular Weight Polyethylene)fiber is tested according to the standard GA1 41-201 0.The results indicate that UD cloth/2D woven fabric composite targets can resist the penetration of 7.62 mm bullet effectively and the fiber of 2D woven fabric is not damaged seriously,which is helpful to resist mul-tiple shooting.%为研究不同织物结构的高性能纤维材料复合时的抗弹性能,采用超高分子量聚乙烯(Ultra-high Molecular Weight Polyethylene,UHMWPE)纤维单向无纬(Unidirectional,UD)布及2维(2D)织物制备 UD 布/2D 织物复合靶板,并根据 GA141-2010标准对其进行靶试试验。结果表明:UD 布/2D 织物的复合结构能够有效抵御7.62 mm 手枪弹侵彻,且2D织物部分在弹丸侵彻之后纤维并未被严重破坏,将其与 UD布复合后,有利于抵御多发弹的侵彻。

  20. Role of in-situ formed nano-and micro-fibrils in micro-fatigue resistance of bio-polyethylene

    Institute of Scientific and Technical Information of China (English)

    EJisheng; M.J.Bevis

    2001-01-01

    In response to the need for the reduction of micro-debris generation in artificial humanjoints for extending the service life, a novel polymer process technology, SCORIM (shear con-trolled orientation injection moulding), was employed to manufacture a polyethylene compositereinforced by in-situ formed nano- and micro-fibrils. Tribological performance of a blend of ultrahigh molecular weight polyethylene (UHMWPE) and high density polyethylene (HDPE) was evalu-ated on a pin-on-disc wear machine. Results indicate a significant improvement in micro fatiguewear resistance compared with those moulded by a conventional injection moulding technology.Scanning electron microscopy reveals that a micro-fibril structure forms as an in-situ fibre rein-forced composite using SCORIM while an aggregated structure occurs in specimens moulded byconventional technology. DSC analysis shows the occurrence of a second phase: shish kebabmicrostructure using SCORIM. Transmission electron microscopy reveals the transformation ofmicrostructure from randomly orientated lamella in the specimens moulded by conventional injec-tion moulding into nano-fibril shish kebab microstructure, which results in a significant reduction inthe possibility of the initiation and development of micro-cracks parallel to the contact surfacesusing SCORIM. Consequently, the formation of nano-fibril shish kebab and micro-fibril microstruc-ture by using the novel SCORIM technology results in a significant reduction in micro-fatigue whenusing the surface normal to the direction of the orientated molecular fibril microstructure as a con-tact surface.

  1. 76 FR 70896 - Polyethylene Glycol; Tolerance Exemption

    Science.gov (United States)

    2011-11-16

    ... AGENCY 40 CFR Part 180 Polyethylene Glycol; Tolerance Exemption AGENCY: Environmental Protection Agency... amu), 17,000; also known as polyethylene glycol, when used as an inert ingredient in a pesticide...(oxyethylene, minimum number average molecular weight (in amu), 17,000; also known as polyethylene...

  2. Effect of Different Polypropylene on the Rheological and Mechanical Properties of Ultrahigh Molecular Weight Polyethylene%不同聚丙烯对超高分子量聚乙烯流变行为和力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    左源; 盖景刚; 李惠林

    2010-01-01

    研究了不同共聚聚丙烯(PP-C)对超高分子量聚乙烯(UHMWPE)/均聚聚丙烯(PP-H)体系的增容作用,考察了UHMWPE/PP-H和UHMWPE/PP-B(嵌段共聚PP)体系的流变和力学性能.结果表明,加入分子量较大的PP-B(EPS30R)能提高UHMWPE/PP-H体系的力学性能且不影响其加工性,UHMWPE/EPS30R体系的力学性能优于UHMWPE/PP-H.扫描电镜(SEM)和动态力学分析(DMA)结果表明,EPS30R改善了UHMWPE/PP-H体系的相容性,UHMWPE/EPS30R体系的相容性优于UHMWPE/PP-H.

  3. Improvement in enzyme activity and stability by addition of low molecular weight polyethylene glycol to sodium bis(2-ethyl-L-hexyl)sulfosuccinate/isooctane reverse micellar system.

    Science.gov (United States)

    Talukder, M M R; Takeyama, T; Hayashi, Y; Wu, J C; Kawanishi, T; Shimizu, N; Ogino, C

    2003-08-01

    The activity and stability of Chromobacterium viscosum lipase (glycerolester hydrolase, EC 3.1.1.3)-catalyzed olive oil hydrolysis in sodium bis (2-ethyl-l-hexyl)sulfosuccinate (AOT)/isooctane reverse micelles is increased appreciably when low molecular weight polyethylene glycol (PEG 400) is added to the reverse micelles. To understand the effect of PEG 400 on the phase behavior of the reverse micellar system, the phase diagram of AOT/ PEG 400/water/isooctane system was studied. The influences of relevant parameters on the catalytic activity in AOT/PEG 400 reverse micelles were investigated and compared with the results in the simple AOT reverse micelles. In the presence of PEG 400, the linear decreasing trend of the lipase activity with AOT concentration, which is observed in the simple AOT reverse micelles, disappeared. Enzyme entrapped in AOT/PEG reverse micelles was very stable, retaining >75% of its initial activity after 60 d, whereas the half-life in simple AOT reverse micelles was 38 d. The kinetics parameter maximum velocity (Vmax) exhibiting the temperature dependence and the activation energy obtained by Arrhenius plot was suppressed significantly by the addition of PEG 400.

  4. Interactions of silica nanoparticles with poly(ethylene oxide) and poly(acrylic acid): effect of the polymer molecular weight and of the surface charge.

    Science.gov (United States)

    Joksimovic, R; Prévost, S; Schweins, R; Appavou, M-S; Gradzielski, M

    2013-03-15

    The properties and the structure of polymer-modified silica nanoparticles were investigated by several characterization methods, with an emphasis on scattering techniques. Both bare and amino functionalized nanoparticles were used. To determine the effect of the charge, the polymer used was either nonionic poly(ethylene oxide) (PEO) or partially deprotonated poly(acrylic acid) (PAA). The particles coated with PEO were investigated by small-angle neutron scattering using the method of external contrast variation to observe the polymer coverage. The quantity adsorbed was found to be increasing with the molecular weight, and the surface type, bare or aminated, did not have a significant influence on the quantity adsorbed. The adsorption of PAA on positively charged aminated particles was investigated by dynamic light scattering and zeta potential measurements. A charge reversal, from positive to negative, was induced by the presence of PAA. Through the derivation of the structure factor, small-angle X-ray scattering provided significant information on the formation of aggregates at low PAA concentrations.

  5. A study of the damage tolerance enhancement of carbon/epoxy laminates by utilizing an outer lamina of ultra high molecular weight polyethylene

    Science.gov (United States)

    Nettles, Alan T.; Lance, David G.

    1991-01-01

    The damage tolerance of carbon/epoxy was examined when an outer layer of ultra high molecular weight polyethylene (Spectra) material was utilized on the specimen. Four types of 16 ply quasi-isotropic panels, (0,+45,90,-45)s2 were tested. The first contained no Spectra, while the others had one lamina of Spectra placed on either the top (impacted side), bottom or both surfaces of the composite plate. A range of impact energies up to approximately 8.5 Joules (6.3 ft-lbs) was used to inflict damage upon these specimens. Glass/Phenolic honeycomb beams with a core density of 314 N/m3 (2.0 lb/ft3) and 8 ply quasi-isotropic facesheets were also tested for compression-after-impact strength with and without Spectra at impact energies of 1,2,3 and 4 Joules (.74, 1.47, 2.21 and 2.95 ft-lbs). It was observed that the composite plates had little change in damage tolerance due to the Spectra, while the honeycomb panels demonstrated a slight increase in damage tolerance when Spectra was added, the damage tolerance level being more improved at higher impact energies.

  6. Effects of alpha-calcitonin gene-related peptide on osteoprotegerin and receptor activator of nuclear factor-κB ligand expression in MG-63 osteoblast-like cells exposed to polyethylene particles

    Directory of Open Access Journals (Sweden)

    Kauther Max D

    2010-11-01

    Full Text Available Abstract Background Recent studies demonstrated an impact of the nervous system on particle-induced osteolysis, the major cause of aseptic loosening of joint replacements. Methods In this study of MG-63 osteoblast-like cells we analyzed the influence of ultra-high molecular weight polyethylene (UHMWPE particles and the neurotransmitter alpha-calcitonin gene-related peptide (CGRP on the osteoprotegerin/receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factorκB (OPG/RANKL/RANK system. MG-63 cells were stimulated by different UHMWPE particle concentrations (1:100, 1:500 and different doses of alpha-CGRP (10-7 M, 10-9 M, 10-11 M. RANKL and OPG mRNA expression and protein levels were measured by RT-PCR and Western blot. Results Increasing particle concentrations caused an up-regulation of RANKL after 72 hours. Alpha-CGRP showed a dose-independent depressive effect on particle-induced expression of RANKL mRNA in both cell-particle ratios. RANKL gene transcripts were significantly (P -7 M lead to an up-regulation of OPG protein. Conclusion In conclusion, a possible osteoprotective influence of the neurotransmitter alpha-CGRP on particle stimulated osteoblast-like cells could be shown. Alpha-CGRP might be important for bone metabolism under conditions of particle-induced osteolysis.

  7. Wear behaviour of UHMWPE reinforced by carbon nanofiller and paraffin oil for joint replacement.

    Science.gov (United States)

    Yousef, Samy; Visco, Annamaria; Galtieri, Giovanna; Nocita, Davide; Espro, Claudia

    2017-04-01

    The majority of artificial joints incorporate biomedical grade Ultra High Molecular Weight Poly Ethylene (UHMWPE), whose wear is considered most important in controlling service time of the whole joint. The aim of this work was to improve wear resistance of UHMWPE through the addition of 0.5-2.0wt% of Carbon Nano Filler (CNF) and 2% wt of Paraffin Oil (PO) using ball milling (BM) and extrusion techniques (EX). The wear tests on these nanocomposites were conducted by a pin on disc in dry (air) and wet media (simulated synovial fluid or artificial lubricant, and bovine synovial fluid or natural lubricant). Mechanical tests (tensile and hardness), physical analysis (calorimetric, density, wet ability, roughness) and morphological observations were also performed. The experimental results showed that natural lubricant provides the greatest reduction in wear rate while the largest one occurred in air. Furthermore, the BM mixed nanocomposites with a filler load of 1.0% exhibited the best wear resistance among all the samples with an improvement of 42%, 64% and 83% in air, artificial and natural lubricant, respectively. This is due to its higher ductility and thermal features, and lower wet ability in the two lubricants.

  8. SUPPORTED ZIEGLER-NATTA CATALYSTS FOR ETHYLENE SLURRY POLYMERIZATION AND CONTROL OF MOLECULAR WEIGHT DISTRIBUTION OF POLYETHYLENE

    Institute of Scientific and Technical Information of China (English)

    Vladimir Zakharov; Ludmila Echevskaya; Tatiana Mikenas; Mikhail Matsko; Andrey Tregubov; Marina Vanina; Marina Nikolaeva

    2008-01-01

    The effect of chemical composition of highly active supported Ziegler-Natta catalysts with controlled morphology on the MWD of PE has been studied.It was shown the variation of transition metal compound in the MgCI2-supported catalyst affect of MWD of PE produced in broad range:Vanadium-magnesium catalyst(VMC)produce PE with broad and bimodal MWD(Mw、Mn=14-21).MWD of PE,produced over titanium-magnesium catalyst(TMC) is narrow or medium depending on Ti content in the catalyst(Mw/Mn=3.1-4.8).The oxidation state of the initial titanium compounds in TMC has only slight effeCt on MWD of PE produced.Based on MWD data of PE heterogeneity of active centers of TMC and VMC was studied.The results of resolution of experimental GPC curves into Flory components indicated three Flory components are snfficient to describe MWD curve of PE,produced with TMC:six Flory components are required in the case of VMC.In the case of copolymerization of ethylene with 1-hexene over TMC the addition of 1-hexene leads to decrease of MW and to slight effect on Mw/Mn values.On the contrary the strong effect of 1-hexene on MWD of PE produced over VMC was found:the introduction of 1-hexene results in considerable broadening of MWD due to the shifting of the main MWD peak tO low MW region.At that comonomer does not affect the position of high molecular weight shoulder The results indicate that some of active centers of VMC producing high MW polymer are not active in the reaction of chain transfer with comonomer.

  9. Análisis experimental del desgaste entre UHMWPE y acero inoxidable 316l empleados en la manufactura de prótesis coxofemorales

    Directory of Open Access Journals (Sweden)

    Ricardo Gustavo Rodríguez Cañizo

    2010-10-01

    ículas desprendidas disminuyen considerablemente cuando se utiliza suero bovino como lubricante para replicar las condiciones reales de operación del sistema por tener propiedades muy semejantes a las del fluido sinovial presente en la articulación de la cadera. El caso seco representó el peor escenario en donde se produce mayor daño. Palabras clave: pruebas pin-on-disk, copa acetabular, cabeza femoral, suero bovino, tasa anual de desgaste, coeficientes de fricción. Abstract The most common cause of failure in coxofemoral prostheses is the loosening between the components of the system, namely the acetabular cup and the femoral head. In this work a tribologic analysis of wear suffered in the components is presented, due to when the surfaces in contact are worn, the mechanical function of the system is compromised as the wearing implies a change in the geometry of the components, thus in their dimensions, resulting on a looseness between the cup and the head. The materials considered in this study are Ultra High Molecular Weight Polyethylene (UHMWPE for the cup and 316L Stainless Steel for the femoral head, which represent the surgeons choice for elderly patients. The annual wearing rate between these components was experimentally determined, as well as the amount of debris produced during contact. Firstly, the loading conditions were determined analytically considering those acting on the femoral head taking into consideration the wearing area during human walk. Secondly, the experimental analysis consisted in wearing tests using a tribology pin-on-disk machine, specifically built for this study. The tests to determine the volumetric loss of the components were performed under three different operational conditions: dry, lubricated with bovine serum and lubricated with destilated water. The experimental set up consisted on UHMWPE pins and 316L Stainless steel discs simulating the equivalent wear of ten years of usage of the prostheses. Lastly, the obtained results proved that

  10. Vitamin E-diffused highly cross-linked UHMWPE particles induce less osteolysis compared to highly cross-linked virgin UHMWPE particles in vivo.

    Science.gov (United States)

    Bichara, David A; Malchau, Erik; Sillesen, Nanna H; Cakmak, Selami; Nielsen, G Petur; Muratoglu, Orhun K

    2014-09-01

    Recent in vitro findings suggest that UHMWPE wear particles containing vitamin E (VE) may have reduced biologic activity and decreased osteolytic potential. We hypothesized that particles from VE-stabilized, radiation cross-linked UHMWPE would cause less osteolysis in a murine calvarial bone model when compared to virgin gamma irradiated cross-linked UHMWPE. Groups received equal amount of particulate debris overlaying the calvarium for 10 days. Calvarial bone was examined using high resolution micro-CT and histomorphometric analyses. There was a statistically significant difference between virgin (12.2%±8%) and VE-UHMWPE (3%±1.4%) groups in regards to bone resorption (P=0.005) and inflammatory fibrous tissue overlaying the calvaria (0.48 vs. 0.20, PUHMWPE particles have reduced osteolytic potential in vivo when compared to virgin UHMWPE.

  11. The effect of short polyethylene fiber with different weight percentages on diametral tensile strength of conventional and resin modified glass ionomer cements

    Science.gov (United States)

    Sharafeddin, Farahnaz; Ghaboos, Seyed-Ali

    2017-01-01

    Background The aim of this study was to investigate the effect of polyethylene fiber on diametral tensile strength of conventional and resin modified glass ionomer cements. Material and Methods 60 specimens in 6 groups (n=10) were prepared. In group 1 conventional glass ionomer (Fuji GC) and in group 2 resin modified glass ionomer (Fuji LC) were as control groups. In group 3 and 4 conventional glass ionomers mixed with short polyethylene fibers in proportion of 1 wt% and 3 wt%, respectively. In fifth and sixth groups, resin modified glass ionomer and short polyethylene fibers were mixed in 1 and 3% wt, respectively. Samples were prepared in a round brass mold (6.5×2.5 mm). After thermo-cycling, the diametral tensile strength of the specimens were tested and data were analyzed with ANOVA and post-hoc tests (p<0.05). Results Diametral tensile strength of both conventional and resin modified glass ionomer cements increased after mixing with polyethylene fiber (p<0.001). Also, reinforcement occurred as the mixing percentage increased from 1% wt to 3% wt in either conventional and resin modified glass ionomer (p<0.001). Conclusions The polyethylene fiber was shown to have a significant positive influence on diametral tensile strength of two types of glass ionomers. Key words:Conventional glass ionomer, diametral tensile strength, polyethylene fiber, resin modified glass ionomer. PMID:28298993

  12. Effect of plasma surface modification on the biocompatibility of UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Kaklamani, G; Chen, J; Dong, H; Stamboulis, A [School of Metallurgy and Materials, College of Engineering and Physical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Mehrban, N; Bowen, J; Grover, L, E-mail: a.stamboulis@bham.ac.u [School of Chemical Engineering, College of Engineering and Physical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2010-10-01

    In this paper active screen plasma nitriding (ASPN) is used to chemically modify the surface of UHMWPE. This is an unexplored and new area of research. ASPN allows the homogeneous treatment of any shape or surface at low temperature; therefore, it was thought that ASPN would be an effective technique to modify organic polymer surfaces. ASPN experiments were carried out at 120 {sup 0}C using a dc plasma nitriding unit with a 25% N{sub 2} and 75% H{sub 2} atmosphere at 2.5 mbar of pressure. UHMWPE samples treated for different time periods were characterized by nanoindentation, FTIR, XPS, interferometry and SEM. A 3T3 fibroblast cell line was used for in vitro cell culture experiments. Nanoindentation of UHMWPE showed that hardness and elastic modulus increased with ASPN treatment compared to the untreated material. FTIR spectra did not show significant differences between the untreated and treated samples; however, some changes were observed at 30 min of treatment in the range of 1500-1700 cm{sup -1} associated mainly with the presence of N-H groups. XPS studies showed that nitrogen was present on the surface and its amount increased with treatment time. Interferometry showed that no significant changes were observed on the surfaces after the treatment. Finally, cell culture experiments and SEM showed that fibroblasts attached and proliferated to a greater extent on the plasma-treated surfaces leading to the conclusion that ASPN surface treatment can potentially significantly improve the biocompatibility behaviour of polymeric materials.

  13. Effect of plasma surface modification on the biocompatibility of UHMWPE.

    Science.gov (United States)

    Kaklamani, G; Mehrban, N; Chen, J; Bowen, J; Dong, H; Grover, L; Stamboulis, A

    2010-10-01

    In this paper active screen plasma nitriding (ASPN) is used to chemically modify the surface of UHMWPE. This is an unexplored and new area of research. ASPN allows the homogeneous treatment of any shape or surface at low temperature; therefore, it was thought that ASPN would be an effective technique to modify organic polymer surfaces. ASPN experiments were carried out at 120 °C using a dc plasma nitriding unit with a 25% N(2) and 75% H(2) atmosphere at 2.5 mbar of pressure. UHMWPE samples treated for different time periods were characterized by nanoindentation, FTIR, XPS, interferometry and SEM. A 3T3 fibroblast cell line was used for in vitro cell culture experiments. Nanoindentation of UHMWPE showed that hardness and elastic modulus increased with ASPN treatment compared to the untreated material. FTIR spectra did not show significant differences between the untreated and treated samples; however, some changes were observed at 30 min of treatment in the range of 1500-1700 cm(-1) associated mainly with the presence of N-H groups. XPS studies showed that nitrogen was present on the surface and its amount increased with treatment time. Interferometry showed that no significant changes were observed on the surfaces after the treatment. Finally, cell culture experiments and SEM showed that fibroblasts attached and proliferated to a greater extent on the plasma-treated surfaces leading to the conclusion that ASPN surface treatment can potentially significantly improve the biocompatibility behaviour of polymeric materials.

  14. UHMWPE/PP共混改性体系研究(Ⅰ)%Reinforced Modified UHMWPE/PP Blend System Composition(Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    张炜; 麦永懿; 唐颂超; 吴向阳; 张玉梅; 洪尉

    2008-01-01

    制备了UHMWPE/PP合金材料,研究了UHMWPE/PP共混体系的流动性和力学性能及相容剂对共混体系的增容作用,研究表明:PP能有效地改善UHMWPE流动性,但与UHMWPE为不相客体系,相容荆D能够有效提高UHMWPE/PP体系的相容性,提高了材料的拉伸强度和冲击强度,达到一定的增强和增韧效果.

  15. UHMWPE/MMT纳米复合材料的研制%STUDY ON UHMWPE/MONTMORILLONITE NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    张玉梅; 周立斌; 洪尉; 张炜; 吴向阳; 单渊复

    2005-01-01

    采用复配阳离子交换剂对蒙脱土(MMT)进行有机化处理,通过固相接枝技术对超高分子量聚乙烯(UHMWPE)进行表面改性,然后采用熔融插层法制备UHMWPE/MMT纳米复合材料.XRD和SEM分析表明,MMT在UHMWPE基体中达到了纳米级分散,同时,有机MMT能较大幅度改善UHMWPE的流动性能,少量有机MMT的加入就可使UHMWPE的力学性能有所提高.

  16. Effects of the molecular weight and the valency of guest-modified poly(ethylene glycol)s on the stability, size and dynamics of supramolecular nanoparticles

    NARCIS (Netherlands)

    Stoffelen, C.; Staltari-Ferraro, E.; Huskens, Jurriaan

    2015-01-01

    The influence of the polymer length and the valency of guest-modified poly(ethylene glycol) (PEG) on the stability, size tunability and formation dynamics of supramolecular nanoparticles (SNPs) has been studied. SNPs were formed by molecular recognition between multi- and monovalent supramolecular

  17. Characterization of network parameters for UHMWPE by plane strain compression.

    Science.gov (United States)

    Abreu, E L; Ngo, H D; Bellare, A

    2014-04-01

    Ultra-high molecular weight polyethylene (PE) is used as a bearing material for total joint replacement prostheses since it is a tough, wear-resistant semicrystalline polymer. Despite its high resistance to wear, PE components have shown measureable wear in vivo, which can cause wear-particle induced osteolysis. Crosslinking of PE using ionizing radiation has been shown to increase wear resistance since both chemical crosslinks and physical entanglements provide high resistance to wear. Molecular characterization of crosslinked PEs is usually conducted using equilibrium swelling or by quantifying gel content. In this study, we compared crosslink densities and molecular weight between crosslinks derived from equilibrium swelling to those obtained by applying the Gaussian and Eight-Chain model to describe plane strain compression of the PE melt. The latter approach has the advantage of accounting for contributions of entanglements to the overall crosslink density, which solvent-based techniques largely neglect. As expected, the crosslink density calculated from model fitting increased monotonically with increase in radiation dose in a 0-200kGy dose range, with a corresponding monotonic decrease in molecular weight between crosslinks, but provided higher values of crosslink density and correspondingly lower values of molecular weight between crosslinks compared to the equilibrium swelling technique.

  18. Synthesis of Dichloride-Diphenylacetonitrile Palladium and Metal-Polymer Composite Based on Uhmwpe

    Directory of Open Access Journals (Sweden)

    A. M. Nemeryuk

    2016-05-01

    Full Text Available New complex of Pd (II with phenylacetonitrile, suitable for use as a precursor of palladium nano particles in the composition of metal-based composite UHMWPE was obtained. The thermodynamic characteristics of metal-polymer composite, found the effect of nano particles of palladium in the crystallization processes in UHMWPE and other characteristics of the material.

  19. Vitamin E-diffused highly cross-linked UHMWPE particles induce less osteolysis compared to highly cross-linked virgin UHMWPE particles in vivo

    DEFF Research Database (Denmark)

    Bichara, David A; Malchau, Erik; Sillesen, Nanna H

    2014-01-01

    when compared to virgin gamma irradiated cross-linked UHMWPE. Groups received equal amount of particulate debris overlaying the calvarium for 10 days. Calvarial bone was examined using high resolution micro-CT and histomorphometric analyses. There was a statistically significant difference between...... virgin (12.2%±8%) and VE-UHMWPE (3%±1.4%) groups in regards to bone resorption (P=0.005) and inflammatory fibrous tissue overlaying the calvaria (0.48 vs. 0.20, P

  20. Mechanical Properties of PP/UHMWPE Blends%UHMWPE改性PP共混物的力学性能

    Institute of Scientific and Technical Information of China (English)

    安峰; 李炳海; 庞波; 陈业军; 王隆

    2003-01-01

    研究了UHMWPE型号及UHMWPE的用量对PP材料力学性能的影响.结果表明:在PPH/PPR/PPB为60/20/20时分别加入UHMWPE 2401和UHMWPE 2402,可起到增强增韧的效果,在开炼机上制试样UHMWPE 2402的效果要好于UHMWPE 2401,注射制样为UHMWPE 2401好于UHMWPE 2402;随UHMWPE含量的增加,PPH/PPR/PPB共混物的缺口冲击强度大体呈直线上升趋势,在UHMWPE 2401为20份时,达到29.4 kJ/m2.

  1. Structural modifications induced by compressive plastic deformation in single-step and sequentially irradiated UHMWPE for hip joint components.

    Science.gov (United States)

    Puppulin, Leonardo; Sugano, Nobuhiko; Zhu, Wenliang; Pezzotti, Giuseppe

    2014-03-01

    Structural modifications were studied at the molecular scale in two highly crosslinked UHMWPE materials for hip-joint acetabular components, as induced upon application of (uniaxial) compressive strain to the as-manufactured microstructures. The two materials, quite different in their starting resins and belonging to different manufacturing generations, were a single-step irradiated and a sequentially irradiated polyethylene. The latter material represents the most recently launched gamma-ray-irradiated polyethylene material in the global hip implant market. Confocal/polarized Raman spectroscopy was systematically applied to characterize the initial microstructures and the microstructural response of the materials to plastic deformation. Crystallinity fractions and preferential orientation of molecular chains have been followed up during in vitro deformation tests on unused cups and correlated to plastic strain magnitude and to the recovery capacity of the material. Moreover, analyses of the in vivo deformation behavior of two short-term retrieved hip cups are also presented. Trends of preferential orientation of molecular chains as a function of residual strain were similar for both materials, but distinctly different in their extents. The sequentially irradiated material was more resistant to plastic deformation and, for the same magnitude of residual plastic strain, possessed a higher capacity of recovery as compared to the single-step irradiated one.

  2. Polyethylene Glycol 3350

    Science.gov (United States)

    Polyethylene glycol 3350 is used to treat occasional constipation. Polyethylene glycol 3350 is in a class of medications called ... Polyethylene glycol 3350 comes as a powder to be mixed with a liquid and taken by mouth. It ...

  3. Radiation-crosslinked polyethylene for wire and cable applications

    Science.gov (United States)

    Ueno, Keiji; Uda, Ikujiro; Tada, Shotaro

    Polyethylene is used as an insulation material for wires and cables because of its excellent electrical properties. Polyethylene is also a typical irradiated crosslinked polymer. The characteristics of irradiated polyethylene, the effects of density, molecular weight and so on, were studied.

  4. 21 CFR 178.3760 - Polyethylene glycol (400) monolaurate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyethylene glycol (400) monolaurate. 178.3760... SANITIZERS Certain Adjuvants and Production Aids § 178.3760 Polyethylene glycol (400) monolaurate. Polyethylene glycol (400) monolaurate containing not more than 0.1 percent by weight of ethylene...

  5. Effects of UHMWPE on Performance of UHMWPE/UHMWPP Blend Gel Fiber%UHMWPE对UHMWPE/UHMWPP共混冻胶纤维性能的影响

    Institute of Scientific and Technical Information of China (English)

    陈建军; 司小娟; 王依民

    2007-01-01

    研究了超高分子质量聚乙烯(UHMWPE)对超高分子质量聚丙烯(UHMWPP)/ UHMWPE共混冻胶纤维结晶性能、热学性能、形态结构以及力学性能的影响.结果表明:随着UHMWPE含量的增加,共混纤维结构具有更好的连贯性,并显示出较好的热学性能; 当UHMWPE含量超过一定比例时,虽然共混纤维的热学性能下降,但在共混纤维中呈现出明显的类似"钢筋混凝土"结构, 从而大大地提高了共混纤维的力学性能.

  6. Influence of crystallization conditions on the tensile properties of radiation crosslinked, vitamin E stabilized UHMWPE.

    Science.gov (United States)

    George, A; Ngo, H D; Bellare, A

    2014-12-01

    Radiation crosslinking for ultra-high molecular weight polyethylene results in improved wear resistance but a reduction in mechanical properties. Incorporation of vitamin E has been known to decrease the rate of oxidative degradation occurring through radiation crosslinking and prevents the need for post-irradiation melting with subsequent loss of crystallinity. In this study, we aimed to determine the effect of thermal treatments prior to crosslinking on the morphology and tensile properties of vitamin-E-containing polyethylene. Vitamin-E-blended polyethylene was melted and subsequently quenched in ice water in order to induce high rate crystallization. A second group was additionally annealed at 126°C following quenching and all samples were irradiated using electron beam radiation to a dose of 100kGy. The morphology of control, quenched and quench-annealed polyethylene was characterized using small angle x-ray scattering and differential scanning calorimetry. Tensile properties of these polyethylenes were measured before and after radiation crosslinking with equilibrium swelling experiments performed to assess the crosslink density of irradiated samples. This study shows how the tensile properties of polyethylene can be enhanced by varying thermal treatments prior to crosslinking; and thus how it may be possible to offset the reduction in tensile properties afforded by the crosslinking process.

  7. Research on Mechanical Behaviors of Micro-crystal Muscovite/UHMWPE Composites to Impact Loading

    Directory of Open Access Journals (Sweden)

    Hu Huarong

    2016-01-01

    Full Text Available UHMWPE composites were prepared by hot pressing process with micro-crystal muscovite as reinforced particulates. The mechanical behaviors of composites to impact loading was evaluated by split Hopkinson bar. The results demonstrated that dynamic yield stress and failure stress of UHMWPE composites were gradually increased when the filling amount was less than 20%; when the filling content of muscovite was around 15%, the energy absorption efficiency of the composite reaches maximum value. It was also found that when strain rate within 3200/s, the dynamic yield stress, failure stress and energy absorption efficiency of UHMWPE composites increased with the increase of strain rate and display strain rate enhancement effect.

  8. The influence of molecular weight of polyethylene glycol on separation and purification of pectinases from Penicillium cyclopium in aqueous two-phase system

    Directory of Open Access Journals (Sweden)

    Prodanović Jelena M.

    2008-01-01

    Full Text Available In this study the possibility of the partitioning and purification of pectinases from Penicillium cyclopium by their partitioning in polymer/polymer and polymer/salt aqueous two-phase systems was investigated. In the system with 10% (w/w polyethylene glycol 1500/5% (w/w dextran 500 000/85% (w/w crude enzyme, the highest values for partitioning parameters were achieved - the partition coefficient was 2.11, followed by the top phase yield of 85.68% and purification factor 1.28 for the endo-pectinase activity. The partition coefficient, yield in the top phase and purification factor for the exo-pectinase activity in the same system were 1.89, 84.28% and 3.82, respectively. In the system with 10% (w/w polyethylene glycol 6000/15% (w/w (NH42SO4/75% (w/w crude enzyme purification factor 37.85 for exo-pectinase, and 19.52 for endo-pectinase in the bottom phase were obtained.

  9. Effects of vitamin E-diffused highly cross-linked UHMWPE particles on inflammation, apoptosis and immune response against S. aureus.

    Science.gov (United States)

    Chen, Weishen; Bichara, David A; Suhardi, Jeremy; Sheng, Puyi; Muratoglu, Orhun K

    2017-10-01

    Particle-induced osteolysis and periprosthetic joint infection (PJI) are closely associated with periprosthetic tissue immune function. The objective of this study was to determine the effects of polyethylene particles on inflammation and response against S. aureus. Effects that vitamin E-diffused cross-linked UHMWPE (VE-PE) particles had on apoptosis, inflammation, and bactericidal activities compared to virgin cross-linked UHMWPE (control PE) particles were examined. Murine RAW 264.7 macrophages exposed to VE-PE particles in vitro were less apoptotic, secreted less tumor necrosis factor (TNF)-α, and responded more effectively against lipopolysaccharide or S. aureus compared to control PE particles. Implantation of VE-PE particles in murine calvaria in vivo caused less reactive oxygen species generation, less apoptosis, and less osteolysis compared to control PE particles. Implantation of PE particles in mice calvaria for 28 days, followed by inoculation with S. aureus in the same site where PE particles were implanted, demonstrated enhanced S. aureus clearance in the VE-PE group at day 33 after inoculation. These findings indicate that VE-PE particles might be less inflammatory and might preserve innate immunity of local tissue, allowing for enhanced clearance of bacteria. Copyright © 2017. Published by Elsevier Ltd.

  10. Laser-generated plasma by carbon nanoparticles embedded into polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, L., E-mail: lorenzo.torrisi@unime.it [Dipartimento di Scienze Fisiche MIFT, Università di Messina, V.le F.S. D’Alcontres 31, 98166 S. Agata, Messina (Italy); Ceccio, G. [Dipartimento di Scienze Fisiche MIFT, Università di Messina, V.le F.S. D’Alcontres 31, 98166 S. Agata, Messina (Italy); Cutroneo, M. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic)

    2016-05-15

    Highlights: • Advanced targets are prepared using UHMWPE containing CNT at different concentrations. • The composite has different optical, mechanical, electrical and compositional properties with respect to polyethylene. • Higher ion accelerations with respect to the pure polyethylene are obtained from laser generated plasmas at 10{sup 10} W/cm{sup 2} intensity. • High carbon ion yields with respect to the pure polyethylene are obtained from laser generated plasmas at 10{sup 10} W/cm{sup 2} intensity. • Advanced targets were prepared to be irradiated in TNSA regime using laser at 10{sup 18} W/cm{sup 2} intensity. - Abstract: Carbon nanoparticles have been embedded into polyethylene at different concentrations by using chemical–physical processes. The synthesized material was characterized in terms of physical modifications concerning the mechanical, compositional and optical properties. Obtained flat targets have been irradiated by Nd:YAG laser at intensities of the order of 10{sup 10} W/cm{sup 2} in order to generate non-equilibrium plasma in vacuum. The laser–matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon ion beams from laser-generated plasma are presented and discussed.

  11. Extremely high fracture rate of a modular acetabular component with a sandwich polyethylene ceramic insertion for THA: a preliminary report.

    Science.gov (United States)

    Kircher, Jörn; Bader, Rainer; Schroeder, Bettina; Mittelmeier, Wolfram

    2009-09-01

    Improvements of ceramic components and design changes have reduced failure rates over the past 30 years in total hip arthroplasty. We present a series of n = 11 cases with ceramic failure out of n = 113 implantations, from which n = 66 were ceramic-on-ceramic (n = 50 with ceramic insert with sandwich in polyethylene and n = 16 with directly fixed ceramic inlay) and n = 47 ceramic on polyethylene bearings, between 1999 and 2001 after introduction of a new implantation system to the market. The overall fracture rate of ceramic for the whole series (n = 113) was 9.7%. For the combination ceramic head with UHMW-PE (n = 47) the fracture rate was 2.1%. For the combination ceramic with ceramic (n = 66) the fracture rate was 15.2%. For the combination ceramic with ceramic sandwich in PE (n = 50) the failure rate was 18%. Only three patients experienced a trauma. Demography of patients (age, gender, body weight and BMI) was not statistically different between patients with failed ceramics and the rest of the patients making patient-specific risk factors unlikely to be an explanation for the failures. Retrospective X-ray analysis of the cup positioning did not show significant difference between failed and non-failed implants in terms of mean cup inclination and version making also operation-specific factors unlikely to be the only reason of this high failure rate. Therefore, manufacturer-specific factors such as design features may have contributed to this high failure rate. Further analysis of the whole series with biomechanical testing of the retrieved material needs to be performed.

  12. A Coarse-Grained Model for Polyethylene Oxide and Polyethylene Glycol : Conformation and Hydrodynamics

    NARCIS (Netherlands)

    Lee, Hwankyu; de Vries, Alex H.; Marrink, Siewert-Jan; Pastor, Richard W.

    2009-01-01

    A coarse-grained (CG) model for polyethylene oxide (PEO) and polyethylene glycol (PEG) developed within the framework of the MARTINI CG force field (FF) using the distributions of bonds, angles, and dihedrals from the CHARMM all-atom FF is presented. Densities of neat low molecular weight PEO agree

  13. A Coarse-Grained Model for Polyethylene Oxide and Polyethylene Glycol : Conformation and Hydrodynamics

    NARCIS (Netherlands)

    Lee, Hwankyu; de Vries, Alex H.; Marrink, Siewert-Jan; Pastor, Richard W.

    2009-01-01

    A coarse-grained (CG) model for polyethylene oxide (PEO) and polyethylene glycol (PEG) developed within the framework of the MARTINI CG force field (FF) using the distributions of bonds, angles, and dihedrals from the CHARMM all-atom FF is presented. Densities of neat low molecular weight PEO agree

  14. Statistical Tensile Strength for High Strain Rate of Aramid and UHMWPE Fibers

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; XIONG Tao; XIONG Jie

    2006-01-01

    Dynamic tensile impact properties of aramid (Technora(R)) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.

  15. Effect of Boundary Conditions on the Back Face Deformations of Flat UHMWPE Panels

    Science.gov (United States)

    2014-12-01

    Zhang [2] carried out a numerical study of the effects of clamping type and clamping pressure on the ballistic performance of woven Kevlar , and found...effects of composite size were also studied. Singletary [5] studied the effects of boundary conditions and panel sizes on V50 for Kevlar KM2 fabric. The...on the BFD in flat UHMWPE panels. UHMWPE possesses high tenacity and high strength compared to Kevlar , as a result of which it is the material of

  16. The effect of geometry and abduction angle on the stresses in cemented UHMWPE acetabular cups – finite element simulations and experimental tests

    Directory of Open Access Journals (Sweden)

    Santavirta Seppo S

    2005-05-01

    Full Text Available Abstract Background Contact pressure of UHMWPE acetabular cup has been shown to correlate with wear in total hip replacement (THR. The aim of the present study was to test the hypotheses that the cup geometry, abduction angle, thickness and clearance can modify the stresses in cemented polyethylene cups. Methods Acetabular cups with different geometries (Link®: IP and Lubinus eccentric were tested cyclically in a simulator at 45° and 60° abduction angles. Finite element (FE meshes were generated and two additional designs were reconstructed to test the effects of the cup clearance and thickness. Contact pressures at cup-head and cup-cement interfaces were calculated as a function of loading force at 45°, 60° and 80° abduction angles. Results At the cup-head interface, IP experienced lower contact pressures than the Lubinus eccentric at low loading forces. However, at higher loading forces, much higher contact pressures were produced on the surface of IP cup. An increase in the abduction angle increased contact pressure in the IP model, but this did not occur to any major extent with the Lubinus eccentric model. At the cup-cement interface, IP experienced lower contact pressures. Increased clearance between cup and head increased contact pressure both at cup-head and cup-cement interfaces, whereas a decreased thickness of polyethylene layer increased contact pressure only at the cup-cement interface. FE results were consistent with experimental tests and acetabular cup deformations. Conclusion FE analyses showed that geometrical design, thickness and abduction angle of the acetabular cup, as well as the clearance between the cup and head do change significantly the mechanical stresses experienced by a cemented UHMWPE acetabular cup. These factors should be taken into account in future development of THR prostheses. FE technique is a useful tool with which to address these issues.

  17. Synthesis by high-efficiency liquid-phase (HELP) method of oligonucleotides conjugated with high-molecular weight polyethylene glycols (PEGs)

    National Research Council Canada - National Science Library

    Bonora, G M; Zaramella, S; Veronese, F M

    1998-01-01

    .... The large scale production of these molecules as demanded for commercial purposes is hampered by the heterogeneity of the solid-phase processes and by the low reactivity of high-molecular weight PEGs in solution...

  18. Friction Coefficient of UHMWPE During Dry Reciprocating Sliding

    Directory of Open Access Journals (Sweden)

    F. Zivic

    2014-09-01

    Full Text Available This paper deals with the friction coefficient behaviour during dry reciprocating sliding of UHMWPE in contact with alumina (Al2O3, within a range of velocities typical for hip implants. Five values of normal force (100 - 1000 mN and three values of sliding speed (4 - 12 mm/s have been observed. Real time diagrams of the friction coefficient as a function of the sliding cycles were recorded for each test. Dynamic friction coefficient curves exhibited rather uniform behavior for all test conditions. Somewhat larger values of friction coefficient could be observed during the running-in period in case of low loads (100 - 250 mN and the lowest velocity (4 mm/s. In case of high loads and speeds, friction coefficient reached steady state values shortly after the beginning of the test.

  19. Radiation processing of polyethylene

    Science.gov (United States)

    Barlow, A.; Biggs, J. W.; Meeks, L. A.

    This paper covers two areas (a) the use of high energy radiation for the synthesis and improvement of polymer properties and (b) the formulation of radiation curable compounds for automotive/appliance wire applications and high voltage insulation. The first part discusses the use of gamma radiation for the bulk polymerization of ethylene and the properties of the polymer produced. The use of low dose radiation to increase polymer molecular weight and modify polydispersity is also described together with its projected operational cost. An update is provided of the cost savings that can be realized when using radiation crosslinked heavy duty film, which expands its applications, compared with noncrosslinked materials. The second section of the paper considers the advantages and disadvantages of radiation vs. peroxide curing of wire and cable compounds. The formulation of a radiation curable, automotive/appliance wire compound is discussed together with the interactions between the various ingredients; i.e., base resin, antioxidants, flame retardant filler, coupling agents, processing aids and radiation to achieve the desired product. In addition, the general property requirements of a radiation curable polyethylene for high voltage insulation are discussed; these include crosslinking efficiency, thermal stability, wet tree resistance and satisfactory dielectric properties. Preliminary data generated in the development of a 230KV radiation crosslinked polyethylene insulation are included.

  20. Crosslink density, oxidation and chain scission in retrieved, highly cross-linked UHMWPE tibial bearings.

    Science.gov (United States)

    Reinitz, Steven D; Currier, Barbara H; Levine, Rayna A; Van Citters, Douglas W

    2014-05-01

    Irradiated, thermally stabilized, highly cross-linked UHMWPE bearings have demonstrated superior wear performance and improved in vitro oxidation resistance compared with terminally gamma-sterilized bearings, yet retrieval analysis reveals unanticipated in vivo oxidation in these materials despite fewer or no measurable free radicals. There has been little evidence to date that the oxidation mechanism in thermally stabilized materials is the same as that in conventional materials, and so it is unknown whether oxidation in these materials is leading to chain scission and a degradation of mechanical properties, molecular weight, and crosslink density. The aim of this study was to determine whether measured in vivo oxidation in retrieved, highly cross-linked tibial bearings corresponds with a decreasing crosslink density. Analysis of three tibial bearing materials revealed that crosslink density decreased following in vivo duration, and that the change in crosslink density was strongly correlated with oxidation. The results suggest that oxidation in highly cross-linked materials is causing chain scissions that may, in time, impact the material properties. If in vivo oxidation continues over longer durations, there is potential for a clinically significant degradation of mechanical properties.

  1. Perubahan Faktor Keausan Die Drawn UHMWPE Akibat Tegangan Kontak untuk Aplikasi Sendi Lutut Tiruan

    Directory of Open Access Journals (Sweden)

    Jefri S. Bale

    2009-01-01

    Full Text Available The aim of this research is to study the effects of contact stress on the wear of die drawn UHMWPE GUR 1120 against nitrogen ion implanted cobalt chrome alloy used pin on plate unidirectional reciprocating movement wear test. A constant load was applied to each UHMWPE pin to produce a contact stress, whereas the contact stress was varied of 5 MPa, 9 MPa and 12 MPa with constant sliding velocity of 116.5 mm/s. The result shows the wear factor decreasing with increasing contact stress. The lowest contact stress (5 MPa gives the highest wear factor that is: 2.67x10-7 mm3/Nm. The different wear factor is caused by increasing contact stress changed wear mechanism of surface contact. The lowest contact stress dominated by abrasive wear mechanism while along increasing contact stress changing the dominate wear mechanism into burnishing wear mechanism and also surface deformation wear mechanism. Abstract in Bahasa Indonesia: Penelitian ini bertujuan untuk mengetahui pengaruh tegangan kontak terhadap faktor keausan die drawn GUR 1120 UHMWPE berpasangan dengan cobalt chrome alloy yang diimplantasi ion berbasis nitrogen menggunakan pin on plate unidirectional reciprocating movement wear test. Pin die drawn UHMWPE dibebani sehingga menghasilkan tegangan kontak berkisar 5 MPa, 9 MPa dan 12 MPa dengan kecepatan gesekan konstan 116,5 mm/dtk. Dari hasil penelitian yang telah dilakukan, disimpulkan bahwa faktor keausan UHMWPE akan menurun seiring dengan meningkatnya tegangan kontak. Tegangan kontak terkecil (5 MPa menghasilkan faktor keausan rata-rata UHMWPE yang terbesar yaitu 2,67x10-7 mm3/Nm. Perbedaan nilai faktor keausan ini disebabkan karena peningkatan tegangan kontak merubah mekanisme keausan pada permukaan kontak. Tegangan kontak terkecil di dominasi mekanisme abrasive wear sedangkan seiring peningkatan tegangan kontak mekanisme keausan didominasi oleh burnishing wear mechanism serta adanya mekanisme surface deformation wear. Kata kunci: Faktor keausan

  2. UHMWPE/PP-X/PP共混物滑动摩擦性能研究%STUDY ON SLIDING WEAR PROPERTIES OF UHMWPE/PP-X/PP BLENDS

    Institute of Scientific and Technical Information of China (English)

    周勇; 蔡松; 梁兵

    2008-01-01

    采用自制的交联聚丙烯(PP-X)与超高分子量聚乙烯(UHMWPE)、聚丙烯(PP)共混,对共混物的力学性能和滑动摩擦性能进行了研究.结果表明,在力学性能改变不大的情况下,当UHMWPE/PP-X/PP的质量比为80/20/10时,共混物的磨痕宽度为5.69 mm,摩擦系数为0.125,比纯UHMWPE的磨痕宽度、摩擦系数分别下降了21.73%和39.90%,比UHMWPE)/PP(100/10)共混物分别下降了2.0%和18.83%.扫描电子显微镜照片显示,在UHMWPE的磨损表面存在严重的刮痕、裂纹及磨屑,而在UHMWPE/PP-X/PP共混物的磨损表面却很少发现上述现象.

  3. Computation and Analysis of Ultra High Molecular Weight Polyethylene Gear Based on Viscoelasticity%基于黏弹性的超高分子量聚乙烯齿轮计算分析

    Institute of Scientific and Technical Information of China (English)

    郑晓雯; 陆松; 孟惠荣

    2007-01-01

    为给超高分子量聚乙烯(UHMWPE)齿轮的承载能力计算及校核提供理论依据和参考,本文以UHMWPE的非线性黏弹性为基础,采用了黏弹性力学模型和超弹性力学模型(Arruda-Boyce模型)相结合的方法,建立了UHMWPE齿轮的力学模型和几何模型,应用ABAQUS 非线性有限元分析软件,对与钢齿轮啮合运转时的UHMWPE齿轮进行了动态模拟,并对它的应力和应变大小、分布及承载能力进行了计算和分析研究.结果表明,齿根部位的Von Mises应力和弯曲应力最大,轮齿节点处的接触压应力最大.建立在非线性黏弹性基础上的UHMWPE齿轮动态模拟和计算分析结果更符合实际.

  4. Blends of POSS-PEO(n=4)(8) and high molecular weight poly(ethylene oxide) as solid polymer electrolytes for lithium batteries.

    Science.gov (United States)

    Zhang, Hanjun; Kulkarni, Sunil; Wunder, Stephanie L

    2007-04-12

    Solid polymer electrolyte blends were prepared with POSS-PEO(n=4)8 (3K), poly(ethylene oxide) (PEO(600K)), and LiClO4 at different salt concentrations (O/Li = 8/1, 12/1, and 16/1). POSS-PEO(n=4)8/LiClO4 is amorphous at all O/Li investigated, whereas PEO(600K) is amorphous only for O/Li = 8/1 and semicrystalline for O/Li = 12/1 and 16/1. The tendency of PEO(600K) to crystallize limited the amount of POSS-PEO(n=4)(8) that could be incorporated into the blends, so that the greatest incorporation of POSS-PEO(n=4)(8) occurred for O/Li = 8/1. Blends of POSS-PEO(n=4)(8)/PEO(600K)/LiClO4 (O/Li = 8/1 and 12/1) microphase separated into two amorphous phases, a low T(g) phase of composition 85% POSS-PEO(n=4)(8)/15% PEO(600K) and a high T(g) phase of composition 29% POSS-PEO(n=4)(8)/71% PEO(600K). For O/Li = 16/1, the blends contained crystalline (pure PEO(600K)), and two amorphous phases, one rich in POSS-PEO(n=4)(8) and one rich in PEO(600K). Microphase, rather than macrophase separation was believed to occur as a result of Li(+)/ether oxygen cross-link sites. The conductivity of the blends depended on their composition. As expected, crystallinity decreased the conductivity of the blends. For the amorphous blends, when the low T(g) (80/20) phase was the continuous phase, the conductivity was intermediate between that of pure PEO(600K) and POSS-PEO(n=4)(8). When the high T(g) (70/30, 50/50, 30/70, and 20/80) phase was the continuous phase, the conductivity of the blend and PEO(600K) were identical, and lower than that for the POSS-PEO(n=4)(8) over the whole temperature range (10-90 degrees C). This suggests that the motions of the POSS-PEO(n=4)(8) were slowed down by the dynamics of the long chain PEO(600K) and that the minor, low Tg phase was not interconnected and thus did not contribute to enhanced conductivity. At temperatures above T(m) of PEO(600K), addition of the POSS-PEO(n=4)(8) did not result in conductivity improvement. The highest RT conductivity, 8 x 10(-6) S

  5. Effect of UHMWPE particle size, dose, and endotoxin on in vitro macrophage response.

    Science.gov (United States)

    Alley, Carie; Haggard, Warren; Smith, Richard

    2014-01-01

    Ultra-high molecular weight polyethylene wear debris generated by a prosthetic hip or knee has been linked to osteolysis and the limited lifespan of the implant. However, research results are conflicting with regard to which characteristics of the polyethylene wear debris are most inflammatory. The goal of this study was to determine whether particle size, number, and the presence of endotoxin significantly contribute to increased secretion of pro-inflammatory mediators by macrophages in vitro in response to polyethylene wear debris generated by a hip simulator. The results show that the prevailing inflammatory factor is endotoxin. The macrophages released only minimal levels of TNF-α and IL-6 in response to cleaned polyethylene particles, but these cytokines were released in significantly higher amounts in response to particles spiked with lipopolysaccharide (LPS). The number (up to 500 particles per cell) and size of the particles tested in this study had no significant influence on any of the measured outputs (macrophage viability, TNF-α, IL-6, or PGE₂) unless associated with LPS.

  6. Physical properties and biocompatibility of UHMWPE-derived materials modified by synchrotron radiation.

    Science.gov (United States)

    Bykova, Iu; Weinhardt, V; Kashkarova, A; Lebedev, S; Baumbach, T; Pichugin, V; Zaitsev, K; Khlusov, I

    2014-08-01

    The applications of synchrotron radiation (SR) in medical imaging have become of great use, particularly in angiography, bronchography, mammography, computed tomography, and X-ray microscopy. Thanks to recently developed phase contrast imaging techniques non-destructive preclinical testing of low absorbing materials such as polymers has become possible. The focus of the present work is characterization and examination of UHMWPE-derived materials widely used in medicine, before and after their exposure to SR during such testing. Physical properties, such as wettability, surface energy, IR-spectroscopy, roughness, optical microscopy, microhardness measurements of UHMWPE samples were studied before and after SR. The relationship between a growth of UHMWPE surface hydrophilicity after SR and surface colonization by stromal cells was studied in vitro. Obtained results demonstrate that SR may be used as prospective direction to examine bulk (porous) structure of polymer materials and/or to modify polymer surface and volume for tissue engineering.

  7. Biomechanical characteristics of polymeric UHMWPE composites with hybrid matrix and dispersed fillers

    Science.gov (United States)

    Panin, Sergey; Kornienko, Lyudmila; Shilko, Sergey; Thuc, Nguyen Xuan; Korchagin, Mikhail; Chaikina, Marina

    2015-11-01

    In order to develop artificial joint implants some biomechanical properties of composites with UHMWPE and hybrid (polymer-polymeric) "UHMWPE+PTFE" matrix with dispersed fillers were studied. A comparative analysis of the effectiveness of adding hydroxyapatite micron- and nanopowders as a biocompatible filler was carried out. It was shown that under dry sliding friction the wear rate of nanocomposites with the hybrid matrix is lower as compared with composites with the non-hybrid one. Mechanical activation of components further enhances the durability of nano- and microcomposites to almost double it without any significant reduction in the strength characteristics.

  8. UHMWPE/PA6尼龙合金材料的研究

    Institute of Scientific and Technical Information of China (English)

    江水青; 李海玲

    2007-01-01

    本文针对国内外有关尼龙合金的发展及研究讨论了马来酸酐(MAH)熔融接枝超高分子量聚乙烯(UHMWPE)过程中研究接枝物对PA6/UHMWPE合金的增容作用PA6/UHMWPE的配比为90:8、增容剂UHMWPE-g-MAH用量为15份时,PA6/UHMWPE合金的冲击韧性及综合性能有所改善.

  9. Correlation between in vivo stresses and oxidation of UHMWPE in total hip arthroplasty.

    Science.gov (United States)

    Regis, M; Bracco, P; Giorgini, L; Fusi, S; Dalla Pria, P; Costa, L; Schmid, C

    2014-09-01

    The possibility of in vivo, stress-induced oxidation in orthopaedic UHMWPE has been investigated. EtO sterilised, uncrosslinked UHMWPE liners, explanted or shelf-aged, have been collected. Linear wear and wear rate were assessed and FTIR spectroscopy was employed to detect oxidation and to build up oxidation products spatial maps across the liners section. Oxidation profiles have been compared to stress distribution profiles, resulting from a FE analysis conducted on the same liners geometries and couplings. It was found that oxidised and stressed areas followed the same asymmetrical, localized distribution profile. It was therefore possible to establish a correlation between stressed areas and observed oxidation.

  10. Polyurethane modified with an antithrombin-heparin complex via polyethylene oxide linker/spacers: influence of PEO molecular weight and PEO-ATH bond on catalytic and direct anticoagulant functions.

    Science.gov (United States)

    Sask, Kyla N; Berry, Leslie R; Chan, Anthony K C; Brash, John L

    2012-10-01

    A segmented polyurethane (PU) was modified with polyethylene oxides (PEO) of varying molecular weight and end group. The PEO served as linker/spacers to immobilize an antithrombin-heparin (ATH) anticoagulant complex on the PU. Isocyanate groups were introduced into the PU to enable attachment of either "conventional" homo-bifunctional dihydroxy-PEO (PEO-OH surface) or a hetero-bifunctional amino-carboxy-PEO (PEO-COOH surface). The PEO surfaces were functionalized with N-hydroxysuccinimide (NHS) groups using appropriate chemistries, and ATH was attached to the distal NHS end of the PEO (PEO-OH-ATH and PEO-COOH-ATH surfaces). Water contact angle and fibrinogen adsorption measurements showed increased hydrophilicity and reduced fibrinogen adsorption from buffer on all PEO surfaces compared to unmodified PU. ATH uptake on NHS-functionalized PEO was quantified by radiolabeling. Despite the different PEO molecular weights and end groups, and NHS-functionalization chemistries, the surface densities of ATH were similar. The adsorption of fibrinogen and antithrombin (AT) from plasma was measured in a single experiment using dual radiolabeling. On PEO-ATH surfaces fibrinogen adsorption was minimal while AT adsorption was high showing the selectivity of the heparin moiety of ATH for AT. The PEO-COOH-ATH surfaces showed slightly greater AT adsorption than the PEO-OH-ATH surfaces. Thrombin adsorption on all of the PEO-ATH surfaces was greater than on the corresponding PEO surfaces without ATH, and was highest on the PEO-OH-ATH, suggesting potential anticoagulant properties for this surface via direct thrombin inhibition by the AT portion of ATH.

  11. Radiation resistivity of polyacenaphthylene-grafted polyethylene

    Science.gov (United States)

    Hayakawa, Kiyoshi; Kawase, Kaoru; Yamakita, Hiromi

    Thin poly (ethylene-g-acenaphthylene) films prepared by the vapor-phase grafting method were subjected to the γ-irradiation in air, and various changes in tensile and structural properties of the film were investigated by comparing with those of the untreated or crosslinked polyethylene film. Polyethylene got to lose its inherent necking property by oxidative degradation and to be brittle-fractured by the irradiation dose less than 100 Mrad in air. The polyacenaphthylene-grafted polyethylenes (extent of grafting, ˜ 54 by {100( P-P°) }/{P°}), however, kept their ductility up to 200 Mrad or more, and the rate of increase in elastic modulus as well as yield strength with the increasing irradiation dose was considerably lower than that of untreated or crosslinked polyethylene. The effect of the grafting extent, and that of the irradiation dose-rate on the fracture energy were also examined. The weight increase of polyethylene due to the oxygen consumption and the resulting formation of carbonyl group which proceeded proportionally with the irradiation dose were remarkably suppressed by the grafting, whereas the double bond formation seemed to be unaffected by it. The grafted film held the original content of gel fraction unchanged during the irradiation in air, but the average molecular weight of the sol fraction decreased gradually. Meanwhile, the gel fraction of the crosslinked polyethylene was degenerated by a small dose of irradiation. The analysis of gaseous products revealed the formation of water, methanol, acetaldehyde and so forth from the irradiated grafted film. The grafting procedure and the subsequent irradiation of the grafted film did not affect the degree of crystallinity of the backbone polyethylene. The role played by the grafted polyacenaphthylene for endowing the radiation resistivity to polyethylene and its inherent limitation in effect were discussed from the structural point of view of the grafted film.

  12. 超高相对分子质量聚乙烯用钛系催化剂的研究进展%Research advance of titanium catalyst on UHMWPE

    Institute of Scientific and Technical Information of China (English)

    吴小林; 张晓霞

    2016-01-01

    综述了国内外超高相对分子质量聚乙烯(UHMWPE)用钛系催化剂的优势、合成方法的研究现状及进展。UHMWPE所用催化剂正朝着超高活性、形态可控、聚合物相对分子质量及其分布精确可调的方向发展。通过改进催化剂合成技术,可制备更符合加工要求的聚合物,并有力地推进了UHMWPE新应用领域的开发。新一代性能优良的UHMWPE用催化剂应充分考虑:提高催化活性,为实现聚合物性质的精确控制提供基础;均匀的活性中心分布;优良的共聚合性能;优异的相对分子质量调变性能。%The paper summarizes the superiority and synthetic method of titanium-containing catalyst on ultrahigh relative molecular mass polyethylene(UHMWPE). Development of catalyst for UHMWPE is in the direction toward ultrahigh activity,morphology to be controlled,polymer relative molecular mass and its distribution adjusted with high precision. The polymer meeting process requirements could be produced through modification of catalyst synthetic technology,which accelerates its development in new field. The development of new catalyst with excellent performances for UHMWPE should be considered that:1)improving catalytic activity to provide the basis of polymer properties controll;2)homogeneous activity center distribution;3)excellent copolymerization performances;4)outstanding modulation properties for relative molecular mass.

  13. Effect of counterface surface roughness on the friction and wear properties of ultra-high molecular weight polyethylene%对偶件表面粗糙度对UHMWPE摩擦磨损性能的影响

    Institute of Scientific and Technical Information of China (English)

    李嫱; 冷永祥; 谢东; 黄楠

    2010-01-01

    人工关节在服役过程中的磨损主要发生在超高分子量聚乙烯(UHMWPE)关节臼的表面.UHMWPE的磨擦磨损性能受多因素影响,其中与UHMWPE对磨的硬质材料(对偶件)表面粗糙度是关键因素之一.综述了近年来在对偶件表面粗糙度对UHMWPE摩擦磨损性能影响方面的研究工作,结合UHMWPE的磨损机制,重点阐述对偶件表面粗糙度对UHMWPE磨损率、UHMWPE磨屑尺寸和人工关节润滑机制的影响.

  14. Polyethylene magnetic nanoparticle: a new magnetic material for biomedical applications

    Science.gov (United States)

    Chatterjee, Jhunu; Haik, Yousef; Chen, Ching-Jen

    2002-05-01

    Polyethylene magnetic nanoparticles were synthesized by nonsolvent and temperature induced crystallization along with ultrasonication. Low molecular weight polyethylene wax and maghemite were used for forming the composite particles. These particles were further coated with avidin. The nanoparticles are characterized using STEM, AFM and SQUID. Nanomagnetic particles were found to have two distinct morphologies and have superparamagnetic properties.

  15. Determination of Crystallinity and Crystal Structure of Hylamer™ Polyethylene after in vivo Wear

    OpenAIRE

    Visentin, M; Stea, S.; De Clerico, M.; Reggiani, M.; Fagnano, C.; Squarzoni, S.; De Toni, A

    2006-01-01

    Abstract Hylamer? polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer? components used in joint prostheses, if sterilized ...

  16. Determination of Crystallinity and Crystal Structure of Hylamer™ Polyethylene after in vivo Wear

    OpenAIRE

    Visentin, M; Stea, S.; Clerico, M; Reggiani, M.; Fagnano, C.; Squarzoni, S.; Toni, A.

    2006-01-01

    Abstract Hylamer? polyethylene is a crystalline form of polyethylene of 70% crystallinity whereas conventional polyethylene (PE) has 50% crystallinity. Crystallinity is the percentage by weight of the crystalline phase present in the whole polymer, which comprises both amorphous and crystalline phases. Clinical experience has shown that Hylamer? components used in joint prostheses, if sterilized ...

  17. Polyethylene glycol-grafted polystyrene particles

    NARCIS (Netherlands)

    Meng, Fenghua; Engbers, Gerard H.M.; Feijen, Jan

    2004-01-01

    Densely pegylated particles that can serve as a model system for artificial cells were prepared by covalently grafting amino polyethylene glycol (PEG, molecular weight 3400 or 5000) onto carboxyl polystyrene particles (PS-COOH) using carbodiimide chemistry. PEG-modified particles (PS-PEG) were chara

  18. Graft Modification of UHMWPE and Tribological Properties of the Graft UHMWPE Composites with Nano-PTFE%UHMWPE的接枝改性及其与Nano-PTFE复合材料的摩擦学性能

    Institute of Scientific and Technical Information of China (English)

    李东亮; 魏刚; 黄亚; 邓小亮; 曾文浩

    2015-01-01

    通过紫外光引发聚合将全氟烷基乙基甲基丙烯酸酯共聚物(PFAMAE)单体接枝到超高摩尔质量聚乙烯(UHMWPE)上,制备出超高摩尔质量聚乙烯接枝全氟烷基乙基甲基丙烯酸酯共聚物(UHMWPE-g-PFAMAE).再采用热压成型法制备出UHMWPE-g-PFAMAE/纳米聚四氟乙烯(nano-PTFE)复合材料.采用红外光谱(FTIR)对接枝前后的UHMWPE进行表征,并借助磨损试验机和扫描电子显微镜(SEM)考察了UHMWPE、UHMWPE-g-PFAMAE和UHMWPE-g-PFAMAE/nano-PTFE复合材料的摩擦学性能和机理.结果表明,PFAMAE单体已成功接枝到UHMWPE上;与纯UHMWPE相比,UHMWPE-g-PFAMAE的摩擦因数和磨损率均明显减小;在UHMWPE-g-PFAMAE中加入nano-PTFE后,复合材料的摩擦因数和磨损率进一步降低,当nano-PTFE质量分数为1%时,复合材料的性能最佳.接枝改性有效抑制了纯UHMWPE的磨粒磨损和塑性变形,加入适量的nano-PTFE,UHMWPE-g-PFAMAE/nano-PTFE复合材料仅表现为轻微的疲劳磨损.

  19. Swing Friction Behavior of the Contact Interface Between CoCrMo and UHMWPE Under Dynamic Loading

    Science.gov (United States)

    Chen, Kai; Zhang, Dekun; Yang, Xuehui; Zhang, Xin; Wang, Qingliang; Qi, Jianwei

    2016-12-01

    CoCrMo alloy and UHMWPE have been widely used in knee joint prosthesis implantation materials. In this paper, swing friction behavior of the contact interface between CoCrMo alloy and UHMWPE is studied under dynamic loading. Swing friction characteristic and damage mechanism are discussed. The results show that swing friction coefficients increase with the rising of maximum normal load and swing angular amplitude. Unloading-standing could play alleviative roles in friction and wear to a large degree. As the cycle number gradually increases, the surface roughness of UHMWPE decreases, while the roughness of CoCrMo increases. During the swing friction, the main damage mechanism of CoCrMo is abrasive wear and the main damage mechanisms of UHMWPE are abrasive wear, fatigue wear and plastic deformation. Besides, it is easier to generate surface damages with small angle and heavy load.

  20. Evaluation of carbon nanotubes and graphene as reinforcements for UHMWPE-based composites in arthroplastic applications: A review.

    Science.gov (United States)

    Puértolas, J A; Kurtz, S M

    2014-11-01

    In this review we have evaluated the state of the art of CNT/UHMWPE and graphene/UHMWPE composites from four different points of view: mechanical properties, chemical stability, wear resistance and biocompatibility. The performance of these new carbonaceous composites allows us to conclude that these materials have overcome a first step on the way to developing into an alternative to the current HXLPEs used in orthopedic applications.

  1. [Biodegradation of polyethylene].

    Science.gov (United States)

    Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

    2007-05-01

    Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.

  2. Biotribological behavior of ultra high molecular weight polyethylene composites containing coralline hydroxyapatite in a hip joint simulator%CHA/UHMWPE复合关节材料的生物摩擦学研究

    Institute of Scientific and Technical Information of China (English)

    王庆良; 张德坤; 葛世荣

    2008-01-01

    采用热压成型工艺制备了超高分子量聚乙烯(UHMWPE)/珊瑚羟基磷灰石(CHA)复合关节材料,利用人工髋关节模拟磨损试验系统,研究了该类复合材料与CoCrMo合金组合关节在小牛关节液润滑条件下的摩擦磨损性能.实验结果表明,添加CHA能有效提高UHMWPE关节材料的表面硬度,降低其磨损率.当CHA添加量为20 wt%时,可获得表面硬度与抗磨损性能的良好匹配.小牛关节液润滑条件下,UHMWPE及其复合材料的磨损机理主要表现为研磨磨损和疲劳磨损,磨损颗粒尺寸随CHA粉体添加量的增加而增大.

  3. 血浆润滑下超高分子量聚乙烯磨损行为研究%Study on the Wear Behavior of Ultrahigh Molecular Weight Polyethylene Using Plasma as Lubricant

    Institute of Scientific and Technical Information of China (English)

    黄传辉

    2005-01-01

    在全髋关节模拟试验机上,以血浆作润滑剂考察了超高分子量聚乙烯(UHMWPE)-Al2O3关节副的生物摩擦学特性,采用扫描电子显微镜(SEM)观察UHMWPE的磨损表面形貌,探讨了磨损机理,利用WDX-2A波谱分析仪测定对摩表面的N元素.结果表明:UHMWPE的磨损率为40.55×10-6mg/cycle左右;其主要磨损机制为磨粒磨损、粘着磨损及塑性变形导致的表层剥落;UHMWPE及Al2Oa陶瓷对摩表面上均发现有血浆蛋白沉积现象发生.

  4. Healing of interfaces of high and ultra-high-molecular- weight polystyrene below the bulk glass transition temperature

    DEFF Research Database (Denmark)

    Boiko, Yuri M.; Lyngaae-Jørgensen, Jørgen

    2004-01-01

    Amorphous bulk samples of high-molecular-weight (HMW) polystyrene (PS) with a weight-average molecular weight M-w of 102.5 kg/mol and a number-average molecular weight M. of 97 kg/mol and of ultra-high-molecular-weight PS (UHMWPS) with M-w=1110.5 kg/mol and M-n = 965.6 kg/mol were brought...

  5. On the structural and physicochemical properties of gamma irradiated UHMWPE/silane hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Shafiq, Muhammad [Advanced Polymer Laboratory, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, 45650 Islamabad (Pakistan); Mehmood, Malik Sajjad [Advanced Polymer Laboratory, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, 45650 Islamabad (Pakistan); Department of Basic Sciences and Humanities, University of Engineering and Technology, 47050 Taxila (Pakistan); Yasin, Tariq, E-mail: yasintariq@yahoo.com [Advanced Polymer Laboratory, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, 45650 Islamabad (Pakistan)

    2013-12-16

    This study has been carried to investigate the influence of gamma rays on the structural and physicochemical properties of UHMWPE/silane hybrid. UHMWPE was mixed with vinyltriethoxysilane (VTES) and compression molded sheets were irradiated at different doses of gamma rays. Fourier transform infrared spectroscopy indicated the formation of siloxane linkages in hybrids, which were found to be shifted towards lower wave number upon irradiation. The X-ray diffraction patterns showed significant increase in the percentage crystallinity of hybrid upon gamma irradiation, especially at 65 kGy absorbed dose. Scanning electron micrographs showed good consolidation and compaction with no surface defects. Moreover, the rough topography was changed to smooth ripple-like appearance upon γ-irradiation. Thermal analysis revealed that irradiated hybrids exhibited higher onset thermal degradation temperature, peak melting temperature, and crystalline lamellae thickness compared with the water treated hybrid. In addition, the tensile testing confirmed an increase of 41% and 133% in yield strength and Young's modulus in 100 kGy irradiated hybrid respectively than that of water treated hybrid. We hope that the irradiated UHMWPE/silane hybrids can be used in various high-strength applications such as total joint replacements, pickers for textile machinery, lining for coal chutes and dump trucks. - Highlights: • UHMWPE/silane hybrids have been prepared and irradiated using gamma rays. • The structural analysis revealed the formation siloxane linkages in the hybrid. • The crystallinity, thermal stability and mechanical properties of hybrids were improved with irradiation. • The irradiated hybrids can be used in various high-strength applications.

  6. Comparison of the Wear Behavior of UHMWPE Lubricated by Human Plasma and Brine

    Institute of Scientific and Technical Information of China (English)

    WANG Shi-bo; GE Shi-rong; NORM Gitis; MICHAEL Vinogradov; XIAO Jun

    2007-01-01

    The effect of plasma and brine lubricants on the friction and wear behavior of UHMWPE were studied by using the geometry of a Si3N4 ball sliding on a UHMWPE disc under patterns of uni-directional reciprocation and bi-directional sliding motions. The worn surface and wear particles produced in these two lubricants were analyzed. Sliding motion pattern affected the friction coefficients lubricated with plasma, while seldom affected that lubricated with brine. UHMWPE lubricated with plasma showed about half of the wear rate of that lubricated with brine. The two rates were 0.75 pg/m and 2.19 pg/m for the two motion patterns, respectively. However, wear particles generated in plasma included a greater amount of small particles, compared to that in brine. In uni-directional reciprocation, the main wear mechanism is ploughing both in plasma and in brine. In bi-directional sliding modes, the significant characteristic is ripples on the worn surface in plasma, while there are oriented fibers on the worn surface in brine.

  7. Influence of MWCNTs and gamma irradiation on thermal characteristics of medical grade UHMWPE

    Indian Academy of Sciences (India)

    P S Rama Sreekanth; S Kanagaraj

    2014-04-01

    Several techniques are available to characterize the influence of -irradiation on structural parameters of polymers; among which thermal characterization is more often used. The present work is aimed to study the influence of multi walled carbon nanotubes (MWCNTs) and -irradiation on polymer crystallinity, lamellar thickness, coefficient of thermal expansion (CTE) and thermal stability of UHMWPE. The chemically treated MWCNTs were homogenously dispersed in UHMWPE using a ball milling machine and compression moulded to make the nanocomposites with different concentration of MWCNTs. The nanocomposites were then -irradiated at a dose rate of 2.5 kGy/h up to 25, 50, 75, 100 kGy irradiation doses. The results obtained from TGA studies revealed that the presence of MWCNTs improved the thermal stability and onset temperature of degradation of nanocomposites. The CTE of nanocomposites was decreased with an increase of MWCNTs concentration and irradiation dose. The reduction of thermal expansion of nanocomposites aids in minimizing the dimensional fluctuation of them. It is concluded that irradiation and the presence of MWCNTs in UHMWPE not only improved the thermal stability of the composites but also enhanced their crystallinity and lamellar thickness.

  8. 超高分子量聚乙烯气辅挤出影响因素的数值模拟及分析%Numerical Simulation and Analysis of the Effect of Some Materials and Processing Parameters on the Gas Assisted Extrusion of Ultra-high Molecular Weight Polyethylene

    Institute of Scientific and Technical Information of China (English)

    柳和生; 张小霞

    2012-01-01

    After the numerical simulation of the isothermal flow of ultra-high molecular weight polyethylene melt in a gas assisted circular tube die, the numerical simulation and analysis were finished for the effect of such materials and processing parameters as entrance flow rate, relax time and zero-shear viscosity on the die swell rate, velocity distribution, die pressure drop and shear rate on the melt external face. Such analysis indicated that gas assisted extrusion was an effective technique for extrusion of ultra-high molecular weight polyethylene, which could overcome the difficulty occurring in the conventional extrusion of ultra-high molecular weight polyethylene.%以超高分子量聚乙烯的圆形轴对称气辅口模挤出为研究对象,在采用Polyflow软件对气辅口模挤出时的等温流动进行数值模拟之后,就入口流率、松弛时间以及零剪切黏度等物性和工艺参数对挤出胀大、速度分布、口模压降和熔体外表面上剪切速率的影响进行了数值模拟和分析.分析表明:气辅挤出是克服超高分子量聚乙烯传统挤出时面临一系列困难的有效加工方式.

  9. Properties of high density polyethylene – Paulownia wood flour composites via injection molding

    Science.gov (United States)

    Paulownia wood (PW) flour is evaluated as a bio-based fiber reinforcement. Composites of high density polyethylene (HDPE), 25% by weight of PW, and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding followed by injection molding. Molded test composite...

  10. On the Structural Analysis of γ-Ray Induced Primary Free Radicals in UHMWPE and Vitamin E Stabilized UHMWPE by ESR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Malik Sajjad Mehmood

    2015-01-01

    Full Text Available Oriented allyl radicals are detected at room temperature in gamma irradiated UHMWPE. The effects of vitamin E and storage at room temperature on this oriented structure are also investigated during the study. While testing powder as well as compression-molded solids, with or without vitamin E, a typical ESR spectrum was recorded at room temperature following 100 kGy gamma dose and subsequent storage at −78.5°C for one year. The simulated results show that the relative abundance of 5% alkyl, 68% allyl, and 27% polyenyl produced a 98.7% best fit of experimental ones. Furthermore, the allyl radical signal gives approximately 20% of random orientations and 80% of oriented molecules. In oriented PE, measured at −196°C, Ohnishi et al. (1916 observed 25 lines within a total magnetic field width of approximately 133 G. Our spectra also show 25 lines spread over 136 G in UHMWPE powder samples and at room temperature after one year of storage.

  11. Physical characterization of Ge films on polyethylene obtained by pulsed laser deposition

    Science.gov (United States)

    Giuffrida, L.; Torrisi, L.; Rosinski, M.; Caridi, F.; Cutroneo, M.

    2012-05-01

    A Nd:YAg laser, operating in fundamental wavelength at 1064 nm, is focused at an intensity of the order of 1010 W/cm2 to ablate a solid Ge target. A Laser Ion Source (LIS) system is employed to produce ion emission at high directionality, high current, high rate of production and high charge states. LIS is used to implant and/or to deposit Ge ions in polyethylene (UHMWPE). Mechanical (roughness, wetting ability and microhardness), optical (reflectivity and transmission) and electrical properties (resistivity) were investigated, in comparison to the pristine values, in order to reach understanding of the ion implantation/deposition effects as a function of the irradiation ion dose.

  12. Physical characterization of Ge films on polyethylene obtained by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Giuffrida, L. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Torrisi, L. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Universita di Messina, Dipartimento di Fisica, Messina (Italy); Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Caridi, F. [Universita di Messina, Facolta di Scienze MM.FF.NN., Messina (Italy); INFN-Sez. CT, Gr. Coll. di ME, Messina (Italy); Cutroneo, M. [Universita di Messina, Dipartimento di Fisica, Messina (Italy); INFN-Sez. CT, Gr. Coll. di ME, Messina (Italy)

    2012-05-15

    A Nd:YAg laser, operating in fundamental wavelength at 1064 nm, is focused at an intensity of the order of 10{sup 10} W/cm{sup 2} to ablate a solid Ge target. A Laser Ion Source (LIS) system is employed to produce ion emission at high directionality, high current, high rate of production and high charge states. LIS is used to implant and/or to deposit Ge ions in polyethylene (UHMWPE). Mechanical (roughness, wetting ability and microhardness), optical (reflectivity and transmission) and electrical properties (resistivity) were investigated, in comparison to the pristine values, in order to reach understanding of the ion implantation/deposition effects as a function of the irradiation ion dose. (orig.)

  13. Towards an accurate understanding of UHMWPE visco-dynamic behaviour for numerical modelling of implants.

    Science.gov (United States)

    Quinci, Federico; Dressler, Matthew; Strickland, Anthony M; Limbert, Georges

    2014-04-01

    Considerable progress has been made in understanding implant wear and developing numerical models to predict wear for new orthopaedic devices. However any model of wear could be improved through a more accurate representation of the biomaterial mechanics, including time-varying dynamic and inelastic behaviour such as viscosity and plastic deformation. In particular, most computational models of wear of UHMWPE implement a time-invariant version of Archard's law that links the volume of worn material to the contact pressure between the metal implant and the polymeric tibial insert. During in-vivo conditions, however, the contact area is a time-varying quantity and is therefore dependent upon the dynamic deformation response of the material. From this observation one can conclude that creep deformations of UHMWPE may be very important to consider when conducting computational wear analyses, in stark contrast to what can be found in the literature. In this study, different numerical modelling techniques are compared with experimental creep testing on a unicondylar knee replacement system in a physiologically representative context. Linear elastic, plastic and time-varying visco-dynamic models are benchmarked using literature data to predict contact deformations, pressures and areas. The aim of this study is to elucidate the contributions of viscoelastic and plastic effects on these surface quantities. It is concluded that creep deformations have a significant effect on the contact pressure measured (experiment) and calculated (computational models) at the surface of the UHMWPE unicondylar insert. The use of a purely elastoplastic constitutive model for UHMWPE lead to compressive deformations of the insert which are much smaller than those predicted by a creep-capturing viscoelastic model (and those measured experimentally). This shows again the importance of including creep behaviour into a constitutive model in order to predict the right level of surface deformation

  14. Enzymatic hydrolysis of poly(ethylene furanoate).

    Science.gov (United States)

    Pellis, Alessandro; Haernvall, Karolina; Pichler, Christian M; Ghazaryan, Gagik; Breinbauer, Rolf; Guebitz, Georg M

    2016-10-10

    The urgency of producing new environmentally-friendly polyesters strongly enhanced the development of bio-based poly(ethylene furanoate) (PEF) as an alternative to plastics like poly(ethylene terephthalate) (PET) for applications that include food packaging, personal and home care containers and thermoforming equipment. In this study, PEF powders of various molecular weights (6, 10 and 40kDa) were synthetized and their susceptibility to enzymatic hydrolysis was investigated for the first time. According to LC/TOF-MS analysis, cutinase 1 from Thermobifida cellulosilytica liberated both 2,5-furandicarboxylic acid and oligomers of up to DP4. The enzyme preferentially hydrolyzed PEF with higher molecular weights but was active on all tested substrates. Mild enzymatic hydrolysis of PEF has a potential both for surface functionalization and monomers recycling. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Molecular deformation mechanisms in polyethylene

    CERN Document Server

    Coutry, S

    2001-01-01

    adjacent labelled stems is significantly larger when the DPE guest is a copolymer molecule. Our comparative studies on various types of polyethylene lead to the conclusion that their deformation behaviour under drawing has the same basis, with additional effects imputed to the presence of tie-molecules and branches. Three major points were identified in this thesis. The changes produced by drawing imply (1) the crystallisation of some of the amorphous polymer and the subsequent orientation of the newly formed crystals, (2) the re-orientation of the crystalline ribbons and (3) the beginning of crystallite break-up. However, additional effects were observed for the high molecular weight linear sample and the copolymer sample and were attributed, respectively, to the presence of tie-molecules and of branches. It was concluded that both the tie-molecules and the branches are restricting the molecular movement during deformation, and that the branches may be acting as 'anchors'. This work is concerned with details...

  16. Different influence of Ti, PMMA, UHMWPE, and Co-Cr particles on peripheral blood monocytes during periprosthetic inflammation.

    Science.gov (United States)

    Zhang, Kai; Yang, Shang-You; Yang, Shuye; Bai, Ling; Li, Peng; Liu, Dong; Schurman, John R; Wooley, Paul H

    2015-01-01

    This study investigated cellular trafficking and inflammatory markers in orthopedic biomaterial particle-challenged human peripheral blood monocytes (PBMCs) using a murine immunodeficiency (SCID) model. Periprosthetic tissues from aseptic loosening patients were transplanted into muscles of SCID mice. PBMCs from the same patients were stimulated in vitro with Ti-6Al-4V, PMMA, UHMWPE, or Co-Cr particles for 3 days before administered intraperitoneally to the periprosthetic tissue-implanted mice. The xenografts were harvested 2 weeks later for histological and molecular analyses. Significant cell infiltration was obvious in the transplanted tissues from mice transfused with Ti-alloy, PMMA and UHMWPE-provoked PBMCs compared to controls, and UHMWPE-provoked PBMCs group accumulated significantly more cells among all groups. There were ubiquitous TRAP+ stained cells in all xenografts from particle-stimulated PBMCs mice. Immunohistochemical staining indicated that significantly more IL-1β and TNF positive cells occurred in Ti and PMMA groups; while the UHMWPE group resulted in stronger positive MCP-1 and IL-6 stains. Polymerase chain reaction (PCR) confirmed overexpression of both IL-1β and TNF in Ti and PMMA-stimulated groups; and more MIP-1α gene expression developed in the UHMWPE group. Overall, different type of orthopedic materials influenced the trafficking ability of particle-activated PBMCs which may depend on upregulation of various proinflammatory cytokines and chemokines.

  17. Hydration of polyethylene glycol-grafted liposomes.

    OpenAIRE

    Tirosh, O; Barenholz, Y.; Katzhendler, J; Priev, A

    1998-01-01

    This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG...

  18. Oxidation and other property changes of retrieved sequentially annealed UHMWPE acetabular and tibial bearings.

    Science.gov (United States)

    Reinitz, Steven D; Currier, Barbara H; Van Citters, Douglas W; Levine, Rayna A; Collier, John P

    2015-04-01

    This investigation analyzed retrieved sequentially crosslinked and annealed (SXL) ultra-high molecular weight polyethylene bearings to determine whether the material is chemically stable in vivo. A series of retrieved tibial and acetabular components were analyzed for changes in ketone oxidation, crosslink density, and free radical concentration. Oxidation was observed to increase with in vivo duration, and the rate of oxidation in tibial inserts was significantly greater than in acetabular liners. SXL acetabular bearings oxidized at a rate comparable to gamma-sterilized liners, while SXL tibial inserts oxidized at a significantly faster rate than their gamma-sterilized counterparts. A significant decrease in crosslink density with increased mean ketone oxidation index was observed, suggesting that in vivo oxidation may be causing material degradation. Furthermore, a subsurface whitened damage region was also found in a subset of the bearings, indicating the possibility of a clinically relevant decrease in mechanical properties of these components.

  19. Dynamic compressive behavior of foamed polyethylene film

    Directory of Open Access Journals (Sweden)

    Tateyama Kohei

    2015-01-01

    Full Text Available The foamed film as the shock absorption material has attracted much attention because it is thin (100 μm ∼ 400 μm and has a closed cell structure. However, the dynamic mechanical properties have not been reported in the foamed film. The purpose of this study is to elucidate the compressive behavior of the foamed polyethylene film at the wide strain rate range. First, the new compressive test apparatus for the dynamic strain rate, the drop-weight testing machine with opposed load cell, was developed, which can be also evaluated the dynamic stress equilibrium of the specimen. It is confirmed that the compressive flow stress increased with increasing the strain rate, regardless of the film thickness. The foamed polyethylene film has the high strain rate sensitivity in the quasi-static deformation. On the other hand, there is almost no change of the strain rate sensitivity in the dynamic and the impact deformation. In order to investigate the mechanism of strain rate dependence, the foamed polyethylene film was observed by X-ray computed tomography scanner before and after compressive test. The fracture of the closed cell only occurred in the quasi-static deformation. It was clarified that the strain rate sensitivity of the foamed film depends strongly on that of the construction material, polyethylene.

  20. Final report on the safety assessment of polyethylene.

    Science.gov (United States)

    2007-01-01

    Polyethylene is an ethylene polymer used for a variety of purposes in cosmetics as an abrasive, adhesive, binder or bulking agent, an emulsion stabilizer, a film former, an oral care agent, and as a nonaqueous viscosity-increasing agent. Polyethylene is also used in food packaging materials and medical products, including prosthetics. The molecular weight of Polyethylene as used in cosmetics varies over a wide range. The lowest reported molecular weight is 198 Daltons and the highest is 150,000. In any given polymer preparation, there can be a broad range of molecular weights. Cellular and tissue responses to Polyethylene, determined as part of implant biocompatibility testing, include fibrous connective tissue build-up around the implant material that varies as a function of the physical form of the implant material. Specific assays for osteoblast proliferation and collagen synthesis demonstrated a reduction as a function of exposure to Polyethylene particles that is inversely related to particle size. The effect of Polyurethane particles on monocyte-derived macrophages, however, had a stimulatory effect, prolonging the survival of these cells in culture. The LD50 for Polyethylene, with an average molecular weight of 450, in rats was > 2000 mg/kg. For Polyethylene with an average molecular weight of 655, the LD50 was > 5.0 g/kg. Toxicity testing in rats shows no adverse effects at Polyethylene (molecular weight not given) doses of 7.95 g/kg or at 1.25%, 2.50%, or 5.00% in feed for 90 days. Dermal irritation studies on rabbits in which 0.5 g of Polyethylene (average molecular weight of 450) was administered in 0.5 ml of water caused no irritation or corrosive effects; Polyethylene with an average molecular weight of 655 was a mild irritant. Polyethylene (average molecular weight of 450) did not cause dermal sensitization in guinea pigs tested with 50% Polyethylene (w/w) in arachis oil BP. Polyethylene, with a molecular weight of 450 and a molecular weight of 655

  1. UHMWPE/LDPE复合材料拉伸破坏的声发射特性研究(Ⅱ)%STUDY ON ACOUSTIC EMISSION FEATURE OF TENSILE FRACTURE IN UHMWPE/LDPE (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    崔建伟; 王旭; 张同华; 晏雄

    2006-01-01

    本文续"UHMWPE/LDPE复合材料拉伸破坏的声发射特性研究(Ⅰ)",进一步研究了UHMWPE/LDPE复合材料拉伸破坏的声发射特性,具体研究了[0°]、[90°]在拉伸破坏过程中声发射参数特征,并对拉伸破坏机理进行了初步的研究.

  2. STUDY ON ACOUSTIC EMISSION FEATURE OF TENSILE FRACTURE IN UHMWPE/LDPE(Ⅰ)%UHMWPE/LDPE复合材料拉伸破坏的声发射特性研究(Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    王旭; 张同华; 崔建伟; 崔晏雄

    2006-01-01

    本文试验研究了UHMWPE/LDPE复合材料拉伸破坏的声发射特性.利用声发射仪结合参数分析得出了增强纤维和基体在拉伸破坏过程中声发射参数特征.对后续研究UHMWPE/LDPE复合材料声发射特性和拉伸破坏机理具有参考价值.

  3. UHMWPE/CNTs复合纤维的制备及其性能研究%Preparation and properties of UHMWPE/CNTs composite fiber

    Institute of Scientific and Technical Information of China (English)

    韩亚刚; 赵国樑

    2013-01-01

    A UHMWPE/carbon nanotubes (CNTs) composite fiber was prepared via gel spinning process successive to the purification and functionalization of CNTs.The CNTs' orientation,alignment and crystalhne structure were studied by polarized Raman spectrometry.The creep and mechanical properties of the composite fiber were discussed.The results showed that CNTs had clear shape and dispersion stability considerably increased in white oil after purification and functionalization; CNTs was aligned along the orientation direction of the composite fiber and the crystallinity of the composite fiber was increased while increasing the draw ratio of the fiber; the tensile strength and Young's modulus appeared an upward and then downward tendency and the elongation at break and creep rate gradually decreased as the content of CNTs was raised; as compared with UHMWPE fiber,the composite fiber containing 2% CNTs by mass fraction had the tensile strength and Young' s modulus in increasing by 29.3% and 18.9%,respectively and lower creep deformation.%通过对碳纳米管(CNTs)进行纯化功能化处理,采用凝胶纺丝制备了UHMWPE/CNTs复合纤维;利用激光拉曼光谱研究了纤维中CNTs的取向排列、结晶结构,探讨了复合纤维的蠕变性能及力学性能.结果表明:经纯化和功能化的CNTs轮廓清楚,在白油中的分散稳定性大大提高,随着纤维拉伸倍数的提高,CNTs趋向于沿着纤维取向方向排列,纤维结晶度提高;随着CNTs含量的增加,复合纤维的拉伸强度和杨氏模量呈现先升高后下降趋势,而断裂伸长率和蠕变率逐渐下降;添加质量分数2%的CNTs的复合纤维同UHM-WPE纤维相比,其蠕变量降低,拉伸强度和杨氏模量分别提高了29.3%和18.9%.

  4. Adhesion improvement of fibres by continuous plasma treatment at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Sørensen, Bent F.

    2013-01-01

    Carbon fibres and ultra-high-molecular-weight polyethylene (UHMWPE) fibres were continuously treated by a dielectric barrier discharge plasma at atmospheric pressure for adhesion improvement with epoxy resins. The plasma treatment improved wettability, increased the oxygen containing polar...

  5. Efficient and selective degradation of polyethylenes into liquid fuels and waxes under mild conditions

    OpenAIRE

    Jia, Xiangqing; Qin, Chuan; Friedberger, Tobias; Guan, Zhibin; Huang, Zheng

    2016-01-01

    Polyethylene (PE) is the largest-volume synthetic polymer, and its chemical inertness makes its degradation by low-energy processes a challenging problem. We report a tandem catalytic cross alkane metathesis method for highly efficient degradation of polyethylenes under mild conditions. With the use of widely available, low-value, short alkanes (for example, petroleum ethers) as cross metathesis partners, different types of polyethylenes with various molecular weights undergo complete convers...

  6. The Wear behavior of UHMWPE against Surface Modified CP-Titanium by Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    B.T. Prayoga

    2016-12-01

    Full Text Available The effects of thermal oxidation duration on hardness, roughness, and wettability of the CP-titanium surfaces were investigated in this paper. The thermal oxidation treatment was done at 700 oC for 12-36 hours in an air atmosphere. The wear behavior of the UHMWPE sliding against treated thermal oxidation of the CP-titanium was tested by a pin-on-plate tribometer under lubrication of the solution of 75 % distilled water and 25 % bovine serum. The results showed that the layer of the oxide titanium was formed on the surface after being treated by the thermal oxidation for 12-36 hours. The oxide titanium layer was dominated by rutile form of TiO2, that offers an improvement of hardness and wettability of the CP-titanium surfaces. The average wear factor of the UHMWPE reduced significantly when the sliding against of the CP-titanium was modified by the thermal oxidation, and the lowest average wear factor was reached when the sliding against the 12 hour oxidized CP-titanium counterfaces.

  7. Polyethylene Glycol Propionaldehydes

    Science.gov (United States)

    Harris, Joe M.; Sedaghat-Herati, Mohammad R.; Karr, Laurel J.

    1992-01-01

    New class of compounds derived from polyethylene glycol (PEG's) namely, PEG-propionaldehydes, offers two important advantages over other classes of PEG aldehyde derivatives: compounds exhibit selective chemical reactivity toward amino groups and are stable in aqueous environment. PEG's and derivatives used to couple variety of other molecules, such as, to tether protein molecules to surfaces. Biotechnical and biomedical applications include partitioning of two phases in aqueous media; immobilization of such proteins as enzymes, antibodies, and antigens; modification of drugs; and preparation of protein-rejecting surfaces. In addition, surfaces coated with PEG's and derivatives used to control wetting and electroosmosis. Another potential application, coupling to aminated surfaces.

  8. Platelet deposition studies on copolyether urethanes modified with poly(ethylene oxide)

    NARCIS (Netherlands)

    Brinkman, E.; Foot, A.; van der Does, L.; Bantjes, A.

    1990-01-01

    Pellethane ® 2363 80A films and tubings were chemically modified and the effect of these modifications on platelet deposition was studied. Grafting of high molecular weight poly(ethylene oxide) and graft polymerization of methoxy poly(ethylene glycol) 400 methacrylate resulted in surfaces with a

  9. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Şule ALTUN

    2003-01-01

    Full Text Available Polyethylene terephthalate (PET is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understand degradation processes of PET during melt extrusion.

  10. Tribological characterisation of UHMWPE used in dual mobility total hip prosthesis

    Science.gov (United States)

    Essefi, I.; Hakkouna, H.; Ouenzerfi, G.; Mollon, G.; Hamza, S.; Renault, E.; Berthier, Y.; Trunfio-Sfarghiu, A.-M.

    2016-08-01

    Total hip arthroplasty represents an effective solution for bone and joint diseases. Nevertheless, the hip prosthesis has a limited lifetime, in the average around fifteen years. Their improvement, especially their dual mobility is the objective of this study. Therefore, our strategy is focused on improving the material by comparing three types of polyethylene to determine the best one from a friction mechanism and wear rate minimization standpoint. A dual mobility hip prosthesis, containing a two-sided steel and cobalt chrome cup, was tested with a TORNIER hip joint simulator in calf serum. The rubbed surfaces were characterized using scanning electron microscopy (SEM), contact angle measurements, atomic force microscopy (AFM) and confocal fluorescence microscopy. All these multiscale characterization techniques (from nanoscale to millimeter and micro- scale) showed that the velocity accommodation mechanism is different from one type of polyethylene to another. The wear in the case of standard polyethylene was noticeable and the particles were large and scattered between the surface of polyethylene, the surface of the cup and in the calf serum. For the crosslinked polyethylene, the particles coming from the wear, were not as large, but they were spread the same way as the first case. Even though it shares the same accommodation principle on the detachment of the material with the crosslinked polyethylene the wear particles for the crosslinked vitaminized polyethylene were large and they were only found on the surface of the polyethylene.

  11. Highly Branched Polyethylenes as Lubricant Viscosity and Friction Modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Joshua W.; Zhou, Yan; Qu, Jun; Bays, John T.; Cosimbescu, Lelia

    2016-10-08

    A series of highly branched polyethylenes (BPE) were prepared and used in a Group I base oil as potential viscosity and friction modifiers. The lubricating performance of these BPEs supports the expected dual functionality. Changes in polarity, topology, and molecular weight of the BPEs showed significant effects on the lubricants’ performance, which provide scientific insights for polymer design in future lubricant development.

  12. 增容剂对HDPE/UHMWPE/纳米HA生物复合材料性能的影响%Effect of Compatibilizers on Properties of HDPE/UHMWPE/Nano-hydroxyapatite Biomaterial Composite

    Institute of Scientific and Technical Information of China (English)

    沈惠玲; 张娜

    2011-01-01

    通过熔融共混法制备了高密度聚乙烯/超高分子量聚乙烯,纳米羟基磷灰石(HDPE/UHMWPE/纳米HA)生物复合材料,研究了增容剂三元乙丙橡胶接枝马来酸酐(EPDM-g-MAH)和聚烯烃弹性体接枝马来酸酐(POE-g-MAH)对复合材料力学性能的影响,并利用红外光谱、扫描电镜、热重分析仪及熔体流动速率仪表征了复合材料的微观结构.热性能和流动性能.结果表明:EPDM-g-MAH和POE-g-MAH均可提高HDPE/UHMWPE/纳米HA复合材科的相容性.其中EPDM-g-MAH的增容效果更明显;随着增容剂用量的增大,复合材料的熔体流动速率、热变形温度和热稳定性逐渐下降;与添加POE-g-MAH相比,含有EPDM-g-MAH的复合材料的综台性能较好.%The biomaterial composites of HDPE/UHMWPE/nano-hydroxyapatite (nano-HA) were prepared by means of melt blending. The effects of compatibilizers (EPDM-g-MAH and POE-g-MAH) on mechanical properties of HDPE/UHMWPE/nano-HA composite were investigated. The microstructure, melt flowability and thermal stability of the composite were characterized by IR, SEM, TGA and MFR. The results show that both EPDM-g-MAH and POE-g-MAH can improve the compatibility of HDPE/UHMWPE/nano-HA composite, wherein the compatibilization effect of EPDM-g-MAH is better; with the increase of compatibilizer content, the MFR, heat deflection temperature and thermal stability of the composite decrease; compared with the addition of POE-g-MAH, the comprehensive properties of HDPE/UHMWPE/nano-HA composite added with EPDM-g-MAH is better.

  13. Radiation resistivity of polyacenaphthylene-grafted polyethylene. [Gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, K.; Kawase, K.; Yamakita, H. (Government Industrial Research Inst., Nagoya (Japan))

    1983-01-01

    Thin poly(ethylene-g-acenaphthylene) films prepared by the vapor-phase grafting method were subjected to the ..gamma..-irradiation in air, and various changes in tensile and structural properties of the film were investigated by comparing with those of the untreated or crosslinked polyethylene film. Polyethylene got to lose its inherent necking property by oxidative degradation and to be brittle-fractured by the irradiation dose less than 100 Mrad in air. The polyacenaphthylene-grafted polyethylenes, however, kept their ductility up to 200 Mrad or more, and the rate of increase in elastic modulus as well as yield strength with the increasing irradiation dose was considerably lower than that of untreated or crosslinked polyethylene. The effect of the grafting extent, and that of the irradiation dose-rate on the fracture energy were also examined. The weight increase of polyethylene due to the oxygen consumption and the resulting formation of carbonyl group which proceeded proportionally with the irradiation dose were remarkably suppressed by the grafting, whereas the double bond formation seemed to be unaffected by it. The grafted film held the original content of gel fraction unchanged during the irradiation in air, but the average molecular weight of the sol fraction decreased gradually.

  14. Tribological behavior of UHMWPE against TiAl6V4 and CoCr28Mo alloys under dry and lubricated conditions.

    Science.gov (United States)

    Guezmil, M; Bensalah, W; Mezlini, S

    2016-10-01

    This work is focused on the study of the tribological behavior of TiAl6V4 and CoCr28Mo against UHMWPE. Wear tests were achieved on a reciprocating pin-on-disc tribometer under dry and lubricated conditions. Four bio-lubricants were retained namely: saline solution (NaCl 0.9%), sesame oil, nigella sativa oil and Hyalgan® which is a pharmaceutical intra-articular injection containing sodium hyaluronate active agent (20mg/2mL). The coefficient of friction and wear volume of UHMWPE were evaluated after tribological tests. It is found that, the friction and wear behaviors of CoCr28Mo/UHMWPE pair under dry and bio-lubrication were the best. Results show that the use of natural oils improved significantly the tribological behavior of CoCr28Mo/UHMWPE and TiAl6V4/UHMWPE pairs. Microscopic and chemical analyses of wear tracks on UHMWPE were carried out and wear mechanisms were proposed for each materials pair. The tribological performance of the used oils was linked to their chemical composition and to their adsorption ability on the metallic surfaces.

  15. Multifunctional Carbon Nanotube/Polyethylene Complex Composites for Space Radiation Shielding Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polyethylene (PE), due to its high hydrogen content relative to its weight, has been identified by NASA as a promising radiation shielding material against galactic...

  16. ANALYSIS OF BRANCHING DISTRIBUTION IN POLYETHYLENES BY DIFFERENTIAL SCANNING CALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    Robert Shanks; Fei Chen; Gandara Amarasinghe

    2003-01-01

    Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallization technique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distribution was also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four different polyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single site catalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with melting temperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethylene and the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used to calculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branch content were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branch content polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient was necessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling to below ambient because the calibration data were not performed in this way.

  17. ANALYSIS OF BRANCHING DISTRIBUTION IN POLYETHYLENES BY DIFFERENTIAL SCANNING CALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    RobertShanks; FeiChan; GandaraAmarasinghe; RobertShanks

    2003-01-01

    Short chain branching has been characterized using thermal fractionation,a stepwise isothermal crystallization technique,followed by a melting analysis scan using differential scanning calorimetry.Short chain branching distribution was also characterized by a continuous slow cooling crystallization,followed by a melting analysis scan.Four different polyethylenes were studied:Ziegler-Natta gas phase,Ziegler-Natta solution,metallocene,constrained-geometry single site catalyzed polyethylenes.The branching distribution was calculated from a calibration of branch content with melting temperature.The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethylene and the surface free energy of the crystal face.The branching distribution and lamellar thickness distribution were used to calculate weight average branch content,mean lamellar thickness,and a branch dispersity index.The results for the branch content were in good agreement with the known comonomer content of the polyethylenes.A limitation was that high branch content polyethylenes did not reach their potential crystallization at ambient temperatures.Cooling to sub-ambient was necessary to equilibrate the crystallization,but melting temperature versus branch content was not applicable after cooling to below ambient because the calibration data were not performed in this way.

  18. The Determination of Polyethylene Glycol in Untreated Urine Samples by High Performance Liquid Chromatography for Intestinal Permeability Studies

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Pedersen, Walther Batsberg; Philipsen, E.

    1985-01-01

    Polyethylene glycol in urine samples has been investigated by high performance liquid chromatography. The molecular weights ranged from 634 to 1338. The urine samples were applied to the chromatographic system without any pre-treatment. For samples with a concentration of 0.2% polyethylene glycol...

  19. Study on the Erosion Wear Characteristics and Mechanisms of UHMWPE/Kaolin Composites%高岭土填充改性超高分子量聚乙烯的浆体冲蚀磨损特性

    Institute of Scientific and Technical Information of China (English)

    龚国芳; 曲敬信; 杨华勇

    2001-01-01

    分别采用机械混合和釜内聚合方法在UHMWPE基体上填充高岭土,制得两类UHMWPE/Kaolin复合材料,考察了两类UHMWPE/Kaolin复合材料的浆体冲蚀磨损特性及其与冲击速度和高岭土含量之间的关系,通过对磨损表面形貌的观察分析,探讨了UHMWPE/Kaolin复合材料的磨损机理.结果表明,采用聚合方法制备的含高岭土约6.6%(质量分数)UHMWPE/Kaolin复合材料的浆体冲蚀磨损性能优于UHMWPE,是一种有应用前景的复合材料.

  20. Factors associated with the loss of thickness of polyethylene tibial bearings after knee arthroplasty.

    Science.gov (United States)

    Collier, Matthew B; Engh, C Anderson; McAuley, James P; Engh, Gerard A

    2007-06-01

    Wear of the polyethylene tibial bearing is a leading cause of failure of knee replacements done prior to the current decade. The objective of this study was to determine how patient-related factors, implant-related factors, and limb or tibial component alignment influenced the amount of thickness loss in polyethylene tibial bearings that were retrieved at the time of revision surgery or after the death of the patient. We retrieved polyethylene tibial bearings from eighty-one unicondylar and eighty-nine total knee replacements that had been performed because of osteoarthritis with varus deformity from 1984 to 1998. All of the polyethylene bearings had been sterilized with gamma radiation in air. Polyethylene loss was quantified as the change in the minimum bearing thickness per years in vivo (the mean time in vivo [and standard deviation] was 8 +/- 4 years). Multiple linear regression was used to assess whether polyethylene loss was associated with age, weight, gender, varus angle of the tibial component, postoperative hip-knee-ankle angle, initial thickness of the polyethylene, shelf age of the polyethylene, and either the type of polyethylene (for total knee replacements, which were of one posterior cruciate ligament-retaining design) or the manufacturer (for unicondylar knee replacements), and to determine the magnitude by which polyethylene loss would change if any of the significant risk factors were changed. The mean loss (and standard deviation) of polyethylene thickness in the medial compartment of total knee replacements (0.33 +/- 0.28 mm/yr) and that in medial unicompartmental knee replacements (0.49 +/- 0.40 mm/yr) were significantly (p return for follow-up care. Whether the study findings have relevance to bearings sterilized with other methods is unclear and will remain so for many years. Prognostic Level II.

  1. RESEARCH ON NEW TYPE AND HIGH EFFICIENCY QTE-1 CATALYST FOR UNLTRA HIGH MOLECULAR WEIGHT POLYETHYLENE%新型高效UHMWPE催化剂QTE-1的研究

    Institute of Scientific and Technical Information of China (English)

    李晓庆; 周建勇; 毕晓龙; 李留忠; 齐立芳

    2012-01-01

    QTE-1 catalyst for production of ultra high molecular weight polyetnylene was prepared by adopting process intensification technology. Using laboratory polymerization evaluation device, the process conditions including process intensification technology, polymerization temperature, pressure and etc. were studied emphatically to understand their effects on the catalyst performances. The study results showed QTE-1 catalyst had the following features involving high reactivity, stable reaction kinetics and slow decay of activity, excellent properties of polymerized resin.%利用过程强化技术制备了UHMWPE催化剂QTE-1,并进行了小试聚合评价,蓖点考察了过程强化技术以及聚合温度、聚合压力等工艺条件对其性能的影响。研究结果表明,QTE-1催化剂具有聚合活性高、反应动力学曲线平稳、活性衰减缓慢等特点,聚合所得树脂性能优异。

  2. Polyethylene-Based Tadpole Copolymers

    KAUST Repository

    Alkayal, Nazeeha

    2017-02-15

    Novel well-defined polyethylene-based tadpole copolymers ((c-PE)-b-PS, PE: polyethylene, PS: polystyrene) with ring PE head and linear PS tail are synthesized by combining polyhomologation, atom transfer radical polymerization (ATRP), and Glaser coupling reaction. The -OH groups of the 3-miktoarm star copolymers (PE-OH)-b-PS, synthesized by polyhomologation and ATRP, are transformed to alkyne groups by esterification with propiolic acid, followed by Glaser cyclization and removal of the unreacted linear with Merrifield\\'s resin-azide. The characterization results of intermediates and final products by high-temperature size exclusion chromatography, H NMR spectroscopy, and differential scanning calorimetry confirm the tadpole topology.

  3. Research on Friction and Wear Resistance Properties of Modified UHMWPE%改性UHMWPE塑料的摩擦磨损性能研究

    Institute of Scientific and Technical Information of China (English)

    陈国昌; 康明强; 乔红斌

    2014-01-01

    分别研究Mos2、PTFE和石墨对UHMWPE耐摩擦性能的影响.结果表明:在载荷200N,转速400 r/min的试验条件下,UHMWPE/石墨、UHMWPE、UHMWPE/MoS2和UHMWPE/PTFE的平均摩擦系数分别为0.27,0.30,0.35和0.39.掺杂石墨(质量分数9%)降低了UHMWPE的摩擦系数,在试验过程中减少了由于摩擦而产生的热量,从而提高了UHMWPE石墨复合材料的耐磨性能.

  4. Relations between thickness of UHMWPE's wear debris and positive pressure of tribological system

    Institute of Scientific and Technical Information of China (English)

    LIU HongTao; GE ShiRong

    2008-01-01

    MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler is introduced to research the relations be-tween thickness of UHMWPE's wear debris and positive pressure of tribological system. Research re-sults show that thickness of wear debris owns evident classification, and the first grade thickness math model and the second grade thickness math model are built. By the second grade thickness math model, the true force condition in the tribological system can be gotten, and the model can be used as a tool to modify simulating parameters of the tribological system, and it is an important inspecting method to the airtight system which cannot be examined in real time. The first grade thickness math model can describe the true working load and surface condition of work piece in the tribological sys-tem, and is an effective description method for the running condition of frictional pairs. The research results at different lubricating conditions testify the relations between thicknesses of wear debris and positive pressure of the tribological system. The fractal relation between maximal thickness of wear debris and positive pressure is discussed. The conceptions of the immutability principle and charac-teristic granularity of wear debris thickness are brought forward and discussed. In conclusion, as a stable tribological parameter owning mechanical theory basis, wear debris thickness will play an im-portant part in fault diagnosis, especially for the airtight system such as artificial joint.

  5. SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE

    Institute of Scientific and Technical Information of China (English)

    Ning Zhu; Yong Cui; Zi-long Li; Yong Chen; Wen-Hua Sun

    2003-01-01

    8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp2ZrC12) were supported simultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supported polymerization results showed that the molecular weight of polyethylene increased while the molecular weight distribution became wider and the molecular chains of oligomers remaining in the final solution became shorter as compared to the oligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as the Cp2ZrC12 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while a-olefin selectivity increased.

  6. Depolymerization of polyethylene terephthalate in supercritical methanol

    Science.gov (United States)

    Goto, Motonobu; Koyamoto, Hiroshi; Kodama, Akio; Hirose, Tsutomu; Nagaoka, Shoji

    2002-11-01

    The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573-623 K under an estimated pressure of 20 MPa for a reaction time of 2-120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography-mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.

  7. Polyethylene glycol-grafted polystyrene particles.

    Science.gov (United States)

    Meng, Fenghua; Engbers, Gerard H M; Feijen, Jan

    2004-07-01

    Densely pegylated particles that can serve as a model system for artificial cells were prepared by covalently grafting amino polyethylene glycol (PEG, molecular weight 3400 or 5000) onto carboxyl polystyrene particles (PS-COOH) using carbodiimide chemistry. PEG-modified particles (PS-PEG) were characterized by determination of the PEG surface concentration, zeta-potential, size, and morphology. Under optimized grafting conditions, a dense "brush-like" PEG layer was formed. A PEG surface concentration of approximately 60 pmol/cm2, corresponding with an average distance between grafted PEG chains of approximately 17 A can be realized. It was shown that grafting of PEG onto PS-COOH reduced the adsorption of proteins from human plasma (85 vol %) in phosphate-buffered saline up to 90%.

  8. 硅烷交联UHMWPE非等温结晶动力学%Non-isothermal Crystallization Kinetics of Silane Compound-Induced Crosslinked UHMWPE

    Institute of Scientific and Technical Information of China (English)

    王琛; 胡文玺; 朱小磊; 张刚; 刘春林

    2012-01-01

    The non-isothermal crystallization kinetics of UHMWPE and silane compound-induced crosslined UHMWPE were studied with differential scanning calorimetry (DSC). Jeziorny and Mo for Non-isothermal crystallization Kinetics were used to analyze the crystallization characters. It was found that the crystallization rate of crosslinked UHMWPE was slower than the pure UHMWPE, due to stronger effect among rules arrangement of molecule chain and partial destruction of crystal. The rate of crystallization decreased and crystal growth slowed. The fact that all samples had Avrami exponents in a range of 1.6~2.0, implies the nucleation mechanism and geometry of crystal growth UHMWPE was not changed.%利用差示扫描量热分析(DSC)方法研究了超高分子量聚乙烯(UHMWPE),硅烷交联UHMWPE的非等温结晶动力学.通过Jeziorny法和Mo法分别对非等温结晶过程进行处理,结果表明:硅烷交联UHMWPE分子链之间形成的三维网状结构抑制了分子链及链段之间的相对运动,阻碍了分子链的规则排列,影响了链段在晶区扩散迁移规整排列的速度,使结晶速率变慢,对晶体生长产生抑制作用.但在所有的结晶速率下,试样的Avrami指数n的值均在1.6~2.0之间,说明交联对UHMWPE的结晶成核机理和生长方式没有改变.

  9. Multimeric, Multifunctional Derivatives of Poly(ethylene glycol

    Directory of Open Access Journals (Sweden)

    Gian Maria Bonora

    2011-07-01

    Full Text Available This article reviews the use of multifunctional polymers founded on high-molecular weight poly(ethylene glycol (PEG. The design of new PEG derivatives assembled in a dendrimer-like multimeric fashion or bearing different functionalities on the same molecule is described. Their use as new drug delivery systems based on the conjugation of multiple copies or diversely active drugs on the same biocompatible support is illustrated.

  10. Production of an extracellular polyethylene-degrading enzyme(s) by Streptomyces species.

    Science.gov (United States)

    Pometto, A L; Lee, B T; Johnson, K E

    1992-01-01

    Extracellular culture concentrates were prepared from Streptomyces viridosporus T7A, Streptomyces badius 252, and Streptomyces setonii 75Vi2 shake flask cultures. Ten-day-heat-treated (70 degrees C) starch-polyethylene degradable plastic films were incubated with shaking with active or inactive enzyme for 3 weeks (37 degrees C). Active enzyme illustrated changes in the films' Fourier transform infrared spectra, mechanical properties, and polyethylene molecular weight distributions. PMID:1610196

  11. Study on stab-resistant performance of STF/UHMWPE fabric composite materials%STF/UHMWPE织物复合材料防刺性能的研究

    Institute of Scientific and Technical Information of China (English)

    徐素鹏; 张玉芳

    2012-01-01

    为拓宽STF/防刺织物复合材料的种类,寻求更轻、更薄、更软和更经济的防刺材料,用原生粒径20nm的SiO2分散于PEG200中制得不同SiO2含量的STF,通过浸泡的方式制备出STF/UHMWPE织物复合材料.参照GA68-2003《防刺服》标准,在TLC-30A微处理器控制落锤式防刺服专用冲击试验机上测定不同条件下STF/UHMWPE复合材料的防刺性能.结果表明,STF能明显增强UHMWPE织物的防刺性能,STF/UHMWPE无纺布复合材料的防刺性能优于STF/UHMWPE机织布复合材料;并且随着STF固含量的增大,STF增强织物防刺性能的效果越显著; STF/UHMWPE复合材料与纯UHMWPE复合铺层的防刺性能优于STF/UHMWPE复合材料单独铺层时,而且STF/UHMWPE复合材料放在最上层效果较好.%To broaden STF/UHMWPE stab-resistant composite materials species and seek more milder, thinner,better and economical stab-resistant materials, STF with different amount of nano-SiO2 was prepared by dispering nano-SiO2 with particle size 20 nm in PEG200,then STF/UHMWPE stab-resistant composite materials were prepared by immersion ways. The stab-resistant behavior of composite materials in different conditions was tested by falling tup machine controlled by TLC-30A microprocessor and referring to GA 68—20