Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

Science.gov (United States)

Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2015-01-01

Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for

Polyurethane Membranes Modified with Isopropyl Myristate as a Potential Candidate for Encapsulating Electronic Implants: A Study of Biocompatibility and Water Permeability

Directory of Open Access Journals (Sweden)

Deepen Paul

2010-07-01

Full Text Available Medical polyurethanes have shown good bio-stability and mechanical properties and have been used as coating for implantable medical devices. However, despite their excellent properties, they are relatively permeable to liquid water and water vapour which is a drawback for electronic implant encapsulation. In this study polyether polyurethanes with different soft segment molecular weights were modified by incorporating isopropyl myristate (IPM, as a hydrophobic modifying agent, and the effect of IPM on water resistant and biocompatibility of membranes were investigated. IPM changed the surface properties of the polyurethane film and reduced its surface energy. Polyurethane films were found to be stable with IPM concentrations of 1–5 wt% based upon their chemistry; however it leached out in BSA at higher concentrations. Though, low concentrations of IPM reduced both liquid water and water vapour permeability; at higher IPM content liquid permeability did not improved significantly. In general, the polyurethane materials showed much lower water permeability compared with currently used silicone packaging material for electronic implants. In addition, cytotoxicity assessment of IPM containing polyurethanes showed no evidence of cytotoxcity up to 5 wt% IPM.

Waterborne polyurethane-acrylic hybrid nanoparticles by miniemulsion polymerization: applications in pressure-sensitive adhesives.

Science.gov (United States)

Lopez, Aitziber; Degrandi-Contraires, Elise; Canetta, Elisabetta; Creton, Costantino; Keddie, Joseph L; Asua, José M

2011-04-05

Waterborne polyurethane-acrylic hybrid nanoparticles for application as pressure-sensitive adhesives (PSAs) were prepared by one-step miniemulsion polymerization. The addition of polyurethane to a standard waterborne acrylic formulation results in a large increase in the cohesive strength and hence a much higher shear holding time (greater than seven weeks at room temperature), which is a very desirable characteristic for PSAs. However, with the increase in cohesion, there is a decrease in the relative viscous component, and hence there is a decrease in the tack energy. The presence of a small concentration of methyl methacrylate (MMA) in the acrylic copolymer led to phase separation within the particles and created a hemispherical morphology. The tack energy was particularly low in the hybrid containing MMA because of the effects of lower energy dissipation and greater cross-linking. These results highlight the great sensitivity of the viscoelastic and adhesive properties to the details of the polymer network architecture and hence to the precise composition and synthesis conditions.

Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

DEFF Research Database (Denmark)

Kanjwal, Muzafar Ahmad; Barakat, Nasser A.M.; Chronakis, Ioannis S.

2015-01-01

Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver-titanium dioxide nanofibers (AgTiO2 NFs) and silver-titanium dioxide nanoparticles (AgTiO2 NPs) were individually...... incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth...

Guanidine hydrochloride embedded polyurethanes as antimicrobial and absorptive wound dressing membranes with promising cytocompatibility

Energy Technology Data Exchange (ETDEWEB)

Sahraro, Maryam; Yeganeh, Hamid, E-mail: h.yeganeh@ippi.ac.ir; Sorayya, Marziyeh

2016-02-01

Preparation and assessments of novel absorptive wound dressing materials with efficient antimicrobial activity as well as very good cytocompatibility were described in this work. An amine terminated poly(hexamethylene guanidine hydrochloride) was prepared and used as curing agent of different epoxy-terminated polyurethane prepolymers. The structures of prepared materials were elucidated by evaluation of their {sup 1}H NMR and FTIR spectra. The recorded tensile strength of membranes confirmed the excellent dimensional stability of the film type dressings even at fully hydrated conditions. Therefore, these dressings could protect the wound bed from external forces during the healing period. The structurally optimized dressing membranes could preserve the desired moist environment over the wounded area, as a result of their balanced equilibrium, water absorption and water vapor transmission rate. Therefore, a very good condition for stimulation of self-healing of wound bed was attained. Also, owing to the presence of guanidine hydrochloride moieties embedded into the structure of dressings, efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were detected. In vitro cytotoxicity assay of the prepared dressings revealed cytocompatibility of these materials against fibroblast cells. Therefore, they could support cell growth and proliferation at the wounded area. - Highlights: • New polyurethane wound dressings with guanidine hydrochloride based antimicrobials • Maintaining moist and warm wound environment for accelerating healing • Proper tensile strength of dressings even at fully hydrated state • Excellent biocompatibility index due to proper selection of starting materials.

Evaluation of the release behavior of the dexamethasone embedded in polycarbonate polyurethane membranes: an in vitro study

International Nuclear Information System (INIS)

Kim, Dong Hyun; Kang, Sung Gwon; Lee, Chul Gab; Park, Sang Soo; Lee, Don Haeng; Lee, Gyu Baek; Song, Ho Young

2003-01-01

To evaluate the release behavior of dexamethasone embedded in a polycarbonate polyurethane membrane. Both water-soluble and water-insoluble dexamethasone were tested, and the release behavior of five water-insoluble dexamethasone films of different thickness (78 to 211 μm) was also evaluated. The amount of dexamethasone used was 10% of the total weight of the polyurethan film mass. Each film was placed in a centrifuge tube containing 25 ml of 0.1-M neutral phosphate buffer, and the tubes were placed in a shaking incubator to quantify the amount of drug released into the buffer, absorption spectroscopy (λ max=242 nm) was employed. In the test involving water-soluble dexamethasone, 60%, of the drug was released during the first two hours of the study. Films containing water-insoluble dexamethasone, on the other hand, released 40%, 60% and 75% of the dexamethasone in one, three and seven days, respectively. Both types of film maintained low-dose drug release for 28 days. When release behavior was compared between water-insoluble films of different thickness, thicker film showed less initial burst and more sustained release. Dexamethasone release behavior varies according to drug solubility and membrane thickness, and may thus be conrolled

Effects of ZnO Nanoparticle on the Gas Separation Performance of Polyurethane Mixed Matrix Membrane.

Science.gov (United States)

Soltani, Banafsheh; Asghari, Morteza

2017-08-11

Polyurethane (PU)-ZnO mixed matrix membranes (MMM) were fabricated and characterized for gas separation. A thermogravimetric analysis (TGA), a scanning electron microscope (SEM) test and an atomic-force microscopy (AFM) revealed that the physical properties and thermal stability of the membranes were improved through filler loading. Hydrogen Bonding Index, obtained from the Fourier transform infrared spectroscopy (FTIR), demonstrate that the degree of phase separation in PU-ZnO 0.5 wt % MMM was more than the neat PU, while in PU-ZnO 1.0 wt % MMM, the phase mixing had increased. Compared to the neat membrane, the CO₂ permeability of the MMMs increased by 31% for PU-ZnO 0.5 wt % MMM and decreased by 34% for 1.0 wt % ZnO MMM. The CO₂/CH₄ and CO₂/N₂ selectivities of PU-ZnO 0.5 wt % were 18.75 and 64.75, respectively.

Enhanced Performance of Polyurethane Hybrid Membranes for CO2 Separation by Incorporating Graphene Oxide: The Relationship between Membrane Performance and Morphology of Graphene Oxide.

Science.gov (United States)

Wang, Ting; Zhao, Li; Shen, Jiang-nan; Wu, Li-guang; Van der Bruggen, Bart

2015-07-07

Polyurethane hybrid membranes containing graphene oxide (GO) with different morphologies were prepared by in situ polymerization. The separation of CO2/N2 gas mixtures was studied using these novel membranes. The results from the morphology characterization of GO samples indicated that the oxidation process in the improved Hummers method introduced oxygenated functional groups into graphite, making graphite powder exfoliate into GO nanosheets. The surface defects on the GO sheets increased when oxidation increased due to the introduction of more oxygenated functional groups. Both the increase in oxygenated functional groups on the GO surface and the decrease in the number of GO layers leads to a better distribution of GO in the polymer matrix, increasing thermal stability and gas separation performance of membranes. The addition of excess oxidant destroyed the structure of GO sheets and forms structural defects, which depressed the separation performance of membranes. The hybrid membranes containing well-distributed GO showed higher permeability and permeability selectivity for the CO2. The formation of GO aggregates in the hybrid membranes depressed the membrane performance at a high content of GO.

Attachment of inorganic moieties onto aliphatic polyurethanes

Directory of Open Access Journals (Sweden)

Eliane Ayres

2007-06-01

Full Text Available Polyurethanes have been used in a series of applications due basically to their versatility in terms of controlling the behavior by altering basically the type of reagents used. However, for more specific and advanced applications, such as in membranes, biomaterials and sensors, well-organized and defined chemical functionalities are necessary. In this work, inorganic functionalities were incorporated into aliphatic polyurethanes (PU having different macromolecular architectures. Polyurethanes were synthesized using a polyether diol and dicyclohexylmethane 4,4' diisocyanate (H12-MDI. Polyurethanes having carboxylic acid groups were also produced by introducing 2,2- bis (hydroxymethyl propionic acid in the polymerization process. Inorganic functionalities were inserted into polyurethanes by reacting isocyanate end capped chains with aminopropyltriethoxysilane followed by tetraethoxysilane. PU having carboxylic acid groups yielded transparent samples after the incorporation of inorganic entities, as an evidence of smaller and better dispersed inorganic entities in the polymer network. FTIR and swelling measurements showed that polyurethanes having carboxylic acid groups had inorganic domains less packed, condensed and cross-linked when compared to polyurethanes with no carboxylic acid groups. Results also suggested that the progressive incorporation of inorganic moieties in both types of polyurethanes occurred in regions previously activated with inorganic functionalities, instead of by the creation of new domains. The temperatures of thermal decomposition and glass transition were also shifted to higher temperatures when inorganic functionalities were incorporated into polyurethanes.

Effect of tackifier and crosslinkers on electron beam curable polyurethane pressure sensitive adhesive

International Nuclear Information System (INIS)

Kumar Singh, Anil; Singh Mehra, Dayal; Kumar Niyogi, Utpal; Sabharwal, Sunil; Kumar Khandal, Rakesh

2012-01-01

Polyurethane based pressure sensitive adhesive using monofunctional urethane acrylate and difunctional urethane acrylate has been made using electron beam irradiation. The effect of varying electron beam doses on the adhesion properties viz., peel adhesion, shear adhesion and initial tack has been studied. Effect of tackifier and crosslinkers viz., polymeric methylene diphenyl diisocynate, carbodiimide modified methylene diphenyl diisocynate and triallyl cynurate on adhesion properties as well as on moisture vapor transmission rate and gel content of the polyurethane based pressure sensitive adhesive has also been studied. It was found that with increasing dose, tackifier and crosslinkers concentration, all the adhesion properties viz., peel adhesion, shear adhesion strength and initial tack were increased upto a certain dose, concentration of tackifier and crosslinkers, reached a plateau and then levelled off with further increasing the dose, tackifier and crosslinkers concentration. Similarly, moisture vapor transmission rate was decreased and the gel content increased with increasing dose of electron beam. - Highlights: ► The optimized e-beam dose was 20 kGy. ► Optimized concentration of tackifier was 15% while PMDI, CMDI 6% and TAC 4%. ► CMDI has highest while TAC has lowest adhesion properties. ► Tackifier has highest while TAC has lowest MVTR. ► TAC has highest while tackifier has lowest gel content.

A novel silanized CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane pressure sensitive adhesive

Energy Technology Data Exchange (ETDEWEB)

Fu, Heqing, E-mail: fuhq@scut.edu.cn; Wang, Yin; Chen, Weifeng; Zhou, Wei; Xiao, Jing

2015-10-01

Highlights: • The hydrophobicity, thermal stability, dynamic mechanical properties, as well as adhesive properties of silanized. • CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane (SC/FWPU) were improved with the incorporation of silanized CoFe{sub 2}O{sub 4} into FWPU. • The higher the spreading-penetration parameter is, the faster the contact angle reaches equilibrium, and the faster the SC/FWPU pressure sensitive adhesive penetrates and spreads. - Abstract: A novel silanized CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane (SC/FWPU) pressure sensitive adhesive was synthesized and characterized by atomic force microscopy (AFM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and contact angle tester. The adhesive properties were measured in a test machine. Experimental results showed that the hydrophobicity, thermal stability, dynamic mechanical properties, as well as adhesive properties of SC/FWPU were improved with the incorporation of SC into FWPU. The dynamic hydrophobicity can be well described by the wetting kinetic model. The spreading-penetration parameter increased with an increase in SC content. The higher the spreading-penetration parameter is, the faster the contact angle reaches equilibrium, and the faster the SC/FWPU pressure sensitive adhesive penetrates and spreads.

Inspired by nonenveloped viruses escaping from endo-lysosomes: a pH-sensitive polyurethane micelle for effective intracellular trafficking

Science.gov (United States)

Song, Nijia; Zhou, Lijuan; Li, Jiehua; Pan, Zhicheng; He, Xueling; Tan, Hong; Wan, Xinyuan; Li, Jianshu; Ran, Rong; Fu, Qiang

2016-03-01

A multifunctional drug delivery system (DDS) for cancer therapy still faces great challenges due to multiple physiological barriers encountered in vivo. To increase the efficacy of current cancer treatment a new anticancer DDS mimicking the response of nonenveloped viruses, triggered by acidic pH to escape endo-lysosomes, is developed. Such a smart DDS is self-assembled from biodegradable pH-sensitive polyurethane containing hydrazone bonds in the backbone, named pHPM. The pHPM exhibits excellent micellization characteristics and high loading capacity for hydrophobic chemotherapeutic drugs. The responses of the pHPM in acidic media, undergoing charge conversion and hydrophobic core exposure, resulting from the detachment of the hydrophilic polyethylene glycol (PEG) shell, are similar to the behavior of a nonenveloped virus when trapped in acidic endo-lysosomes. Moreover, the degradation mechanism was verified by gel permeation chromatography (GPC). The endo-lysosomal membrane rupture induced by these transformed micelles is clearly observed by transmission electron microscopy. Consequently, excellent antitumor activity is confirmed both in vitro and in vivo. The results verify that the pHPM could be a promising new drug delivery tool for the treatment of cancer and other diseases.A multifunctional drug delivery system (DDS) for cancer therapy still faces great challenges due to multiple physiological barriers encountered in vivo. To increase the efficacy of current cancer treatment a new anticancer DDS mimicking the response of nonenveloped viruses, triggered by acidic pH to escape endo-lysosomes, is developed. Such a smart DDS is self-assembled from biodegradable pH-sensitive polyurethane containing hydrazone bonds in the backbone, named pHPM. The pHPM exhibits excellent micellization characteristics and high loading capacity for hydrophobic chemotherapeutic drugs. The responses of the pHPM in acidic media, undergoing charge conversion and hydrophobic core

Pentiptycene-based polyurethane with enhanced mechanical properties and CO2-plasticization resistance for thin film gas separation membranes.

Science.gov (United States)

Pournaghshband Isfahani, Ali; Sadeghi, Morteza; Wakimoto, Kazuki; Shrestha, Binod Babu; Bagheri, Rouhollah; Sivaniah, Easan; Ghalei, Behnam

2018-04-30

Development of thin film composite (TFC) membranes offers an opportunity to achieve the permeability/selectivity requirements for optimum CO2 separation performance. However, the durability and performance of thin film gas separation membranes are mostly challenged by weak mechanical properties and high CO2 plasticization. Here, we designed new polyurethane (PU) structures with bulky aromatic chain extenders that afford preferred mechanical properties for ultra-thin film formation. An improvement of about 1500% in Young's modulus and 600% in hardness was observed for pentiptycene-based PUs compared to typical PU membranes. Single (CO2, H2, CH4, and N2) and mixed (CO2/N2 and CO2/CH4) gas permeability tests were performed on the PU membranes. The resulting TFC membranes showed a high CO2 permeance up to 1400 GPU (10-6 cm3(STP) cm-2s-1 cmHg-1) and the CO2/N2 and CO2/H2 selectivities of about 22 and 2.1, respectively. The enhanced mechanical properties of pentiptycene-based PUs results in high performance thin membranes with the similar selectivity of the bulk polymer. The thin film membranes prepared from pentiptycene-based PUs also showed a two-fold enhanced plasticization resistance compared to non-pentiptycene containing PU membranes.

Thermo-sensitive intelligent track membrane

International Nuclear Information System (INIS)

Pang Deling; Ren Lihua; Qian Zhilin; Huang Gang; Zhang Jinhua

1999-01-01

Using N-isopropylacryl-amide (NIP AAm) thermo-sensitive function material as monomer and nuclear track microporous membrane (NTMM) as baseline material, a thermo-sensitive intelligent track membrane (TsITM) has been prepared by the over-oxidization and pre-irradiation grafting techniques. The TsITM can be used to make a micro-switch controlled by temperature and to adjust particle screening and osmosis. To obtain sub-micron responsive grafted track pores only a very thin thermo-sensitive layer is needed. The TsITM pores are capable of swelling and shrinking rapidly and respond more sensitively to temperature

Environment-sensitive ion-track membranes

International Nuclear Information System (INIS)

Yoshida, Masaru

1996-01-01

Development of an environment-sensitive porous membrane from ion-track membranes may realize by combining the techniques of ion beam radiation and those of molecular designing and synthesis for intelligent materials. Now, the development of such membrane is progressing with an aim at selecting some specific substances and accurately control its pore size in response to any small environmental stimulus such as temperature change. The authors have been studying the molecular design, synthesis and functional expression of intelligent materials, which are called here as environment-sensitive gels. In this report, the outlines of the apparatus for the production of such porous membrane was described. An organic polymer membrane was irradiated with an ion beam and followed by chemical etching to make ion track pores. Scanning electron microscopic observation for the cross section of the membrane showed that the pore shape varies greatly depending on the ion nuclide used. The characteristics of newly produced porous membranes consisting of CR-30/A-ProDMe and polyethylene-telephtharate were investigated in respect of pore size change responding to temperature. These studies of design, synthesis and functions of such gels would enable to substitute artificial materials for the functions of human sensors. (M.N.). 54 refs

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

Science.gov (United States)

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Characterization of Novel Castor Oil-Based Polyurethane Polymer Electrolytes

Directory of Open Access Journals (Sweden)

Salmiah Ibrahim

2015-04-01

Full Text Available Castor oil-based polyurethane as a renewable resource polymer has been synthesized for application as a host in polymer electrolyte for electrochemical devices. The polyurethane was added with LiI and NaI in different wt% to form a film of polymer electrolytes. The films were characterized by using attenuated total reflectance-Fourier transform infrared spectroscopy, dynamic mechanical analysis, electrochemical impedance spectroscopy, linear sweep voltammetry and transference number measurement. The highest conductivity of 1.42 × 10−6 S cm−1 was achieved with the addition of 30 wt% LiI and 4.28 × 10−7 S·cm−1 upon addition of 30 wt% NaI at room temperature. The temperature dependence conductivity plot indicated that both systems obeyed Arrhenius law. The activation energy for the PU-LiI and PU-NaI systems were 0.13 and 0.22 eV. Glass transition temperature of the synthesized polyurethane decreased from −15.8 °C to ~ −26 to −28 °C upon salts addition. These characterizations exhibited the castor oil-based polyurethane polymer electrolytes have potential to be used as alternative membrane for electrochemical devices.

Thermoresponsive polyurethane/siloxane membrane for wound dressing and cell sheet transplantation: In-vitro and in-vivo studies

Energy Technology Data Exchange (ETDEWEB)

Rezapour-Lactoee, Alireza [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 14177-55469 Tehran (Iran, Islamic Republic of); Yeganeh, Hamid, E-mail: h.yeganeh@ippi.ac.ir [Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of); Ostad, Seyed Nasser, E-mail: ostadnas@sina.tums.ac.ir [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 14177-55469 Tehran (Iran, Islamic Republic of); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tehran University of Medical Sciences, 16 Azar St, Enqelab Sq, Tehran 1417614411 (Iran, Islamic Republic of); Gharibi, Reza [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 14177-55469 Tehran (Iran, Islamic Republic of); Mazaheri, Zohreh [Department of Anatomical Sciences, Faculty of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ai, Jafar [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 14177-55469 Tehran (Iran, Islamic Republic of)

2016-12-01

Polyurethane/siloxane based wound dressing for transferring fibroblast cell sheet to wounded skin and ability to provide an optimum condition for cellular activity at damaged tissue was prepared in this research. The dressing was made thermoresponsive, via the introduction of a poly(N-isopropyl acrylamide) copolymer into the backbone of dressing. The ability of membrane for adhesion, growth, and proliferation of fibroblast cells was improved via surface modification with gelatin. The optimized dressing exhibited appropriate tensile strength (4.5 MPa) and elongation at break (80%) to protect wound against physical forces. Due to controlled equilibrium water absorption of about 89% and water vapor transmission rate of 2040 g/m{sup 2} day, the dressing could maintain the favorable moist environment over moderate to high exuding wounds. The grown cell sheet on dressing membrane could easily roll up from the surface just with lowering the temperature. The in vivo study of the wound dressed with cell loaded membrane confirmed the accelerated healing and production of tissue with complete re-epithelization, enhanced vascularization, and increased collagen deposition on the damaged area. - Highlights: • Versatile polymerization procedure to prepare wound dressing membranes • Improved cytocompatibility to support growth and proliferation of seeded fibroblasts • Utilizing thermoresponsive characteristic to transfer cell sheet to damaged tissue • Excellent physicomechanical properties of dressings to protect wound bed • Excellent fluid handling to provide moist environment over wounded tissue.

Fully glutathione degradable waterborne polyurethane nanocarriers: Preparation, redox-sensitivity, and triggered intracellular drug release

Energy Technology Data Exchange (ETDEWEB)

Omrani, Ismail; Babanejad, Niloofar; Shendi, Hasan Kashef; Nabid, Mohammad Reza, E-mail: m-nabid@sbu.ac.ir

2017-01-01

Polyurethanes are important class of biomaterials that are extensively used in medical devices. In spite of their easy synthesis, polyurethanes that are fully degradable in response to the intracellular reducing environment are less explored for controlled drug delivery. Herein, a novel glutathione degradable waterborne polyurethane (WPU) nanocarrier for redox triggered intracellular delivery of a model lipophilic anticancer drug, doxorubicin (DOX) is reported. The WPU was prepared from polyaddition reaction of isophorone diisocyanate (IPDI) and a novel linear polyester polyol involving disulfide linkage, disulfide labeled chain extender, dimethylolpropionic acid (DMPA) using dibutyltin dilaurate (DBTDL) as a catalyst. The resulting polyurethane self-assembles into nanocarrier in water. The dynamic light scattering (DLS) measurements and scanning electron microscope (SEM) revealed fast swelling and disruption of nanocarriers under an intracellular reduction-mimicking environment. The in vitro release studies showed that DOX was released in a controlled and redox-dependent manner. MTT assays showed that DOX-loaded WPU had a high in vitro antitumor activity in both HDF noncancer cells and MCF- 7 cancer cells. In addition, it is found that the blank WPU nanocarriers are nontoxic to HDF and MCF-7 cells even at a high concentration of 2 mg/mL. Hence, nanocarriers based on disulfide labeled WPU have appeared as a new class of biocompatible and redox-degradable nanovehicle for efficient intracellular drug delivery. - Highlights: • A novel fully glutathione degradable waterborne polyurethane was developed. • The waterborne nanocarrier with disulfide bonds in both hard and soft segment were developed for redox-triggered intracellular delivery of DOX. • The polyester diol bearing disulfide bonds in the backbone was prepared by a polycondensation polymerization reaction.

Evaluation of Polyurethane Membrane as a Barrier in Treatment of Intrabony Defects

Directory of Open Access Journals (Sweden)

Haghighati F

2000-05-01

Full Text Available Clinical healing following guided tissue regeneration (GTR in intrabony pockets using a"npolyurethane membrane was compared to healing following gingival flap surgery (GFS."nTen patients with adult periodontitis and the presence of intrabony defects were selected. Oral hygenic"ntreatments were performed during a 4- weeks period prior to surgery."nOne intrabony defects on each patient was randomly chosen to be treated according to the guided tissue"nregeneration (GTR procedure. The other side received the control treatment GFS. Test group received"nthe GTP treatment including polyurethane membrane after reflecting the flap and curettage of defect."nHowever, flap surgery and curettage were done in control group."nThe patients were evaluated for changes in probing depth (PD, clinical attachment level (CAL,"nrecession changes in crestai resorting, and defect bone fill. Clinical examinations were performed again 6"nmonths post operatively."nThe average of (PD, (CAL and defect depth (DD before surgery in test group was 3.23, 13.87 and 7.3"nmm respectively and in control group was 3.1, 8.9, 7.4 mm. After 6 months the average of (PD, (CAL"nand (DD was 1.69, 1.68, 3.5 mm, respectively and in control group was 1.24, 1.09, and 2.90mm."nTest group and control group showed successful results in treatment of intrabony defects. Test group"nshowed better results than control."nNo significant difference was observed between two treatment procedures from the point of view of"npocket depth reduction, attachment gain, and recession."nThe bony fill and crestai resorption results suggest similar clinical potential of GTR procedures"ncompared to GFS in treatment of intrabony pocket. However, in order to gain future insight, larger"nsamples and longer observation periods should be evaluated.

Post-Synthetic Polymerization of UiO-66-NH2 Nanoparticles and Polyurethane Oligomer toward Stand-Alone Membranes for Dye Removal and Separation.

Science.gov (United States)

Yao, Bing-Jian; Jiang, Wei-Ling; Dong, Ying; Liu, Zhi-Xian; Dong, Yu-Bin

2016-07-18

Metal-organic frameworks (MOFs) are widely used as porous materials in the fields of adsorption and separation. However, their practical application is largely hindered by limitations to their processability. Herein, new UiO-66-Urea-based flexible membranes with MOF loadings of 50 (1), 60 (2), and 70 wt % (3) were designed and prepared by post-synthetic polymerization of UiO-66-NH2 nanoparticles and a polyurethane oligomer under mild conditions. The adsorption behavior of membrane 3 towards four hydrophilic dyes, namely, eosin Y (EY), rhodamine B (RB), malachite green (MG), and methylene blue (MB), in aqueous solution was studied in detail. It exhibits strong adsorption of EY and RB but weak adsorption of MG and MB in aqueous solution. Owing to the selective adsorption of these hydrophilic dyes, membrane 3 can remove EY and RB from aqueous solution and completely separate EY/MB, RB/MG, and RB/MB mixtures in aqueous solution. In addition, the membrane is uniformly textured, easily handled, and can be reused for dye adsorption and separation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoclay Dispersion and its Effect on Properties of Waterborne Polyurethanes

Directory of Open Access Journals (Sweden)

H. Honarkar

2014-01-01

Full Text Available In recent years, waterborne polyurethanes as in coatings and adhesives formulations have attracted considerable attention because they are non-toxic, non-flammable and friendly to environment. Besides environmental management, the flexibility, low temperature property, high tensile strength, good adhesion and improved rheological property are specific properties of waterborne polyurethanes. Also low production cost of water borne polyurethanes over solvent-borne polyurethanes is also a reason for their applications. However, these materials have some defects such as weak water resistance and low adhesion in the moisture environment due to sensitivity of their hydrophilic ionic bonds, ether groups, urethane and ester groups to hydrolysis which need to be improved. Also, low heat resistance of these materials is due to a relatively low crystalline melting point or glass transition temperature of hard segments. One of the ways to solve this problem and improve its properties for different applications is the addition of inorganic fillers especially nano-sized layered silicates within polyurethane matrix. In this way water resistance, heat resistance, mechanical properties and modulus increase simultaneously. In this research, waterborne polyurethane nanocomposites with PTMG polyol, IPDI, DMPA (internal emulsifier, TEA (neutralizer and 1, 3 and 5weight % of Cloisite 30B as reinforcement were synthesized and characterized. Polarity of the samples was investigated by contact angle test and dispersion of nano particles in the samples was characterized by X-Ray and TEM, Thermal properties and dynamic mechanical properties were measured by TGA and DMTA, respectively. The results showed that incorporation of clay into polyurethanes did reduce water absorption and increased heat resistance, modulus, particle size and contact angle.In recent years, waterborne polyurethanes including coatings and adhesives have attracted considerable attention because they

High molecular weight polyurethanes and a polyurethane urea based on 1,4-butanediisocyanate

NARCIS (Netherlands)

Spaans, CJ; de Groot, JH; Dekens, FG; Pennings, AJ

New biomedical polyurethanes and a polyurethane urea based on epsilon-caprolactone and 1,4-butanediisocyanate have been developed. On degradation, only non-toxic products are produced. The polyurethane urea with poly(epsilon-caprolactone) soft segments and butanediisocyanate/butanediamine hard

Electromechanical study of polyurethane films with carbon black nanoparticles for MEMS actuators

International Nuclear Information System (INIS)

Roussel, M; Deman, A-L; Chateaux, J-F; Malhaire, C; Petit, L; Seveyrat, L; Galineau, J; Guiffard, B; Seguineau, C; Desmarres, J-M; Martegoutte, J

2014-01-01

Pure polyurethane and nanocomposite carbon black (CB) polyurethane solutions were deposited by spin-coating on a silicon substrate using gold as the adhesion layer and electrode. Different test structures were achieved for electrical and mechanical characterizations. The incorporation of CB nanoparticles in the polyurethane matrix has a significant influence on the dielectric permittivity of the material with an increase of about one third of its value. The Young's modulus of PU and nanocomposite PU films was determined by different characterization methods. Nanoindentation experiments have pointed out a Young's modulus gradient through the film thickness. By performing mechanical tests (tensile, bulge, point deflection) on freestanding films, an average Young's modulus value of about 30 MPa was found as well as a residual stress value of about 0.4 MPa. However, no influence of the presence of the nanoparticles was found. Finally, several MEMS actuators were realized and characterized. At their fundamental resonance frequency, the actuation of the nanocomposite membranes is more efficient than that of pure polyurethane. However, the time constant of the material seems to provide a major barrier for the development of high-frequency PU-based micro-actuators. (paper)

Characterization of a poly(ether urethane)-based controlled release membrane system for delivery of ketoprofen

International Nuclear Information System (INIS)

Macocinschi, Doina; Filip, Daniela; Vlad, Stelian; Oprea, Ana Maria; Gafitanu, Carmen Anatolia

2012-01-01

Highlights: ► Ketoprofen incorporation in poly(ether urethane) microporous membrane. ► Moisture sorption properties of as-cast membrane. ► Drug release mechanisms in function of pH and composition of membranes. - Abstract: A poly(ether urethane) based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Kinetic and drug release mechanisms were studied. The pore size and pore size distribution of the polyurethane membranes were investigated by scanning electron microscopy. Surface tension characteristics as well as moisture sorption properties such as diffusion coefficients and equilibrium moisture contents of the membrane material were studied. It was found that kinetics and release mechanisms are in function of medium pH, composition of polymer–drug system, pore morphology and pore size distribution. Prolonged nature of release of ketoprofen is assured by low amount of drug in polyurethane membrane and physiological pH.

Unloaded polyether type polyurethane foams as solid extractants for trace elements

International Nuclear Information System (INIS)

Palagyi, S.; Braun, T.

1992-01-01

Polyether type polyurethane foams (PU) are regular stacks of solid quasi-spherical membranes produced by the reaction of polyisocyanates with polyols of polyether nature in the presence of a catalyst and a blowing agent. Contrary to conventional membrane separations, where a solid membrane is merely a differentially separating agent, or a transport medium, PU foams, apart from separation and preconcentration, also retain, i.e., sorb the species on, or in the membranes. Therefore, PU foam membranes can be considered to act as true sorbents. The membrane properties of PU foam sorbents offer unique advantages over conventional bulk type granular sorbents in rapid, versatile and effective separations and preconcentrations of different compounds from fluid samples. Unloaded PU foam sorbents have received considerable attention in the separation of different trace inorganic species. (author) 74 refs.; 1 fig.; 1 tab

Polyurethane compounds having carbon nanotubes

NARCIS (Netherlands)

2010-01-01

The invention relates to semi-crystalline polyurethane (PUR) compositions filled with carbon nanotubes (CNT) and having improved electrical properties, which can be obtained on the basis of water-based polyurethane/CNT mixtures. The invention further relates to a method for producing polyurethane

Study on polyurethane foamed concrete for use in structural applications

Directory of Open Access Journals (Sweden)

Iman Kattoof Harith

2018-06-01

Full Text Available Recently, foamed concrete is being widely used in civil construction and building, because of its high fluidity and settlement, low self-weight and low thermal conductivity. However, it has some major setbacks such as low strength and increased shrinkage at later ages. The strength gain of concrete depends upon several variables; one of these is the curing conditions. This work aims to study the potential production of foamed concrete as a sustainable structural material by varying the curing methods. For this purpose, sample cubes, cylinders and prisms were prepared to find the compressive strength, modulus of elasticity and drying shrinkage at different ages. Samples of the polyurethane foamed concrete cured under four different curing regimes (water, moisture, sealing by membrane-forming curing compound and air curing. At the end of the study, polyurethane foamed concrete used for this study has shown the potential for use in structural applications. Also, the results show that the samples cured by moisture have the highest compressive strength at all ages. Keywords: Polyurethane foamed concrete, Curing conditions, Fly ash, Compressive strength, Static modulus of elasticity drying shrinkage

Evaluation of the biodurability of polyurethane-covered stent using a flow phantom

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Hyun; Kang, Sung Gwon; Choi, Jung Ryul; Byun, Ju Nam; Kim, Young Chul [Chosun University Hospital, Gwangju (Korea, Republic of); Ahn, Young Moo [Hansung Universkty, Seoul (Korea, Republic of)

2001-06-01

To evaluate the biodurability of the covering material in retrievable metallic stents covered with polycarbonate polyurethane. Using a peristaltic pump at a constant rate of 1ml/min, bile was recirculated from a reservoir through a long tube containing four stents. Each of these was removed from the system every two weeks and a radial tensile strength test and scanning electron microscopy (SEM) were performed. Each stent, removed at 2, 4, 6 and 8 weeks, was compared with a control stent not exposed to bile juice. Gross examination showed that stents were intact at 2 weeks, but at 4, 6 and 8 weeks cracks were observed. The size of these increased gradually in accordance with the duration of exposure, and at 8 weeks several large holes in the polyurethane membrane were evident. With regard to radial tensile strength, extension and peak load at break were 84.47% and 10.030 N/mm, 54.90% and 6.769 N/mm, 16.55% and 2.452 N/mm, 11.21% and 1.373 N/mm at 0, 2, 4 and 6 weeks, respectively. Scanning electron microscopy at 2 weeks revealed intermittent pitting and cracking, and examination at 4, 6 and 8 weeks showed that the size of these defects was gradually increasing. When the polyurethane membrane was exposed to bile, biodegradation was first observed at week two and increased gradually according to the duration of exposure.

21 CFR 177.1680 - Polyurethane resins.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyurethane resins. 177.1680 Section 177.1680 Food... of Single and Repeated Use Food Contact Surfaces § 177.1680 Polyurethane resins. The polyurethane...) For the purpose of this section, polyurethane resins are those produced when one or more of the...

Fabrication of superhydrophobic polyurethane/organoclay nano-structured composites from cyclomethicone-in-water emulsions

Energy Technology Data Exchange (ETDEWEB)

Bayer, I.S., E-mail: ibayer1@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Steele, A.; Martorana, P.J. [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Loth, E. [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, IL 61801 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, VA 22904 (United States)

2010-11-15

Nano-structured polyurethane/organoclay composite films were fabricated by dispersing moisture-curable polyurethanes and fatty amine/amino-silane surface modified montmorillonite clay (organoclay) in cyclomethicone-in-water emulsions. Cyclomethicone Pickering emulsions were made by emulsifying decamethylcyclopentasiloxane (D{sub 5}), dodecamethylcyclohexasiloxane (D{sub 6}) and aminofunctional siloxane polymers with water using montmorillonite particles as emulsion stabilizers. Polyurethane and organoclay dispersed emulsions were spray coated on aluminum surfaces. Upon thermosetting, water repellent self-cleaning coatings were obtained with measured static water contact angles exceeding 155{sup o} and low contact angle hysteresis (<8{sup o}). Electron microscopy images of the coating surfaces revealed formation of self-similar hierarchical micro- and nano-scale surface structures. The surface morphology and the coating adhesion strength to aluminum substrates were found to be sensitive to the relative amounts of dispersed polyurethane and organoclay in the emulsions. The degree of superhydrophobicity was analyzed using static water contact angles as well as contact angle hysteresis measurements. Due to biocompatibility of cyclomethicones and polyurethane, developed coatings can be considered for specific bio-medical applications.

Fabrication of superhydrophobic polyurethane/organoclay nano-structured composites from cyclomethicone-in-water emulsions

International Nuclear Information System (INIS)

Bayer, I.S.; Steele, A.; Martorana, P.J.; Loth, E.

2010-01-01

Nano-structured polyurethane/organoclay composite films were fabricated by dispersing moisture-curable polyurethanes and fatty amine/amino-silane surface modified montmorillonite clay (organoclay) in cyclomethicone-in-water emulsions. Cyclomethicone Pickering emulsions were made by emulsifying decamethylcyclopentasiloxane (D 5 ), dodecamethylcyclohexasiloxane (D 6 ) and aminofunctional siloxane polymers with water using montmorillonite particles as emulsion stabilizers. Polyurethane and organoclay dispersed emulsions were spray coated on aluminum surfaces. Upon thermosetting, water repellent self-cleaning coatings were obtained with measured static water contact angles exceeding 155 o and low contact angle hysteresis ( o ). Electron microscopy images of the coating surfaces revealed formation of self-similar hierarchical micro- and nano-scale surface structures. The surface morphology and the coating adhesion strength to aluminum substrates were found to be sensitive to the relative amounts of dispersed polyurethane and organoclay in the emulsions. The degree of superhydrophobicity was analyzed using static water contact angles as well as contact angle hysteresis measurements. Due to biocompatibility of cyclomethicones and polyurethane, developed coatings can be considered for specific bio-medical applications.

Efficient DNP NMR of Membrane Proteins: Sample Preparation Protocols, Sensitivity, and Radical Location

Science.gov (United States)

Liao, Shu Y.; Lee, Myungwoon; Wang, Tuo; Sergeyev, Ivan V.; Hong, Mei

2016-01-01

Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~4 fold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105–160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes. PMID:26873390

Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location

Energy Technology Data Exchange (ETDEWEB)

Liao, Shu Y.; Lee, Myungwoon; Wang, Tuo [Massachusetts Institute of Technology, Department of Chemistry (United States); Sergeyev, Ivan V. [Bruker Biospin (United States); Hong, Mei, E-mail: meihong@mit.edu [Massachusetts Institute of Technology, Department of Chemistry (United States)

2016-03-15

Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~fourfold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105–160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes.

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications

Energy Technology Data Exchange (ETDEWEB)

Sheikh, Zeeshan [Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, 150 College Street, Toronto, ON M5S 3E2 (Canada); School of Engineering and Materials Science, Queen Mary, University of London, Mile End Rd, London, E1 4NS (United Kingdom); Khan, Abdul Samad, E-mail: draskhan@ciitlahore.edu.pk [Interdisciplinary Research Centre in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Roohpour, Nima [Oral Care R& D, GSK St., Georges Ave., Weybridge KT13 8PA (United Kingdom); Glogauer, Michael [Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, 150 College Street, Toronto, ON M5S 3E2 (Canada); Rehman, Ihtesham u [Department of Materials Science and Engineering, The Kroto Research Institute, North Campus, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom)

2016-11-01

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4′-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37 °C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86 ± 1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87 ± 3.16°). The ultimate tensile strength and elastic modulus of PEU (27 ± 1 MPa and 14 ± 2 MPa) and PEU-PDMS (8 ± 1 MPa and 26 ± 1 MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications

International Nuclear Information System (INIS)

Sheikh, Zeeshan; Khan, Abdul Samad; Roohpour, Nima; Glogauer, Michael; Rehman, Ihtesham u

2016-01-01

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4′-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37 °C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86 ± 1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87 ± 3.16°). The ultimate tensile strength and elastic modulus of PEU (27 ± 1 MPa and 14 ± 2 MPa) and PEU-PDMS (8 ± 1 MPa and 26 ± 1 MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial

Polyurethane nanofibers containing copper nanoparticles as future materials

DEFF Research Database (Denmark)

Sheikh, Faheem A.; Kanjwal, Muzafar Ahmed; Saran, Saurabh

2011-01-01

nanofibers. Typically, a colloidal gel consisting of copper NPs and polyurethane has been electrospun. SEM-EDX and TEM results confirmed well oriented nanofibers and good dispersion of pure copper NPs. Copper NPs have diameter in the range of 5–10nm. The thermal stability of the synthesized nanofibers...... the antimicrobial efficacy of these nanofiber mats. Subsequently, antimicrobial tests have indicated that the prepared nanofibers do posses good bactericidal effect. Accordingly, it is noted that the obtained nanofiber mats can be used as future filter membranes with good antimicrobial activities....

Temperature-sensitive porous membrane production through radiation co-grafting of NIPAAm on/in PVDF porous membrane

International Nuclear Information System (INIS)

Liu Qi; Zhu Zhiyong; Yang Xiaomin; Chen Xiliang; Song Yufeng

2007-01-01

N-isopropylacrylamide (NIPAAm) monomer was grafted on and in poly(vinylidene fluoride) (PVDF) micro-pore membrane by γ-irradiation. The influence of irradiation and reaction conditions on the grafting yield was investigated in detail. The chemical structure of NIPAAm-grafted PVDF (NIPAAm-g-PVDF) membrane was characterized by Fourier transform infrared spectra and X-ray photoelectron spectra measurements. The morphology of the sample surface as well as the cross-section before and after grafting was characterized by scanning electron microscope. The temperature sensitive properties of the membrane were monitored by measuring the conductance as well as the water flux through the sample thickness. The results show that the membrane exhibits clearly temperature-sensitive permeability to water as expected, i.e. the permeability of water changes dramatically as the temperature goes over the lower critical solution temperature of NIPAAm

40 CFR 721.8095 - Silylated polyurethane.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Silylated polyurethane. 721.8095... Substances § 721.8095 Silylated polyurethane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a silylated polyurethane (PMN P-95-1356) is...

Fabrication and characterization of an asymmetric polyurethane membrane for use as a wound dressing

NARCIS (Netherlands)

Hinrichs, W.L.J.; Hinrichs, W.L.J.; Lommen, E.J.C.M.P.; Wildevuur, C.R.H.; Feijen, Jan

1993-01-01

To prevent wound dehydration and bacterial penetration, a wound dressing should be occlusive, but on the other hand it should also be permeable for wound exudate to prevent bullae formation. To meet these requirements a new type of polyurethane wound dressing which consists of a microporous top

FABRICATION AND CHARACTERIZATION OF AN ASYMMETRIC POLYURETHANE MEMBRANE FOR USE AS A WOUND DRESSING

NARCIS (Netherlands)

HINRICHS, WLJ; LOMMEN, EJCMP; WILDEVUUR, CRH; FEIJEN, J

1992-01-01

To prevent wound dehydration and bacterial penetration, a wound dressing should be occlusive, but on the other hand it should also be permeable for wound exudate to prevent bullae formation. To meet these requirements a new type of polyurethane wound dressing which consists of a microporous top

40 CFR 721.8090 - Polyurethane polymer.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyurethane polymer. 721.8090 Section... Substances § 721.8090 Polyurethane polymer. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (P-94-47) is subject...

Preconcentration of traces of radionuclides with sorbents based on spherical polyurethane membrane systems in the analysis of environmental samples

International Nuclear Information System (INIS)

Palagyi, S.; Braun, T.

1986-01-01

In the paper the importance of preconcentration and a permanent need for efficient preconcentrating agents in environmental analysis are pointed out. The increased attention is devoted to the foamed polyurethane sorbents as a novel advance in the separation chemistry. The paper has two main aims. The first is to present a survey of recent applications of unloaded and reagent loaded open-cell type resilient polyurethane foams to the separation and preconcentration of radionuclides from environmental samples. The second is to show the newest results in the use of these foams for the preconcentration and determination of traces of some mainly inorganic species in environmental samples by radioanalytical techniques. Some future possibilities of the use of polyurethane foams in trace elemental determinations in environmental analysis are also outlined. (author)

Neutron gauging to detect voids in polyurethane

International Nuclear Information System (INIS)

Tsang, F.Y.; Alger, D.M.; Brugger, R.M.

1978-01-01

Thermal-neutron radiography and fast-neutron gauging measurements were made to evaluate the feasibility of detecting voids in a polyurethane block placed between steel plates. This sandwich of polyurethane and steel simulates the walls of a canister being designed to hold explosive devices. The polyurethane would act as a shock absorber in the canister. A large fabrication cost saving would result by casting the polyurethane, but a nondestructive testing (NDT) method is needed to determine the uniformity of the polyurethane fill. The radiography measurements used a beam of thermal neutrons, while the gauging used filtered beams of 24 keV and fission spectrum neutrons. For the 83-mm-thick polyurethane and 130-mm-thick steel matrix, the thermal-neutron radiography was able to detect only those voids equal to about one-half the polyurethane thickness. The gauging detected voids in the path of the neutron beam of a few millimetres thickness in seconds to minutes. The gauging is feasible as an NDT method for the canister application

Developement of Spherical Polyurethane Beads

Institute of Scientific and Technical Information of China (English)

K. Maeda; H. Ohmori; H. Gyotoku

2005-01-01

@@ 1Results and Discussion We established a new method to produce the spherical polyurethane beads which have narrower distribution of particle size. This narrower distribution was achieved by the polyurethane prepolymer which contains ketimine as a blocked chain-extending agent. Firstly, the prepolymer is dispersed into the aqueous solution containing surfactant. Secondaly, water comes into the inside of prepolymer as oil phase. Thirdly, ketimine is hydrolyzed to amine, and amine reacts with prepolymer immediately to be polyurethane.Our spherical polyurethane beads are very suitable for automotive interior parts especially for instrument panel cover sheet producing under the slush molding method, because of good process ability, excellent durability to the sunlight and mechanical properties at low temperature. See Fig. 1 ,Fig. 2 and Fig. 3 (Page 820).

Polyurethane Filler for Electroplating

Science.gov (United States)

Beasley, J. L.

1984-01-01

Polyurethane foam proves suitable as filler for slots in parts electroplated with copper or nickel. Polyurethane causes less contamination of plating bath and of cleaning and filtering tanks than wax fillers used previously. Direct cost of maintenance and indirect cost of reduced operating time during tank cleaning also reduced.

Breathability studies of electron beam curable polyurethane pressure sensitive adhesive for bio-medical application

International Nuclear Information System (INIS)

Singh, Anil Kumar; Mehra, Dayal Singh; Niyogi, Utpal Kumar; Sabharwal, Sunil; Singh, Gurdeep

2014-01-01

Polyurethane (PU) based pressure sensitive adhesive (PSA) commonly used in surgical dressing has been made by electron beam (e-beam) irradiation. In contact with biological substrate like skin, PSAs generally lose their adhesive strength due to very low moisture vapor transmission rate (MVTR). In the present study, effects of varying e-beam dose and different crosslinkers on the MVTR of the PU-PSA have been investigated. A comparative study of effects of different crosslinkers showed that PU-PSA with IPDI has the least while that with TAC has the highest gel content and crystallinity and a reverse trend was observed for the MVTR. - Highlights: • On increasing e-beam dose from 5 kGy to 60 kGy the MVTR decreased continuously. • Increasing crosslinker concentration from 2% to10% resulted in decrease of MVTR. • IPDI has the highest and TAC has the least MVTR in PU-PSA system among the crosslinkers. • MVTR/peel adhesion/shear adhesion/initial tack: IPDI>MDI>CMDI>PMDI>TAIC>TAC. • Gel content/T g /crystallinity: TAC>TAIC>PMDI>CMDI>MDI>IPDI

Sustained Release Drug Delivery Applications of Polyurethanes

Directory of Open Access Journals (Sweden)

Michael B. Lowinger

2018-05-01

Full Text Available Since their introduction over 50 years ago, polyurethanes have been applied to nearly every industry. This review describes applications of polyurethanes to the development of modified release drug delivery. Although drug delivery research leveraging polyurethanes has been ongoing for decades, there has been renewed and substantial interest in the field in recent years. The chemistry of polyurethanes and the mechanisms of drug release from sustained release dosage forms are briefly reviewed. Studies to assess the impact of intrinsic drug properties on release from polyurethane-based formulations are considered. The impact of hydrophilic water swelling polyurethanes on drug diffusivity and release rate is discussed. The role of pore formers in modulating drug release rate is examined. Finally, the value of assessing mechanical properties of the dosage form and approaches taken in the literature are described.

Listening to membrane potential: photoacoustic voltage-sensitive dye recording

Science.gov (United States)

Zhang, Haichong K.; Yan, Ping; Kang, Jeeun; Abou, Diane S.; Le, Hanh N. D.; Jha, Abhinav K.; Thorek, Daniel L. J.; Kang, Jin U.; Rahmim, Arman; Wong, Dean F.; Boctor, Emad M.; Loew, Leslie M.

2017-04-01

Voltage-sensitive dyes (VSDs) are designed to monitor membrane potential by detecting fluorescence changes in response to neuronal or muscle electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo systems for external detection. By contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near-infrared light excitation and ultrasound detection. Here, we show that voltage-dependent quenching of dye fluorescence leads to a reciprocal enhancement of PA intensity. We synthesized a near-infrared photoacoustic VSD (PA-VSD), whose PA intensity change is sensitive to membrane potential. In the polarized state, this cyanine-based probe enhances PA intensity while decreasing fluorescence output in a lipid vesicle membrane model. A theoretical model accounts for how the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate PA voltage sensing but also emphasize the interplay of both fluorescence and absorbance properties in the design of optimized PA probes. Together, our results demonstrate PA sensing as a potential new modality for recording and external imaging of electrophysiological and neurochemical events in the brain.

40 CFR 721.8082 - Polyester polyurethane acrylate.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyester polyurethane acrylate. 721... Substances § 721.8082 Polyester polyurethane acrylate. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as polyester polyurethane acrylate...

Spectral Properties and Orientation of Voltage-Sensitive Dyes in Lipid Membranes

KAUST Repository

Matson, Maria

2012-07-24

Voltage-sensitive dyes are frequently used for probing variations in the electric potential across cell membranes. The dyes respond by changing their spectral properties: measured as shifts of wavelength of absorption or emission maxima or as changes of absorption or fluorescence intensity. Although such probes have been studied and used for decades, the mechanism behind their voltage sensitivity is still obscure. We ask whether the voltage response is due to electrochromism as a result of direct field interaction on the chromophore or to solvatochromism, which is the focus of this study, as result of changed environment or molecular alignment in the membrane. The spectral properties of three styryl dyes, di-4-ANEPPS, di-8-ANEPPS, and RH421, were investigated in solvents of varying polarity and in model membranes using spectroscopy. Using quantum mechanical calculations, the spectral dependence of monomer and dimer ANEPPS on solvent properties was modeled. Also, the kinetics of binding to lipid membranes and the binding geometry of the probe molecules were found relevant to address. The spectral properties of all three probes were found to be highly sensitive to the local environment, and the probes are oriented nearly parallel with the membrane normal. Slow binding kinetics and scattering in absorption spectra indicate, especially for di-8-ANEPPS, involvement of aggregation. On the basis of the experimental spectra and time-dependent density functional theory calculations, we find that aggregate formation may contribute to the blue-shifts seen for the dyes in decanol and when bound to membrane models. In conclusion, solvatochromic and other intermolecular interactions effects also need to be included when considering electrochromic response voltage-sensitive dyes. © 2012 American Chemical Society.

Membrane-based torque magnetometer: Enhanced sensitivity by optical readout of the membrane displacement

Science.gov (United States)

Blankenhorn, M.; Heintze, E.; Slota, M.; van Slageren, J.; Moores, B. A.; Degen, C. L.; Bogani, L.; Dressel, M.

2017-09-01

The design and realization of a torque magnetometer is reported that reads the deflection of a membrane by optical interferometry. The compact instrument allows for low-temperature measurements of tiny crystals less than a microgram with a significant improvement in sensitivity, signal-to-noise ratio as well as data acquisition time compared with conventional magnetometry and offers an enormous potential for further improvements and future applications in different fields. Magnetic measurements on single-molecule magnets demonstrate the applicability of the membrane-based torque magnetometer.

Sintesis membran Poliuretan dari Karagenan dan 2, 4 Toylulene diisosianat

Directory of Open Access Journals (Sweden)

Marlina Marlina

2010-06-01

Full Text Available This research studied the synthesis of Polyurethane (PU Membrane from Carrageenan and 2,4 toylulene diisocyanante (TDI. The PU membrane made from the Gracilaria sp of red seaweed has rendement of 60.5% from the total weight of the dried sea grass. The produced Carrageenan has pure properties with containing many OH groups which can be used to synthesize membrane. The dope solution to produce good membrane was made at the temperature of 60 oC for the reaction of 5 minutes by varying concentration of carrageenan 5-35 % (b/v. PU membrane was constructed using petri dish with the thickness of about 0.1 mm. To control the thickness of the membrane, the volume of dope solution was used about 12 mL, and the membrane was produced with 10 cm in diameter. The membrane had been synthesized at the temperature of 60 oC with varied concentration of Carrageenan 15% (b/v to the toylulene diisocyanate (TDI. The produced membrane has the optimal properties with the tensile strength of 340 kgf/mm2, the elongation percentage of 9%, the glass temperature transition of 243.6 oC and the melting point of 423.02 oC. The optimum PU membrane obtained was good in mechanical and physical properties, strong, elastic and transparent. Keywords: carrageenan, flux, membrane, polyurethane, rejection factor, TDI

40 CFR 721.9959 - Polyurethane polymer (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyurethane polymer (generic). 721... Substances § 721.9959 Polyurethane polymer (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polyurethane polymer (PMN P-01...

Biodegradable polyurethane nanocomposites containing dexamethasone for ocular route

Energy Technology Data Exchange (ETDEWEB)

Rodrigues da Silva, Gisele [Federal University of Sao Joao Del Rei, School of Pharmacy, Divinopolis, Minas Gerais (Brazil); Silva-Cunha, Armando da [Federal University of Minas Gerais, School of Pharmacy, Belo Horizonte, Minas Gerais (Brazil); Behar-Cohen, Francine [INSERM, Physiopathology of ocular diseases: Therapeutic innovations, Institut des Cordeliers, Paris (France); Laboratoire d' Innovations Therapeutiques, Fondation Rothschild, Paris (France); Universite Rene Descartes, Hotel Dieu University Hospital, Paris (France); Ayres, Eliane [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil); Orefice, Rodrigo L., E-mail: rorefice@demet.ufmg.br [Federal University of Minas Gerais, Department of Metallurgical and Materials Engineering, Belo Horizonte, Minas Gerais (Brazil)

2011-03-12

The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane containi clay nanoparticles. Biodegradable polyurethane nanocomposites having poly(caprolactone) oligomers as soft segments were obtained by delaminating clay particles within a polyurethane aqueous dispersion. The drug was incorporated into the polymer by dispersing it in the waterborne polyurethane followed by a drying step. Nanoparticles derived from clay were demonstrated to be able to tailor the mechanical properties of polyurethanes to achieve values that can match the properties of ocular soft tissues. Infrared spectra (FTIR) showed that the presence of clay particles was able to change the microphase separation process typical of polyurethanes. X-ray diffraction and small angle x-ray scattering (SAXS) results were explored to show that the incorporation of both dexamethasone acetate and nanocomponents derived from clay led to a less defined two-phase polyurethane. The presence of clay nanoparticles increased the rate of drug release measured in vitro. Human retinal pigment epithelial cells (ARPE-19) were cultured in contact with polyurethanes and polyurethane nanocomposites, and the viability of them (evaluated by using MTT assay after 7 days) showed that no toxic components were released from polyurethanes containing no drugs during the test.

Biodegradable polyurethane nanocomposites containing dexamethasone for ocular route

International Nuclear Information System (INIS)

Rodrigues da Silva, Gisele; Silva-Cunha, Armando da; Behar-Cohen, Francine; Ayres, Eliane; Orefice, Rodrigo L.

2011-01-01

The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane containi clay nanoparticles. Biodegradable polyurethane nanocomposites having poly(caprolactone) oligomers as soft segments were obtained by delaminating clay particles within a polyurethane aqueous dispersion. The drug was incorporated into the polymer by dispersing it in the waterborne polyurethane followed by a drying step. Nanoparticles derived from clay were demonstrated to be able to tailor the mechanical properties of polyurethanes to achieve values that can match the properties of ocular soft tissues. Infrared spectra (FTIR) showed that the presence of clay particles was able to change the microphase separation process typical of polyurethanes. X-ray diffraction and small angle x-ray scattering (SAXS) results were explored to show that the incorporation of both dexamethasone acetate and nanocomponents derived from clay led to a less defined two-phase polyurethane. The presence of clay nanoparticles increased the rate of drug release measured in vitro. Human retinal pigment epithelial cells (ARPE-19) were cultured in contact with polyurethanes and polyurethane nanocomposites, and the viability of them (evaluated by using MTT assay after 7 days) showed that no toxic components were released from polyurethanes containing no drugs during the test.

New membrane materials for potassium-selective ion-sensitive field-effect transistors

NARCIS (Netherlands)

van der Wal, P.D.; van der Wal, Peter D.; Skowronska-Ptasinska, Maria; van den Berg, Albert; Bergveld, Piet; Sudholter, Ernst; Sudholter, Ernst J.R.; Reinhoudt, David

1990-01-01

Several polymeric materials were studied as membrane materials for potassium-selective ion-sensitive field-effect transistors (ISFETs) to overcome the problems related with the use of conventional plasticized poly(vinyl chloride) membranes casted on ISFET gate surfaces. Several acrylate materials,

Chemical speciation of polyurethane polymers by soft-x-ray spectromicroscopy

Energy Technology Data Exchange (ETDEWEB)

Rightor, E.G. [Dow Chemical, Freeport, TX (United States); Hitchcock, A.P.; Urquhart, S.G. [McMaster Univ., Hamilton, Ontario (Canada)] [and others

1997-04-01

Polyurethane polymers are a versatile class of materials which have numerous applications in modern life, from automotive body panels, to insulation, to household furnishings. Phase segregation helps to determine the physical properties of several types of polyurethanes. Polymer scientists believe that understanding the connections between formulation chemistry, the chemical nature of the segregated phases, and the physical properties of the resulting polymer, would greatly advance development of improved polyurethane materials. However, the sub-micron size of segregated features precludes their chemical analysis by existing methods, leaving only indirect means of characterizing these features. For the past several years the authors have been developing near edge X-ray absorption spectromicroscopy to study the chemical nature of individual segregated phases. Part of this work has involved studies of molecular analogues and model polymers, in conjunction with quantum calculations, in order to identify the characteristic near edge spectral transitions of important chemical groups. This spectroscopic base is allowing the authors to study phase segregation in polyurethanes by taking advantage of several unique capabilities of scanning transmission x-ray microscopy (STXM) - high spatial resolution ({approximately} 0.1 {mu}m), high spectral resolution ({approximately}0.1 eV at the C 1s edge), and the ability to record images and spectra with relatively low radiation damage. The beamline 7.0 STXM at ALS is being used to study microtomed sections or cast films of polyurethanes. Based on the pioneering work of Ade, Kirz and collaborators at the NSLS X-1A STXM, it is clear that scanning X-ray transmission microscopy using soft X-rays can provide information about the chemical origin of phase segregation in radiation-sensitive materials on a sub-micron scale. This information is difficult or impossible to obtain by other means.

Characterization and properties of sepiolite/polyurethane nanocomposites

International Nuclear Information System (INIS)

Chen Hongxiang; Zheng Maosheng; Sun Hongying; Jia Qingming

2007-01-01

In situ polymerization method is employed to prepare sepiolite/polyurethane nanocomposite. The morphology and the dispersion of sepiolite in polyurethane have been characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy. The results show the sepiolite is dispersed homogeneously in the polyurethane matrix at a nanometer scale. The tensile test shows that the tensile strength and elongation at break for the nanocomposites increase with the addition of sepiolite as compared to those of the pure polyurethane. The TGA analysis reveals that the addition of nanofillers results in the higher thermal stability

Recording membrane potential changes through photoacoustic voltage sensitive dye

Science.gov (United States)

Zhang, Haichong K.; Kang, Jeeun; Yan, Ping; Abou, Diane S.; Le, Hanh N. D.; Thorek, Daniel L. J.; Kang, Jin U.; Gjedde, Albert; Rahmim, Arman; Wong, Dean F.; Loew, Leslie M.; Boctor, Emad M.

2017-03-01

Monitoring of the membrane potential is possible using voltage sensitive dyes (VSD), where fluorescence intensity changes in response to neuronal electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo systems for external detection. In contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near infrared light excitation and ultrasound detection. In this work, we develop the theoretical concept whereby the voltage-dependent quenching of dye fluorescence leads to a reciprocal enhancement of PA intensity. Based on this concept, we synthesized a novel near infrared photoacoustic VSD (PA-VSD) whose PA intensity change is sensitive to membrane potential. In the polarized state, this cyanine-based probe enhances PA intensity while decreasing fluorescence output in a lipid vesicle membrane model. With a 3-9 μM VSD concentration, we measured a PA signal increase in the range of 5.3 % to 18.1 %, and observed a corresponding signal reduction in fluorescence emission of 30.0 % to 48.7 %. A theoretical model successfully accounts for how the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate the voltage sensing capability of the dye, but also indicate the necessity of considering both fluorescence and absorbance spectral sensitivities in order to optimize the characteristics of improved photoacoustic probes. Together, our results demonstrate photoacoustic sensing as a potential new modality for sub-second recording and external imaging of electrophysiological and neurochemical events in the brain.

Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold

International Nuclear Information System (INIS)

Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

2014-01-01

The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO 3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. - Highlights: • The hydroxyapatite and silver nanoparticles were grown on the polyurethane scaffold • The hydroxyapatite/polyurethane acts as reducing agent, stabilizer and matrix for Ag • The samples were well characterized by SEM-EDX, XRD, XPS, UV-visible spectroscopy • The hydroxyapatite/silver polyurethane scaffold shows antibacterial property

Superficial physicochemical properties of polyurethane biomaterials as osteogenic regulators in human mesenchymal stem cells fates.

Science.gov (United States)

Shahrousvand, Mohsen; Sadeghi, Gity Mir Mohamad; Shahrousvand, Ehsan; Ghollasi, Marzieh; Salimi, Ali

2017-08-01

All of the cells' interactions are done through their surfaces. Evaluation of surface physicochemical scaffolds along with other factors is important and determines the fate of stem cells. In this work, biodegradable and biocompatible polyester/polyether based polyurethanes (PUs) were synthesized by polycaprolactone diol (PCL) and poly (tetra methylene ether) glycol (PTMEG) as the soft segment. To assess better the impact of surface parameters such as stiffness and roughness effects on osteogenic differentiation of the human mesenchymal stem cell (hMSC), the dimension effect of substrates was eliminated and two-dimensional membranes were produced by synthesized polyurethane. Surface and bulk properties of prepared 2D membranes such as surface chemistry, roughness, stiffness and tensile behavior were evaluated by Attenuated total reflectance Fourier transform infrared (ATR-FTIR), atomic force microscopy (AFM) and tensile behavior. The prepared 2D PU films had suitable hydrophilicity, biodegradability, water absorption, surface roughness and bulk strength. The hMSCs showed greater osteogenesis expression in PU substrates with more roughness and stiffness than others. The results demonstrated that surface parameters along with other differentiation cues have a synergistic effect on stem cells fates. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical sensitivity of Piezo1 ion channels can be tuned by cellular membrane tension

Science.gov (United States)

Lewis, Amanda H; Grandl, Jörg

2015-01-01

Piezo1 ion channels mediate the conversion of mechanical forces into electrical signals and are critical for responsiveness to touch in metazoans. The apparent mechanical sensitivity of Piezo1 varies substantially across cellular environments, stimulating methods and protocols, raising the fundamental questions of what precise physical stimulus activates the channel and how its stimulus sensitivity is regulated. Here, we measured Piezo1 currents evoked by membrane stretch in three patch configurations, while simultaneously visualizing and measuring membrane geometry. Building on this approach, we developed protocols to minimize resting membrane curvature and tension prior to probing Piezo1 activity. We find that Piezo1 responds to lateral membrane tension with exquisite sensitivity as compared to other mechanically activated channels and that resting tension can drive channel inactivation, thereby tuning overall mechanical sensitivity of Piezo1. Our results explain how Piezo1 can function efficiently and with adaptable sensitivity as a sensor of mechanical stimulation in diverse cellular contexts. DOI: http://dx.doi.org/10.7554/eLife.12088.001 PMID:26646186

Structure and Properties of Polyurethanes. Part 1,

Science.gov (United States)

1979-03-23

since the solidification of varnish coatings on basis it is polyurethane usually it occurs under conditions for contact wita moisture of air. Page...containing fluorine is polyurethane. In works (44, 84-86] is given the information about synthesis 11 DOC = 79011105 PAGE and special feature/peculiarities...of the phase transformations of the series/number of the fluorine -bedrlng aliphatic ones it is polyurethane. Page 87. In particular, were investigated

Mechanical Characterization of Rigid Polyurethane Foams

Energy Technology Data Exchange (ETDEWEB)

Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials

2014-12-01

Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

Characterization of synthesized polyurethane/montmorillonite nanocomposites foams

International Nuclear Information System (INIS)

Ansari, Farahnaz; Njuguna, James; Sachse, Sophia; Kavosh, Masoud; Michalowski, S; Pielichowski, Krzysztof

2014-01-01

Nanophased hybrid composites based on polyurethane/montmorillonite (PU/MMT) have been fabricated. The nanocomposite which was formed by the addition of a polyol premix with 4,4'-diphenylmethane diisocyanate to obtain nanophased polyurethane foams which were then used for fabrication of nanocomposite panels has been shown to have raised strength, stiffness and thermal insulation properties. The nanophased polyurethane foam was characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) measurements and X-ray diffraction (XRD). TEM and SEM analysis indicated that nanophased particles are dispersed homogeneously in the polyurethane matrix on the nanometer scale indicating that PU/MMT is an intercalated nanocomposite with a 2-3 nm nanolayer thickness

POLYURETHANE COMPOSITES AS DRUG CARRIERS:: RELEASE PATTERNS

Directory of Open Access Journals (Sweden)

M. V. Grigoreva

2013-10-01

Full Text Available Biodegradable polyurethanes attract interest of those developing composite materials for biomedical applications. One of their features is their ability to serve as carriers, or matrixes, for medicines and other bioactive compounds to produce a therapeutic effect in body through targeted and/or prolonged delivery of these compounds in the process of their controlled release from matrix. The review presents polyurethane composites as matrices for a number of drugs. The relation between structure of the composites and their degradability both in vitro and in vivo and the dependence of drug release kinetics on physicochemical properties of polyurethane matrix are highlighted. The release of drugs (cefazolin, naltrexone and piroxicam from the composites based on cross-linked polyurethanes (synthesized from laprols, Mw between 1,500 and 2,000 Da and toluylene diisocyanate demonstrated more or less the same pattern (about 10 days in vitro and three to five days in vivo. In contrast, the composites with dioxydine based on a linear polyurethanes (synthesized from oligotetramethilene glycol, Mw 1,000 Da, diphenylmethane-4,4’-diisocyanate and 1,4-butanediol retained their antimicrobial activity at least 30 days. They also showed a significantly higher breaking strength as compared to that of the composites based on cross-linked polyurethanes.

Novel route of synthesis for cellulose fiber-based hybrid polyurethane

Science.gov (United States)

Ikhwan, F. H.; Ilmiati, S.; Kurnia Adi, H.; Arumsari, R.; Chalid, M.

2017-07-01

Polyurethanes, obtained by the reaction of a diisocyanate compound with bifunctional or multifunctional reagent such as diols or polyols, have been studied intensively and well developed. The wide range modifier such as chemical structures and molecular weight to build polyurethanes led to designs of materials that may easily meet the functional product demand and to the extraordinary spreading of these materials in market. Properties of the obtained polymer are related to the chemical structure of polyurethane backbone. A number polyurethanes prepared from biomass-based monomers have been reported. Cellulose fiber, as a biomass material is containing abundant hydroxyl, promising material as chain extender for building hybrid polyurethanes. In previous researches, cellulose fiber was used as filler in synthesis of polyurethane composites. This paper reported a novel route of hybrid polyurethane synthesis, which a cellulose fiber was used as chain extender. The experiment performed by reacting 4,4’-Methylenebis (cyclohexyl isocyanate) (HMDI) and polyethylene glycol with variation of molecular weight to obtained pre-polyurethane, continued by adding micro fiber cellulose (MFC) with variation of type and composition in the mixture. The experiment was evaluated by NMR, FTIR, SEM and STA measurement. NMR and FTIR confirmed the reaction of the hybrid polyurethane. STA showed hybrid polyurethane has good thermal stability. SEM showed good distribution and dispersion of sorghum-based MFC.

Sorption of heteropoly acids by polyurethane foam

International Nuclear Information System (INIS)

Dmitreinko, S.G.; Goncharova, L.V.; Runov, V.K.; Zakharov, V.N.; Aslanova, L.A.

1997-01-01

Sorption of oxidized and reduced forms of molybdosilicic, molybdophosphoric and molybdovanadophosphoric acids by polyurethane foam based on ethers and esters is studied. On the basis of sorption dependence on solution pH, polyurethane foam type and spectral characteristics of sorbates the suggestion has been made that in the polyurethane foam phase there are two main types of sorbent-sorbate interaction: electrostatic (ion-ion) and with hydrogen bond formation: and it is impossible to determine the contribution of every interaction

Adhesion aspects of polyurethane foam sandwich panels.

OpenAIRE

Ng, Simon L.

2016-01-01

Sandwich panels, polyurethane foam sandwiched between two sheets of steel, form the walls and roofs in the construction of buildings. ArcelorMittal is a manufacturer of the steel as well as these finished panels. For this project they combined with a supplier of the polyurethane foams, Huntsman Polyurethanes, to joint-fund a research project investigating the fundamental mechanisms of adhesion, as well as the causes of failures in the product which manifests primarily in two different ways...

Polyurethane doped with low-concentration erbium

NARCIS (Netherlands)

Ciobanu, C.; Stoica, E.; Cascaval, C.N.; Rosu, D.; Rosu, L.; State, M.; Emandi, A.; Nemes, I.; Petrescu, F.

2007-01-01

ABSTRACT: Polyurethane (PU) with lactate structures inits conformation can be used as a biological and biodegradablepolymer. Polyurethane lactate (PUL) was dopedwith small quantities of an erbium (Er3þ) complex, whichhindered the N¼N group. 2,20-Dihydroxyazobenzene wasused as a ligand for the Er3þ

Thermal insulating materials consisting of polyurethane rigid foam. Production - application - properties. 2. ed.; Waermedaemmstoffe aus Polyurethan-Hartschaum. Herstellung - Anwendung - Eigenschaften

Energy Technology Data Exchange (ETDEWEB)

Endres, Edmund; Kleser, Joachim

2008-02-15

Using rigid polyurethane (PU) / polyisocyanurate (PIR) foam as a thermal insulation material enables a conservation of resources and energy conservation. Environmentally harmful emissions significantly are reduced. Under this aspect, the authors of the contribution report on the production, application, technical and physical properties of rigid polyurethane foams. Sustainable construction with rigid polyurethane foam, quality assurance and product certification are further topics of this paper.

SYNTHESIS, CHARACTERIZATION AND APPLICATION OF A POLYURETHANE-BASED SUPPORT FOR IMMOBILIZING MEMBRANE-BOUND LIPASE

Directory of Open Access Journals (Sweden)

M. S. Soares

Full Text Available Abstract This study conducted an assessment of polyurethane foams that were synthesized by one-shot process and used as a low-cost support to immobilize Mucor circinelloides URM 4182 whole-cells presenting high lipolytic activity. Polyols with different molecular weights (1100 to 6000 g mol-1 were applied to synthesize the polymer matrix, and the agitation speed effect was used for controlling the average pore size of the investigated polyurethane foams. The physical and mechanical properties of the polymers were evaluated by standard test methods, and their morphology was identified by Scanning Electron Microscopy. The immobilization procedure efficiency was assessed by quantifying the capability of the matrices to attach the cells and the catalytic activity of the biocatalysts in both aqueous (olive oil hydrolysis and non-aqueous media (ethanolysis of babassu oil under single and consecutive batch runs. Although all synthesized matrices were suitable to immobilize the whole cells with high catalytic performance, a better set of parameters was attained when the polyol ether with molecular weight of 6000 g mol-1 and 1100 g mol-1 was used. Both matrices yielded immobilized biocatalysts with high hydrolysis and transesterification activities, and exhibited a satisfactory operational stability with 96% and 81% retention of their initial hydrolytic and transesterification activities after three consecutive batch runs.

Palm oil based polyols for acrylated polyurethane production

International Nuclear Information System (INIS)

Rida Tajau; Mohd Hilmi Mahmood; Mek Zah Salleh; Khairul Zaman Mohd Dahlan; Rosley Che Ismail

2006-01-01

Palm oil becomes important renewable resources for the production of polyols for the polyurethane manufacturing industry. The main raw materials used for the production of acrylated polyurethane are polyols, isocyanates and hydroxyl terminated acrylate compounds. In these studies, polyurethane based natural polymer (palm oil), i.e., POBUA (Palm Oil Based Urethane Acrylate) were prepared from three different types of palm oil based polyols i.e., epoxidised palm oil (EPOP), palm oil oleic acid and refined, bleached and deodorized (RBD) palm olein based polyols. The performances of these three acrylated polyurethanes when used for coatings and adhesives were determined and compared with each other. (Author)

Marine biofouling resistance of polyurethane with biodegradation and hydrolyzation.

Science.gov (United States)

Xu, Wentao; Ma, Chunfeng; Ma, Jielin; Gan, Tiansheng; Zhang, Guangzhao

2014-03-26

We have prepared polyurethane with poly(ε-caprolactone) (PCL) as the segments of the main chain and poly(triisopropylsilyl acrylate) (PTIPSA) as the side chains by a combination of radical polymerization and a condensation reaction. Quartz crystal microbalance with dissipation studies show that polyurethane can degrade in the presence of enzyme and the degradation rate decreases with the PTIPSA content. Our studies also demonstrate that polyurethane is able to hydrolyze in artificial seawater and the hydrolysis rate increases as the PTIPSA content increases. Moreover, hydrolysis leads to a hydrophilic surface that is favorable to reduction of the frictional drag under dynamic conditions. Marine field tests reveal that polyurethane has good antifouling ability because polyurethane with a biodegradable PCL main chain and hydrolyzable PTIPSA side chains can form a self-renewal surface. Polyurethane was also used to carry and release a relatively environmentally friendly antifoulant, and the combined system exhibits a much higher antifouling performance even in a static marine environment.

Radiation-resistance of polyurethane pipes for cooling liquid in BES III

International Nuclear Information System (INIS)

Li Xunfeng; Zheng Lifang; Ji Quan; Wu Ping; Wang Li

2009-01-01

Gamma ray radiation and neutron radiation are predominant in the working conditions of BES III, and the radiation-resistance aging of polyurethane pipes is very important in this condition, as the pipes of cooling liquid for beam pipe and SCQ (superconducting quadrupole) vacuum pipe in BESIII. Polyester polyurethane pipes and polyether polyurethane pipes were irradiated by gamma ray and neutron. The radiation doses were as much as ten years' doses in BES. Pressure test, FTIR and thermal analysis were used to study the radiation-resistance of these two kinds of polyurethane pipes. The results show that the radiation-resistance and thermal stability of polyester polyurethane pipes are prior to those of polyether polyurethane pipes, and the pressure resistance of polyester polyurethane pipes is almost maintained after the irradiation by gamma ray and neutron, but the polyether polyurethane pipes can be aged and ruptured after the irradiation by neutron. (authors)

Development of a smart, anti-water polyurethane polymer hair coating for style setting.

Science.gov (United States)

Liu, Y; Liu, Y J; Hu, J; Ji, F L; Lv, J; Chen, S J; Zhu, Y

2016-06-01

The goal of this work was to develop a novel polyurethane polymer coating for the surface of the hair that could be used for style setting via the shape memory effect (SME). The features of the films are in accordance with conventional hair styling methods used in the laboratory. In this study, a new polyurethane polymer was synthesized; the morphology and mechanical behaviour of the coated hair were systematically investigated using a scanning electron microscope (SEM) and an Instron 5566 (with a temperature oven). The SME of the hair was tested using a 35-g weight and over five washing and drying cycles. The experimental result shows that the polyurethane polymer has effects on the mechanical behaviour of the hair. It indicates that the fixed shape (at 22°C) and recover rate (at 60°C) of different casted thickness films are similar. And the stress of the film becomes larger with increasing film thickness. Furthermore, the shape memory ability could be endowed with the hair styling using this polymer; the hair fibre could recover to the 65% of its original shape after five cycle deformation by 35 g mass under the heat-treated condition; it could recover its original setting styling even after 5th water washing and drying. The SEM results indicated that the microsurface of the hair is coated with the polymer membrane; it contributes to the shape memory ability of the coated hair to keep and recover to the original setting styling. The styling hair can return to the original hair because the polyurethane polymer can be washed out by water with suitable strength and shampoo totally which does not leave any flake. The polyurethane polymer-based hair setting agent has been developed successfully, and it could be coated evenly on the human hair with good hand feeling and SMEs. The SME is highly related to the quantity of polyurethane polymer solution, and the effect could be improved by increasing the solution quantity. The maximum deformation of the coated hair could

Time-dependent crashworthiness of polyurethane foam

Science.gov (United States)

Basit, Munshi Mahbubul; Cheon, Seong Sik

2018-05-01

Time-dependent stress-strain relationship as well as crashworthiness of polyurethane foam was investigated under constant impact energy with different velocities, considering inertia and strain-rate effects simultaneously during the impact testing. Even though the impact energies were same, the percentage in increase in densification strain due to higher impact velocities was found, which yielded the wider plateau region, i.e. growth in crashworthiness. This phenomenon is analyzed by the microstructure of polyurethane foam obtained from scanning electron microscopy. The equations, coupled with the Sherwood-Frost model and the impulse-momentum theory, were employed to build the constitutive equation of the polyurethane foam and calculate energy absorption capacity of the foam. The nominal stress-strain curves obtained from the constitutive equation were compared with results from impact tests and were found to be in good agreement. This study is dedicated to guiding designer use polyurethane foam in crashworthiness structures such as an automotive bumper system by providing crashworthiness data, determining the crush mode, and addressing a mathematical model of the crashworthiness.

Polyurethane-Foam Maskant

Science.gov (United States)

Bodemeijer, R.

1985-01-01

Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

Science.gov (United States)

Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

2014-02-01

The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. © 2013.

The Modification of Polyurethane Foams Using New Boroorganic Polyols (II) Polyurethane Foams from Boron-Modified Hydroxypropyl Urea Derivatives

Science.gov (United States)

2014-01-01

The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150°C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

Polyurethane-Coated Breast Implants Revisited: A 30-Year Follow-Up

Directory of Open Access Journals (Sweden)

Nikki Castel

2015-03-01

Full Text Available BackgroundPolyurethane coating of breast implants has been shown to reduce capsular contracture in short-term follow-up studies. This 30-year study is the longest examination of the use of polyurethane-coated implants and their correlation with capsular contracture.MethodsThis study evaluates the senior surgeon's (F.D.P. experience with the use of polyurethane-coated implants in aesthetic breast augmentation in 382 patients over 30 years. Follow-up evaluations were conducted for six months after surgery. After the six-month follow-up period, 76 patients returned for reoperation. The gross findings, histology, and associated capsular contracture were noted at the time of explantation.ResultsNo patient during the six-month follow-up period demonstrated capsular contracture. For those who underwent reoperation for capsular contracture, Baker II/III contractures were noted nine to 10 years after surgery and Baker IV contractures were noted 12 to 21 years after surgery. None of the explanted implants had macroscopic evidence of polyurethane, which was only found during the first five years after surgery. The microscopic presence of polyurethane was noted in all capsules up to 30 years after the original operation.ConclusionsAn inverse correlation was found between the amount of polyurethane coating on the implant and the occurrence of capsular contracture. Increasingly severe capsular contracture was associated with a decreased amount of polyurethane coating on the surface of the implants. No contracture occurred in patients whose implants showed incomplete biodegradation of polyurethane, as indicated by the visible presence of polyurethane coating. We recommend research to find a non-toxic, non-biodegradable synthetic material as an alternative to polyurethane.

Hydrophilic polyurethane matrix promotes chondrogenesis of mesenchymal stem cells☆

Science.gov (United States)

Nalluri, Sandeep M.; Krishnan, G. Rajesh; Cheah, Calvin; Arzumand, Ayesha; Yuan, Yuan; Richardson, Caley A.; Yang, Shuying; Sarkar, Debanjan

2016-01-01

Segmental polyurethanes exhibit biphasic morphology and can control cell fate by providing distinct matrix guided signals to increase the chondrogenic potential of mesenchymal stem cells (MSCs). Polyethylene glycol (PEG) based hydrophilic polyurethanes can deliver differential signals to MSCs through their matrix phases where hard segments are cell-interactive domains and PEG based soft segments are minimally interactive with cells. These coordinated communications can modulate cell–matrix interactions to control cell shape and size for chondrogenesis. Biphasic character and hydrophilicity of polyurethanes with gel like architecture provide a synthetic matrix conducive for chondrogenesis of MSCs, as evidenced by deposition of cartilage-associated extracellular matrix. Compared to monophasic hydrogels, presence of cell interactive domains in hydrophilic polyurethanes gels can balance cell–cell and cell–matrix interactions. These results demonstrate the correlation between lineage commitment and the changes in cell shape, cell–matrix interaction, and cell–cell adhesion during chondrogenic differentiation which is regulated by polyurethane phase morphology, and thus, represent hydrophilic polyurethanes as promising synthetic matrices for cartilage regeneration. PMID:26046282

Hydrophilic polyurethane matrix promotes chondrogenesis of mesenchymal stem cells.

Science.gov (United States)

Nalluri, Sandeep M; Krishnan, G Rajesh; Cheah, Calvin; Arzumand, Ayesha; Yuan, Yuan; Richardson, Caley A; Yang, Shuying; Sarkar, Debanjan

2015-09-01

Segmental polyurethanes exhibit biphasic morphology and can control cell fate by providing distinct matrix guided signals to increase the chondrogenic potential of mesenchymal stem cells (MSCs). Polyethylene glycol (PEG) based hydrophilic polyurethanes can deliver differential signals to MSCs through their matrix phases where hard segments are cell-interactive domains and PEG based soft segments are minimally interactive with cells. These coordinated communications can modulate cell-matrix interactions to control cell shape and size for chondrogenesis. Biphasic character and hydrophilicity of polyurethanes with gel like architecture provide a synthetic matrix conducive for chondrogenesis of MSCs, as evidenced by deposition of cartilage-associated extracellular matrix. Compared to monophasic hydrogels, presence of cell interactive domains in hydrophilic polyurethanes gels can balance cell-cell and cell-matrix interactions. These results demonstrate the correlation between lineage commitment and the changes in cell shape, cell-matrix interaction, and cell-cell adhesion during chondrogenic differentiation which is regulated by polyurethane phase morphology, and thus, represent hydrophilic polyurethanes as promising synthetic matrices for cartilage regeneration. Copyright © 2015 Elsevier B.V. All rights reserved.

Biodegradative Activities of Selected Environmental Fungi on a Polyester Polyurethane Varnish and Polyether Polyurethane Foams.

Science.gov (United States)

Álvarez-Barragán, Joyce; Domínguez-Malfavón, Lilianha; Vargas-Suárez, Martín; González-Hernández, Ricardo; Aguilar-Osorio, Guillermo; Loza-Tavera, Herminia

2016-09-01

Polyurethane (PU) is widely used in many aspects of modern life because of its versatility and resistance. However, PU waste disposal generates large problems, since it is slowly degraded, there are limited recycling processes, and its destruction may generate toxic compounds. In this work, we isolated fungal strains able to grow in mineral medium with a polyester PU (PS-PU; Impranil DLN) or a polyether PU (PE-PU; Poly Lack) varnish as the only carbon source. Of the eight best Impranil-degrading strains, the six best degraders belonged to the Cladosporium cladosporioides complex, including the species C. pseudocladosporioides, C. tenuissimum, C. asperulatum, and C. montecillanum, and the two others were identified as Aspergillus fumigatus and Penicillium chrysogenum The best Impranil degrader, C. pseudocladosporioides strain T1.PL.1, degraded up to 87% after 14 days of incubation. Fourier transform infrared (FTIR) spectroscopy analysis of Impranil degradation by this strain showed a loss of carbonyl groups (1,729 cm(-1)) and N-H bonds (1,540 and 1,261 cm(-1)), and gas chromatography-mass spectrometry (GC-MS) analysis showed a decrease in ester compounds and increase in alcohols and hexane diisocyanate, indicating the hydrolysis of ester and urethane bonds. Extracellular esterase and low urease, but not protease activities were detected at 7 and 14 days of culture in Impranil. The best eight Impranil-degrading fungi were also able to degrade solid foams of the highly recalcitrant PE-PU type to different extents, with the highest levels generating up to 65% of dry-weight losses not previously reported. Scanning electron microscopy (SEM) analysis of fungus-treated foams showed melted and thinner cell wall structures than the non-fungus-treated ones, demonstrating fungal biodegradative action on PE-PU. Polyurethane waste disposal has become a serious problem. In this work, fungal strains able to efficiently degrade different types of polyurethanes are reported, and

Microfabricated hydrogen sensitive membranes

Energy Technology Data Exchange (ETDEWEB)

Naddaf, A.; Kraetz, L. [Lehrstuhl fuer Thermische Verfahrenstechnik, Technische Universitaet Kaiserslautern (Germany); Detemple, P.; Schmitt, S.; Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Faqir, N. [University of Jordan, Amman (Jordan); Bart, H.J.

2009-01-15

Thin, defect-free palladium, palladium/copper and palladium/silver hydrogen absorbing membranes were microfabricated. A dual sputtering technique was used to deposit the palladium alloy membranes of only 1 {mu}m thickness on a nonporous silicon substrate. Advanced silicon etching (ASE) was applied on the backside to create a mechanically stable support structure for the thin films. Performance evaluation was carried out for different gases in a temperature range of 20 C to 298 C at a constant differential pressure of 110 kPa at the two sides of the membrane. The composite membranes show an excellent permeation rate of hydrogen, which appears to be 0.05 Pa m{sup 3} s{sup -1} and 0.01.10{sup -3} Pa m{sup 3} s{sup -1} at 20 C for the microfabricated 23 % silver and the 53 % copper composite membranes, respectively. The selectivity to hydrogen over a gas mixture containing, in addition to hydrogen, carbon monoxide, carbon dioxide and nitrogen was measured. The mass spectrometer did not detect any CO{sub 2} or CO, showing that the membrane is completely hydrogen selective. The microfabricated membranes exhibit both high mechanical strength (they easily withstand pressures up to 4 bar) and high thermal stability (up to 650 C). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Rigid Polyurethane Foam Reinforced Coconut Coir Fiber Properties

OpenAIRE

Mohd Azham Azmi

2012-01-01

This research work studied the properties of composite foam panels. Coconut coir fibers were used as reinforcement in polyurethane (PU) foam in order to increase the properties of foam. This composite foam panels were fabricated by using polyurethane molded method. The polyurethane foam panels reinforced from 5 to 20wt% coconut coir were produced to investigate the physical and mechanical test via density test and three point bending test respectively. It was found that the density test resul...

Thermo-and pH-sensitive hydrogel membranes composed of poly(N-isopropylacrylamide)-hyaluronan for biomedical applications: Influence of hyaluronan incorporation on the membrane properties.

Science.gov (United States)

Kamoun, Elbadawy A; Fahmy, Alaa; Taha, Tarek H; El-Fakharany, Esmail M; Makram, Mohamed; Soliman, Hesham M A; Shehata, Hassan

2018-01-01

Interpenetrating hydrogel membranes consisting of pH-sensitive hyaluronan (HA) and thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAM) were synthesized using redox polymerization, followed by N,N-methylenebisacrylamide (BIS) and epichlorohydrin (EPI) were added as chemical crosslinkers. The interaction between membrane compositions has been characterized by FTIR spectroscopy and discussed intensively. The result indicates that HA incorporation in membranes increase the gel fraction, swelling uptake, and the flexibility/elasticity of crosslinked membranes, however it reduced oppositely the mechanical elongation of membranes. PNIPAAm-HA hydrogels responded to both temperature and pH changes and the stimuli-responsiveness was reversible. However, in vitro bioevaluation results revealed that the released ampicillin during the burst release time was sharply influenced and increased with increasing HA contents in membranes; afterwards it became sustainable. Whereas, high HA contents in hydrogels unexpectedly impacted negatively on the cells viability, owing to the viscosity of cell culture media changed. A big resistance was observed against microbial growth of Staphylococcus aureus, Salmonella typhi, and Candida albicans in case of pure PNIPAAm hydrogel membranes without HA or ampicillin. However, HA incorporation or the loaded ampicillin in membranes showed unexpected easily microbial growth. The fast release performance with dual pH-thermo-sensitive hydrogels were suggested as promising materials for quick drug carrier in the biomedical field. Copyright © 2017 Elsevier B.V. All rights reserved.

Formulation, Preparation, and Characterization of Polyurethane Foams

Science.gov (United States)

Pinto, Moises L.

2010-01-01

Preparation of laboratory-scale polyurethane foams is described with formulations that are easy to implement in experiments for undergraduate students. Particular attention is given to formulation aspects that are based on the main chemical reactions occurring in polyurethane production. This allows students to develop alternative formulations to…

Morphology and damping behavior of polyurethane/PMMA simultaneous interpenetrating networks

Directory of Open Access Journals (Sweden)

Wang S.H.

2001-01-01

Full Text Available A series of polyurethane/PMMA simultaneous interpenetrating networks (SINs with various hard segment contents (X in the polyurethane phase (X = 15.5 to 36.5% in polyurethane and wide range of polyurethane (PU to polyacrylate (PA ratio (PU/PA = 20:80 to 80:20 were prepared, and the damping and mechanical properties of these materials were studied. The damping of polyurethane soft phase was increased and shifted to lower temperature with increased content of PA vitreous phase. The mechanical properties were improved with increasing PA contents. The results show that PA and the polyurethane hard segment interaction play a special role in chain interpenetration density and its magnitude is revealed by the decreased dispersed domain size observed by scanning electron microscopy (SEM and increased loss area as measured by dynamic mechanical thermal analysis (DMTA. When the weight ratio of PU/PA was 40:60, the resulting SIN materials possessed better damping properties, independent of X concentration.

Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

Directory of Open Access Journals (Sweden)

Wenjing Xia

2017-08-01

Full Text Available The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI, hydroxyl terminated polybutadiene (HTPB, 1,4-butanediol (BDO, and 2-hydroxyethyl acrylate (HEA. Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane coatings significantly enhanced the hydrophobic property, mechanical property, pencil hardness, and glossiness of the polyurethane coatings. This method of preparing UV crosslinkable, hydrophobic polyurethane coatings based on thiol-ene chemistry exhibited numerous advantages over other UV photocuring systems.

Double-chain phospholipid end-capped polyurethanes: Synthesis, characterization and platelet adhesion study

International Nuclear Information System (INIS)

Tan Dongsheng; Zhang Xiaoqing; Li Jiehua; Tan Hong; Fu Qiang

2012-01-01

A novel phospholipid containing double chains and phosphotidylcholine polar head groups, 2-(10-(2-aminoethylamino)-10-oxodecanamido)-3-(decyloxy)-3-oxopropyl phosphorylcholine (ADDPC), was synthesized and characterized. Two kinds of double-chain phospholipid end-capped polyurethanes with different soft segments were prepared. The structure of prepared polyurethanes was characterized by X-ray photoelectron spectroscopic (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometry and atomic force microscope (AFM), which indicated that the double-chain phospholipids enriched onto the top surface of the prepared polyurethane films. The preliminary evaluation of blood compatibility showed that these novel phospholipid end-capped polyurethanes could suppress platelet adhesion and activation effectively. This property did not depend on the chemical structure of polyurethanes. In addition, according to tensile test results, the phospholipid polyurethanes kept good mechanical properties in comparison with original polyurethanes. It is suggested that double-chain phospholipid end-caption has good potential for achieving both hemocompatibility and good mechanical properties simultaneously for polyurethanes.

Study on thermal properties of synthetic and bio-based polyurethane

Directory of Open Access Journals (Sweden)

Šercer Mladen

2015-01-01

Full Text Available Polymers that are created by the chemical polymerization of naturally occurring monomers are attracting considerable commercial interest in the last few years because of their non-toxicity, biodegradability and biocompatibility and use of feedstock that is renewable. The development of specialized lignin compounds, such as electrically conducting polymers, engineering plastics and polyurethane, is an area of highest interest and growth. The paper will present the comparison of the mechanical and thermal properties of conventional polyurethane and bio-based polyurethane, i.e. polyurethane based on polyols produced by liquefaction of waste wood biomass.

Bioactive polyurethane implants with hydroxyapatite

Energy Technology Data Exchange (ETDEWEB)

Rozhnova, R.; Kebuladze, I.; Galatenko, N. [NAS Ukraine, Kiev (Ukraine). Dept. of Polymers of Medical Appointment

2001-07-01

Biologically active polyurethane compositions for plastic of bone defects that contain bioceramic - hydroxyapatite (HAP) and immunomodulator - levamisole (LEV) were designed. The influence of the biologically active fillers in structure polyurethane compositions on their physical and chemical properties in condition in vivo by method of Equilibrium Swelling, method of IR-spectroscopy, roentgen-structural analysis was studied. The introduce in structure of the biodegraded polymeric matrix of HAP is established to promote accumulation of the inorganic component of bone tissue in vivo which is being by basis of the bone formation in regenerating tissue. (orig.)

Spectral Properties and Orientation of Voltage-Sensitive Dyes in Lipid Membranes

KAUST Repository

Matson, Maria; Carlsson, Nils; Beke-Somfai, Tamá s; Nordé n, Bengt

2012-01-01

Voltage-sensitive dyes are frequently used for probing variations in the electric potential across cell membranes. The dyes respond by changing their spectral properties: measured as shifts of wavelength of absorption or emission maxima

Recording membrane potential changes through photoacoustic voltage sensitive dye

DEFF Research Database (Denmark)

Zhang, Haichong K.; Kang, Jeeun; Yan, Ping

2017-01-01

Monitoring of the membrane potential is possible using voltage sensitive dyes (VSD), where fluorescence intensity changes in response to neuronal electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo...... systems for external detection. In contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near infrared light excitation and ultrasound detection. In this work, we develop the theoretical concept whereby the voltage-dependent quenching...... the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate the voltage sensing capability of the dye, but also indicate the necessity of considering both fluorescence and absorbance spectral sensitivities in order to optimize...

Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility.

Science.gov (United States)

Dawlee, S; Jayabalan, Muthu

2011-10-01

Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility

International Nuclear Information System (INIS)

Dawlee, S; Jayabalan, Muthu

2011-01-01

Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility

Energy Technology Data Exchange (ETDEWEB)

Dawlee, S; Jayabalan, Muthu, E-mail: muthujayabalan@rediffmail.com [Polymer Science Division, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala 695 012 (India)

2011-10-15

Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

Urinary catheter with polyurethane coating modified by ion implantation

International Nuclear Information System (INIS)

Kondyurina, I.; Nechitailo, G.S.; Svistkov, A.L.; Kondyurin, A.; Bilek, M.

2015-01-01

A low friction urinary catheter that could be used without a lubricant is proposed in this work. A polyurethane coating was synthesised on the surface of a metal guide wire catheter. Ion implantation was applied to surface modify the polyurethane coating. FTIR ATR, wetting angle, AFM and friction tests were used for analysis. Low friction was found to be provided by the formation of a hard carbonised layer on the polyurethane surface

Monitoring voltage-sensitive membrane impedance change using radio frequency interrogation.

Science.gov (United States)

Dharia, Sameera; Rabbitt, Richard D

2010-01-01

Here we present a new technique to monitor dynamic conformational changes in voltage-sensitive membrane-bound proteins using radio frequency (RF) impedance measurements. Xenopus oocytes were transfected to express ShakerB-IR K(+) ion channels, and step changes in membrane potential were applied using two-electrode voltage clamp (TEVC). Simultaneously, bipolar extracellular electrodes were used to measure the RF electrical impedance across the cell (300 kHz - 1 MHz). RF current will either pass through the media, around the cell, or displace charge across the cell membrane. The change in displacement current in the cell membrane during voltage clamp resulted in measurable RF impedance change. RF impedance change during DC membrane depolarization was significantly greater in ShakerB-IR expressing oocytes than in endogenous controls at 300 kHz, 500 kHz and, to a lesser extent, 1 MHz. Since the RF were too high to modulate ShakerB-IR protein conformational state (e.g. open channel probability), impedance changes are interpreted as reflections of voltage-dependent protein conformation and associated biophysics such as ion-channel dipole interactions, fluctuations in bound water, or charged lipid head-group rotations.

Szycher's handbook of polyurethanes

National Research Council Canada - National Science Library

Szycher, M

2013-01-01

.... Filled with tables, charts, and photographs, it includes new data on green polyurethanes, automotive applications, new coatings, new manufacturing equipment, new health-care uses, and other topics...

Molecular simulation of fibronectin adsorption onto polyurethane surfaces

Science.gov (United States)

Polyethylene glycol-based polyurethanes have been widely used in biomedical applications, however are prone to swelling. A natural polyol, castor oil can be incorporated into these polyurethanes to control the degree of the swelling, which alters mechanical properties and protein adsorption characte...

Indoor air pollution evaluation with emphasize on HDI and biological assessment of HDA in the polyurethane factories.

Science.gov (United States)

Mirmohammadi, Mirtaghi; Hakimi Ibrahim, M; Ahmad, Anees; Kadir, Mohd Omar Abdul; Mohammadyan, M; Mirashrafi, S B

2010-06-01

Today, many raw materials used in factories may have a dangerous effect on the physiological system of workers. One of them which is widely used in the polyurethane factories is diisocyanates. These compounds are widely used in surface coatings, polyurethane foams, adhesives, resins, elastomers, binders, and sealants. Exposure to diisocyanates causes irritation to the skin, mucous membranes, eyes, and respiratory tract. Hexamethylene diamine (HDA) is metabolite of hexamethylene diisocyanate (HDI). It is an excretory material by worker's urine who is exposed to HDI. Around 100 air samples were collected from five defined factories by midget impinger which contained dimethyl sulfoxide absorbent as a solvent and tryptamine as reagent. Samples were analyzed by high-performance liquid chromatography with EC\\UV detector using NIOSH 5522 method of sampling. Also, 50 urine samples collected from workers were also analyzed using William's biological analysis method. The concentration of HDI into all air samples were more than 88 microg/m(3), and they have shown high concentration of pollutant in the workplaces in comparison with NIOSH standard, and all of the workers' urine were contaminated by HDA. The correlation and regression test were used to obtain statistical model for HDI and HDA, which is useful for the prediction of diisocyanates pollution situation in the polyurethane factories.

Polyurethane adhesives in flat roofs

Directory of Open Access Journals (Sweden)

Bogárová Markéta

2017-01-01

Full Text Available It is necessary to stabilize individual layers of flat roofs, mainly because of wind suction. Apart from anchoring and surcharge, these layers can be secured by bonding. At present gluing is an indispensable and widely used stabilization method. On our market we can found many types of adhesives, most widely used are based on polyurethane. This paper focuses on problematic about stabilization thermal insulation from expanded polystyrene to vapor barrier from bitumen. One of the main issues is to calculate the exact amount of adhesive, which is required to guarantee the resistance against wind suction. In this problematic we can not find help neither in technical data sheets provided by the manufactures. Some of these data sheets contain at least information about amount of adhesive depending on location in roof plane and building height, but they do not specify the strength of such connection. It was therefore resorted to select several representatives polyurethane adhesives and their subsequent testing on specimens simulating the flat roof segment. The paper described the test methodology and results for two types of polyurethane adhesives.

40 CFR 63.1293 - Standards for slabstock flexible polyurethane foam production.

Science.gov (United States)

2010-07-01

... polyurethane foam production. 63.1293 Section 63.1293 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CATEGORIES National Emission Standards for Hazardous Air Pollutants for Flexible Polyurethane Foam Production § 63.1293 Standards for slabstock flexible polyurethane foam production. Each owner or operator of a...

Cylindrical multiwire two-coordinate chamber with foam-polyurethane supporting element

International Nuclear Information System (INIS)

Vakhtin, V.G.; Travkin, V.I.

1988-01-01

Construction and technology of producing the two-coordinate cylindrical chamber with foam-polyurethane supporting element are described. Use of foam-polyurethane permits to reduce the substance quantity at particle path up to 0.2 g/cm 2 . The supporting element represents a foam-polyurethane tube the outside diameter being 126 mm, the thickness - 6.5 mm and the length 600 mm. Special attention was paid to study of elastic properties of foam-polyurethane tubes and to the effect of the chamber working fluid vapors on the tube sizes. It is stated that after a sustained load (3750 N for 6 days) the tube shrinks by 1.25 %. The foam-polyurethane supporting element arranged in 50% argon + 33% methane + 17% methylane mixture didn't change its sizes in the limit of 0.05% for three weeks. The chamber operates under self-qquenching streamer conditions

Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

OpenAIRE

Wenjing Xia; Nianqing Zhu; Rongjie Hou; Wengui Zhong; Mingqing Chen

2017-01-01

The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI), hydroxyl terminated polybutadiene (HTPB), 1,4-butanediol (BDO), and 2-hydroxyethyl acrylate (HEA). Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane ...

40 CFR 721.8079 - Isophorone diisocyanate neopentyl glycol adipate polyurethane prepolymer.

Science.gov (United States)

2010-07-01

... glycol adipate polyurethane prepolymer. 721.8079 Section 721.8079 Protection of Environment ENVIRONMENTAL... adipate polyurethane prepolymer. (a) Chemical substance and significant new uses subject to reporting. (1... polyurethane prepolymer (PMN P-94-1743) is subject to reporting under this section for the significant new uses...

40 CFR 63.1300 - Standards for molded flexible polyurethane foam production.

Science.gov (United States)

2010-07-01

... polyurethane foam production. 63.1300 Section 63.1300 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CATEGORIES National Emission Standards for Hazardous Air Pollutants for Flexible Polyurethane Foam Production § 63.1300 Standards for molded flexible polyurethane foam production. Each owner or operator of a new...

Applicability of liquid radiopaque polyurethane for transcatheter embolization

International Nuclear Information System (INIS)

Novak, D.; Wieners, H.; Rueckner, R.

1983-01-01

Polyurethane Bayer was tested as an occlusive agent for experimental embolization in postmortem and postnephrectomy kidneys which served as a tumor model. Coaxial and balloon catheters were used for the embolization. To make polyurethane radiopaque, the material was labeled with different water-soluble, oily and solid contrast agents. Best results were achieved with oily contrast materials, e.g., Pantopaque. We found that polyurethane can easily be injected during a predetermined working time of 8-10 min. The embolization results in a complete, permanent, and homogeneous occlusion of the proximal arterial branches and small peripheral vessels. (orig.)

Membrane distillation with porous metal hollow fibers for the concentration of thermo-sensitive solutions

NARCIS (Netherlands)

Shukla, Sushumna

2014-01-01

This thesis presents an original approach for the concentration of thermo-sensitive solutions: the Sweep Gas Membrane Distillation (SGMD) process. A new membrane contactor with metallic hollow fibers has been designed and allows the distillation process to be operational at low temperature. Heat is

Microphase separated structure and surface properties of fluorinated polyurethane resin

International Nuclear Information System (INIS)

Sudaryanto; Nishino, T.; Hori, Y.; Nakamae, K.

2000-01-01

The effect of fluorination on microphase separation and surface properties of segmented polyurethane (PU) resin were investigated. A series of fluorinated polyurethane resin (FPU) was synthesized by reacting a fluorinated diol with aromatic diisocyanate. The microphase separated structure of FPU was studied by thermal analysis, and small angle X-ray scattering (SAXS) as well as wide angle X-ray diffraction (WAXD). The surface structure and properties were characterized by X-ray photoelectron spectroscopy (XPS) and dynamic contact angle measurement. The incorporation of fluorine into hard segment brings the FPU to have a higher hard domain cohesion and increase the phase separation, however localization of fluorine on the surface could not be observed. On the other hands, localization of fluorine on the surface could be achieved for soft segment fluorinated PU without any significant change in microphase separated structure. The result from this study give an important basic information for designing PU coating material with a low surface energy and strong adhesion as well as for development of release film on pressure sensitive adhesive tape. (author)

Second order elasticity at hypersonic frequencies of reactive polyurethanes as seen by generalized Cauchy relations

International Nuclear Information System (INIS)

Philipp, M; Vergnat, C; Mueller, U; Sanctuary, R; Baller, J; Krueger, J K; Possart, W; Alnot, P

2009-01-01

The non-equilibrium process of polymerization of reactive polymers can be accompanied by transition phenomena like gelation or the chemical glass transition. The sensitivity of the mechanical properties at hypersonic frequencies-including the generalized Cauchy relation-to these transition phenomena is studied for three different polyurethanes using Brillouin spectroscopy. As for epoxies, the generalized Cauchy relation surprisingly holds true for the non-equilibrium polymerization process and for the temperature dependence of polyurethanes. Neither the sol-gel transition nor the chemical and thermal glass transitions are visible in the representation of the generalized Cauchy relation. Taking into account the new results and combining them with general considerations about the elastic properties of the isotropic state, an improved physical foundation of the generalized Cauchy relation is proposed.

Second order elasticity at hypersonic frequencies of reactive polyurethanes as seen by generalized Cauchy relations

Energy Technology Data Exchange (ETDEWEB)

Philipp, M; Vergnat, C; Mueller, U; Sanctuary, R; Baller, J; Krueger, J K [Laboratoire de Physique des Materiaux, Universite du Luxembourg, 162A, avenue de la Faiencerie, L-1511 Luxembourg (Luxembourg); Possart, W [Fachbereich Werkstoffwissenschaften, Universitaet des Saarlandes, D-66123 Saarbruecken (Germany); Alnot, P [LPMI, Universite Nancy (France)], E-mail: martine.philipp@uni.lu

2009-01-21

The non-equilibrium process of polymerization of reactive polymers can be accompanied by transition phenomena like gelation or the chemical glass transition. The sensitivity of the mechanical properties at hypersonic frequencies-including the generalized Cauchy relation-to these transition phenomena is studied for three different polyurethanes using Brillouin spectroscopy. As for epoxies, the generalized Cauchy relation surprisingly holds true for the non-equilibrium polymerization process and for the temperature dependence of polyurethanes. Neither the sol-gel transition nor the chemical and thermal glass transitions are visible in the representation of the generalized Cauchy relation. Taking into account the new results and combining them with general considerations about the elastic properties of the isotropic state, an improved physical foundation of the generalized Cauchy relation is proposed.

Second order elasticity at hypersonic frequencies of reactive polyurethanes as seen by generalized Cauchy relations.

Science.gov (United States)

Philipp, M; Vergnat, C; Müller, U; Sanctuary, R; Baller, J; Possart, W; Alnot, P; Krüger, J K

2009-01-21

The non-equilibrium process of polymerization of reactive polymers can be accompanied by transition phenomena like gelation or the chemical glass transition. The sensitivity of the mechanical properties at hypersonic frequencies-including the generalized Cauchy relation-to these transition phenomena is studied for three different polyurethanes using Brillouin spectroscopy. As for epoxies, the generalized Cauchy relation surprisingly holds true for the non-equilibrium polymerization process and for the temperature dependence of polyurethanes. Neither the sol-gel transition nor the chemical and thermal glass transitions are visible in the representation of the generalized Cauchy relation. Taking into account the new results and combining them with general considerations about the elastic properties of the isotropic state, an improved physical foundation of the generalized Cauchy relation is proposed.

Hyaluronan Immobilized Polyurethane as a Blood Contacting Material

Directory of Open Access Journals (Sweden)

Feirong Gong

2010-01-01

Full Text Available Hyaluronan (hyaluronic acid, HA was immobilized onto the surface of amino-functionalized polyurethane films with the goal of obtaining a novel kind of biomaterial which had the potential in blood-contacting applications. The amino-functionalized polyurethane was prepared by synthesized acidic polyurethane whose pendant carboxyl groups were treated with an excess amount of 1,3-diaminopropane in the presence of N,N-carbonyldiimidazole (CDI. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR, Raman spectroscopy (RS, scanning electron microscopy (SEM, and water contact angle measurement were used to confirm the surface changes at each step of treatment, both in morphologies and chemical compositions. APTT and PT results showed that HA immobilization could prolong the blood coagulation time, thus HA-immobilized polyurethane (PU-HA exhibited improved blood compatibility. Cytotoxicity analysis showed that the PU-HA films synthesized in this study were cytocompatible and could support human vein endothelial cells (HUVECs adhesion and proliferation.

Fast-Responding Bio-Based Shape Memory Thermoplastic Polyurethanes.

Science.gov (United States)

Petrović, Zoran S; Milić, Jelena; Zhang, Fan; Ilavsky, Jan

2017-07-14

Novel fast response shape-memory polyurethanes were prepared from bio-based polyols, diphenyl methane diisocyanate and butane diol for the first time. The bio-based polyester polyols were synthesized from 9-hydroxynonanoic acid, a product obtained by ozonolysis of fatty acids extracted from soy oil and castor oil. The morphology of polyurethanes was investigated by synchrotron ultra-small angle X-ray scattering, which revealed the inter-domain spacing between the hard and soft phases, the degree of phase separation, and the level of intermixing between the hard and soft phases. We also conducted thorough investigations of the thermal, mechanical, and dielectric properties of the polyurethanes, and found that high crystallization rate of the soft segment gives these polyurethanes unique properties suitable for shape-memory applications, such as adjustable transition temperatures, high degree of elastic elongations, and good mechanical strength. These materials are also potentially biodegradable and biocompatible, therefore suitable for biomedical and environmental applications.

Reflectance spectroscopy from TiO2 particles embedded in polyurethane

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

2013-01-01

This paper presents the results of a physical simulation carried out using TiO2-Polyurethane composite coating on bright aluminium surface to understand the light scattering effect for designing white surfaces. Polyurethane matrix is selected due to the matching refractive index (1.7) with Al2O3...... layer on anodized aluminium surfaces. Three different TiO2 particle distributions were dispersed in polyurethane and spin coated onto high gloss and caustic etched aluminium substrates. Reflectance spectra of TiO2-polyurethane films of various concentrations were analysed using an integrating sphere....... The results show that the TiO2-polyurethane coatings have a high diffuse reflectance as a result of multiple scattering from TiO2 particles. Diffuse reflectance spectra of TiO2 containing films vary weakly with particle concentration and reach a steady state value at a concentration of 0.75 wt.%. Using...

[In Situ Polymerization and Characterization of Hydroxyapatite/polyurethane Implanted Material].

Science.gov (United States)

Gu, Muqing; Xiao, Fengjuan; Liang, Ye; Yue, Lin; Li, Song; Li, Lanlan; Feng, Feifei

2015-08-01

In order to improve the interfacial bonding strength of hydroxyapatite/polyurethane implanted material and dispersion of hydroxyapatite in the polyurethane matrix, we in the present study synthesized nano-hydroxyapatite/polyurethane composites by in situ polymerization. We then characterized and analyzed the fracture morphology, thermal stability, glass transition temperature and mechanical properties. We seeded MG63 cells on composites to evaluate the cytocompatibility of the composites. In situ polymerization could improve the interfacial bonding strength, ameliorate dispersion of hydroxyapatite in the properties of the composites. After adding 20 wt% hydroxyapatite into the polyurethane, the thermal stability was improved and the glass transition temperatures were increased. The tensile strength and maximum elongation were 6.83 MPa and 861.17%, respectively. Compared with those of pure polyurethane the tensile strength and maximum elongation increased by 236.45% and 143.30%, respectively. The composites were helpful for cell adhesion and proliferation in cultivation.

The In Vivo Pericapsular Tissue Response to Modern Polyurethane Breast Implants.

Science.gov (United States)

Frame, James; Kamel, Dia; Olivan, Marcelo; Cintra, Henrique

2015-10-01

Polyurethane breast implants were first introduced by Ashley (Plast Reconstr Surg 45:421-424, 1970), with the intention of trying to reduce the high incidence of capsular contracture associated with smooth shelled, high gel bleed, silicone breast implants. The sterilization of the polyurethane foam in the early days was questionable. More recently, ethylene oxide (ETO)-sterilized polyurethane has been used in the manufacturing process and this has been shown to reduce the incidence of biofilm. The improved method of attachment of polyurethane onto the underlying high cohesive gel, barrier shell layered, silicone breast implants also encourages bio-integration. Polyurethane covered, cohesive gel, silicone implants have also been shown to reduce the incidence of other problems commonly associated with smooth or textured silicone implants, especially with reference to displacement, capsular contracture, seroma, reoperation, biofilm and implant rupture. Since the introduction of the conical polyurethane implant (Silimed, Brazil) into the United Kingdom in 2009 (Eurosurgical, UK), we have had the opportunity to review histology taken from the capsules of polyurethane implants in three women ranging from a few months to over 3 years after implantation. All implants had been inserted into virgin subfascial, extra-pectoral planes. The results add to the important previously described histological findings of Bassetto et al. (Aesthet Plast Surg 34:481-485, 2010). Five distinct layers are identified and reasons for the development of each layer are discussed. Breast capsule around polyurethane implants, in situ for fifteen and 20 years, has recently been obtained and analysed in Brazil, and the histology has been incorporated into this study. After 20 years, the polyurethane is almost undetectable and capsular contracture may appear. These findings contribute to our understanding of polyurethane implant safety, and give reasoning for a significant reduction in clinical

Occupational allergic and irritant contact dermatitis in workers exposed to polyurethane foam

Directory of Open Access Journals (Sweden)

Marta Kieć-Świerczyńska

2014-04-01

Full Text Available Objectives: To evaluate sensitization to chemicals present in work environment after an outbreak of contact dermatitis in workers of vehicle equipment factory, exposed to polyurethane foam, based on 4,4'-diphenylmethane diisocyanate (MDI. Material and Methods: From among 300 employees, 21 individuals reporting work-related skin and/or respiratory tract symptoms underwent clinical examination, patch testing, skin prick tests, spirometry and MDI sIgE measurement in serum. Patch tests included isocyanates series, selected rubber additives, metals, fragrances, preservatives, and an antiadhesive agent. Results: Clinical examination revealed current eczema in the area of hands and/or forearms in 10 workers. Positive patch test reactions were found in 10 individuals, the most frequent to diaminodiphenylmethane and 4-phenylenediamine (7 persons. Reactions to an antiadhesive agent were assessed as irritant (5 workers. Except for sensitization to common aeroallergens, no significant abnormalities were found in the remaining tests. Occupational allergic contact dermatitis was diagnosed in 7 workers, irritant contact dermatitis in 10 and coexisiting allergic and irritant contact dermatitis in 3 workers. Conclusions: In workers manufacturing products from polyurethane foam, attention should be paid to the risk of developing contact dermatitis. Skin problems in our study group were attributable probably to insufficient protection of the skin.

Polyurethane Production from Waste Bale Fibers

Directory of Open Access Journals (Sweden)

İbrahim BİLİCİ

2017-12-01

Full Text Available Nowadays, the methods of eliminating the pollution from wastes of the materials produced as much as the production methods are important. This requires efficiently use of sources economical and ecologically. Polyester based polymers, which is one of the most important consumed plastic materials in the world, have lots of number of recycling methods. Basically it is called chemical and physical recycling. Chemical recycle methods include glycolysis, aminolysis, methanolysis, hydrolysis and etc.. In this study aromatic polyester polyols produced from bale fiber wastes via glycolysis method. Zinc Acetate used as a catalysts and diethylene glycol used for the glycolysis reaction and moiety of glycol investigated as an experimental parameter. Polyurethane material produced via obtained polyol and TDI (Toluene di Isocyanate reaction. Obtained polyurethane material investigated via FTIR and TGA and compared with the commercial polyurethane. As a result, it has been decided that glycolysis is usable and applicable method for the waste bale fibers.

Degradation mechanism of polyurethane foam induced by electron beam irradiation

International Nuclear Information System (INIS)

Huang Wei; Fu Yibei; Bian Zhishang; He Meiying

2002-01-01

The degradation mechanism of irradiated polyurethane foam has been studied in detail. The changes of chemical structure and micro-phase separation have been determined by DTG. The gas products from irradiated samples are analyzed quantitatively and qualitatively by GC. The degradation mechanism of irradiated polyurethane foam has been deduced according to the experimental results. It provides some basis of the application on the polyurethane in the radiation field

Szycher's handbook of polyurethanes

National Research Council Canada - National Science Library

Szycher, M

2013-01-01

"Written as a reference for polyurethane technologists and end users, raw materials suppliers, and students in the field, this second edition covers the technical advances in the field over the past 10 years...

The effect of radiosterilization on surface properties of polyurethane film

International Nuclear Information System (INIS)

Sheikh, N.

2003-01-01

In this paper the effect of sterilization method by gamma-ray on structure and cytotoxicity of polyurethane film surface has been investigated. For this purpose reactive urethan prepolymer was synthesized by the reaction between Tdi with a mixture of Peg and castro oil (50/50, w/w). The cured prepolymer films were prepared due to the reaction of reactive prepolymer with air moister under ambient conditions. The polyurethane films were sterilized by gamma-ray (25 kGy). The surface of sterilized polyurethane film was observed by Sem and compared to that of the unsterilized film. Also, the in vitro interaction of fibroblast L 929 cells and sterilized polyurethane film was evaluated. Results showed no signs of cell toxicity

Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

Energy Technology Data Exchange (ETDEWEB)

Alves, P., E-mail: palves@eq.uc.pt [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Ferreira, P. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Kaiser, Jean-Pierre [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Salk, Natalie [Mikrofertigung – Micro Engineering, Fraunhofer IFAM, Wiener Strasse 12, D-288359 Bremen (Germany); Bruinink, Arie [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Sousa, Hermínio C. de; Gil, M.H. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal)

2013-10-15

The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan{sup ®}) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

Polyurethanes for potential use in transparent armour investigated using DSC and DMA

NARCIS (Netherlands)

Ekeren, P.J. van; Carton, E.P.

2011-01-01

A material combination that may be applied as transparent armour is glass-clad polyurethane. These are comprised of a relatively thin glass strike face and a relatively thick (transparent) polyurethane backing layer. Three transparent polyurethane samples were investigated using differential

Optimization of polyurethane foam cube in enhancing the ...

African Journals Online (AJOL)

Attachment of microalgae biomass to polyurethane foam material is believed could reduce the cost and time needed for harvesting process in making it reliable to be used in industry for biodiesel production. This paper aim to optimize the usage of polyurethane for higher attachment of microalgae biomass yield in term of it ...

Polyurethane Foams with Pyrimidine Rings

Directory of Open Access Journals (Sweden)

Kania Ewelina

2014-09-01

Full Text Available Oligoetherols based on pyrimidine ring were obtained upon reaction of barbituric acid with glycidol and alkylene carbonates. These oligoetherols were then used to obtain polyurethane foams in the reaction of oligoetherols with isocyanates and water. The protocol of foam synthesis was optimized by the choice of proper kind of oligoetherol and synthetic composition. The thermal resistance was studied by dynamic and static methods with concomitant monitoring of compressive strength. The polyurethane foams have similar physical properties as the classic ones except their enhanced thermal resistance. They stand long-time heating even at 200°C. Moreover thermal exposition of foams results generally in increase of their compressive strength.

Polyurethane - positioning aids in radiotherapy

International Nuclear Information System (INIS)

Alzen, G.; Boeck, E.G.; Thelen, M.; Kutzner, J.

1985-01-01

A simple and cheap method is described for the manufacturing of individual positioning aids made of foamed polyurethane. Some examples are given to demonstrate the applicability of these positioning aids for the irradiation of different body regions. The reproducibility of the radiation field in the head and neck area was investigated with and without positioning aid. It was proved that the field is adjusted more exactly when positioning aids are applied. The dosimetric investigations performed showed a negligible influence of foamed polyurethane on the radiation quality. So the positioning aids could be left within the radiation field when drawing the field borders. (orig.) [de

Presence of Biofilms on Polyurethane-Coated Breast Implants: Preliminary Results.

Science.gov (United States)

Rieger, Ulrich M; Djedovic, Gabriel; Pattiss, Alexander; Raschke, Gregor F; Frei, Reno; Pierer, Gerhard; Trampuz, Andrej

2016-01-01

Polyurethane-coated breast implants seem to be associated with lower medium- and long-term capsular contracture rates in comparison to textured or smooth implant surfaces. Although the etiology of capsular contracture is uncertain, bacterial biofilms have been suggested to trigger chronic peri-implant inflammation, eventually leading to capsular contracture. It is unknown whether polyurethane-coated implants are less prone to biofilm colonization than other implant surfaces. We extracted data from patient records included in a prospective cohort between 2008 and 2011. All patients who underwent removal of polyurethane-coated implants were included in this current study and screened for presence of biofilms by sonication. In addition, implant- and patient-related data were analyzed. Of the ten included polyurethane-coated breast implants, six had been inserted for reconstructive purposes and four for aesthetic reasons. The median implant indwelling time was 28.3 mo. Overall, sonication cultures were positive in 50% of implants. Propionibacterium acnes and coagulase-negative staphylococci were the predominant pathogens isolated from biofilm cultures. Like other implant surfaces, polyurethane-coated implants are prone to biofilm colonization. Further investigations are needed to determine why capsular contracture rates seem to be lower in polyurethane implants than in other implant surfaces. Notably, in this study, 40% of the implants were explanted from breasts with severe capsular contracture.

Flexible polyurethane foams

NARCIS (Netherlands)

2012-01-01

Embodiments of the invention provide for a method of preparing a polyurethane foam, including reacting least one initiator comprising at least two hydroxyl groups with at least one 12-hydroxystearic acid to form at least one polyester polyol, reacting the at least one polyester polyol with at least

Electrospun propolis/polyurethane composite nanofibers for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong In [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561–756 (Korea, Republic of); Pant, Hem Raj, E-mail: hempant@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561–756 (Korea, Republic of); Department of Engineering Science and Humanities, Pulchowk Campus, Tribhuvan University, Kathmandu (Nepal); Research Institute for Next Generation, Kalanki, Kathmandu (Nepal); Sim, Hyun-Jaung [Department of Bioactive Material Science, Research Center of Bioactive Material, Chonbuk National University, Jeonju, Chonbuk (Korea, Republic of); Lee, Kang Min [Department of Molecular Biology, College of Natural Science, Chonbuk National University, Jeonju, 561–756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561–756 (Korea, Republic of)

2014-11-01

Tissue engineering requires functional polymeric membrane for adequate space for cell migration and attachment within the nanostructure. Therefore, biocompatible propolis loaded polyurethane (propolis/PU) nanofibers were successfully prepared using electrospinning of propolis/PU blend solution. Here, composite nanofibers were subjected to detailed analysis using electron microscopy, FT-IR spectroscopy, thermal gravimetric analysis (TGA), and mechanical properties and water contact angle measurement. FE-SEM images revealed that the composite nanofibers became point-bonded with increasing amounts of propolis in the blend due to its adhesive properties. Incorporation of small amount of propolis through PU matrix could improve the hydrophilicity and mechanical strength of the fibrous membrane. In order to assay the cytocompatibility and cell behavior on the composite scaffolds, fibroblast cells were seeded on the matrix. Results suggest that the incorporation of propolis into PU fibers could increase its cell compatibility. Moreover, composite nanofibers have effective antibacterial activity. Therefore, as-synthesized nanocomposite fibrous mat has great potentiality in wound dressing and skin tissue engineering. - Highlights: • Sufficient amount of propolis is simply loaded through PU fibers. • Propolis increases the hydrophilicity and mechanical properties of PU fibers. • Composite mat shows excellent antibacterial activity. • Small amount of propolis can enhance the cell compatibility of PU fibers.

Electrospun propolis/polyurethane composite nanofibers for biomedical applications

International Nuclear Information System (INIS)

Kim, Jeong In; Pant, Hem Raj; Sim, Hyun-Jaung; Lee, Kang Min; Kim, Cheol Sang

2014-01-01

Tissue engineering requires functional polymeric membrane for adequate space for cell migration and attachment within the nanostructure. Therefore, biocompatible propolis loaded polyurethane (propolis/PU) nanofibers were successfully prepared using electrospinning of propolis/PU blend solution. Here, composite nanofibers were subjected to detailed analysis using electron microscopy, FT-IR spectroscopy, thermal gravimetric analysis (TGA), and mechanical properties and water contact angle measurement. FE-SEM images revealed that the composite nanofibers became point-bonded with increasing amounts of propolis in the blend due to its adhesive properties. Incorporation of small amount of propolis through PU matrix could improve the hydrophilicity and mechanical strength of the fibrous membrane. In order to assay the cytocompatibility and cell behavior on the composite scaffolds, fibroblast cells were seeded on the matrix. Results suggest that the incorporation of propolis into PU fibers could increase its cell compatibility. Moreover, composite nanofibers have effective antibacterial activity. Therefore, as-synthesized nanocomposite fibrous mat has great potentiality in wound dressing and skin tissue engineering. - Highlights: • Sufficient amount of propolis is simply loaded through PU fibers. • Propolis increases the hydrophilicity and mechanical properties of PU fibers. • Composite mat shows excellent antibacterial activity. • Small amount of propolis can enhance the cell compatibility of PU fibers

Direct transfer of graphene films for polyurethane substrate

Energy Technology Data Exchange (ETDEWEB)

Vilani, C.; Romani, E.C.; Larrudé, D.G. [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Barbosa, Gelza M. [Diretoria de Sistemas de Armas da Marinha, Marinha do Brasil, 20010-00 Rio de Janeiro, RJ (Brazil); Freire, F.L., E-mail: lazaro@vdg.fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

2015-11-30

Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

Direct transfer of graphene films for polyurethane substrate

International Nuclear Information System (INIS)

Vilani, C.; Romani, E.C.; Larrudé, D.G.; Barbosa, Gelza M.; Freire, F.L.

2015-01-01

Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

Cell–material interactions on biphasic polyurethane matrix

Science.gov (United States)

Dicesare, Patrick; Fox, Wade M.; Hill, Michael J.; Krishnan, G. Rajesh; Yang, Shuying; Sarkar, Debanjan

2013-01-01

Cell–matrix interaction is a key regulator for controlling stem cell fate in regenerative tissue engineering. These interactions are induced and controlled by the nanoscale features of extracellular matrix and are mimicked on synthetic matrices to control cell structure and functions. Recent studies have shown that nanostructured matrices can modulate stem cell behavior and exert specific role in tissue regeneration. In this study, we have demonstrated that nanostructured phase morphology of synthetic matrix can control adhesion, proliferation, organization and migration of human mesenchymal stem cells (MSCs). Nanostructured biodegradable polyurethanes (PU) with segmental composition exhibit biphasic morphology at nanoscale dimensions and can control cellular features of MSCs. Biodegradable PU with polyester soft segment and hard segment composed of aliphatic diisocyanates and dipeptide chain extender were designed to examine the effect polyurethane phase morphology. By altering the polyurethane composition, morphological architecture of PU was modulated and its effect was examined on MSC. Results show that MSCs can sense the nanoscale morphology of biphasic polyurethane matrix to exhibit distinct cellular features and, thus, signifies the relevance of matrix phase morphology. The role of nanostructured phases of a synthetic matrix in controlling cell–matrix interaction provides important insights for regulation of cell behavior on synthetic matrix and, therefore, is an important tool for engineering tissue regeneration. PMID:23255285

Fluorinated Polyurethane Scaffolds for 19F Magnetic Resonance Imaging

NARCIS (Netherlands)

Lammers, Twan; Mertens, Marianne E.; Schuster, Philipp; Rahimi, Khosrow; Shi, Yang; Schulz, Volkmar; Kuehne, Alexander J.C.; Jockenhoevel, Stefan; Kiessling, Fabian

2017-01-01

Researchers used fluorinated polyurethane scaffolds for 19F magnetic resonance imaging. They generated a novel fluorinated polymer based on thermoplastic polyurethane (19F -TPU) which possesses distinct properties rendering it suitable for fluorine-based MRI. The 19F -TPU is synthesized from a

Nano-TiO2/polyurethane composites for antibacterial and self-cleaning coatings

International Nuclear Information System (INIS)

Charpentier, P A; Burgess, K; Wang, L; Chowdhury, R R; Lotus, A F; Moula, G

2012-01-01

Grafting from polymerization was used to synthesize nano-titania/polyurethane (nTiO 2 /polyurethane) composite coatings, where nTiO 2 was chemically attached to the backbone of the polyurethane polymer matrix with a bifunctional monomer, 2,2-bis(hydroxymethyl) propionic acid (DMPA). This bifunctional monomer can coordinate to nTiO 2 through an available –COOH group, with two available hydroxyl groups that can react with diisocyanate terminated pre-polyurethane through step-growth polymerization. The coordination reaction was monitored by FTIR and TGA, with the coordination reaction found to follow first order kinetics. After step-growth polymerization, the polyurethane nanocomposites were found to be stable on standing with excellent distribution of Ti in the polymer matrix without any significant agglomeration compared to simple physical mixtures of nTiO 2 in the polyurethane coatings. The functionalized nTiO 2 –polyurethane composite coatings showed excellent antibacterial activity against gram-negative bacteria Escherichia coli; 99% of E. coli were killed within less than one hour under solar irradiation. Self-cleaning was also demonstrated using stearic acid as a model for ‘dirt’. (paper)

Sub-Surface and Bulk Creep Behaviour of Polyurethane/Clay Nanocomposites.

Science.gov (United States)

Jin, J; Yusoh, K; Zhang, H X; Song, M

2016-03-01

A series of exfoliated and intercalated polyurethane organoclay nanocomposites were prepared by in situ polymerization of polyol/organoclay mixture, chain extender and diisocyanate. The creep behaviour of subsurface and bulk of the polyurethane coatings was investigated by nanoindentation technique and uniaxial conventional creep testing method, respectively. The results showed that the creep resistance of the nanocomposites was significantly improved by incorporation of organoclay. The enhancement of creep resistance was dependent on clay content as well as organoclay structure (exfoliation or intercalation) in the polymer matrix. With 1 wt% organoclay, the creep resistance increased by about 50% for the intercalated organoclay and 6% for the exfoliated organoclay systems, respectively, compared to the pristine polyurethane. Viscoelastic model was employed to investigate the effect of organoclay loadings on the creep performance of the polyurethane. Results showed the model was in good agreement with the experimental data. Incorporation of clay leads to an increase in elastic deformation especially in exfoliated polyurethane nanocomposites and induces a higher initial displacement at the early stage of creep.

TOPEM DSC study of glass transition region of polyurethane cationomers

International Nuclear Information System (INIS)

Pielichowska, Kinga; Król, Piotr; Król, Bożena; Pagacz, Joanna

2012-01-01

Highlights: ► TOPEM DSC method was employed to investigate the glass transition (T g ) region of fluorinated polyurethane cationomers. ► Introduction of fluorine compounds significantly changes thermal behaviour of cationomers in the T g region of hard segments. ► Introduction of fluorine compound leads to changes of the slope in activation diagram of glass transition. - Abstract: In this paper TOPEM DSC method was employed to investigate the glass transition region of fluorinated polyurethane cationomers. Fluorinated polyurethane cationomers have been synthesised in the reaction of MDI with poly(ethylene glycol) (600) and butane1,4-diol or N-methyl- or N-butyldiethanolamine and 2,2,3,3-tetrafluoro-1,4-butanediol. Better rigidity was found for generally amorphous cationomer coats. It was found that introduction of fluorine compound changes thermal behaviour of polyurethane cationomers as well as leads to changes in the slope in activation diagram profiles of glass transition in comparison to polyuretahene cationomer without fluorine compound. Application of TOPEM DSC allows to obtain more information concerning frequency dependence of glass transition region and thermodynamical stability of polyurethane structures.

Bio-Based Polyurethane Containing Isosorbide for Use in Composites and Coatings

Science.gov (United States)

2015-04-01

ARL-TR-7259 ● APR 2015 US Army Research Laboratory Bio-Based Polyurethane Containing Isosorbide for Use in Composites and...copyright notation hereon. ARL-TR-7259 ● APR 2015 US Army Research Laboratory Bio-Based Polyurethane Containing Isosorbide for Use...4. TITLE AND SUBTITLE Bio-Based Polyurethane Containing Isosorbide for Use in Composites and Coatings 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

The effect of radiosterilization on cytotoxicity of polyurethane film

International Nuclear Information System (INIS)

Sheikh, N.

2003-01-01

Nowadays a sequence of tests for evaluation of sterilized biomaterial includes an initial set of tests in vitro, both biological (cell culture) and non-biological (mechanical tests). In this paper the cytotoxicity of a sterilized polyurethane film, in order to use as biomaterial, has been investigated. For this purpose NCO-terminated urethane prepolymer in medical quality was synthesized without ingredients beside monomers (polyethylene glycol/castor oil and toluene diisocyanate). The cured prepolymer films were prepared under ambient conditions due to the reaction of free NCO-groups of prepolymer with air moisture. The polyurethane films were sterilized by gamma-ray (25 kGy). The surface structure of sterilized polyurethane film was observed by SEM and compared to that of the unsterilized film. Also, the in vitro interaction of fibroblast cells and sterilized polyurethane film in culture medium containing serum was evaluated in comparison with control samples. Results showed no signs of cell toxicity

A highly sensitive pressure sensor using a Au-patterned polydimethylsiloxane membrane for biosensing applications

International Nuclear Information System (INIS)

Liu, Xinchuan; Zhu, Yihao; Nomani, Md W; Koley, Goutam; Wen, Xuejun; Hsia, Tain-Yen

2013-01-01

We report on the fabrication and characterization of a highly sensitive pressure sensor using a Au film patterned on a polydimethylsiloxane (PDMS) membrane. The strain-induced change in the film resistance was utilized to perform the quantitative measurement of absolute pressure. The highest sensitivity obtained for a 200 µm thick PDMS film sensor was 0.23/KPa with a range of 50 mm Hg, which is the best result reported so far, over that range, for any pressure sensor on a flexible membrane. The noise-limited pressure resolution was found to be 0.9 Pa (0.007 mm Hg), and a response time of ∼200 ms, are the best reported results for these sensors. The ultrahigh sensitivity is attributed to the strain-induced formation of microcracks, the effect of which on the resistance change was found to be highly reversible within a certain pressure range. A physical model correlating the sensitivity with the sensor parameters and crack geometry has been proposed. (paper)

SPECIFIC FEATURES OF OLIGOMERIC PRODUCT SOLIDIFICATION FROM POLYURETHANE WASTES AND THEIR PRACTICAL APPLICATION

OpenAIRE

V. Belyatsky; Yu. Kryvogus

2012-01-01

The paper considers a possibility to use secondary polyurethane obtained by  thermal depolymerization of wastes on the basis of cross-linked polyurethane (polyurethane adduct) and isocyanate. An effect of density dependence of the obtained polyurethane samples on nature and quantity of solvent has been revealed and it is significantly observed while using low-boiling solvents. The influence of adduct/solidification agent ratio on mechanical hardness of the obtained samples has been studied in...

Synthesis and optical properties of polyurethane foam modified with silver nanoparticles

International Nuclear Information System (INIS)

Apyari, V V; Volkov, P A; Dmitrienko, S G

2012-01-01

This paper for the first time describes peculiarities of synthesis of polyurethane foam modified with silver nanoparticles as a potential material for optical sensors in analytical chemistry. We found that the unique sorptional properties of polyurethane foam gave an opportunity to perform such a synthesis by two different approaches. The first one was based on sorption of previously synthesized in-solution nanoparticles by polyurethane foam, the second one consisted in preparation of nanoparticles directly in polyurethane foam matrix. This possibility is novel and interesting for practical use because the nanoparticles in polyurethane foam are capable of surface plasmon resonance. The influence of different factors during the synthesis was investigated and the optimal conditions were found. The samples prepared were characterized by diffuse reflectance spectroscopy and scanning electron microscopy. On the basis of the results obtained we first suggested that this material is attractive from the viewpoint of analytical chemistry as a convenient analytical form for determination of oxidants and reductants

Effects of surface modification with hydroxyl terminated polydimethylsiloxane on the corrosion protection of polyurethane coating

International Nuclear Information System (INIS)

Jeon, Jae Hong; Shon, Min Young

2014-01-01

Polyurethane coating was designed to give a hydrophobic property on its surface by modifying it with hydroxyl terminated polydimethylsiloxane and then effects of surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified polyurethane coating were examined using FT-IR/ATR spectroscopy, contact angle measurement and electrochemical impedance test. As results, the surface of polyurethane coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between polyurethane and modifier by the modification. The phase separation tendency is more appreciable when modified by polydimethylsiloxane with higher content. Water transport behavior of the modified polyurethane coating decreased more in that with higher hydrophobic surface property. The decrease in the impedance modulus ⅠZⅠ at low frequency region in immersion test for polyurethane coatings was associated with the water transport behavior and surface hydrophobic properties of modified polyurethane coatings. The corrosion protectiveness of the modified polyurethane coated carbon steel generally increased with an increase in the modifier content, confirming that corrosion protectiveness of the modified polyurethane coating is well agreed with its water transport behavior

Thermoplastic shape-memory polyurethanes based on natural oils

International Nuclear Information System (INIS)

Saralegi, Ainara; Eceiza, Arantxa; Corcuera, Maria Angeles; Johan Foster, E; Weder, Christoph

2014-01-01

A new family of segmented thermoplastic polyurethanes with thermally activated shape-memory properties was synthesized and characterized. Polyols derived from castor oil with different molecular weights but similar chemical structures and a corn-sugar-based chain extender (propanediol) were used as starting materials in order to maximize the content of carbon from renewable resources in the new materials. The composition was systematically varied to establish a structure–property map and identify compositions with desirable shape-memory properties. The thermal characterization of the new polyurethanes revealed a microphase separated structure, where both the soft (by convention the high molecular weight diol) and the hard phases were highly crystalline. Cyclic thermo-mechanical tensile tests showed that these polymers are excellent candidates for use as thermally activated shape-memory polymers, in which the crystalline soft segments promote high shape fixity values (close to 100%) and the hard segment crystallites ensure high shape recovery values (80–100%, depending on the hard segment content). The high proportion of components from renewable resources used in the polyurethane formulation leads to the synthesis of bio-based polyurethanes with shape-memory properties. (paper)

Sanitary and hygienic assessment of polyurethane foam compositions

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, V V; Putilina, O.N. (Donetskii NII Gigieny Truda i Professional' nykh Zabolevanii (USSR))

1990-07-01

Describes and presents the results of a long-term study performed by the Skochinski Institute and DonUGI into the suitability of various Soviet and foreign polyurethane foams as rock strengtheners in coal mines. Concludes that although further research is needed to clarify the effect of polyurethane absorbed by coal particles and on pneumoconioses, the industrial use of injectable polyisocyanite-based polyurethanes in amounts of up to 1 t/shift and with a minimum air exchange rate of 300 m{sup 3}/min is feasible as long as the safety laws are strictly observed. Those working with this material should be given a medical examination at least once a year. If the substance comes into contact with the skin or eyes, they should be washed with a 1-3% solution of sodium bicarbonate and then pure water; if it contaminates protective clothing this should be degassed in a 5-10% solution of ammonia for 24 hours and then washed. Due to the risk of toxic substances being released from the components of the polyurethane in the event of an endogenic fire, all workers should be equipped with their own personal breathing apparatus.

Synthesis and Application of Jatropha Oil based Polyurethane as Paint Coating Material

Directory of Open Access Journals (Sweden)

Zainal Alim Mas’ud

2012-08-01

Full Text Available Recently, the use of renewable sources in the preparation of various industrial materials has been revitalized in response to environmental concerns. Natural oils are considered to be the most important genre of renewable sources. Jatropha curcas oil (JPO based polyol is an alternative material that may possibly replace petrochemical-based polyol for polyurethane coating material. Polyurethane was synthesized by reacting JPO-based polyol with isocyanate. To produce JPO-based polyol, JPO was first epoxidized to form epoxidized J. curcas oil (EJP, subsequently it was converted to polyol by the opening ring reaction with acrylic acid (AA using triethylamine (TEA as a catalyst. The JPO-based polyurethane film resulting from this study is compared with polyurethane film from commercial polyol for gloss, hardness, and adhesion quality. The result showed that the source of polyol has an influence on gloss, hardness, and adhesion of polyurethane film, but the differences with using isocyanate has less influence. Using visual observation, polyurethane film produced from L.OHV polyol, H.OHV polyol and commercial polyol have similar quality.

Study of the morphology exhibited by linear segmented polyurethanes

International Nuclear Information System (INIS)

Pereira, I.M.; Orefice, R.L.

2009-01-01

Five series of segmented polyurethanes with different hard segment content were prepared by the prepolymer mixing method. The nano-morphology of the obtained polyurethanes and their microphase separation were investigated by infrared spectroscopy, modulated differential scanning calorimetry and small-angle X-ray scattering. Although highly hydrogen bonded hard segments were formed, high hard segment contents promoted phase mixture and decreased the chain mobility, decreasing the hard segment domain precipitation and the soft segments crystallization. The applied techniques were able to show that the hard-segment content and the hard-segment interactions were the two controlling factors for determining the structure of segmented polyurethanes. (author)

Thermal behaviour and corrosion resistance of nano-ZnO/polyurethane film

Science.gov (United States)

Virgawati, E.; Soegijono, B.

2018-03-01

Hybrid materials Nano-ZnO/polyurethane film was prepared with different zinc oxide (ZnO) content in polyurethane as a matrix. The film was deposited on low carbon steel plate using high volume low pressure (HVLP) method. To observe thermal behaviour of the film, the sample was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to see whether any chemical reaction of ZnO in polyurethane occured. TGA and FTIR results showed that the decomposition temperature shifted to a higher point and the chemical reaction of zinc oxide in polyurethane occurred. The surface morphology changed and the corrosion resistance increased with an increase of ZnO content

Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-06-01

Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.

Mixed field radiation modification of polyurethanes based on castor oil

Energy Technology Data Exchange (ETDEWEB)

Mortley, A.; Bonin, H.W.; Bui, V.T. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)]. E-mail: aba.mortley@rmc.ca

2006-07-01

Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing {sup 13}C-NMR and FTIR spectra. (author)

Mixed field radiation modification of polyurethanes based on castor oil

International Nuclear Information System (INIS)

Mortley, A.; Bonin, H.W.; Bui, V.T.

2006-01-01

Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing 13 C-NMR and FTIR spectra. (author)

Synthesis and characterization of waterborne polyurethane acrylate copolymers

International Nuclear Information System (INIS)

Sultan, Misbah; Bhatti, Haq Nawaz; Zuber, Mohammad; Barikani, Mehdi

2013-01-01

Polyurethane acrylate copolymers were synthesized by emulsion polymerization process. To reduce the environmental hazards, organic solvents were replaced by eco-friendly aqueous system. Concentration of polyurethane and acrylate monomer was varied to investigate the effect of chemical composition on performance properties of copolymers. FTIR spectroscopy was used as a key tool to record the chemical synthesis route. The synthesized copolymer emulsions were characterized by evaluating their particle size, viscosity, dry weight content, chemical and water resistance. Thermal decomposition was studied by thermogravimetric analysis. Scanning electron microscope was used to visualize the morphological structure of copolymers. The experimental results indicate better polyurethane acrylate compatibility till the ratio of 30/70. However, these copolymers exhibited synergistic effects between the two polymers and revealed a remarkable improvement in numerous coating properties

Biobased composites from cross-linked soybean oil and thermoplastic polyurethane

Science.gov (United States)

Soybean oil is an important sustainable material. Crosslinked acrylated epoxidized soybean oil (AESO) is brittle and the incorporation of thermoplastic polyurethane improves its toughness. The hydrophilic functional groups from both oil and polyurethane contribute to the adhesion of the blend compon...

Studies on polyurethane adhesives and surface modification of hydrophobic substrates

Science.gov (United States)

Krishnamoorthy, Jayaraman

This thesis work deals with (a) Curing of reactive, hot-melt polyurethane adhesives and (b) Adsorption studies using different interactions. Research on polyurethanes involves characterization of polyurethane prepolymers and a novel mechanism to cure isocyanate-terminated polyurethane prepolymer by a "trigger" mechanism. Curing of isocyanate-terminated polyurethane prepolymers has been shown to be influenced by morphology and environmental conditions such as temperature and relative humidity. Although the initial composition, final morphology and curing kinetics are known, information regarding the intermediate prepolymer mixture is yet to be established. Polyurethane prepolymers prepared by the reaction of diisocyanates with the primary hydroxyls of polyester diol (PHMA) and secondary hydroxyls of polyether diol (PPG) were characterized. The morphology and crystallization kinetics of a polyurethane prepolymer was compared with a blend of PPG prepolymer (the product obtained by the reaction of PPG with diisocyanate) and a PHMA prepolymer (the product obtained by the reaction of PHMA with diisocyanate) to study the effect of copolymer formed in the polyurethane prepolymer on the above-mentioned properties. Although the morphology of the polyurethane prepolymer is determined in the first few minutes of application, the chemical curing of isocyanate-terminated prepolymer occurs over hours to days. In the literature, different techniques are described to follow the curing kinetics. But there is no established technique to control the curing of polyurethane prepolymer. To make the curing process independent of environmental factors, a novel approach using a trigger mechanism was designed and implemented by using ammonium salts as curing agents. Ammonium salts that are stable at room temperature but decompose on heating to yield active hydrogen-containing compounds, NH3 and H2O, were used as 'Trojan horses' to cure the prepolymer chemically. Research on adsorption

Rheokinetics and effect of shear rate on the kinetics of linear polyurethane formation

NARCIS (Netherlands)

Navarchian, AH; Picchioni, F; Janssen, LPBM

In this article, the rheokinetics of polyurethane formation and the influence of shear rate on its kinetics have been studied. Two different linear polyurethane systems with 0% and 100% hard segments are examined in a cone and plate rheometer. The isothermal increase of viscosity during polyurethane

The Use of Biodiesel Residues for Heat Insulating Biobased Polyurethane Foams

Directory of Open Access Journals (Sweden)

Nihan Özveren

2017-01-01

Full Text Available The commercial and biobased polyurethane foams (PUF were produced and characterized in this study. Commercial polyether polyol, crude glycerol, methanol-free crude glycerol, and pure glycerol were used as polyols. Crude glycerol is byproduct of the biodiesel production, and it is a kind of biofuel residue. Polyol blends were prepared by mixing the glycerol types and the commercial polyol with different amounts, 10 wt%, 30 wt%, 50 wt%, and 80 wt%. All types of polyol blends were reacted with polymeric diphenyl methane diisocyanates (PMDI for the production of rigid foams. Thermal properties of polyurethane foams are examined by thermogravimetric analysis (TGA and thermal conductivity tests. The structures of polyurethane foams were examined by Fourier Transformed Infrared Spectroscopy (FTIR. Changes in morphology of foams were investigated by Scanning Electron Microscopy (SEM. Mechanical properties of polyurethane foams were determined by compression tests. This study identifies the critical aspects of polyurethane foam formation by the use of various polyols and furthermore offers new uses of crude glycerol and methanol-free crude glycerol which are byproducts of biodiesel industry.

Helical polyurethane-attapulgite nanocomposite: Preparation, characterization and study of optical activity

International Nuclear Information System (INIS)

Wang Zhiqiang; Zhou Yuming; Sun Yanqing; Fan Kai; Guo Xingxing; Jiang Xiaolei

2009-01-01

Helical polyurethane-attapulgite (BM-ATT) based on R-1,1'-binaphthyl-2',2-diol (R-BINOL) composite was prepared after the surface modification of attapulgite (ATT). BM-ATT was characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HTEM) and vibrational circular dichroism (VCD) spectroscopy. FT-IR and XRD analyses indicate that the helical polyurethane has been successfully grafted onto the surfaces of the modified ATT without destroying the original crystalline structure of ATT. BM-ATT exhibits the rod-like structure by SEM, TEM, and HTEM photographs. BM-ATT displays obvious Cotton effect for some absorbance in VCD spectrum, and its optical activity results from the singlehanded conformation of helical polyurethane. - Graphical Abstract: Helical polyurethane-attapulgite (BM-ATT) based on R-1,1'-binaphthyl-2',2-diol (R-BINOL) nanocomposite was prepared after surface modification of attapulgite (ATT). This rod-like composite is coated by the optically active polyurethane shell on the surfaces.

Comparison of polyurethane with cyanoacrylate in hemostasis of vascular injury in guinea pigs.

Science.gov (United States)

Kubrusly, Luiz Fernando; Formighieri, Marina Simões; Lago, José Vitor Martins; Graça, Yorgos Luiz Santos de Salles; Sobral, Ana Cristina Lira; Lago, Marianna Martins

2015-01-01

To evaluate the behavior of castor oil-derived polyurethane as a hemostatic agent and tissue response after abdominal aortic injury and to compare it with 2-octyl-cyanoacrylate. Twenty-four Guinea Pigs were randomly divided into three groups of eight animals (I, II, and III). The infrarenal abdominal aorta was dissected, clamped proximally and distally to the vascular puncture site. In group I (control), hemostasis was achieved with digital pressure; in group II (polyurethane) castor oil-derived polyurethane was applied, and in group III (cyanoacrylate), 2-octyl-cyanoacrylate was used. Group II was subdivided into IIA and IIB according to the time of preparation of the hemostatic agent. Mean blood loss in groups IIA, IIB and III was 0.002 grams (g), 0.008 g, and 0.170 g, with standard deviation of 0.005 g, 0.005 g, and 0.424 g, respectively (P=0.069). The drying time for cyanoacrylate averaged 81.5 seconds (s) (standard deviation: 51.5 seconds) and 126.1 s (standard deviation: 23.0 s) for polyurethane B (P=0.046). However, there was a trend (P=0.069) for cyanoacrylate to dry more slowly than polyurethane A (mean: 40.5 s; SD: 8.6 s). Furthermore, polyurethane A had a shorter drying time than polyurethane B (P=0.003), mean IIA of 40.5 s (standard deviation: 8.6 s). In group III, 100% of the animals had mild/severe fibrosis, while in group II only 12.5% showed this degree of fibrosis (P=0.001). Polyurethane derived from castor oil showed similar hemostatic behavior to octyl-2-cyanoacrylate. There was less perivascular tissue response with polyurethane when compared with cyanoacrylate.

Novel metallomesogenic polyurethanes: Synthesis, characterization and properties

International Nuclear Information System (INIS)

Senthilkumar, Natarajan; Narasimhaswamy, Tanneru; Kim, Il-Jin

2012-01-01

A series of tetradentate Schiff base metallomesogenic diols were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varying terminal chain length. A series of metallomesogenic polyurethanes were synthesized using these metallomesogenic diols as chain extenders for the prepolymers based on polytetramethylene glycol (PTMG) of varying molecular weight (M n = 650, 2000) and 2,4-toluene diisocyanate (TDI), or 4,4′-methylene bis(phenyl isocyanate) (MDI). The molar ratio of metallomesogenic diol and PTMG were varied in the polyurethane to find their role in liquid crystalline and mechanical properties. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1 H and 13 C NMR, EPR, VSM, Mass (EI and FAB) and UV–visible spectroscopy. Hot stage polarizing microscope and differential scanning calorimetry were used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. - Highlights: ► Design and synthesis of metallomesogenic diols. ► Metallomesogenic polyurethanes were prepared using these diols as chain extenders. ► Liquid crystalline and mechanical properties were studied. ► A square pyramidal structure for the copper(II) complexes have been proposed. ► Polyurethanes exhibited enantiotropic smectic A phases.

Graded porous polyurethane foam: A potential scaffold for oro-maxillary bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Giannitelli, S.M. [Department of Engineering, Tissue Engineering Unit, Università Campus Bio-Medico di Roma, Rome (Italy); Basoli, F. [Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Rome (Italy); Mozetic, P. [Department of Engineering, Tissue Engineering Unit, Università Campus Bio-Medico di Roma, Rome (Italy); Piva, P.; Bartuli, F.N.; Luciani, F. [University of Rome “Tor Vergata”, Rome (Italy); Arcuri, C. [Department of Periodontics, University of Rome “Tor Vergata”, Rome (Italy); U.O.C.C. Odontostomatology, “S. Giovanni Calibita, Fatebenefratelli” Hospital, Rome (Italy); Trombetta, M. [Department of Engineering, Tissue Engineering Unit, Università Campus Bio-Medico di Roma, Rome (Italy); Rainer, A., E-mail: a.rainer@unicampus.it [Department of Engineering, Tissue Engineering Unit, Università Campus Bio-Medico di Roma, Rome (Italy); Licoccia, S. [Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Rome (Italy)

2015-06-01

Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material—characterized by a dense shell and a porous core—for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications. - Highlights: • Graded porous polyurethane foams were synthesized via a one-pot foaming reaction. • The inner porous core might act as a scaffold for guided bone regeneration. • A dense outer shell was introduced to act as a barrier to gingival tissue ingrowth. • The synthesized foams were non-toxic and supportive of hBMSC adhesion.

Graded porous polyurethane foam: A potential scaffold for oro-maxillary bone regeneration

International Nuclear Information System (INIS)

Giannitelli, S.M.; Basoli, F.; Mozetic, P.; Piva, P.; Bartuli, F.N.; Luciani, F.; Arcuri, C.; Trombetta, M.; Rainer, A.; Licoccia, S.

2015-01-01

Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material—characterized by a dense shell and a porous core—for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications. - Highlights: • Graded porous polyurethane foams were synthesized via a one-pot foaming reaction. • The inner porous core might act as a scaffold for guided bone regeneration. • A dense outer shell was introduced to act as a barrier to gingival tissue ingrowth. • The synthesized foams were non-toxic and supportive of hBMSC adhesion

Extraction behavior of uranium(VI) with polyurethane foam

International Nuclear Information System (INIS)

Tingchia Huang; Donghwang Chen; Muchang Shieh; Chingtsven Huang

1992-01-01

The extraction of uranium(VI) from aqueous solution with polyether-based polyurethane (PU) foam was studied. The effects of the kinds and concentrations of nitrate salts, uranium(VI) concentration, temperature, nitric acid concentration, pH, the content of poly(ethylene oxide) in the polyurethane foam, and the ratio of PU foam weight and solution volume on the extraction of uranium(VI) were investigated. The interferences of fluoride and carbonate ions on the extraction of uranium(VI) were also examined, and methods to overcome both interferences were suggested. It was found that no uranium was extracted in the absence of a nitrate salting-out agent, and the extraction behaviors of uranium(IV) with polyurethane foam could be explained in terms of an etherlike solvent extraction mechanism. In addition, the percentage extraction of a multiple stage was also estimated theoretically

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

International Nuclear Information System (INIS)

Katragadda, S.; Gesser, H.D.; Chow, A.

1997-01-01

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH = 7.0 ± 1.5 over a wide range of temperatures. (author)

Comparison of anti-corrosion properties of polyurethane based composite coatings with low infrared emissivity

International Nuclear Information System (INIS)

Wang Yajun; Xu Guoyue; Yu Huijuan; Hu Chen; Yan Xiaoxing; Guo Tengchao; Li Jiufen

2011-01-01

Four polyurethane resins, pure polyurethane (PU), epoxy modified polyurethane (EPU), fluorinated polyurethane (FPU) and epoxy modified fluorinated polyurethane (EFPU), with similar polyurethane backbone structure but different grafting group were used as organic adhesive for preparing low infrared emissivity coatings with an extremely low emissivity near 0.10 at 8-14 μm, respectively. By using these four resins, the effect of different resin matrics on the corrosion protection of the low infrared emissivity coatings was investigated in detail by using neutral salt spray test, SEM and FTIR. It was found that the emissivity of the coatings with different resin matrics changes significantly in corrosion media. And the results indicated that the coating using EFPU as organic adhesive exhibited excellent corrosion resistance property which was mainly attributed to the presence of epoxy group and atomic fluorine in binder simultaneously.

Multifunctional composite material based on carbon-filled polyurethane

International Nuclear Information System (INIS)

Malinovskaya, T; Melentyev, S; Pavlov, S

2015-01-01

The research paper deals with the performance of composite resistive material heating coatings based on the polyurethane binder, filled with colloidal-graphite preparation C- 1, which can be used in structures of electric heaters. Frequency dependences of transmission and reflection coefficients, dielectric permeability of composite materials with the various content of carbon fillers (technical carbon, graphite) in polyurethane varnish in ranges of frequencies 26-40 GHz and 110-260 GHz are experimentally investigated. (paper)

Comparison of polyurethane with cyanoacrylate in hemostasis of vascular injury in guinea pigs

Directory of Open Access Journals (Sweden)

Luiz Fernando Kubrusly

2015-02-01

Full Text Available Objective: To evaluate the behavior of castor oil-derived polyurethane as a hemostatic agent and tissue response after abdominal aortic injury and to compare it with 2-octyl-cyanoacrylate. Methods: Twenty-four Guinea Pigs were randomly divided into three groups of eight animals (I, II, and III. The infrarenal abdominal aorta was dissected, clamped proximally and distally to the vascular puncture site. In group I (control, hemostasis was achieved with digital pressure; in group II (polyurethane castor oil-derived polyurethane was applied, and in group III (cyanoacrylate, 2-octyl-cyanoacrylate was used. Group II was subdivided into IIA and IIB according to the time of preparation of the hemostatic agent. Results: Mean blood loss in groups IIA, IIB and III was 0.002 grams (g, 0.008 g, and 0.170 g, with standard deviation of 0.005 g, 0.005 g, and 0.424 g, respectively (P=0.069. The drying time for cyanoacrylate averaged 81.5 seconds (s (standard deviation: 51.5 seconds and 126.1 s (standard deviation: 23.0 s for polyurethane B (P=0.046. However, there was a trend (P=0.069 for cyanoacrylate to dry more slowly than polyurethane A (mean: 40.5 s; SD: 8.6 s. Furthermore, polyurethane A had a shorter drying time than polyurethane B (P=0.003, mean IIA of 40.5 s (standard deviation: 8.6 s. In group III, 100% of the animals had mild/severe fibrosis, while in group II only 12.5% showed this degree of fibrosis (P=0.001. Conclusion: Polyurethane derived from castor oil showed similar hemostatic behavior to octyl-2-cyanoacrylate. There was less perivascular tissue response with polyurethane when compared with cyanoacrylate.

Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

Science.gov (United States)

Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

2014-09-01

Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Studies on incorporation of exfoliated bentonitic clays in polyurethane foams for increasing flame retardancy

International Nuclear Information System (INIS)

Quagliano, J; García, Irma Gavilán

2012-01-01

In this contribution we report the results of studying the incorporation of exfoliated bentonitic clays into polyurethane foams. A suspension in water of a sodium bentonite from Argentine Patagonia was interchanged with cetyl trimethyl ammonium bromide (CTAB) for 4 h at 80°C, rendering an exfoliated clay, which is nanometric in only one dimension. This nanoclay, when dispersed in the polyurethane, resulted in the same fire retardancy rating (UL-94) than when polyurethane was treated with a commercial nanoclay. Scanning electron microscopy (SEM) at low augmentations of polyurethane samples treated with the synthethized nanoclay (2,5% w/w) showed no differences respect to untreated polyurethane, except for the irregularity of void edges.

Crosslinked polyurethanes based on hyperbranched polymers

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Vuković Jasna

2008-01-01

Full Text Available In this paper, two samples of polyurethane (PU crosslinked with hydroxy -functonal hyperbranched aliphatic polyester of the second pseudo generation were investigated. For the synthesis of these crosslinked PUs two different macrodiols were used: poly(tetramethyleneoxide (PTMO for PUPTMO and ethylene oxide-poly(dimethylsiloxane-ethylene oxide (PDMS-EO for PUPDMS-EO sample. Synthesized samples behave as elastomers and have yellow color. Obtained results show that swelling degree of the sample PUPDMS-EO in N-methyl-2-pyrrolidinon (NMP determined at room temperature is higher than for the sample PUPTMO. It has been also observed that thermal properties of these polyurethane networks can be changed by incorporation of siloxane sequences in their structure.

Synthesis and Properties of Some polyurethane/ Partially Aromatic Polyester Casting Samples

International Nuclear Information System (INIS)

Sadek, E.M.; Mazroua, A.M.; Emam, A.S.; Motawie, A.M.

2005-01-01

A series of partially aromatic terephthalate polyesters were synthesized by melt transesterification of dimethyl terephthalate with various types of aliphatic diol compounds in 1:1.1 molar ratio. Ethylene-, di-, tri-, tetra ethylene glycol and polyethylene glycol with different molecular weights 1000, 4000, 6000 as well as the prepared dihydroxy natural rubber were used. Another series of partially aromatic adipate and sebacate polyesters based on the prepared bisphenol A and its tetrabromo derivative were also synthesized by direct polycondensation esterification with adipic and sebacic acid. Polyurethane with NCO/OH ratio equal 4 was prepared from the reaction of 2,4 toluene diisocyanate with polyethylene glycol 1000. The prepared polyurethane was mixed with different weight percentages (2, 4, 6, 8, 10 or 12 % w/w) of the prepared partially aromatic polyesters to give polyurethane/polyester compositions. Mechanical and electrical properties as well as water and chemical resistance of the prepared film samples with thickness 3-4 mm were determined and compared with those of polyurethane film sample without polyester. The data indicate that 10 % w/w of the added partially aromatic polyester increases polyurethane tensile strength, improves its insulation properties and hydrolytic stability as well as its chemical resistance. Film samples based on bisphenol A impart excellent properties as compared with those based on aliphatic glycol species and dihydroxy natural rubber. Keywords: Partially aromatic polyesters, Dimethyl terephthalate, Glycols, Bisphenol A, Tetrabromo bisphenol A, Natural rubber, Adipic acid, Sebacic acid, Polyurethane, Casting

Biodegradation of polyurethanes; Polyurethane no biseibutsu bunkai

Energy Technology Data Exchange (ETDEWEB)

Kinpara, N; Ando, M; Ohira, Z [Suzuki Motor Corp., Shizuoka (Japan); Nakajima, T; Nakahara, T [University of Tsukuba, Tsukuba (Japan)

1997-10-01

Different types of Polyurethane (PUR) are used for various industrial products and are used in increasing quantities every year. We experimented with biodegradation of PURs to dispose of industrial wastes. 2 strains of fungi and 1 strain of bacteria which were seemed to have the ability to degrade PURs well were isolated from various soils and waste water. These strains could degrade ester-type PUR and PUR made from a mixture of ester and ether. However, these strains could not degrade ether-type PUR. From Scanning Electron Microscopy observation, it is suggested that the microbial degradation proceeded in at least 2 patterns. 4 refs., 8 figs., 2 tabs.

Mixed Field Modification of Thermally Cured Castor Oil Based Polyurethanes

International Nuclear Information System (INIS)

Mortley, A.

2006-01-01

Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanatee (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of accumulated doses (0.0-3.0 MGy) produced by the mixed ionizing field of the SLOWPOKE-2 research reactor. The physico-mechanical properties of COPU, unirradiated and irradiated, were characterized by mechanical tests. Increased bond formation resulting from radiation-induced crosslinking was confirmed by favorable increases in mechanical properties and by solid-state 13 C -NMR and FTIR spectra

Thermal behaviour properties and corrosion resistance of organoclay/polyurethane film

Science.gov (United States)

Kurniawan, O.; Soegijono, B.

2018-03-01

Organoclay/polyurethane film composite was prepared by adding organoclay with different content (1, 3, and 5 wt.%) in polyurethane as a matrix. TGA and DSC showed decomposition temperature shifted to a lower point as organoclay content change. FT-IR spectra showed chemical bonding of organoclay and polyurethane as a matrix, which means that the bonding between filler and matrix occured and the composite was stronger but less bonding occur in composite with 5 wt.% organoclay. The corrosion resistance overall increased with the increasing organoclay content. Composite with 5 wt.% organoclay had more thermal stability and corrosion resistance may probably due to exfoliation of organoclay.

SPECIFIC FEATURES OF OLIGOMERIC PRODUCT SOLIDIFICATION FROM POLYURETHANE WASTES AND THEIR PRACTICAL APPLICATION

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V. Belyatsky

2012-01-01

Full Text Available The paper considers a possibility to use secondary polyurethane obtained by  thermal depolymerization of wastes on the basis of cross-linked polyurethane (polyurethane adduct and isocyanate. An effect of density dependence of the obtained polyurethane samples on nature and quantity of solvent has been revealed and it is significantly observed while using low-boiling solvents. The influence of adduct/solidification agent ratio on mechanical hardness of the obtained samples has been studied in the paper. The paper shows that the most optimal ratio is within the following limits – from 7/1 to 10/1. Plasticizing effect of polyurethane adduct on bitumen materials has been also found in the paper.A conclusion has been made that there is a possibility of practical usage of composites in building and road-building materials. 

Electron beam curable branched chain polyurethane acrylates for magnetic media coatings

International Nuclear Information System (INIS)

Ukachi, Takashi; Haga, Kei-ichi; Matsumura, Yoshio

1989-01-01

Electron beam curable binder resins have been studied to realize the high quality magnetic coatings. It was supposed that resins with a higher crosslink density could lead to magnetic coatings with higher abrasion resistance. Branched chain polyurethane acrylates show a higher degree of cure by irradiation with an electron beam in comparison with linear polyurethane acrylates. This paper describes the potential wear resistance between properties of magnetic coatings and the physical properties of the cured unpigmented branched chain polyurethane acrylates that were used as the binder resins. (author)

Electrospun polymethylacrylate nanofibers membranes for quasi-solid-state dye sensitized solar cells

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M. Fathy

2016-06-01

Full Text Available Polymethylacrylate (PMA nanofibers membranes are fabricated by electrospinning technique and applied to the polymer matrix in quasi-solid-state electrolytes for dye sensitized solar cells (DSSCs. There is no previous studies reporting the production of PMA nanofibers. The electrospinning parameters such as polymer concentration, applied voltage, feed rate, tip to collector distance and solvent were optimized. Electrospun PMA fibrous membrane with average fiber diameter of 350 nm was prepared from a 10 wt% solution of PMA in a mixture of acetone/N,N-dimethylacetamide (6:4 v/v at an applied voltage of 20 kV. It was then activated by immersing it in 0.5 M LiI, 0.05 M I2, and 0.5 M 4-tert-butylpyridine in 3-methoxyproponitrile to obtain the corresponding membrane electrolyte with an ionic conductivity of 2.4 × 10−3 S cm−1 at 25 °C. Dye sensitized solar cells (DSSCs employing the quasi solid-state electrolyte have an open-circuit voltage (Voc of 0.65 V and a short circuit current (Jsc of 6.5 mA cm−2 and photoelectric energy conversion efficiency (η of 1.4% at an incident light intensity of 100 mW cm−2.

Isolation and characterization of a bacterium which utilizes polyester polyurethane as a sole carbon and nitrogen source.

Science.gov (United States)

Nakajima-Kambe, T; Onuma, F; Kimpara, N; Nakahara, T

1995-06-01

Various soil samples were screened for the presence of microorganisms which have the ability to degrade polyurethane compounds. Two strains with good polyurethane degrading activity were isolated. The more active strain was tentatively identified as Comamonas acidovorans. This strain could utilize polyester-type polyurethanes but not the polyether-type polyurethanes as sole carbon and nitrogen sources. Adipic acid and diethylene glycol were probably the main degradation products when polyurethane was supplied as a sole carbon and nitrogen source. When ammonium nitrate was used as nitrogen source, only diethylene glycol was detected after growth on polyurethane.

Electrospun Polyurethane Fibers for Absorption of Volatile Organic Compounds from Air

NARCIS (Netherlands)

Scholten, E.; Bromberg, L.; Rutledge, G.C.; Hatton, T.A.

2011-01-01

Electrospun polyurethane fibers for removal of volatile organic compounds (VOC) from air with rapid VOC absorption and desorption have been developed. Polyurethanes based on 4,4-methylenebis(phenylisocyanate) (MDI) and aliphatic isophorone diisocyanate as the hard segments and butanediol and

New insights into polyurethane biodegradation and realistic prospects for the development of a sustainable waste recycling process.

Science.gov (United States)

Cregut, Mickael; Bedas, M; Durand, M-J; Thouand, G

2013-12-01

Polyurethanes are polymeric plastics that were first used as substitutes for traditional polymers suspected to release volatile organic hazardous substances. The limitless conformations and formulations of polyurethanes enabled their use in a wide variety of applications. Because approximately 10 Mt of polyurethanes is produced each year, environmental concern over their considerable contribution to landfill waste accumulation appeared in the 1990s. To date, no recycling processes allow for the efficient reuse of polyurethane waste due to their high resistance to (a)biotic disturbances. To find alternatives to systematic accumulation or incineration of polyurethanes, a bibliographic analysis was performed on major scientific advances in the polyurethane (bio)degradation field to identify opportunities for the development of new technologies to recondition this material. Until polymers exhibiting oxo- or hydro-biodegradative traits are generated, conventional polyurethanes that are known to be only slightly biodegradable are of great concern. The research focused on polyurethane biodegradation highlights recent attempts to reprocess conventional industrial polyurethanes via microbial or enzymatic degradation. This review describes several wonderful opportunities for the establishment of new processes for polyurethane recycling. Meeting these new challenges could lead to the development of sustainable management processes involving polymer recycling or reuse as environmentally safe options for industries. The ability to upgrade polyurethane wastes to chemical compounds with a higher added value would be especially attractive. © 2013.

Thermal Properties of Anionic Polyurethane Composition for Leather Finishing

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Olga KOVTUNENKO

2016-09-01

Full Text Available Thermal properties of anionic polyurethane composition mixed with collagen product and hydrophilic sodium form of montmorillonite for use in the finishing of leather were studied by thermogravimetric method. The thermal indices of processes of thermal and thermo-oxidative destruction depending on the polyurethane composition were determined. The influence of anionic polyurethane composition on thermal behavior of chromium tanned gelatin films that imitate the leather were studied. APU composition with natural compounds increases their thermal stability both in air and in nitrogen atmosphere due to the formation of additional bonds between active groups of APU, protein and chrome tanning agent as the result of chemical reactions between organic and inorganic parts with the new structure formation.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.10043

Polymeric membranes containing silver salts for propylene/propane separation

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L. D. Pollo

2012-06-01

Full Text Available The separation of olefin/paraffin mixtures is one of the most important processes of the chemical industry. This separation is typically carried out by distillation, which is an energy and capital intensive process. One promising alternative is the use of facilitated transport membranes, which contain specific carrier agents in the polymer matrix that interact reversibly with the double bond in the olefin molecule, promoting the simultaneous increase of its permeability and selectivity. In this study, polyurethane (PU membranes were prepared using two different silver salts (triflate and hexafluorantimonate. The membranes were structurally characterized and their performance for the separation of propylene/propane mixtures was evaluated. The results of the characterization analyses indicated that the triflate salt was the most efficient carrier agent. The membranes containing this salt showed the best performance, reaching an ideal selectivity of 10 and propylene permeability of 188 Barrer.

Additive Manufacturing of Polyurethane Materials

Energy Technology Data Exchange (ETDEWEB)

Kunc, Vlastimil [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lindahl, John M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Minneci, Robert P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pyzik, Alek [Dow Chemical Company, Saginaw, MI (United States); Gorin, Craig [Dow Chemical Company, Midland, MI (United States); Allen, Sharon [Dow Chemical Company, Midland, MI (United States); Wilson, Keith [Dow Chemical Company, Midland, MI (United States); Howard, Kevin [Dow Chemical Company, Midland, MI (United States)

2017-08-10

ORNL worked with The DOW Chemical Company to validate the feasibility of 3D printing DOW’s polyurethane (PU) materials using ORNL’s equipment and know-how. This led to the development of the first directly-3D-printable PU material.

DHA-fluorescent probe is sensitive to membrane order and reveals molecular adaptation of DHA in ordered lipid microdomains☆

Science.gov (United States)

Teague, Heather; Ross, Ron; Harris, Mitchel; Mitchell, Drake C.; Shaikh, Saame Raza

2012-01-01

Docosahexaenoic acid (DHA) disrupts the size and order of plasma membrane lipid microdomains in vitro and in vivo. However, it is unknown how the highly disordered structure of DHA mechanistically adapts to increase the order of tightly packed lipid microdomains. Therefore, we studied a novel DHA-Bodipy fluorescent probe to address this issue. We first determined if the DHA-Bodipy probe localized to the plasma membrane of primary B and immortal EL4 cells. Image analysis revealed that DHA-Bodipy localized into the plasma membrane of primary B cells more efficiently than EL4 cells. We then determined if the probe detected changes in plasma membrane order. Quantitative analysis of time-lapse movies established that DHA-Bodipy was sensitive to membrane molecular order. This allowed us to investigate how DHA-Bodipy physically adapted to ordered lipid microdomains. To accomplish this, we employed steady-state and time-resolved fluorescence anisotropy measurements in lipid vesicles of varying composition. Similar to cell culture studies, the probe was highly sensitive to membrane order in lipid vesicles. Moreover, these experiments revealed, relative to controls, that upon incorporation into highly ordered microdomains, DHA-Bodipy underwent an increase in its fluorescence lifetime and molecular order. In addition, the probe displayed a significant reduction in its rotational diffusion compared to controls. Altogether, DHA-Bodipy was highly sensitive to membrane order and revealed for the first time that DHA, despite its flexibility, could become ordered with less rotational motion inside ordered lipid microdomains. Mechanistically, this explains how DHA acyl chains can increase order upon formation of lipid microdomains in vivo. PMID:22841541

Bitumen modified with recycled polyurethane foam for employment in hot mix asphalt

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Miguel Ángel Salas

2018-01-01

Full Text Available A wide variety of modifiers have been applied to bitumen in order to enhance their properties and performance. Among them, polymers have been mainly used. The aim of this paper is to assess the use of polyurethane foam waste as a bitumen modifier for hot mix asphalts. The polyurethane foam is a by-product of the manufacturing of polyurethane for thermal insulation. From a bitumen with a penetration grade of 50/70, various samples with percentages of waste material in weight ranging from 1% to 5% were produced and tested. Samples with 5% of waste material or more became rough and were refused due to their poor workability. A bituminous mixture with modified bitumen with a 4% of polyurethane was manufactured and compared with a sample with the same aggregates and original bitumen. Results in Marshall test showed that a mix with polymer modified bitumen yielded improvements in stability and a lower deformability. This result suggests that the employment of polyurethane foam waste is a promising bitumen modifier, contributing also to recycle waste materials.

Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR

International Nuclear Information System (INIS)

Silva, Marcos Anacleto da; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R

2012-01-01

Polyurethanes are important and versatile materials, mainly due to some of their properties, such as high resistance to abrasion and tearing, excellent absorption of mechanical shocks and good flexibility and elasticity. However, they have some drawbacks as well, such as low thermal stability and barrier properties. To overcome these disadvantages, various studies have been conducted involving organophilic polyurethane/montmorillonite nanocomposites. The investigation of the structure of polyurethane/clay nanocomposites has mainly been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay nanocomposite films obtained by solution intercalation were studied. The nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (LF-NMR). The LF-NMR measurements, with determination of the spin-lattice relaxation time of the hydrogen nucleus, supplied important information about the molecular dynamics of these nanocomposites. The X-ray diffraction measurements validated the results found by NMR. The thermal stability of the material was also determined by thermogravimetric analysis (TGA) under an inert atmosphere. A slight improvement in this stability was observed in the nanocomposite in comparison with polyurethane (author)

Antimicrobial polyurethane thermosets based on undecylenic acid: synthesis and evaluation.

Science.gov (United States)

Lluch, Cristina; Esteve-Zarzoso, Braulio; Bordons, Albert; Lligadas, Gerard; Ronda, Juan C; Galià, Marina; Cádiz, Virginia

2014-08-01

In the present study, plant oil-derived surface-modifiable polyurethane thermosets are presented. Polyol synthesis is carried out taking advantage of thiol-yne photopolymerization of undecylenic acid derivatives containing methyl ester or hydroxyl moieties. The prepared methyl ester-containing polyurethanes allow surface modification treatment to enhance their hydrophilicity and impart antimicrobial activity through the following two steps: i) grafting poly(propylene glycol) monoamine (Jeffamine M-600) via aminolysis and ii) Jeffamine M-600 layer complexation with iodine. The antimicrobial activity of the iodine-containing polyurethanes is demonstrated by its capacity to inhibit the growth of Staphylococcus aureus, and Candida albicans in agar media. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnesium Oxide (MgO) pH-sensitive Sensing Membrane in Electrolyte-Insulator-Semiconductor Structures with CF4 Plasma Treatment.

Science.gov (United States)

Kao, Chyuan-Haur; Chang, Chia Lung; Su, Wei Ming; Chen, Yu Tzu; Lu, Chien Cheng; Lee, Yu Shan; Hong, Chen Hao; Lin, Chan-Yu; Chen, Hsiang

2017-08-03

Magnesium oxide (MgO) sensing membranes in pH-sensitive electrolyte-insulator-semiconductor structures were fabricated on silicon substrate. To optimize the sensing capability of the membrane, CF 4 plasma was incorporated to improve the material quality of MgO films. Multiple material analyses including FESEM, XRD, AFM, and SIMS indicate that plasma treatment might enhance the crystallization and increase the grain size. Therefore, the sensing behaviors in terms of sensitivity, linearity, hysteresis effects, and drift rates might be improved. MgO-based EIS membranes with CF 4 plasma treatment show promise for future industrial biosensing applications.

Acyclic N-halamine-immobilized polyurethane: Preparation and antimicrobial and biofilm-controlling functions

Science.gov (United States)

Luo, Jie; Porteous, Nuala; Lin, Jiajin; Sun, Yuyu

2015-01-01

Hydroxyl groups were introduced onto polyurethane surfaces through 1,6-hexamethylene diisocyanate activation, followed by diethanolamine hydroxylation. Polymethacrylamide was covalently attached to the hydroxylated polyurethane through surface grafting polymerization of methacrylamide using cerium (IV) ammonium nitrate as an initiator. After bleach treatment, the amide groups of the covalently bound polymethacrylamide chains were transformed into N-halamines. The new N-halamine-immobilized polyurethane provided a total sacrifice of 107–108 colony forming units per milliliter of Staphylococcus aureus (Gram-positive bacteria), Escherichia coli (Gram-negative bacteria), and Candida albicans (fungi) within 10 min and successfully prevented bacterial and fungal biofilm formation. The antimicrobial and biofilm-controlling effects were both durable and rechargeable, pointing to great potentials of the new acyclic N-halamine-immobilized polyurethane for a broad range of related applications. PMID:26089593

Development of Styrene-Grafted Polyurethane by Radiation-Based Techniques

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Jin-Oh Jeong

2016-06-01

Full Text Available Polyurethane (PU is the fifth most common polymer in the general consumer market, following Polypropylene (PP, Polyethylene (PE, Polyvinyl chloride (PVC, and Polystyrene (PS, and the most common polymer for thermosetting resins. In particular, polyurethane has excellent hardness and heat resistance, is a widely used material for electronic products and automotive parts, and can be used to create products of various physical properties, including rigid and flexible foams, films, and fibers. However, the use of polar polymer polyurethane as an impact modifier of non-polar polymers is limited due to poor combustion resistance and impact resistance. In this study, we used gamma irradiation at 25 and 50 kGy to introduce the styrene of hydrophobic monomer on the polyurethane as an impact modifier of the non-polar polymer. To verify grafted styrene, we confirmed the phenyl group of styrene at 690 cm−1 by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR and at 6.4–6.8 ppm by 1H-Nuclear Magnetic Resonance (1H-NMR. Scanning Electron Microscope (SEM, X-ray Photoelectron Spectroscopy (XPS, Thermogravimetric Analysis (TGA and contact angle analysis were also used to confirm styrene introduction. This study has confirmed the possibility of applying high-functional composite through radiation-based techniques.

Experimental study of polyurethane foam reinforced soil used as a rock-like material

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Eren Komurlu

2015-10-01

Full Text Available In this study, polyurethane foam type thermoset polymerizing, due to chemical reaction between its liquid ingredients, was tested as binder after solidifying and then a rock-like material mixing with a sandy silt type soil was prepared. The uniaxial compressive strengths (UCSs of polyurethane foam reinforced soil specimens were determined for different polyurethane ratios in the mixture. Additionally, a series of tests on slake durability, impact value, freezing–thawing resistance, and abrasion resistance of polyurethane reinforced soil (PRS mixture was conducted. The UCS values over 3 MPa were measured from the PRS specimens. The testing results showed that treated soil can economically become a desirable rock-like material in terms of slake durability and resistances against freezing–thawing, impact effect and abrasion. As another characteristic of the rock-like material made with polyurethane foam, unit volume weight was found to be quite lower than those of natural rock materials.

Potentiometric determination of trypsin using a polymeric membrane polycation-sensitive electrode based on current-controlled reagent delivery.

Science.gov (United States)

Chen, Yan; Ding, Jiawang; Qin, Wei

2012-12-01

A potentiometric biosensor for the determination of trypsin is described based on current-controlled reagent delivery. A polymeric membrane protamine-sensitive electrode with dinonylnaphthalene sulfonate as cation exchanger is used for in situ generation of protamine. Diffusion of protamine across the polymeric membrane can be controlled precisely by applying an external current. The hydrolysis catalyzed with trypsin in sample solution decreases the concentration of free protamine released at the sample-membrane interface and facilitates the stripping of protamine out of the membrane surface via the ion-exchange process with sodium ions from the sample solution, thus decreasing the membrane potential, by which the protease can be sensed potentiometrically. The influences of anodic current amplitude, current pulse duration and protamine concentration in the inner filling solution on the membrane potential response have been studied. Under optimum conditions, the proposed protamine-sensitive electrode is useful for continuous and reversible detection of trypsin over the concentration range of 0.5-5UmL(-1) with a detection limit of 0.3UmL(-1). The proposed detection strategy provides a rapid and reagentless way for the detection of protease activities and offers great potential in the homogeneous immunoassays using proteases as labels. Copyright © 2012 Elsevier B.V. All rights reserved.

IDENTIFICATION OF CFC AND HCFC SUBSTITUTES FOR BLOWING POLYURETHANE FOAM INSULATION PRODUCTS

Science.gov (United States)

The report gives results of a cooperative effort to identiry chlorofluorocarbons and hydrochlorofluorocarbon substitutes for blowing polyurethane foam insulation products. The substantial ongoing effort is identifying third-generation blowing agets for polyurethane foams to repla...

Nerve regeneration using tubular scaffolds from biodegradable polyurethane.

Science.gov (United States)

Hausner, T; Schmidhammer, R; Zandieh, S; Hopf, R; Schultz, A; Gogolewski, S; Hertz, H; Redl, H

2007-01-01

In severe nerve lesion, nerve defects and in brachial plexus reconstruction, autologous nerve grafting is the golden standard. Although, nerve grafting technique is the best available approach a major disadvantages exists: there is a limited source of autologous nerve grafts. This study presents data on the use of tubular scaffolds with uniaxial pore orientation from experimental biodegradable polyurethanes coated with fibrin sealant to regenerate a 8 mm resected segment of rat sciatic nerve. Tubular scaffolds: prepared by extrusion of the polymer solution in DMF into water coagulation bath. The polymer used for the preparation of tubular scaffolds was a biodegradable polyurethane based on hexamethylene diisocyanate, poly(epsilon-caprolactone) and dianhydro-D-sorbitol. EXPERIMENTAL MODEL: Eighteen Sprague Dawley rats underwent mid-thigh sciatic nerve transection and were randomly assigned to two experimental groups with immediate repair: (1) tubular scaffold, (2) 180 degrees rotated sciatic nerve segment (control). Serial functional measurements (toe spread test, placing tests) were performed weekly from 3rd to 12th week after nerve repair. On week 12, electrophysiological assessment was performed. Sciatic nerve and scaffold/nerve grafts were harvested for histomorphometric analysis. Collagenic connective tissue, Schwann cells and axons were evaluated in the proximal nerve stump, the scaffold/nerve graft and the distal nerve stump. The implants have uniaxially-oriented pore structure with a pore size in the range of 2 micorm (the pore wall) and 75 x 700 microm (elongated pores in the implant lumen). The skin of the tubular implants was nonporous. Animals which underwent repair with tubular scaffolds of biodegradable polyurethanes coated with diluted fibrin sealant had no significant functional differences compared with the nerve graft group. Control group resulted in a trend-wise better electrophysiological recovery but did not show statistically significant

Thermal stability of novel polyurethane adhesives investigated by TGA

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Mariusz Mamiński

2014-05-01

Full Text Available The objective of the work was an assessment of thermal stability of novel polyurethane wood adhesives by means of TGA. Hyperbranched polyglycerols of various structures were used as polyol components cured with polymeric methylenediphenyldiisocyanate (PMDI or polymeric hexamethylenediisocyanate (PHDI. Resultant adhesives were thermally degraded in temperature range 20 - 500ºC. Performance of polyurethane based on fully aliphatic polyglycerol was inferior to those based on polyglycerols bearing aromatic moieties. The differences in 50%-weight loss temperature achieving 27 - 39°C as well as residual weights at 480 ºC indicate the contribution of aromatic units presence within the macromonomer structure to increased thermal stability of polyurethane upon thermal degradation. Furthermore, temperature of 50% weight loss revealed that thermal stability of the developed hyperbranched polyglycerol-based adhesives was comparable to that of the commercial PUR adhesive.

Self-stratifying antimicrobial polyurethane coatings

NARCIS (Netherlands)

Yagci, M.B.; Bolca, S.; Heuts, J.P.A.; Ming, W.; With, de G.

2011-01-01

In this work antimicrobial polyurethane coatings were prepared aiming at self-stratification. A hydroxyl end-capped liquid oligoester consisting of three equimolar diacids and an excess of 1,4-butanediol has been synthesized by a condensation reaction. A set of quaternary ammonium compounds (QACs)

Studies on micro-domain structure in segmented polyether polyurethane-ureas by positron annihilation lifetime and small-angle X-ray scattering

International Nuclear Information System (INIS)

Yin Chuanyuan; Gu Qingchao

1997-01-01

The micro-domain structure of segmented polyether polyurethane-ureas is investigated by means of positron annihilation lifetime spectroscopy, small-angle X-ray scattering and differential scanning calorimetry. The experimental results show that the decrease in the domain volume and free volume results from the increase in the hard segment (polyurethane-urea segment) contents as the number-average molecular weight M n -bar of the soft segments (polyethylene glycol segments) is the same, and that the increase in domain volume and free volume result from the increase in the M n -bar of the soft segments when the hard segment content is the same or nearly the same. These results demonstrate that positron annihilation lifetime spectroscopy is a sensitive technique to probe the micro-domain structure in polymers

Synthesis and Characterization of High-Dielectric-Constant Nanographite-Polyurethane Composite

Science.gov (United States)

Mishra, Praveen; Bhat, Badekai Ramachandra; Bhattacharya, B.; Mehra, R. M.

2018-05-01

In the face of ever-growing demand for capacitors and energy storage devices, development of high-dielectric-constant materials is of paramount importance. Among various dielectric materials available, polymer dielectrics are preferred for their good processability. We report herein synthesis and characterization of nanographite-polyurethane composite with high dielectric constant. Nanographite showed good dispersibility in the polyurethane matrix. The thermosetting nature of polyurethane gives the composite the ability to withstand higher temperature without melting. The resultant composite was studied for its dielectric constant (ɛ) as a function of frequency. The composite exhibited logarithmic variation of ɛ from 3000 at 100 Hz to 225 at 60 kHz. The material also exhibited stable dissipation factor (tan δ) across the applied frequencies, suggesting its ability to resist current leakage.

Characterization of polyurethane based on polyol synthesized from glycerol and hexamethylene diisocyanate

International Nuclear Information System (INIS)

Carvalho, Sabrina M.; Weber, Vanessa; Silva, Tailu N.; Barreto, Pedro L.M.

2009-01-01

A new polyol based on glycerol was synthesized and used in the production of polyurethane by reaction with hexamethylene diisocyanate. The polyol was characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform-infrared spectroscopy (FTIR). The polyurethane produced was characterized by FTIR, thermogravimetry (TG), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The polyol was shown to be reactive with hexamethylene diisocyanate, as the FTIR spectrum showed no free isocyanate groups and identified the presence of group -C=O of urethane groups. Analysis by DSC showed that the sample of polyurethane has a glass transition temperature around -8.53 deg C and SEM micrographs showed fracture and surface continuous and not broken. The thermogravimetric analysis showed that the polyurethane produced has a high thermal stability with a temperature of maximum degradation around 430 deg C. (author)

Polyurethane elastomers from morphology to mechanical aspects

CERN Document Server

Prisacariu, Cristina

2011-01-01

A comprehensive account of the physical / mechanical behaviour of polyurethanes (PU´s) elastomers, films and blends of variable crystallinity. Aspects covered include the elasticity and inelasticity of amorphous to crystalline PUs, in relation to their sensitivity to chemical and physical structure. A study is made of how aspects of the constitutive responses of PUs vary with composition: the polyaddition procedure, the hard segment, soft segment and chain extender (diols and diamines) are varied systematically in a large number of systems of model and novel crosslinked andthermoplastic PUs. Results will be related to: microstructural changes, on the basis of evidence from x-ray scattering (SAXS and WAXS), and also dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC) and IR dichroism. Inelastic effects will be investigated also by including quantitative correlations between the magnitude of the Mullins effect and the fractional energy dissipation by hysteresis under cyclic straining, g...

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites.

Science.gov (United States)

Deka, Harekrishna; Karak, Niranjan

2009-04-25

The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 degrees C of melting point, and 111 degrees C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96-99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

Use of Polyurethane Coating to Prevent Corrosion in Oil and Gas Pipelines Transfer

OpenAIRE

Amir Samimi

2012-01-01

Corrosion is one of the major problems in the oil and gas industry is one that automatically allocates huge sums annually. Polyurethane is a thermoses polymer with various applications. Using form this polymer has spread for military applications by Otto Bayer in 1930. In one general look polyurethane is product of Iso Syanate and ploy with each other, So that: Iso + ploy = polyurethane. Spend large cost for application and launching oil and gas transitions, has cleared the necessity protecti...

Preparation and characterization of polyurethane plasticizer for flexible packaging applications: Natural oils affirmed access

Directory of Open Access Journals (Sweden)

Mohammed A. Mekewi

2017-03-01

Full Text Available Developing bio-renewable feedstock for polyurethane (PU manufacturing and polymer industry as a whole has become highly desirable for both economic and environmental reasons. In this work castor oil (CO and palm olein (PO polyols were synthesized and partially used as renewable feedstock for the manufacturing of polyurethane plasticizing resin for printing ink applications. The chemical structure of the prepared polyols and polyurethanes were characterized using IR spectra and GPC and their solubility in common solvents was tested. As well, properties such as flexibility, mechanical properties, optical properties, heat seal and freeze resistance of these prepared printing inks were determined. The results indicated that the prepared printing inks from 50% synthesized polyurethane have high thermal stability, adhesion and excellent freeze resistance. The net technical properties of the new ink formulations are relatively comparable to the printing ink prepared from standard polyurethane plasticizer.

Mechanical and thermal properties of sisal fiber-reinforced rubber seed oil-based polyurethane composites

International Nuclear Information System (INIS)

Bakare, I.O.; Okieimen, F.E.; Pavithran, C.; Abdul Khalil, H.P.S.; Brahmakumar, M.

2010-01-01

The development of high-performance composite materials from locally sourced and renewable materials was investigated. Rubber seed oil polyurethane resin synthesized using rubber seed monoglyceride derived from glycerolysis of the oil was used as matrix in the composite samples. Rubber seed oil-based polyurethane composite reinforced with unidirectional sisal fibers were prepared and characterized. Results showed that the properties of unidirectional fiber-reinforced rubber seed oil-based polyurethane composites gave good thermal and mechanical properties. Also, the values of tensile strengths and flexural moduli of the polyurethane composites were more than tenfold and about twofold higher than un-reinforced rubber seed oil-based polyurethane. The improved thermal stability and the scanning electron micrographs of the fracture surface of the composites were attributed to good fiber-matrix interaction. These results indicate that high-performance 'all natural products' composite materials can be developed from resources that are readily available locally.

Antimicrobial polyurethane thermosets based on undecylenic acid: synthesis and evaluation

OpenAIRE

Cádiz, V.; Galià, M.; Ronda, J.C.; Lligadas, G.; Bordons, A.; Esteve-Zarzoso, B.; Lluch, C.

2014-01-01

10.1002/mabi.201400017 In the present study, plant oil-derived surface-modifiable polyurethane thermosets are presented. Polyol synthesis is carried out taking advantage of thiol-yne photopolymerization of undecylenic acid derivatives containing methyl ester or hydroxyl moieties. The prepared methyl ester-containing polyurethanes allow surface modification treatment to enhance their hydrophilicity and impart antimicrobial activity through the following two steps: i) grafting poly(propylen...

Development of a phenomenological constitutive model for polyurethane foams

International Nuclear Information System (INIS)

Neilsen, M.K.; Morgan, H.S.; Krieg, R.D.; Yoshimura, H.R.

1989-01-01

Rigid, closed-cell, polyurethane foam is used in impact limiters in nuclear waste transport containers. During a hypothetical nuclear waste transport accident, the foam is expected to absorb a significant amount of impact energy by undergoing large inelastic volume reductions. Consequently, the crushing of polyurethane foams must be well characterized and accurately modeled to properly analyze a transport container accident. At the request of Sandia National Laboratories, a series of uniaxial, hydrostatic and triaxial compression tests on polyurethane foams were performed by the New Mexico Engineering Research Institute (NMERI). The combination of hydrostatic and triaxial tests was chosen to provide sufficient data to characterize both the volumetric and deviatoric behaviors of the foams and the coupling between the two responses. Typical results from the NMERI tests are included in this paper. A complete description of these tests can be found in Neilsen et al., 1987. Constitutive models that have been used in the past to model foam did not capture some important foam behaviors observed in the NMERI tests. Therefore, a new constitutive model for rigid, closed-cell, polyurethane foams was developed and implemented in two finite element codes. Development of the new model is discussed in this paper. Also, results from analyses with the new model and other constitutive models are presented to demonstrate differences between the various models. 4 refs., 6 figs., 1 tab

Cyanex based uranyl sensitive polymeric membrane electrodes.

Science.gov (United States)

Badr, Ibrahim H A; Zidan, W I; Akl, Z F

2014-01-01

Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods. © 2013 Published by Elsevier B.V.

Nano-engineered polyurethane resin-modified concrete.

Science.gov (United States)

2014-04-01

The goal of the proposed work is to investigate the application of nano-engineered polyurethane (NEPU) emulsions for latex modified : concrete (LMC). NEPU emulsions are non-toxic, environment friendly, durable over a wide temperature range, provide b...

Biomaterial based novel polyurethane adhesives for wood to wood and metal to metal bonding

Directory of Open Access Journals (Sweden)

Mitesh Ramanlal Patel

2009-01-01

Full Text Available Polyurethane adhesives made from synthetic chemicals are non-biodegradable, costly and difficult to find raw materials from local market. To avoid solid pollution problem, cost effectiveness and easy availability of raw materials, biomaterials based polyurethane adhesives are used in current industrial interest. Direct use of castor oil in polyurethane adhesive gives limited hardness. Modification on active sites of castor oil to utilize double bond of unsaturated fatty acid and carboxyl group yields new modified or activated polyols, which can be utilized for polyurethane adhesive formulation. In view of this, we have synthesized polyurethane adhesives from polyester polyols, castor oil based polyols and epoxy based polyols with Isocyanate adducts based on castor oil and trimethylolpropane. To study the effects of polyurethane adhesive strength (i.e. lap shear strength on wood-to-wood and metal-to-metal bonding through various types of polyols, cross-linking density, isocyanate adducts and also to compare adhesive strength between wood to wood and metal to metal surface. These polyols and polyurethanes were characterized through GPC, NMR and IR-spectroscopy, gel and surface drying time. Thermal stability of PU adhesives was determined under the effect of cross-linking density (NCO/OH ratio. The NCO/OH ratio (1.5 was optimized for adhesives as the higher NCO/OH ratio (2.0 increasing cross-linking density and decreases adhesion. Lower NCO/OH ratio (1.0 provideslow cross-linking density and low strength of adhesives.

Randomized intubation with polyurethane or conical cuffs to prevent pneumonia in ventilated patients.

Science.gov (United States)

Philippart, François; Gaudry, Stéphane; Quinquis, Laurent; Lau, Nicolas; Ouanes, Islem; Touati, Samia; Nguyen, Jean Claude; Branger, Catherine; Faibis, Frédéric; Mastouri, Maha; Forceville, Xavier; Abroug, Fekri; Ricard, Jean Damien; Grabar, Sophie; Misset, Benoît

2015-03-15

The occurrence of ventilator-associated pneumonia (VAP) is linked to the aspiration of contaminated pharyngeal secretions around the endotracheal tube. Tubes with cuffs made of polyurethane rather than polyvinyl chloride or with a conical rather than a cylindrical shape increase tracheal sealing. To test whether using polyurethane and/or conical cuffs reduces tracheal colonization and VAP in patients with acute respiratory failure. We conducted a multicenter, prospective, open-label, randomized study in four parallel groups in four intensive care units between 2010 and 2012. A cohort of 621 patients with expected ventilation longer than 2 days was included at intubation with a cuff composed of cylindrical polyvinyl chloride (n = 148), cylindrical polyurethane (n = 143), conical polyvinyl chloride (n = 150), or conical polyurethane (n = 162). We used Kaplan-Meier estimates and log-rank tests to compare times to events. After excluding 17 patients who secondarily refused participation or had met an exclusion criterion, 604 were included in the intention-to-treat analysis. Cumulative tracheal colonization greater than 10(3) cfu/ml at Day 2 was as follows (median [interquartile range]): cylindrical polyvinyl chloride, 0.66 (0.58-0.74); cylindrical polyurethane, 0.61 (0.53-0.70); conical polyvinyl chloride, 0.67 (0.60-0.76); and conical polyurethane, 0.62 (0.55-0.70) (P = 0.55). VAP developed in 77 patients (14.4%), and postextubational stridor developed in 28 patients (6.4%) (P = 0.20 and 0.28 between groups, respectively). Among patients requiring mechanical ventilation, polyurethane and/or conically shaped cuffs were not superior to conventional cuffs in preventing tracheal colonization and VAP. Clinical trial registered with clinicaltrials.gov (NCT01114022).

Preparation of polyurethane microcapsule using 1,3 propanediol as the polyol component

International Nuclear Information System (INIS)

Ahmad Randy; Dewi Sondari; Evi Triwulandari; Murni Handayani

2010-01-01

Self-healing property is the ability of a material to heal damages automatically and autonomously. Its application would be ranged from paint coating, anti corrosion coating, space shuttle material, construction (concrete) and automotive. Extrinsic self healing requires self healing agent pre embedded or incorporated into polymer matrix that would be released and close the damage in the polymer system, where the polymer itself is not healable. Healing agents are encapsulated or embedded into the material prior application. Example of monomer encapsulated to give self healing property is isophorone diisocyanate (IPDI) encapsulated in polyurethane shell. In this study, we studied the possibility of 1,3 propanediol, that can be derived from palm oil as polyol monomer for polyurethane microcapsule shell containing IPDI or stannous octoate as a self healing agent. Microcapsule in this study was prepared by interfacial polymerization technique to form IPDI monomer in polyurethane shell. FT-IR analysis show that polyurethane prepolymer produced still have unreacted isocyanate group necessary for interfacial polymerization of polyurethane. Morphological analyses of the microcapsule products show that the products have spherical shapes with smooth surface and some with wrinkled surface. The particle sizes were ranged from 40.29 to 526.80 μm. (author)

Oleic and Undecylenic Acids as Renewable Feedstocks in the Synthesis of Polyols and Polyurethanes

Directory of Open Access Journals (Sweden)

Virginia Cádiz

2010-10-01

Full Text Available Nowadays, the utilization of raw materials derived from renewable feedstock is in the spotlight of the chemical industry, as vegetable oils are one of the most important platform chemicals due to their universal availability, inherent biodegradability and low price. Taking into account that polyurethanes are one of the most important industrial products exhibiting versatile properties suitable for use in many fields, our research is focused on exploiting fatty acids in the preparation of biobased polyols and polyurethanes. This review is organized as a function of the nature of the final polyurethane systems; hence we describe the preparation of linear thermoplastic and crosslinked polyurethanes derived from oleic and undecylenic acids-based diols and polyols, respectively.

Engineering a degradable polyurethane intravaginal ring for sustained delivery of dapivirine.

Science.gov (United States)

Kaur, Manpreet; Gupta, Kavita M; Poursaid, Azadeh E; Karra, Prasoona; Mahalingam, Alamelu; Aliyar, Hyder A; Kiser, Patrick F

2011-06-01

We describe the engineering of a degradable intravaginal ring (IVR) for the delivery of the potent HIV-1 reverse transcriptase inhibitor dapivirine. The degradable polymer used in fabricating the device incorporated poly(caprolactone) ester blocks in a poly(tetramethylene ether) glycol ABA type polyurethane backbone. The polymer was designed to maintain its structure for 1 month during usage and then degrade in the environment post-disposal. In vitro release of dapivirine showed zero-order kinetics for up to 1 month and significant levels of drug release into engineered vaginal tissue. The mechanical properties of the degradable IVR were comparable to those of a widely used contraceptive intravaginal ring upon exposure to simulated vaginal conditions. Incubation under simulated vaginal conditions for a month caused minimal degradation with minimal effect on the mechanical properties of the ring and polymer. The cytotoxicity evaluation of the drug-loaded IVRs against Vk2/E6E7 human vaginal epithelial cells, Lactobacillus jensenii, and engineered vaginal tissue constructs showed the degradable polyurethane to be non-toxic. In vitro evaluation of inflammatory potential monitored through the levels of inflammatory cytokines IL-8, IL-1α, IL-6, IL-1β, and MIP-3α when engineered EpiVaginal™ tissue was incubated with the polyurethanes suggested that the degradable polyurethane was comparable to commercial medical grade polyurethane. These results are encouraging for further development of this degradable IVR for topical vaginal delivery of microbicides.

Evaluation of castor oil-based polyurethane membranes in rat bone-marrow cell culture Avaliação de membranas à base de óleo de polímero de mamona em culturas de células de medula óssea de ratos

Directory of Open Access Journals (Sweden)

Sofia de Amorim Cerejo

2011-10-01

Full Text Available PURPOSE: To evaluate three methods to isolate rats MSCs and to analyze the potential of a castor oil polyurethane base membrane as a scaffold for MSCs. METHODS: Four male Wistar rats, aged 20-30 days were used. Bone marrow aspirates from femur and tibia were harvested using DMEM high glucose and heparin. The cell culture was performed in three different ways: direct culture and two types of density gradients. After 15 days, was made the 1st passage and analyzed cell viability with markers Hoerscht 33342 and propidium iodide. The MSCs were characterized by surface markers with the aid of flow cytometry. After this, three types of castor oil polyurethane membranes associated with the MSCs were kept on the 6-well plate for 5 days and were analyzed by optical microscopy to confirm cell aggregation and growth. RESULTS: Separation procedures 1 and 2 allowed adequate isolation of MSCs and favored cell growth with the passage being carried out at 70% confluence after 15 days in culture. The cells could not be isolated using procedure 3. When the 3 castor oil polyurethane membrane types were compared it was possible to observe that the growth of MSCs was around 80% in membrane type 3, 20% in type 2, and 10% in type 1. CONCLUSION: Both Ficoll-Hypaque densities allow isolation of rat MSCs, and especially castor oil-based membrane type 3 may be used as a scaffold for MSCs.OBJETIVO: Avaliar três formas de cultivo de células-tronco mesenquimais de ratos; e analisar o potencial do polímero de mamona na forma de membrana como arcabouço para CTMs. MÉTODOS: Foram utilizados quatro ratos machos Wistar, de 20 a 30 dias de idade. Aspirados da medula óssea do fêmur e da tíbia foram colhidos com DMEM alta glicose e heparina. As células foram isoladas de três formas diferentes: cultivo direto e com dois tipos de gradientes de densidade. Após 15 dias, foi feita a 1ª passagem e analisada a viabilidade celular com os marcadores Hoerscht 33342 e Iodeto de Prop

Optically active polyurethane@indium tin oxide nanocomposite: Preparation, characterization and study of infrared emissivity

International Nuclear Information System (INIS)

Yang, Yong; Zhou, Yuming; Ge, Jianhua; Yang, Xiaoming

2012-01-01

Highlights: ► Silane coupling agent of KH550 was used to connect the ITO and polyurethanes. ► Infrared emissivity values of the hybrids were compared and analyzed. ► Interfacial synergistic action and orderly secondary structure were the key factors. -- Abstract: Optically active polyurethane@indium tin oxide and racemic polyurethane@indium tin oxide nanocomposites (LPU@ITO and RPU@ITO) were prepared by grafting the organics onto the surfaces of modified ITO nanoparticles. LPU@ITO and RPU@ITO composites based on the chiral and racemic tyrosine were characterized by FT-IR, UV–vis spectroscopy, X-ray diffraction (XRD), SEM, TEM, and thermogravimetric analysis (TGA), and the infrared emissivity values (8–14 μm) were investigated in addition. The results indicated that the polyurethanes had been successfully grafted onto the surfaces of ITO without destroying the crystalline structure. Both composites possessed the lower infrared emissivity values than the bare ITO nanoparticles, which indicated that the interfacial interaction had great effect on the infrared emissivity. Furthermore, LPU@ITO based on the optically active polyurethane had the virtue of regular secondary structure and more interfacial synergistic actions between organics and inorganics, thus it exhibited lower infrared emissivity value than RPU@ITO based on the racemic polyurethane.

Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme

International Nuclear Information System (INIS)

Ribeiro, M A; Ramos, A S; Manfredini, M I; Alves, H A; Ramos, E C T; Honda, R Y; Kostov, K G; Lucena, E F; Mota, R P; Algatti, M A; Kayama, M E

2009-01-01

Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm -1 ), C-H (3000-2900cm -1 ), C=O (1730-1650cm -1 ), C-O and C-O-C bonds at 1200-1600cm -1 . The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85 deg. to 22 deg. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.

Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme

Science.gov (United States)

Ribeiro, M. A.; Ramos, A. S.; Manfredini, M. I.; Alves, H. A.; Y Honda, R.; Kostov, K. G.; Lucena, E. F.; Ramos, E. C. T.; Mota, R. P.; Algatti, M. A.; Kayama, M. E.

2009-05-01

Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm-1), C-H (3000-2900cm-1), C=O (1730-1650cm-1), C-O and C-O-C bonds at 1200-1600cm-1. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85° to 22°. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.

Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, M A; Ramos, A S; Manfredini, M I; Alves, H A; Ramos, E C T [UNIVAP, Sao Jose dos Campos, SP (Brazil); Honda, R Y; Kostov, K G; Lucena, E F; Mota, R P; Algatti, M A; Kayama, M E, E-mail: rmota@feg.unesp.b [FEG-DFQ-UNESP, Av. Ariberto Pereira da Cunha 333, 12516-410 - Guaratingueta, SP (Brazil)

2009-05-01

Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm{sup -1}), C-H (3000-2900cm{sup -1}), C=O (1730-1650cm{sup -1}), C-O and C-O-C bonds at 1200-1600cm{sup -1}. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85 deg. to 22 deg. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.

Preparation of eugenol-based polyurethane

Science.gov (United States)

Li, Yupeng; Luo, Fang; Cheng, Chuanjie

2018-03-01

The regenerative eugenol was used as the starting material to prepare diol species by two steps, with a total yield of 28%. Furthermore, the prepared diol reacts with 1,6-hexadiisocyanate(HDI) to afford the corresponding polyurethane (PU). The structure of intermediates and PU are characterized by 1H-NMR or IR.

Modifications of γ-ray sensitivity of bacterial membranes by pre-exposure to light

International Nuclear Information System (INIS)

Misiti-Dorello, P.; Cancelliere, G.; De Martino, G.; Quintilini, M.

1976-01-01

The exposure of E. coli B/r cells to ultraviolet or to visible light prior to irradiation with γ-rays modifies the sensitivity of the cell membrane to radiation damage responsible for the intracellular K + content. Exposure of bacterial cells to sublethal doses of UV radiation increases their sensitivity to γ-induced membrane damage, while exposure to visible light has the opposite effect. In combined exposures, the visible light, either given before or after the UV always produces a strong photoprotective effect. In either case, the photosensitizing effect of UV is completely suppressed. The photoprotection decays with time if cell suspensions are left in the dark before γ-irradiation. At O 0 C, the half-life of the photoprotective effect is 25 min at pH 7 and 100 min at pH 7.5. The decay is due to the presence of oxygen. The light band responsible for the induction of photoprotection has been estimated to lie in the wavelenght region between 540 and 580 nm. (orig./MG) [de

pH-sensitive membranes for lithium separation

International Nuclear Information System (INIS)

Smolinska, Katarzyna; Bryjak, Marek; Wolska, Joanna; Kujawski, Wojciech

2014-01-01

Dielectric barrier discharge plasma was used to modify track etched poly(ethylene terephthalate) membranes followed by grafting of poly(acrylic acid) and copolymers of acrylic acid and di(ethylene glycol)methyl ether methacrylate. The evaluation by IR and XPS spectroscopies showed that both polymers were successfully grafted to the porous membranes. Determination of permeate fluxes pointed the membranes to have excellent responses to pH changes when grafting yield was not so high. When grafting exceeded 0.1 mg cm −2 stimuli response gel-filled membranes were formed that could be used for transport of alkaline ions. The best permselectivity was observed for poly(ethylene terephthalate) membranes grafted with 1:2 copolymer of acrylic acid and di(ethylene glycol)methyl ether methacrylate. The dialysis was more effectively facilitated for lithium than for potassium or sodium salts at solution of pH = 5.5. - Highlights: • Preparation of pore-filled stimuli response membranes that facilitate transport of alkaline salts. • pH controlled transport of alkaline salts. • Facilitation of lithium transport over sodium and potassium

Preparation and characterization of Jatropha oil-based Polyurethane as non-aqueous solid polymer electrolyte for electrochemical devices

International Nuclear Information System (INIS)

Mustapa, Siti Rosnah; Aung, Min Min; Ahmad, Azizan; Mansor, Ahmad; TianKhoon, Lee

2016-01-01

Jatropha-oil based polyurethane is one of the initiative for replacing conventional petroleum based polyurethane. The vegetable oil-based polyurethane is more cost-effective and synthesize from renewable resources. Polyurethane was synthesized through prepolymerization method between jatropha oil-based polyol and diphenylmethane 4, 4’diisocyanate, (MDI) in inert condition. Then, lithium perchloride ion (LiClO 4 ) was added to the polyurethane system to form electrolyte film via solution casting technique. The polymer electrolytes were prepared by varying the amount of LiClO 4 ion 10 wt.% to 30 wt. %. The highest conductivity is achieved at 25 wt.% of LiClO 4 salt content, which is 1.29 × 10 −4 S/cm at room temperature 30 °C. The FTIR results showed the shifting of carbonyl group (C=O) (1750 cm −1 – 1730 cm −1 ), ether and ester group (C-O-C) (1300 cm −1 –1000 cm −1 ) and amine functional groups (N-H) (1650 cm −1 –1500 cm −1 ) in polyurethane electrolytes from the blank polyurethane shows that oxygen and nitrogen atom acts as electron donor in the electrolytes system. It also confirmed that the intermolecular reaction had occurred in the electrolytes system. While, the XRD analysis showed the semi-crystalline properties of polyurethane have been reduced to amorphous phase upon the increasing addition of lithium ion. SEM results revealed the morphology analysis of the polyurethane electrolytes. There is homogenous and smooth surface in polyurethane and the dissociation of salt was observed after the addition of salt indicates there was interaction between salt and the polymer host.

Biobased composites from thermoplastic polyurethane elastomer and cross-linked acrylated-epoxidized soybean oil

Science.gov (United States)

Soybean oil is an important sustainable material. Crosslinked acrylated epoxidized soybean oil (AESO) is brittle without flexibility and the incorporation of thermoplastic polyurethane improves its toughness for industrial applications. The hydrophilic functional groups from both oil and polyurethan...

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Deka Harekrishna

2009-01-01

Full Text Available Abstract The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

Chemical and Enzymatic Hydrolysis of Polyurethane/Polylactide Blends

Directory of Open Access Journals (Sweden)

Joanna Brzeska

2015-01-01

Full Text Available Polyether-esterurethanes containing synthetic poly[(R,S-3-hydroxybutyrate] (R,S-PHB and polyoxytetramethylenediol in soft segments and polyesterurethanes with poly(ε-caprolactone and poly[(R,S-3-hydroxybutyrate] were blended with poly([D,L]-lactide (PLA. The products were tested in terms of their oil and water absorption. Oil sorption tests of polyether-esterurethane revealed their higher response in comparison to polyesterurethanes. Blending of polyether-esterurethanes with PLA caused the increase of oil sorption. The highest water sorption was observed for blends of polyether-esterurethane, obtained with 10% of R,S-PHB in soft segments. The samples mass of polyurethanes and their blends were almost not changed after incubation in phosphate buffer and trypsin and lipase solutions. Nevertheless the molecular weight of polymers was significantly reduced after degradation. It was especially visible in case of incubation of samples in phosphate buffer what suggested the chemical hydrolysis of polymer chains. The changes of surface of polyurethanes and their blends, after incubation in both enzymatic solutions, indicated on enzymatic degradation, which had been started despite the lack of mass lost. Polyurethanes and their blends, contained more R,S-PHB in soft segments, were degraded faster.

Global sensitivity analysis of a filtration model for submerged anaerobic membrane bioreactors (AnMBR).

Science.gov (United States)

Robles, A; Ruano, M V; Ribes, J; Seco, A; Ferrer, J

2014-04-01

The results of a global sensitivity analysis of a filtration model for submerged anaerobic MBRs (AnMBRs) are assessed in this paper. This study aimed to (1) identify the less- (or non-) influential factors of the model in order to facilitate model calibration and (2) validate the modelling approach (i.e. to determine the need for each of the proposed factors to be included in the model). The sensitivity analysis was conducted using a revised version of the Morris screening method. The dynamic simulations were conducted using long-term data obtained from an AnMBR plant fitted with industrial-scale hollow-fibre membranes. Of the 14 factors in the model, six were identified as influential, i.e. those calibrated using off-line protocols. A dynamic calibration (based on optimisation algorithms) of these influential factors was conducted. The resulting estimated model factors accurately predicted membrane performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison between properties of polyurethane nano composites prepared by two different methods

International Nuclear Information System (INIS)

Barmar, M.; Barikani, M.; Fereidoonnia, M.

2009-01-01

In this work, a thermoplastic polyurethane elastomer model based on polytetramethylene glycol. toluene diisocyanate and 1,4-butanediol was selected and synthesized. According to this model two types of polyurethane nano composites were prepared by in situ polymerization and melt intercalation procedures. The organo-modified nano clay was used in nano composites samples in 0.4 weight percent level. The prepared nano composites were studied by WAXD, tensile and thermal analysis. Thermal properties of the nano composites were higher than those of pure polyurethane elastomers. Nano composites prepared via melt intercalation method showed a lower tensile strength and hardness than those prepared through in situ polymerization method

Differential sensitivity of cellular membranes to peroxidative processes

International Nuclear Information System (INIS)

Huijbers, W.A.R.

1976-01-01

A description is given of a morphological and cytochemical investigation into the effects of both vitamin E deficiency and X-irradiation on the ultrastructure and enzyme activities of several cellular membranes, particularly the plasma membrane and the membranes of lysosomes, mitochondria and endoplasmic reticulum. In the vitamin E deficient situation, the radicals and peroxides only originate near mitochondria and endoplasmic reticulum, so that these membrane systems suffer from changes. After irradiation of the liver of both the control duckling and the deficient duckling, radicals originate in all parts of the cell. Due to their high content of lipids and cholesterols, peroxides will occur mainly in plasma membranes and lysosomal membranes. Moreover, in these membranes there is hardly any protection by vitamin E

Structure-property studies of thermoplastic and thermosetting polyurethanes using palm and soya oils-based polyols.

Science.gov (United States)

Mohammed, Issam Ahmed; Al-Mulla, Emad Abbas Jaffar; Kadar, Nurul Khizien Abdul; Ibrahim, Mazlan

2013-01-01

Palm and soya oils were converted to monoglycerides via transesterification of triglycerides with glycerol by one step process to produce renewable polyols. Thermoplastic polyurethanes (TPPUs) were prepared from the reaction of the monoglycerides which act as polyol with 4,4'-methylenediphenyldiisocyanate (MDI) whereas, thermosetting polyurethanes (TSPUs) were prepared from the reaction of glycerol, MDI and monoglycerides in one pot. Characterization of the polyurethanes was carried out by FT-IR, (1)H NMR, and iodine value and sol-gel fraction. The TSPUs showed good thermal properties compared to TPPUs as well as TSPUs exhibits good properties in pencil hardness and adhesion, however poorer in flexural and impact strength compared to TPPUs. The higher percentage of cross linked fraction, the higher degree of cross linking occurred, which is due to the higher number of double bond presents in the TSPUs. These were reflected in iodine value test as the highest iodine value of the soya-based thermosetting polyurethanes confirmed the highest degree of cross linking. Polyurethanes based on soya oil showed better properties compared to palm oil. This study is a breakthrough development of polyurethane resins using palm and soya oils as one of the raw materials.

Material gap membrane distillation: A new design for water vapor flux enhancement

KAUST Repository

Francis, Lijo

2013-08-19

A new module design for membrane distillation, namely material gap membrane distillation (MGMD), for seawater desalination has been proposed and successfully tested. It has been observed that employing appropriate materials between the membrane and the condensation plate in an air gap membrane distillation (AGMD) module enhanced the water vapor flux significantly. An increase in the water vapor flux of about 200-800% was observed by filling the gap with sand and DI water at various feed water temperatures. However, insulating materials such as polypropylene and polyurethane have no effect on the water vapor flux. The influence of material thickness and characteristics has also been investigated in this study. An increase in the water gap width from 9. mm to 13. mm increases the water vapor flux. An investigation on an AGMD and MGMD performance comparison, carried out using two different commercial membranes provided by different manufacturers, is also reported in this paper. © 2013 Elsevier B.V.

MORPHOLOGICAL CHANGES IN POLYURETHANE COATINGS ON EXPOSURE TO WATER. (R828081E01)

Science.gov (United States)

When a polyurethane self-priming coating on a sol-gel treated aluminum panel was immersed in dilute Harrison's solution, subsequent change of the polyurethane coating surface was inspected with atomic force microscopy (AFM) and scanning electron microscopy (SEM). After immersi...

Flame Retardants Used in Flexible Polyurethane Foam

Science.gov (United States)

The partnership project on flame retardants in furniture seeks to update the health and environmental profiles of flame-retardant chemicals that meet fire safety standards for upholstered consumer products with polyurethane foam

Effect of melamine phosphate on the thermal stability and flammability of bio-based polyurethanes

International Nuclear Information System (INIS)

Yakushin, Vladimir; Sevastyanova, Irina; Vilsone, Dzintra; Avots, Andris

2016-01-01

The effect of melamine phosphate (MP) on the thermal stability of bio-based polyurethane and the flammability parameters of wood samples with polyurethane coatings was studied. Thermogravimetric analysis and cone calorimeter test at a heat flux of 35 kW/m 2 were used for this purpose. The main characteristics of the thermal stability and flammability of the coating with addition of MP were compared with the characteristics of analogous coatings with addition of ammonium polyphosphate (APP), as well as APP in combination with melamine. It was found that the use of MP as an intumescent additive allows a considerable decrease of most of the flammability parameters of the polyurethane based on tall oil fatty acids, like APP. To reach the maximum effect, it is enough to load in the polyurethane 20% of MP. In contrast to APP, MP reduces also the smoke release of the samples. Using MP in combination with APP at definite weight ratios, it is possible to essentially reduce the flammability parameters of polyurethane coatings, such as PHRR, THR and MARHE. (paper)

APPLICATION OF POLYURETHANE FOAM FOR IMPACT ABSORPTION AND THERMAL INSULATION FOR RADIOACTIVE MATERIALS PACKAGINGS

International Nuclear Information System (INIS)

Smith, A; Glenn Abramczyk, G; Paul Blanton, P; Steve Bellamy, S; William Daugherty, W; Sharon Williamson, S

2007-01-01

Polyurethane foam has been widely used as an impact absorbing and thermal insulating material for large radioactive materials packages, since the 1980's. With the adoption of the regulatory crush test requirement, for smaller packages, polyurethane foam has been adopted as a replacement for cane fiberboard, because of its ability to withstand the crush test. Polyurethane foam is an engineered material whose composition is much more closely controlled than that of cane fiberboard. In addition, the properties of the foam can be controlled by controlling the density of the foam. The conditions under which the foam is formed, whether confined or unconfined have an affect on foam properties. The study reported here reviewed the application of polyurethane foam in RAM packagings and compared property values reported in the literature with published property values and test results for foam specimens taken from a prototype 9977 packaging. The study confirmed that, polyurethane foam behaves in a predictable and consistent manner and fully satisfies the functional requirements for impact absorption and thermal insulation

Estimation of efficiency of hydrotransport pipelines polyurethane coating application in comparison with steel pipelines

Science.gov (United States)

Aleksandrov, V. I.; Vasilyeva, M. A.; Pomeranets, I. B.

2017-10-01

The paper presents analytical calculations of specific pressure loss in hydraulic transport of the Kachkanarsky GOK iron ore processing tailing slurry. The calculations are based on the results of the experimental studies on specific pressure loss dependence upon hydraulic roughness of pipelines internal surface lined with polyurethane coating. The experiments proved that hydraulic roughness of polyurethane coating is by the factor of four smaller than that of steel pipelines, resulting in a decrease of hydraulic resistance coefficients entered into calculating formula of specific pressure loss - the Darcy-Weisbach formula. Relative and equivalent roughness coefficients are calculated for pipelines with polyurethane coating and without it. Comparative calculations show that hydrotransport pipelines polyurethane coating application is conductive to a specific energy consumption decrease in hydraulic transport of the Kachkanarsky GOC iron ore processing tailings slurry by the factor of 1.5. The experiments were performed on a laboratory hydraulic test rig with a view to estimate the character and rate of physical roughness change in pipe samples with polyurethane coating. The experiments showed that during the following 484 hours of operation, roughness changed in all pipe samples inappreciably. As a result of processing of the experimental data by the mathematical statistics methods, an empirical formula was obtained for the calculation of operating roughness of polyurethane coating surface, depending on the pipeline operating duration with iron ore processing tailings slurry.

Flexible camphor diamond-like carbon coating on polyurethane to prevent Candida albicans biofilm growth.

Science.gov (United States)

Santos, Thaisa B; Vieira, Angela A; Paula, Luciana O; Santos, Everton D; Radi, Polyana A; Khouri, Sônia; Maciel, Homero S; Pessoa, Rodrigo S; Vieira, Lucia

2017-04-01

Camphor was incorporated in diamond-like carbon (DLC) films to prevent the Candida albicans yeasts fouling on polyurethane substrates, which is a material commonly used for catheter manufacturing. The camphor:DLC and DLC film for this investigation was produced by plasma enhanced chemical vapor deposition (PECVD), using an apparatus based on the flash evaporation of organic liquid (hexane) containing diluted camphor for camphor:DLC and hexane/methane, mixture for DLC films. The film was deposited at a low temperature of less than 25°C. We obtained very adherent camphor:DLC and DLC films that accompanied the substrate flexibility without delamination. The adherence of camphor:DLC and DLC films on polyurethane segments were evaluated by scratching test and bending polyurethane segments at 180°. The polyurethane samples, with and without camphor:DLC and DLC films were characterized by Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and optical profilometry. Candida albicans biofilm formation on polyurethane, with and without camphor:DLC and DLC, was assessed. The camphor:DLC and DLC films reduced the biofilm growth by 99.0% and 91.0% of Candida albicans, respectively, compared to bare polyurethane. These results open the doors to studies of functionalized DLC coatings with biofilm inhibition properties used in the production of catheters or other biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterization of gold nanotube/nanowire-polyurethane composite based on castor oil and polyethylene glycol.

Science.gov (United States)

Ganji, Yasaman; Kasra, Mehran; Salahshour Kordestani, Soheila; Bagheri Hariri, Mohiedin

2014-09-01

Gold nanotubes/nanowires (GNT/NW) were synthesized by using the template-assisted electrodeposition technique and mixed with castor oil-polyethylene glycol based polyurethane (PU) to fabricate porous composite scaffolds for biomedical application. 100 and 50 ppm of GNT/NW were used to synthesize composites. The composite scaffolds were characterized by Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscopy. Cell attachment on polyurethane-GNT/NW composites was investigated using fat-derived mesenchymal stem cells. Addition of 50 or 100 ppm GNT/NW had significant effects on thermal, mechanical, and cell attachment of polyurethane. Higher crosslink density and better cell attachment and proliferation were observed in polyurethane containing 50 ppm GNT/NW. The results revealed that GNT/NW formed hydrogen bonding with the polyurethane matrix and improved the thermomechanical properties of nanocomposites. Compared with pure PU, better cellular attachment on polyurethane-GNT/NW composites was observed resulting from the improved surface properties of composites. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of waterborne, branched, functional poly(urethane)s and theire applications

OpenAIRE

Ongun, Nihan

2014-01-01

Polyurethanes are an important class of polymers that have wide application in a number of different industrial sectors. Their versatile chemistry enables researchers to design novel materials ranging from liquid, soft and rubbery solids to rigid thermoplastic and thermoset polymer for elastomeric materials, coating and adhesive. The present study focuses on synthesizing waterborne, branched and chemically functional polyurethanes with unique architectures via novel methodologies for coating ...

The reactive extrusion of thermoplastic polyurethane

NARCIS (Netherlands)

Verhoeven, Vincent Wilhelmus Andreas

2006-01-01

The objective of this thesis was to increase the understanding of the reactive extrusion of thermoplastic polyurethane. Overall, several issues were identified: • Using a relative simple extrusion model, the reactive extrusion process can be described. This model can be used to further investigate

Inkjet printing of polyurethane colloidal suspensions

NARCIS (Netherlands)

Berg, van den A.M.J.; Smith, P.J.; Perelaer, J.; Schrof, W.; Koltzenburg, S.; Schubert, U.S.

2007-01-01

An aqueous 40 wt% dispersion of polyurethane has been successfully printed at room temperature using a piezoelectric inkjet printer. Simple layered structures, as well as dots, were made and subsequently analyzed using white-light interferometry. A single layer was found to have a structure height

A multilayered polyurethane foam technique for skin graft immobilization.

Science.gov (United States)

Nakamura, Motoki; Ito, Erika; Kato, Hiroshi; Watanabe, Shoichi; Morita, Akimichi

2012-02-01

Several techniques are applicable for skin graft immobilization. Although the sponge dressing is a popular technique, pressure failure near the center of the graft is a weakness of the technique that can result in engraftment failure. To evaluate the efficacy of a new skin graft immobilization technique using multilayered polyurethane foam in vivo and in vitro. Twenty-six patients underwent a full-thickness skin graft. Multiple layers of a hydrocellular polyurethane foam dressing were used for skin graft immobilization. In addition, we created an in vitro skin graft model that allowed us to estimate immobilization pressure at the center and edges of skin grafts of various sizes. Overall mean graft survival was 88.9%. In the head and neck region (19 patients), mean graft survival was 93.6%. Based on the in vitro outcomes, this technique supplies effective pressure (skin graft. This multilayered polyurethane foam dressing is simple, safe, and effective for skin graft immobilization. © 2011 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Synthesis and Characterization of Novel Polyurethanes Based on Vegetable Oils Amide and Ester Polyols

Directory of Open Access Journals (Sweden)

Vladimir YAKUSHIN

2014-09-01

Full Text Available Amide and ester type polyols were synthesized from rapeseed, sunflower and castor oils, and two types of ethanolamine (diethanolamine and triethanolamine at different molar ratio. Poly(urethane amides and polyester urethanes based on the synthesized polyols were prepared. The effect of the chemical structure of the obtained polyurethanes on density, glass transition temperature, thermal stability and mechanical properties was investigated. The influence of the content of OH groups in the synthesized polyols on the specified characteristics was estimated. It has been found that poly(urethane amides have better mechanical characteristics, but their thermal stability is lower than that of polyester urethanes. The chemical structure of the synthesized polyols and polyurethanes is qualitatively confirmed by IR-spectroscopy data. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4532

Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

Energy Technology Data Exchange (ETDEWEB)

Mortley, Aba [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)], E-mail: aba.mortley@rmc.ca; Bonin, H.W.; Bui, V.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)

2007-12-15

Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging {sup 13}C solid state NMR spectra imply limited sample degradation with increasing radiation.

Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

International Nuclear Information System (INIS)

Mortley, Aba; Bonin, H.W.; Bui, V.T.

2007-01-01

Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging 13 C solid state NMR spectra imply limited sample degradation with increasing radiation

Intrinsically radiopaque polyurethanes with chain extender 4,4'-isopropylidenebis [2-(2,6-diiodophenoxy)ethanol] for biomedical applications.

Science.gov (United States)

Dawlee, S; Jayabalan, M

2015-05-01

Radiopaque polyurethanes are used for medical applications as it allows post-operative assessment of the biomaterial devices using X-ray. Inherently, radiopaque polyurethanes based on polytetramethylene glycol (PTMG), polypropylene glycol, 4,4'-methylenebis(phenyl isocyanate), and a new iodinated chain extender 4,4'-isopropylidenebis[2-(2,6-diiodophenoxy)ethanol] with flexible spacers were synthesized and characterized. The iodinated polyurethanes were clear, optically transparent, and had high molecular weights. The polyurethanes also possessed excellent radiopacity and high thermal stability. The biocompatibility of the most promising iodinated polyurethane was evaluated both in vitro (cytotoxicity evaluation by direct contact and MTT assay, using L929 mouse fibroblast cells) and in vivo (toxicology studies in rabbits and subcutaneous implantation in rats). The material was nontoxic and well tolerated by the animals. Thus, these radiopaque and transparent polyurethanes are expected to have potential for various biomedical applications. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Sensitivity of mitochondrial DNA depleted ρ0 cells to H2O2 depends on the plasma membrane status.

Science.gov (United States)

Tomita, Kazuo; Kuwahara, Yoshikazu; Takashi, Yuko; Tsukahara, Takao; Kurimasa, Akihiro; Fukumoto, Manabu; Nishitani, Yoshihiro; Sato, Tomoaki

2017-08-19

To clarify the relationship between mitochondrial DNA (mtDNA)-depleted ρ0 cells and the cellular sensitivity to hydrogen peroxide (H 2 O 2 ), we established HeLa and SAS ρ0 cell lines and investigated their survival rate in H 2 O 2 , radical scavenging enzymes, plasma membrane potential status, and chronological change in intracellular H 2 O 2 amount under the existence of extracellular hydrogen peroxide compared with the parental cells. The results revealed that ρ0 cells had higher sensitivity to H 2 O 2 than their parental cells, even though the catalase activity of ρ0 cells was up-regulated, and the membrane potential of the ρ0 cells was lower than their parental cells. Furthermore, the internal H 2 O 2 amount significantly increased only in ρ0 cells after 50 μM H 2 O 2 treatment for 1 h. These results suggest that plasma membrane status of ρ0 cells may cause degradation, and the change could lead to enhanced membrane permeability to H 2 O 2 . As a consequence, ρ0 cells have a higher H 2 O 2 sensitivity than the parental cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Light Scattering of TiO₂ Nanoparticles Embedded in Polyurethane

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

A new approach of enhancing light scattering in polyurethane polymer through the effect of TiO2 nanoparticles (NP) is explored. The TiO2 NP with sizes of 360 nm, 410 nm and 500 nm were dispersed in polyurethane polymer in concentrations ranging from 0.25 wt% up to 2 wt%. Reflectivity and UV-visible...

Mechanical performance of laminated composites incorporated with nanofibrous membranes

International Nuclear Information System (INIS)

Liu, L.; Huang, Z.-M.; He, C.L.; Han, X.J.

2006-01-01

The effect of non-woven nanofibrous membranes as interlaminar interfaces on the mechanical performance of laminated composites was investigated experimentally. The nanofibrous membranes are porous, thin and lightweight, and exhibit toughness and strength to some extent. They give little increase in weight and thickness when incorporated into a laminate. More important, they can be used as a functional agent carrier for the laminate. The nanofiber membranes used in this paper were prepared by electrospinning of Nylon-6 (PA6), Epoxy 609 (EPO 1691-410) and thermoplastic polyurethane (TPU), with a thickness ranging from 20 to 150 μm. The non-woven fabrics were attached to one side of a glass/epoxy fabric lamina prior to lamination and each fabric was arranged in between two adjacent plies of the laminate. The nanofibrous membranes were characterized through scanning electron microscopy (SEM) and tensile testing, whereas the mechanical properties of the laminate were understood in terms of three-point bending and short-beam shear tests. Results have shown that the nanofibrous membranes in the ply interfaces with a proper thickness did not affect the mechanical performance of the composite laminates significantly

Auxetic Foam-Based Contact-Mode Triboelectric Nanogenerator with Highly Sensitive Self-Powered Strain Sensing Capabilities to Monitor Human Body Movement

KAUST Repository

Zhang, Steven L.; Lai, Ying-Chih; He, Xu; Liu, Ruiyuan; Zi, Yunlong; Wang, Zhong Lin

2017-01-01

The first contact-mode triboelectric self-powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self-powered scale to measure weight, and a seat belt to measure body movements inside a car seat.

Auxetic Foam-Based Contact-Mode Triboelectric Nanogenerator with Highly Sensitive Self-Powered Strain Sensing Capabilities to Monitor Human Body Movement

KAUST Repository

Zhang, Steven L.

2017-05-15

The first contact-mode triboelectric self-powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self-powered scale to measure weight, and a seat belt to measure body movements inside a car seat.

Soy-based UV resistant polyurethane pultruded composites.

Science.gov (United States)

2012-02-01

Aliphatic polyurethane (PU) nanocomposites were synthesized using organically modified nanoclays. X-Ray diffraction results : confirmed good exfoliation of nanoclay particles in the PU resin system. With the addition of just 1% of nanoclay in the bas...

Relationship between free volume and mechanical properties of polyurethane irradiated by gamma rays

International Nuclear Information System (INIS)

Heliang Sui; Xin Ju; Xueyong Liu; Fachun Zhong; Xiaoyan Li; Baoyi Wang

2014-01-01

Polyurethane was irradiated at various gamma radiation doses up to 1,000 kGy at room temperature in nitrogen. Positron annihilation lifetime spectroscopy, tensile test and dynamic mechanical analysis were used to find the relationship between free volume and mechanical properties. An increase of the free volume fraction in soft segments (SS) and a decrease of the free volume fraction in hard segments (HS) during gamma radiation was observed and analyzed. The results showed that HS in polyurethane had the excellent resistance to gamma radiation, whereas SS had a tendency to degrade. The reason for the decrease of the strain at break and the ultimate tensile strength was analyzed, which showed the changes in the mechanical properties of polyurethane irradiated by gamma rays were mainly determined by the changes of free volume in SS. If the resistance properties of polyurethanes exposed to radiations need to be improved, SS should be paid more attention to. (author)

Green waste cooking oil-based rigid polyurethane foam

Science.gov (United States)

Enderus, N. F.; Tahir, S. M.

2017-11-01

Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.

Synthesis of Polydimethylsiloxane-Modified Polyurethane and the Structure and Properties of Its Antifouling Coatings

Directory of Open Access Journals (Sweden)

Zhan-Ping Zhang

2018-04-01

Full Text Available Polydimethylsiloxane (PDMS could be used to improve the antifouling properties of the fouling release coatings based on polyurethane (PU. A series of polydimethylsiloxane-modified polyurethane coatings were synthesized with various PDMS contents, using the solvent-free method. The effects of PDMS content and seawater immersion on the chain structure and surface morphology were investigated by confocal laser scanning microscopy (CLSM, atomic force microscopy (AFM, Fourier transform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and X-ray diffraction (XRD. Based on the measurements of contact angles of deionized water and diiodomethane, surface free energies of the coatings were estimated according to the Owens two-liquid method. The PDMS-modified polyurethane exhibited lower surface free energy and a lower glass transition temperature than polyurethane. The presence of PDMS increased the degree of microphase separation, and enhanced the water resistance of the coatings. The optimum amount of PDMS reduced the elastic modulus and increased the ductility of the coating. The presence of PDMS benefited the removal of weakly attached organisms. Panel tests in the Yellow Sea demonstrated the antifouling activity of the PDMS-modified polyurethane.

Self-Cleaning Photocatalytic Polyurethane Coatings Containing Modified C60 Fullerene Additives

Directory of Open Access Journals (Sweden)

Jeffrey G. Lundin

2014-08-01

Full Text Available Surfaces are often coated with paint for improved aesthetics and protection; however, additional functionalities that impart continuous self-decontaminating and self-cleaning properties would be extremely advantageous. In this report, photochemical additives based on C60 fullerene were incorporated into polyurethane coatings to investigate their coating compatibility and ability to impart chemical decontaminating capability to the coating surface. C60 exhibits unique photophysical properties, including the capability to generate singlet oxygen upon exposure to visible light; however, C60 fullerene exhibits poor solubility in solvents commonly employed in coating applications. A modified C60 containing a hydrophilic moiety was synthesized to improve polyurethane compatibility and facilitate segregation to the polymer–air interface. Bulk properties of the polyurethane films were analyzed to investigate additive–coating compatibility. Coatings containing photoactive additives were subjected to self-decontamination challenges against representative chemical contaminants and the effects of additive loading concentration, light exposure, and time on chemical decontamination are reported. Covalent attachment of an ethylene glycol tail to C60 improved its solubility and dispersion in a hydrophobic polyurethane matrix. Decomposition products resulting from oxidation were observed in addition to a direct correlation between additive loading concentration and decomposition of surface-residing contaminants. The degradation pathways deduced from contaminant challenge byproduct analyses are detailed.

Gamma-ray irradiation, autoclave and ethylene oxide sterilization to thermosetting polyurethane: sterilization to polyurethane

International Nuclear Information System (INIS)

Hirata, Noriko; Matsumoto, Ken-Ichi; Inishita, Takashi; Takenaka, Yoshinori; Suma, Yasunori; Shintani, Hideharu; National Inst. of Health Sciences, Tokyo

1995-01-01

Thermosetting polyurethane (PU) is widely used in a large variety of medical devices. 4,4'-methylenedianiline (MDA) was produced from PU by sterilization and it was studied for the relationship between urethane components or polymer characteristics and formation of MDA upon sterilization, using the commercially available dialyzers fabricated with different combination of isocyanate and polyol. We confirmed that the molecular-weight of polyol influenced the production of MDA upon sterilization. (author)

Effects of Additives on Weather-Resistance Properties of Polyurethane Films Exposed to Ultraviolet Radiation and Ozone Atmosphere

Directory of Open Access Journals (Sweden)

Haiyan Wang

2014-01-01

Full Text Available Three polyurethane films were prepared by adding the antioxidant-1010 and the composite stabilizer to the polyurethane matrix, respectively. The accelerated weathering tests were performed by using self-designed UV/ozone aging test device. The color difference, yellowness index, UV-Vis spectrum, and infrared spectrum were recorded with colorimeter apparatus, UV-Vis spectroscopy, and FT-IR spectroscopy, respectively. The results show that, for the polyurethane film, the composite stabilizer can remarkably decrease UV transmission, the antioxidant-1010 and the composite stabilizer can markedly decrease the photooxidation index and the carbonyl index, respectively, and the antioxidant-1010 can significantly improve the antiyellowing properties after 60 h exposure. With incremental exposure time for the three films, UV-Vis transmission decreases, the photooxidation index, the carbonyl index, color difference, and yellowness index increase gradually. Under current experimental conditions, the order of UV/O3 aging resistance from highness to lowness is as follows: the polyurethane film modified by the antioxidant-1010, the polyurethane film modified by composite stabilizer, and the pure polyurethane film.

A Novel Biodegradable Polyurethane Matrix for Auricular Cartilage Repair: An In Vitro and In Vivo Study.

Science.gov (United States)

Iyer, Kartik; Dearman, Bronwyn L; Wagstaff, Marcus J D; Greenwood, John E

2016-01-01

Auricular reconstruction poses a challenge for reconstructive and burns surgeons. Techniques involving cartilage tissue engineering have shown potential in recent years. A biodegradable polyurethane matrix developed for dermal reconstruction offers an alternative to autologous, allogeneic, or xenogeneic biologicals for cartilage reconstruction. This study assesses such a polyurethane matrix for this indication in vivo and in vitro. To evaluate intrinsic cartilage repair, three pigs underwent auricular surgery to create excisional cartilage ± perichondrial defects, measuring 2 × 3 cm in each ear, into which acellular polyurethane matrices were implanted. Biopsies were taken at day 28 for histological assessment. Porcine chondrocytes ± perichondrocytes were cultured and seeded in vitro onto 1 × 1 cm polyurethane scaffolds. The total culture period was 42 days; confocal, histological, and immunohistochemical analyses of scaffold cultures were performed on days 14, 28, and 42. In vivo, the polyurethane matrices integrated with granulation tissue filling all biopsy samples. Minimal neocartilage invasion was observed marginally on some samples. Tissue composition was identical between ears whether perichondrium was left intact, or not. In vitro, the polyurethane matrix was biocompatible with chondrocytes ± perichondrocytes and supported production of extracellular matrix and Type II collagen. No difference was observed between chondrocyte culture alone and chondrocyte/perichondrocyte scaffold coculture. The polyurethane matrix successfully integrated into the auricular defect and was a suitable scaffold in vitro for cartilage tissue engineering, demonstrating its potential application in auricular reconstruction.

Second and third generation voltage-sensitive fluorescent proteins for monitoring membrane potential

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Amelie Perron

2009-06-01

Full Text Available Over the last decade, optical neuroimaging methods have been enriched by engineered biosensors derived from fluorescent protein (FP reporters fused to protein detectors that convert physiological signals into changes of intrinsic FP fluorescence. These FP-based indicators are genetically encoded, and hence targetable to specific cell populations within networks of heterologous cell types. Among this class of biosensors, the development of optical probes for membrane potential is both highly desirable and challenging. A suitable FP voltage sensor would indeed be a valuable tool for monitoring the activity of thousands of individual neurons simultaneously in a non-invasive manner. Previous prototypic genetically-encoded FP voltage indicators achieved a proof of principle but also highlighted several difficulties such as poor cell surface targeting and slow kinetics. Recently, we developed a new series of FRET-based Voltage-Sensitive Fluorescent Proteins (VSFPs, referred to as VSFP2s, with efficient targeting to the plasma membrane and high responsiveness to membrane potential signaling in excitable cells. In addition to these FRET-based voltage sensors, we also generated a third series of probes consisting of single FPs with response kinetics suitable for the optical imaging of fast neuronal signals. These newly available genetically-encoded reporters for membrane potential will be instrumental for future experimental approaches directed toward the understanding of neuronal network dynamics and information processing in the brain. Here, we review the development and current status of these novel fluorescent probes.

Polyurethane/organo clay nano composite materials via in-situ polymerization

International Nuclear Information System (INIS)

Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

2005-01-01

Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

Fabrication of hierarchical structured SiO2/polyetherimide-polyurethane nanofibrous separators with high performance for lithium ion batteries

International Nuclear Information System (INIS)

Zhai, Yunyun; Xiao, Ke; Yu, Jianyong; Ding, Bin

2015-01-01

Highlights: • Electrospinning followed by dip-coating was used to fabricate SiO 2 /PEI-PU membranes. • Introducing PEI, PU and SiO 2 improved safety, tensile strength and ionic conductivity. • Coating SiO 2 also restrained the micro-shorting and migrated the self-discharge. • SiO 2 /PEI-PU membranes based cell exhibited prominent cycling and rate performance. - ABSTRACT: The performance of lithium ion battery based on electrospun nanofibrous membranes has gained a great deal of attention in the past decades, but the intrinsic low mechanical strength and large pore size of electrospun membranes limit their battery performance. To overcome this limitation, a powerful strategy for designing, fabricating and evaluating silica nanoparticles coated polyetherimide-polyurethane (SiO 2 /PEI-PU) nanofibrous composite membranes is easily developed via electrospinning followed by a dip-coating process. Benefiting from the high porosity, interpenetrating network structure and synergetic effect of PU, PEI and SiO 2 nanoparticles, the as-prepared composite membranes exhibit high ionic conductivity (2.33 mS cm −1 ), robust tensile strength (15.65 MPa) and improved safety (excellent thermal resistance and flame retardant property). Additionally, the as-prepared composite membranes possess relatively narrow pore size distribution with average pore size of 0.58 μm after coating SiO 2 nanoparticles, which plays an important role in hindering the micro-shorting and mitigating self-discharge. Significantly, the SiO 2 /PEI-PU membranes based Li/LiFePO 4 cell exhibits more excellent cycling stability with capacity retention of 98.7% after 50 cycles at 0.2 C rate and better rate capability compared with the Celgard membrane based cell. The results clearly demonstrate that this is a promising separator candidate for next-generation lithium ion batteries, which may represent a significant step toward separators with improved performance

PLATELET ADHESION TO POLYURETHANE UREA UNDER PULSATILE FLOW CONDITIONS

Science.gov (United States)

Navitsky, Michael A.; Taylor, Joshua O.; Smith, Alexander B.; Slattery, Margaret J.; Deutsch, Steven; Siedlecki, Christopher A.; Manning, Keefe B.

2014-01-01

Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s−1. The aim of the current work is to determine platelet adhesion properties to the polyurethane urea surface as a function of time varying shear exposure. A rotating disk system is used to study the influence of steady and pulsatile flow conditions (e.g. cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments retain the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk is rotated in platelet rich bovine plasma for two hours with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow is found to exponentially decay with increasing shear rate. Adhesion levels are found to depend upon peak platelet flux and shear rate regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

Influence of polyurethane resin dies on the fit and adaptation of full veneer crowns.

Science.gov (United States)

Lillywhite, Graeme R R; Vohra, Fahim

2015-01-01

Polyurethane resin is a possible alternative to type IV dental stone for fabrication of indirect restorations however its dimensional accuracy is questionable. The aim was to investigate the dimensional accuracy of silica filled polyurethane resin die material by evaluating the marginal fit and adaptation of indirect gold castings. Experimental, in vitro study. Totally 40 copper plated replicas of a nickel chrome master die analogous to a veneer gold crown preparation were made and impressions recorded using polyvinylsiloxane material. Twenty impressions were poured in type IV dental stone (control group (Vel-mix, Kerr, UK) and the remaining (n = 20) in silica filled polyurethane die material (test group) (Alpha Die MF, CA, USA). Gold castings were fabricated for each die using standardized techniques. The castings were seated on their respective copper plated dies, embedded in resin and sectioned. The specimens were analyzed by measuring marginal opening and the area beneath the casting at a ×63 magnification and using image analysis software. Data were analyzed using a Student's t-test. No significant difference was observed between the experimental groups (P > 0.05). The mean marginal opening for type IV, dental stone and polyurethane resin, was 57 ± 22.6 μm and 63.47 ± 27.1 μm, respectively. Stone displayed a smaller area beneath the casting (31581 ± 16297 μm 2 ) as compared to polyurethane resin (35003 ± 23039 μm 2 ). The fit and adaptation of indirect gold castings made on polyurethane and type IV dental stone dies were comparable.

Managing burn wounds with SMARTPORE Technology polyurethane foam: two case reports.

Science.gov (United States)

Imran, Farrah-Hani; Karim, Rahamah; Maat, Noor Hidayah

2016-05-12

Successful wound healing depends on various factors, including exudate control, prevention of microbial contaminants, and moisture balance. We report two cases of managing burn wounds with SMARTPORE Technology polyurethane foam dressing. In Case 1, a 2-year-old Asian girl presented with a delayed (11 days) wound on her right leg. She sustained a thermal injury from a hot iron that was left idle on the floor. Clinical inspection revealed an infected wound with overlying eschar that traversed her knee joint. As her parents refused surgical debridement under general anesthesia, hydrotherapy and wound dressing using SMARTPORE Technology Polyurethane foam were used. Despite the delay in presentation of this linear thermal pediatric burn injury that crossed the knee joint, the patient's response to treatment and its outcome were highly encouraging. She was cooperative and tolerated each dressing change without the need of supplemental analgesia. Her wound was healed by 24 days post-admission. In Case 2, a 25-year-old Asian man presented with a mixed thickness thermal flame burn on his left leg. On examination, the injury was a mix of deep and superficial partial thickness burn, comprising approximately 3% of his total body surface area. SMARTPORE Technology polyurethane foam was used on his wound; his response to the treatment was very encouraging as the dressing facilitated physiotherapy and mobility. The patient rated the pain during dressing change as 2 on a scale of 10 and his pain score remained the same in every subsequent change. His wound showed evidence of epithelialization by day 7 post-burn. There were no adverse events reported. Managing burn wounds with SMARTPORE Technology polyurethane foam resulted in reduced pain during dressing changes and the successful healing of partial and mixed thickness wounds. The use of SMARTPORE Technology polyurethane foam dressings showed encouraging results and requires further research as a desirable management option in

Application Waste Sawdust as Mixed Polyurethane Insulation in Traditional Cold Storage of Fishing Vessel

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Sutopo Purwono Fitri

2017-03-01

Full Text Available In the process of fishing it takes some supplies such as fishing equipment, instrumentation and storage of fish. The traditional fishermen of their fishing days fishing usually only bring ice cubes. Solid plastic polyurethane foam is a mixture solution of polyols and isocyanates, commonly used as an insulating material storage. From the observation waste generated being sawmill sawdust per spindle with diameter of 30 cm and a length of 1 m with 5 times sawmill, Saws 0.8 cm thick produced 0.0088 m³ / burnable logs only discarded. Therefore takes thermal conductivity test to review mixture of sawdust and polyurethane comparison with variations different dosing. Maximum disposals sawdust can be done is 40% of the total volume of material mixture, polyurethane and sawdust because composite material (sawdust-polyurethane can not be bond with good so easy slab separately from origin form. Thermal Conductivity insulating good and economical on disposals 40% wood flour (0.05252 W / m°C and is able to maintain a 2 kg of ice crystals melt up perfect on 34 hours. Operating profits economical from 4,8 m³insulation composite application with obtained Rp 4.486.000 compared with 100% Polyurethane Insulation Manufacture.

Tetra(p-tolyl)borate-functionalized solvent polymeric membrane: a facile and sensitive sensing platform for peroxidase and peroxidase mimetics.

Science.gov (United States)

Wang, Xuewei; Qin, Wei

2013-07-22

The determination of peroxidase activities is the basis for enzyme-labeled bioaffinity assays, peroxidase-mimicking DNAzymes- and nanoparticles-based assays, and characterization of the catalytic functions of peroxidase mimetics. Here, a facile, sensitive, and cost-effective solvent polymeric membrane-based peroxidase detection platform is described that utilizes reaction intermediates with different pKa values from those of substrates and final products. Several key but long-debated intermediates in the peroxidative oxidation of o-phenylenediamine (o-PD) have been identified and their charge states have been estimated. By using a solvent polymeric membrane functionalized by an appropriate substituted tetraphenylborate as a receptor, those cationic intermediates could be transferred into the membrane from the aqueous phase to induce a large cationic potential response. Thus, the potentiometric indication of the o-PD oxidation catalyzed by peroxidase or its mimetics can be fulfilled. Horseradish peroxidase has been detected with a detection limit at least two orders of magnitude lower than those obtained by spectrophotometric techniques and traditional membrane-based methods. As an example of peroxidase mimetics, G-quadruplex DNAzymes were probed by the intermediate-sensitive membrane and a label-free thrombin detection protocol was developed based on the catalytic activity of the thrombin-binding G-quadruplex aptamer. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The important parameters of polyurethane's properties and preparation

International Nuclear Information System (INIS)

Rad, A.S.

2009-01-01

Polyurethane (PU) is a type of plastic rind is formed by reacting a polyol (a polymeric alcohol with more than. two reactive hydroxyl groups per molecule) with diisocyanates or polymeric isocyanate in the presence of suitable catalysts and additives. Variations in the number of substitutions and the spacing between and within branch chains produce PUs ranging from linear to branched and flexible to rigid. Linear PUs are used for the manufacture of fibers and molding. The structure of polyurethane can be medley containing 'hard' and 'soft' sect, which contribute to the harmony between rigid and elastomeric properties. The chemical composition and molecular weight distribution (MWD)- of the incorporated soft block influence the macroscopic properties of the resulting coating. In modifying the backbone structure of PU coatings it is necessary to consider the end use for the coating and the cost of modification: The properties of the modified PU coating, The resistance of the coating towards mechanical and The compatibility of the coating and the substrate over the temperature range of expected application and The between the benefits to be gained and the additional cost are the parameters that must be A surface functionalization of a synthetic polyurethane was carried out by using biofunctional moieties to obtain a material with the appropriate mechanical properties and processing conditions. (author)

Relationship between red cell membrane fatty acids and adipokines in individuals with varying insulin sensitivity.

Science.gov (United States)

Min, Y; Lowy, C; Islam, S; Khan, F S; Swaminathan, R

2011-06-01

Plasma leptin and adiponectin, and membrane phospholipid fatty acid composition are implicated into the mechanism of insulin resistance but no clear pattern has emerged. Hence, this study examined these variables in subjects presenting to the diabetic clinic for a diagnostic glucose tolerance test. Body composition, glucose, glycated hemoglobin, insulin, leptin, adiponectin, and red cell and plasma phospholipid fatty acids were assessed from 42 normal and 28 impaired glucose tolerant subjects. Insulin sensitivity was determined by homeostatic model assessment. The plasma phosphatidylcholine fatty acid composition of the impaired glucose tolerant subjects was similar to that of normal subjects. However, the impaired glucose tolerant subjects had significantly lower linoleic (Pphosphatidylcholine and phosphatidylethanolamine compared with the normal subjects. Moreover, red cell phosphatidylcholine docosahexaenoic acid correlated positively with adiponectin (r=0.290, Pinsulin (r=-0.335, Pinsulin resistance (r=-0.322, Pinsulin level whereas insulin was the only component that predicted the membrane fatty acids. We postulate that membrane phospholipids fatty acids have an indirect role in determining insulin concentration but insulin has a major role in determining membrane fatty acid composition.

Biodegradability of polyurethane/polysaccharide blends

International Nuclear Information System (INIS)

Mothe, Cheila G.; Leite, Selma G.

2001-01-01

Biodegradable polymers for use in environmental waste-management has been the subject of much discussion over the last few years. Polyurethane mixtures with polysaccharide (80/20 and 90/10 w/w ) have been prepared and films obtained. These films were inoculated, according to ASTM G22-76 rule and analysed by thermogravimetry and scanning electronic microscopy (SEM). The results are discussed in terms of thermal degradation and biodegradability. (author)

Polyurethane as a base for a family of tissue equivalent materials

International Nuclear Information System (INIS)

Griffith, R.V.

1980-01-01

Polyurethane was used as a base material for a wide variety of tissue simulating applications. The technique in fabrication is similar to that of epoxy, however, the end products are generally more flexible for use in applications where flexibility is valuable. The material can be fabricated with relatively small laboratory equipment. The use of polyurethane provides the dosimetrist with the capability of making specific, accurate, on-the-spot tissue equivalent formulations to meet situations which require immediate calibration and response

Micromechanisms of fatigue crack growth in polycarbonate polyurethane: Time dependent and hydration effects.

Science.gov (United States)

Ford, Audrey C; Gramling, Hannah; Li, Samuel C; Sov, Jessica V; Srinivasan, Amrita; Pruitt, Lisa A

2018-03-01

Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates. Fatigue crack propagation characterized three aspects of loading. Study 1 investigated the impact of continuous loading (24h/day) versus intermittent loading (8-10h/day) allowing for relaxation overnight. Study 2 evaluated the effect of frequency and study 3 examined the impact of hydration on the fatigue crack propagation in polycarbonate polyurethane. Samples loaded intermittently failed instantaneously and prematurely upon reloading while samples loaded continuously sustained longer stable cracks. Crack growth for samples tested at 2 and 5Hz was largely planar with little crack deflection. However, samples tested at 10Hz showed high degrees of crack tip deflection and multiple crack fronts. Crack growth in hydrated samples proceeded with much greater ductile crack mouth opening displacement than dry samples. An understanding of the failure mechanisms of this polymer is important to assess the long-term structural integrity of this material for use in load-bearing orthopedic implant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extraction kinetics of uranium (VI) with polyurethane foam

International Nuclear Information System (INIS)

Huang, Ting-Chia; Chen, Dong-Hwang; Huang, Shius-Dong; Huang, Ching-Tsven; Shieh, Mu-Chang.

1993-01-01

The extraction kinetics of uranium(VI) from aqueous nitrate solution with polyether-based polyurethane foam was investigated in a batch reactor with automatic squeezing. The extraction curves of uranium(VI) concentration in solution vs. extraction time exhibited a rather rapid exponential decay within the first few minutes, followed by a slower exponential decay during the remaining period. This phenomenon can be attributed to the presence of two-phase structure, hard segment domains and soft segment matrix in the polyurethane foam. A two-stage rate model expressed by a superposition of two exponential curves was proposed, according to which the experimental data were fitted by an optimization method. The extraction rate of uranium (VI) was also found to increase with increasing temperature, nitrate concentration, and hydration of the cation of nitrate salt. (author)

Sorption of diesel oil from polyurethane composite reinforced with palm fiber

International Nuclear Information System (INIS)

Dantas, I.R.; Cipriano, J.P.; Costa, I.L.M.; Mulinari, D.R.

2016-01-01

One of the methods to contain the diesel oil spill is the application of materials polymeric sorbents and the polyurethane is an option of porous sorbents. In this way, the objective of this study was to evaluate the use of polyurethane composites derivative of castor oil reinforced with palm fibers to sorption of diesel oil and compare with pure polyurethane. The composites were reinforced with 5 to 20% w/w of fibers. Subsequently, the sorption capacity of the composite in function of inserted fiber content in the matrix was analyzed. The physical and morphological characteristics were evaluated by scanning electron microscopy techniques (SEM) and diffraction X-ray (XRD) and the contact angle. The results showed that the composite with 20% w /w showed higher sorption capacity oil diesel compared to pure PU and other composites this fact was due to the heterogeneity of the pores and dispersion of fiber in the matrix. (author)

Preparation of collagen/polyurethane/knitted silk as a composite scaffold for tendon tissue engineering.

Science.gov (United States)

Sharifi-Aghdam, Maryam; Faridi-Majidi, Reza; Derakhshan, Mohammad Ali; Chegeni, Arash; Azami, Mahmoud

2017-07-01

The main objective of this study was to prepare a hybrid three-dimensional scaffold that mimics natural tendon tissues. It has been found that a knitted silk shows good mechanical strength; however, cell growth on the bare silk is not desirable. Hence, electrospun collagen/polyurethane combination was used to cover knitted silk. A series of collagen and polyurethane solutions (4%-7% w/v) in aqueous acetic acid were prepared and electrospun. According to obtained scanning electron microscopy images from pure collagen and polyurethane nanofibers, concentration was set constant at 5% (w/v) for blend solutions of collagen/polyurethane. Afterward, blend solutions with the weight ratios of 75/25, 50/50 and 25/75 were electrospun. Scanning electron microscopy images demonstrated the smooth and uniform morphology for the optimized nanofibers. The least fibers diameter among three weight ratios was found for collagen/polyurethane (25/75) which was 100.86 ± 40 nm and therefore was selected to be electrospun on the knitted silk. Attenuated total reflectance-Fourier transform infrared spectra confirmed the chemical composition of obtained electrospun nanofibers on the knitted silk. Tensile test of the specimens including blend nanofiber, knitted silk and commercial tendon substitute examined and indicated that collagen/polyurethane-coated knitted silk has appropriate mechanical properties as a scaffold for tendon tissue engineering. Then, Alamar Blue assay of the L929 fibroblast cell line seeded on the prepared scaffolds demonstrated appropriate viability of the cells with a significant proliferation on the scaffold containing more collagen content. The results illustrate that the designed structure would be promising for being used as a temporary substitute for tendon repair.

Generalization of the memory integer model for the analysis of the quasi-static behaviour of polyurethane foams

International Nuclear Information System (INIS)

Jmal, Hamdi; Ju, Ming Lei; Dupuis, Raphael; Aubry, Evelyne

2014-01-01

Polyurethane foam is a cellular material characterized by an interesting mechanical spectrum of properties: low density, capacity to absorb the deformation energy and low stiffness. This spectrum of properties makes polyurethane foam commonly used in many thermal, acoustic and comfort applications. Several models, such as memory, hyper-elastic and pseudo-elastic models have been developed in the literature to describe the mechanical response of polyurethane foam under quasi-static and dynamic test conditions. The main disadvantage of these models is the dependence of their parameters against the test conditions (strain rate, maximum compression level, etc). This affects the general character of their representativeness to the quasi-static and dynamic behaviours of polyurethane foam. The main goal of this article is to implement reliable mechanical model which is able to provide the quasi-static response of the polyurethane foam under different strain rates and large compressive deformation. The dimensional parameters of our model can be expressed by the product of two independent parts; the first contain only the test conditions and the second define the dimensionless and invariant parameters that characterize the foam material. The developed model has been proposed after several experimental studies allowing the apprehension of the quasi-static behaviour (through unidirectional compression tests). The polyurethane foam, under large deformations, exhibits a nonlinear elastic behaviour and viscoelastic behaviour. To assess the ability of our model to be a general representation, three industrial polyurethane foams have been considered.

Fabrication and characterization of cellulose nanocrystal based transparent electroactive polyurethane

Science.gov (United States)

Ko, Hyun-U.; Kim, Hyun Chan; Kim, Jung Woong; Zhai, Lindong; Jayaramudu, Tippabattini; Kim, Jaehwan

2017-08-01

This paper reports cellulose nanocrystal (CNC) based transparent and electroactive polyurethane (CPPU), suitable for actively tunable optical lens. CNC is used for high dielectric filler to improve electromechanical behavior of CPPU. For high transparency and homogeneous distribution of CNC in polyurethane, CNC-poly[di(ethylene glycol) adipate] is used to play a role of polyol and isocyanate salt. The fabricated CPPU exhibits high transparency (>90%) and 10% of electromechanical strain under 3 V μm-1 electric field. Mechanical, dielectric properties as well as physical and chemical characteristics are investigated to prove the electromechanical behavior of CPPU.

Surface coated polyurethane with improved bioactivity and cytocompatability

CSIR Research Space (South Africa)

Chetty, AS

2006-02-01

Full Text Available Polyurethane (PU) may be suitable for various implant applications; however, it lacks bioactivity. Bioactivity allows for direct tissue attachment at the bio- interface, enabling implant fixation while preventing fibrous encapsulation. To impart...

Synthesis of PVA/PVP hydrogels having two-layer by radiation and their physical properties

International Nuclear Information System (INIS)

Park, K.R.; Nho, Y.C.

2003-01-01

In these studies, two-layer hydrogels which consisted of polyurethane membrane and a mixture of polyvinyl alcohol(PVA)/poly-N-vinylpyrrolidone(PVP)/glycerin/chitosan were made for the wound dressing. Polyurethane was dissolved in solvent, the polyurethane solution was poured on the mould, and then dried to make the thin membrane. Hydrophilic polymer solutions were poured on the polyurethane membranes, they were exposed to gamma irradiation or two steps of 'freezing and thawing' and gamma irradiation doses to make the hydrogels. The physical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the hydrogels for wound dressing. The physical properties of hydrogels such as gelation and gel strength was greatly improved when polyurethane membrane was used as a covering layer of hydrogel, and the evaporation speed of water in hydrogel was reduced

Influences of the Ratio of Polyol and MDI on the Acoustic Parameters of Polyurethane

Science.gov (United States)

Wang, Yonghua; Liu, Zheming; Wu, Haiquan; Zhang, Chengchun; Yu, Huadong; Ren, Luquan; Ichchou, Mohamed

2018-05-01

In this paper, the influence of different ratio of polyol and MDI on the absorption coefficient and acoustic parameters of polyurethane was studied. Ratio of 100:40 and 100:45 show the best sound absorption performance, and the change trend of transmission loss and sound absorption coefficient are opposite. The flow resistance increased with the increasing of the ratio of polyol and MDI, the greater the flow resistance, the worse the high frequency sound absorption property of the polyurethane. When the ratio of polyol and MDI keep 100:45, the minimum porosity of sample, the polyurethane porosity increase with the ratio of polyol and MDI increase.

Synthesis and Properties of Novel Polyurethane Containing Nitrophenylazocatecholic Group as NLO Chromophore

International Nuclear Information System (INIS)

Song, Mi Young; Kim, Mi Sung; Lee, Ju Yeon

2012-01-01

The promise of NLO polymers lies in their higher nonlinear optical activity, faster response time, and easy fabrication into electro-optic devices. In the developments of NLO polymers for electrooptic device applications, stabilization of electrically induced dipole alignment is one of important considerations; in this context, two approaches to minimize the randomization have been proposed, namely the use of cross-linked systems and the utilization of polymers with high glass transition temperature (T g ) such as polyimides. A polyurethane matrix forms extensive hydrogen bonding between urethane linkages, with increased rigidity preventing the relaxation of induced dipoles. Polyurethanes functionalized with hemicyanine and thiophene ring in side chain show an enhanced thermal stability of aligned dipoles. Polyurethanes with NLO chromophores, whose dipole moments are aligned transverse to the main chains, show large second-order nonlinearity with good thermal stability

Preparation of Self Hardening-modelling Polyurethane for Wood Repairing and Cracks Injection

International Nuclear Information System (INIS)

Meligi, G.A.; Elnahas, H.H.; Ammar, A.H.

2014-01-01

Self hardening composite as a modelling clay was prepared from polyurethane, two parts (A) and (B) where (A) contains polyol (polyether), vinyl acetate versatic ester copolymer (VAcVe) and magnesium silicate or wood powder and (B) contains toluene diisocyanate (TDI) as a hardening agent. The two parts mixed thoroughly giving soft putty like feel, open working time 1-2 h and cures hard overnight (24 h full cure). Factors affecting working time and full cure were evaluated. Also, measurements of surface hardness, compressive strength, scanning electron microscopy (SEM), water absorption and effect of ionizing radiation were studied. The suggestion for using the prepared polyurethane composite as clay dries as hard as a rock in the field of wood repair and cracks injection for building walls were recommended. Keywords: Polyurethane, modelling clay, radiation, wood repair and cracks injection.

The use of polyurethane foam as an antimicrobial dressing material in hand surgery

Directory of Open Access Journals (Sweden)

Nebil Yesiloglu

2015-12-01

Full Text Available Polyurethane foam is generally used in negative pressure-assisted wound closure therapy. It provides an antimicrobial environment around the wound, while reducing the rate of skin maceration. The authors used polyurethane foam in routine hand dressings after hand surgery operations that were performed for both congenital and acquired purposes. [Hand Microsurg 2015; 4(3.000: 91-92

Highly sensitive PMOS photodetector with wide band responsivity assisted by nanoporous anodic aluminum oxide membrane

Science.gov (United States)

Chen, Yung Ting; Chen, Yang Fang

2010-03-01

A new approach for developing highly sensitive PMOS photodetector based on the assistance of AAO membrane is proposed, fabricated, and characterized. It enables the photodetector with the tunability of not only the intensity but also the range of the response. Under a forward bias, the response of the PMOS photodetector with AAO membrane covers the visible as well as infrared spectrum; however, under a reverse bias, the near-infrared light around Si band edge dominates the photoresponse. Notably, the response at the optical communication wavelength of 850 nm can reach up to 0.24 A/W with an external quantum efficiency of 35%. Moreover, the response shows a large enhancement factor of 10 times at 1050 nm under a reverse bias of 0.5 V comparing with the device without AAO membrane. The underlying mechanism for the novel properties of the newly designed device has been proposed.

Determination of arsenate in water by anion selective membrane electrode using polyurethane–silica gel fibrous anion exchanger composite

Energy Technology Data Exchange (ETDEWEB)

Khan, Asif Ali, E-mail: asifkhan42003@yahoo.com; Shaheen, Shakeeba, E-mail: shakeebashaheen@ymail.com

2014-01-15

Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO{sub 4}{sup 3−} in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: Polyurethane (PU)–silica (Si gel) based fibrous anion exchanger composites were prepared by solid–gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU–Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1 × 10{sup −8} M to 1 × 10{sup −1} M), response time (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO{sub 4}{sup 3−}) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

Polyurethanes with bio-based and recycled components

Czech Academy of Sciences Publication Activity Database

Beneš, Hynek; Vlček, T.; Černá, R.; Hromádková, Jiřina; Walterová, Zuzana; Svitáková, Romana

2012-01-01

Roč. 114, č. 1 (2012), s. 71-83 ISSN 1438-7697 R&D Projects: GA MPO 2A-2TP1/135 Institutional research plan: CEZ:AV0Z40500505 Keywords : natural oil * polyol * polyurethane Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.266, year: 2012

Comparison of environmentally friendly, selective polyurethane catalysts

Czech Academy of Sciences Publication Activity Database

Strachota, Adam; Strachotová, Beata; Špírková, Milena

2008-01-01

Roč. 23, č. 6 (2008), s. 566-570 ISSN 1042-6914 R&D Projects: GA MPO FT-TA3/034 Institutional research plan: CEZ:AV0Z40500505 Keywords : amine catalyst * foam * gelation * kinetics * polyurethane Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.706, year: 2008

Blends of natural rubber and polyurethane lattices studied by solid-state NMR

International Nuclear Information System (INIS)

Ricardo, Nagila M.P.S.; Franca, Francisco C.F. de; Price, Colin; Heatley, Frank

2001-01-01

Molecular mixing in films formed from a mixture of a polyurethane and natural rubber lattices has been studied using 1 H and 13 C solid-state NMR. The techniques employed include 1 H relaxation measurements, and 13 C cross-polarisation and direct excitation methods. The spectra of the blends were essentially a weighted superposition of the spectra of the individual components, indicating that the polyurethane and rubber remained phase-separated in large domains. (author)

Label-free and substrate-free potentiometric aptasensing using polycation-sensitive membrane electrodes.

Science.gov (United States)

Ding, Jiawang; Chen, Yan; Wang, Xuewei; Qin, Wei

2012-02-21

A potentiometric label-free and substrate-free (LFSF) aptasensing strategy which eliminates the labeling, separation, and immobilization steps is described in this paper. An aptamer binds specifically to a target molecule via reaction incubation, which could induce a change in the aptamer conformation from a random coil-like configuration to a rigid folded structure. Such a target binding-induced aptamer conformational change effectively prevents the aptamer from electrostatically interacting with the protamine binding domain. This could either shift the response curve for the potentiometric titration of the aptamer with protamine as monitored by a conventional polycation-sensitive membrane electrode or change the current-dependent potential detected by a protamine-conditioned polycation-sensitive electrode with the pulsed current-driven ion fluxes of protamine across the polymeric membrane. Using adenosine triphosphate (ATP) as a model analyte, the proposed concept offers potentiometric detection of ATP down to the submicromolar concentration range and has been applied to the determination of ATP in HeLa cells. In contrast to the current LFSF aptasensors based on optical detection, the proposed strategy allows the LFSF biosensing of aptamer/target binding events in a homogeneous solution via electrochemical transduction. It is anticipated that the proposed strategy will lay a foundation for development of potentiometric sensors for LFSF aptasensing of a variety of analytes where target binding-induced conformational changes such as the formation of folded structures and the opening of DNA hairpin loops are involved.

Properties of polyurethane foam/coconut coir fiber as a core material and as a sandwich composites component

Science.gov (United States)

Azmi, M. A.; Abdullah, H. Z.; Idris, M. I.

2013-12-01

This research focuses on the fabrication and characterization of sandwich composite panels using glass fiber composite skin and polyurethane foam reinforced coconut coir fiber core. The main objectives are to characterize the physical and mechanical properties and to elucidate the effect of coconut coir fibers in polyurethane foam cores and sandwich composite panels. Coconut coir fibers were used as reinforcement in polyurethane foams in which later were applied as the core in sandwich composites ranged from 5 wt% to 20 wt%. The physical and mechanical properties found to be significant at 5 wt% coconut coir fiber in polyurethane foam cores as well as in sandwich composites. It was found that composites properties serve better in sandwich composites construction.

Properties of polyurethane foam/coconut coir fiber as a core material and as a sandwich composites component

International Nuclear Information System (INIS)

Azmi, M A; Abdullah, H Z; Idris, M I

2013-01-01

This research focuses on the fabrication and characterization of sandwich composite panels using glass fiber composite skin and polyurethane foam reinforced coconut coir fiber core. The main objectives are to characterize the physical and mechanical properties and to elucidate the effect of coconut coir fibers in polyurethane foam cores and sandwich composite panels. Coconut coir fibers were used as reinforcement in polyurethane foams in which later were applied as the core in sandwich composites ranged from 5 wt% to 20 wt%. The physical and mechanical properties found to be significant at 5 wt% coconut coir fiber in polyurethane foam cores as well as in sandwich composites. It was found that composites properties serve better in sandwich composites construction

Preparation and bioactive properties of nano bioactive glass and segmented polyurethane composites.

Science.gov (United States)

Aguilar-Pérez, Fernando J; Vargas-Coronado, Rossana F; Cervantes-Uc, Jose M; Cauich-Rodríguez, Juan V; Covarrubias, Cristian; Pedram-Yazdani, Merhdad

2016-04-01

Composites of glutamine-based segmented polyurethanes with 5 to 25 wt.% bioactive glass nanoparticles were prepared, characterized, and their mineralization potential was evaluated in simulated body fluid. Biocompatibility with dental pulp stem cells was assessed by MTS to an extended range of compositions (1 to 25 wt.% of bioactive glass nanoparticles). Physicochemical characterization showed that composites retained many of the matrix properties, i.e. those corresponding to semicrystalline elastomeric polymers as they exhibited a glass transition temperature (Tg) between -41 and -36℃ and a melting temperature (Tm) between 46 and 49℃ in agreement with X-ray reflections at 23.6° and 21.3°. However, with bioactive glass nanoparticles addition, tensile strength and strain were reduced from 22.2 to 12.2 MPa and 667.2 to 457.8%, respectively with 25 wt.% of bioactive glass nanoparticles. Although Fourier transform infrared spectroscopy did not show evidence of mineralization after conditioning of these composites in simulated body fluid, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray microanalysis showed the formation of an apatite layer on the surface which increased with higher bioactive glass concentrations and longer conditioning time. Dental pulp stem cells proliferation at day 5 was improved in bioactive glass nanoparticles composites containing lower amounts of the filler (1-2.5 wt.%) but it was compromised at day 9 in composites containing high contents of nBG (5, 15, 25 wt.%). However, Runx2 gene expression was particularly upregulated for the dental pulp stem cells cultured with composites loaded with 15 and 25 wt.% of bioactive glass nanoparticles. In conclusion, low content bioactive glass nanoparticles and segmented polyurethanes composites deserve further investigation for applications such as guided bone regeneration membranes, where osteoconductivity is desirable but not a demanding mechanical performance. © The

Decreased retinal sensitivity after internal limiting membrane peeling for macular hole surgery.

Science.gov (United States)

Tadayoni, Ramin; Svorenova, Ivana; Erginay, Ali; Gaudric, Alain; Massin, Pascale

2012-12-01

To compare the retinal sensitivity and frequency of microscotomas found by spectral domain optical coherence tomography (SD-OCT) combined with scanning laser ophthalmoscopy (SLO) microperimetry after idiopathic macular hole closure, in eyes that underwent internal limiting membrane (ILM) peeling and eyes that did not. This was a retrospective, non-randomised, comparative study. Combined SD-OCT and SLO microperimetry was performed in 16 consecutive eyes after closure of an idiopathic macular hole. A customised microperimetry pattern with 29 measurement points was used. The ILM was peeled in 8/16 eyes. The main outcome measure was mean retinal sensitivity. Mean retinal sensitivity (in dB) was lower after peeling: 9.80 ± 2.35 dB with peeling versus 13.19 ± 2.92 without (p=0.0209). Postoperative microscotomas were significantly more frequent after ILM peeling: 11.3 ± 6.6 points with retinal sensitivity below 10 dB in eyes that underwent peeling versus 2.9 ± 4.6 in those that did not (p=0.0093). These results suggest that ILM peeling may reduce retinal sensitivity, and significantly increase the incidence of microscotomas. Until a prospective trial confirming or not these results, it seems justified to avoid peeling the ILM when its potential benefit seems minor or unproved, and when peeling is carried out, to limit the surface peeled to the bare minimum.

Rigid polyurethane and kenaf core composite foams

Science.gov (United States)

Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...

Ultra-sensitive bio-sensor based on GMR in self-suspended-membrane-type germanium grating

International Nuclear Information System (INIS)

Ma, Jianyong; Zhang, Dawei

2012-01-01

In this paper, an ultra-sensitive bio-sensor based on the GMR effect in self-suspended-membrane-type gratings (SSGs) is proposed using multilayer plane waveguide theory. It is demonstrated from our calculations that the sensitivity of our bio-sensor is near the theoretical limit compared with a conventional GMR sensor. Based on the normalized eigenfunction of a single-layer homogeneous grating, the resonance curves with respect to different refractive indices of surrounding media are calculated, which confirm the estimated sensitivity. In addition, we design a highly sensitive bio-sensor in the near- and mid-IR wavelength region for liquid and gas detection respectively, the sensor can deliver a resolution over 1 × 10 −5 in the near-IR region in a large refractive index (1.3–1.7) range and provide better than 1 × 10 −6 in the mid-IR region, which is enough for various bio-material detections. Therefore, the bio-sensor we proposed is one or two orders more sensitive than conventional GMR sensors. (paper)

Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

Energy Technology Data Exchange (ETDEWEB)

Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon; Kim, Young-Myeong; Ha, Kwon-Soo, E-mail: ksha@kangwon.ac.kr

2011-07-15

Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainly comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.

Novel water-soluble polyurethane nanomicelles for cancer chemotherapy: physicochemical characterization and cellular activities

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Khosroushahi Ahmad

2012-01-01

Full Text Available Abstract Background Efficient delivery of anticancer chemotherapies such as paclitaxel (PTX can improve treatment strategy in a variety of tumors such as breast and ovarian cancers. Accordingly, researches on polymeric nanomicelles continue to find suitable delivery systems. However, due to biocompatibility concerns, a few micellar nanoformulations have exquisitely been translated into clinical uses. Here, we report the synthesis of novel water-soluble nanomicelles using bioactive polyurethane (PU polymer and efficient delivery of PTX in the human breast cancer MCF-7 cells. Results The amphiphilic polyurethane was prepared through formation of urethane bounds between hydroxyl groups in poly (tetramethylene ether glycol (PTMEG and dimethylol propionic acid with isocyanate groups in toluene diisocyanate (TDI. The free isocyanate groups were blocked with phenol, while the free carboxyl groups of dimethylol propionic acid were reacted with triethylamine to attain ionic centers in the polymer backbone. These hydrophobic PTMEG blocks displayed self-assembly forming polymeric nanomicelles in water. The PTX loaded PU nanomicelles showed suitable physical stability, negative zeta potential charge (-43 and high loading efficiency (80% with low level of critical micelle concentration (CMC. In vitro drug release profile showed a faster rate of drug liberation at pH 5.4 as compared to that of pH 7.4, implying involvement of a pH-sensitive mechanism for drug release from the nanomicelles. The kinetic of release exquisitely obeyed the Higuchi model, confirming involvement of diffusion and somewhat erosion at pH 5.4. These nanomicelles significantly inhibited the growth and proliferation of the human breast cancer MCF-7 cells, leading them to apoptosis. The real time RT-PCR analysis confirmed the activation of apoptosis as result of liberation of cytochrome c in the cells treated with the PTX loaded PU nanomicelles. The comet assay analysis showed somewhat DNA

Synthesis and Characterization of Soy-Based Polyurethane Foam with Utilization of Ethylene Glycol in Polyol

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Flora Elvistia Firdaus

2014-08-01

Full Text Available The use of vegetable oils on replacing petroleum has attracted attention of many researchers. The chemical structure of vegetable oils are different from petrochemicals, so the structure of soybean oil has to be chemicallymodified through its unsaturated fatty acid chain in triglyceride. Atwo step process was conducted for the preparationof soy-polyol in designated temperatures; 50 °C, 60 °C, and 70 °C. Ethylene glycol (EG as co-reagent was taking part in soy-polyol synthesis, and the soy-polyol was used as a sole polyol for polyurethane synthesis. Referred to the previous study, the existence of EG in polyurethane synthesis can improved physical properties of polyurethane foam. The aim of this research is using soy-derived polyol for petro-polyol replacement aligned with drop-off of petro-derived reagent; EG. One step process was applied for the foam synthesis.The ingredients for foam synthesis; soy-polyol, Toluene diisocyanate (TDI: a mixture of 2.4 and 2.6 isomers in ratio of 80:20 (TDI T-80, surfactant, and distilled water. The synergize of stoichiometry ratio of co-reagent EG to soy-epoxide with best temperature, with the absence of EG in polyurethane formula can produce an ultimate property of polyurethane foam. 

Dipodal Silane-modified Nano Fe3O4/Polyurethane Magnetic Nanocomposites: Preparation and Characterization

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Mir Mohammad Alavi Nikje

2016-01-01

Full Text Available Magnetic nanocomposites were prepared by incorporation of pure Fe3O4 and surface-modified Fe3O4 nanoparticles (dipodal silane-modified Fe3O4 into a polyurethane elastomer matrix by in situ polymerization method. In preparation of these magnetic nanocomposites, polycaprolactone (PCL was used as a polyester polyol. Because of dipole-dipole interactions between nanoparticles and a large surface area to volume ratio, the magnetic iron oxide nanoparticles tended to agglomerate. Furthermore, the most important challenge was to coat the surface of magnetic Fe3O4 nanoparticles in order to prepare well dispersed and stabilized Fe3O4 magnetic nanoparticles. It was observed that surface modification of Fe3O4 nanoparticles enhanced the dispersion of the nanoparticles in polyurethane matrices and allowed magnetic nanocomposites to be prepared with better properties. Surface modification of Fe3O4 was performed by dipodal silane synthesized based on 3-aminopropyltriethoxysilane (APTS and γ-glycidoxypropyl trimethoxysilane (GPTS. Dipodal silane-coated magnetic nanoparticles (DScMNPs were synthesized and incorporated into the polyurethane elastomer matrix as reinforcing agents. The formation of dipodal silane was investigated by Fourier transform infrared spectroscopy (FTIR, proton nuclear magnetic resonance spectroscopy (1H NMR and transmission electron microscopy (TEM. Characterization and study on the magnetic polyurethane elastomer nanocomposites were performed by FTIR, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, vibrating sample magnetometry (VSM and dynamic mechanical thermal analysis (DMTA. The VSM results showed that the synthesized polyurethane elastomer nanocomposites had a superparamagnetic behavior. The TGA results showed that the thermal stability of dipodal silane-modified Fe3O4/PU nanocomposite was higher than that of Fe3O4/PU nanocomposite. This could be attributed to better dispersion and compatibility of dipodal silane

The study of the curing of the polyurethane coating by method of IR spectroscopy

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N. A. Korshunova

2016-12-01

Full Text Available The results of the study of the curing process of polyurethane compositions with participation of two different catalysts by the method of IR spectroscopy are given. The time dependences of curing of polyurethane coatings from concentrations of catalysts were determined, on the basis of which the most effective catalyst was selected.

Effect of the carbonyl iron particles on acoustic absorption properties of magnetic polyurethane foam

Science.gov (United States)

Geng, Jialu; Wang, Caiping; Zhu, Honglang; Wang, Xiaojie

2018-03-01

Elastomeric matrix embedded with magnetic micro-sized particles has magnetically controllable properties, which has been investigated extensively in the last decades. In this study we develop a new magnetically controllable elastomeric material for acoustic applications at lower frequencies. The soft polyurethane foam is used as matrix material due to its extraordinary elastic and acoustic absorption properties. One-step method is used to synthesize polyurethane foam, in which all components including polyether polyols 330N, MDI, deionized water, silicone oil, carbonyl iron particle (CIP) and catalyst are put into one container for curing. Changing any component can induce the change of polyurethane foam's properties, such as physical and acoustic properties. The effect of the content of MDI on acoustic absorption is studied. The CIPs are aligned under extra magnetic field during the foaming process. And the property of polyurethane foam with aligned CIPs is also investigated. Scanning electron microscope (SEM) is used to observe the structure of pore and particle-chain. The two-microphone impedance tube and the transfer function method are used to test acoustic absorption property of the magnetic foams.

Polycarbonate-based polyurethane as a polymer electrolyte matrix for all-solid-state lithium batteries

Science.gov (United States)

Bao, Junjie; Shi, Gaojian; Tao, Can; Wang, Chao; Zhu, Chen; Cheng, Liang; Qian, Gang; Chen, Chunhua

2018-06-01

Four kinds of polycarbonate-based polyurethane with 8-14 wt% hard segments content are synthesized via reactions of polycarbonatediol, hexamethylene diisocyanate and diethylene glycol. The mechanical strength of the polyurethanes increase with the increase of hard segments content. Solid polymer electrolytes composed of the polycarbonate-based polyurethanes and LiTFSI exhibits fascinating characteristics for all-solid-state lithium batteries with a high ionic conductivity of 1.12 × 10-4 S cm-1 at 80 °C, an electrochemical stability window up to 4.5 V (vs. Li+/Li), excellent mechanical strength and superior interfacial stability against lithium metal. The all-solid-state batteries using LiFePO4 cathode can deliver high discharge capacities (161, 158, 134 and 93 mAh g-1 at varied rates of 0.2, 0.5, 1 and 2 C) at 80 °C and excellent cycling performance (with 91% capacity retention after 600 cycles at 1 C). All the results indicate that such a polyurethane-based solid polymer electrolyte can be a promising candidate for all-solid-state lithium batteries.

Synthesis and characterization of novel fluoroalkyl-terminated hyperbranched polyurethane latex

Science.gov (United States)

Xu, Wei; Zhao, Weijia; Hao, Lifen; Wang, Sha; Pei, Mengmeng; Wang, Xuechuan

2018-04-01

Waterborne polyurethane (PU) emulsions are widely used in various fields and the demand for them is ever-increasing over the years. However, the hydrophilic chain extender inevitably bonded into the PU backbone can affect the water tolerance of PU. Thus, it is of great importance to improve PU water resistance effectively. Herein, novel fluoroalkyl-terminated hyperbranched polyurethane (HBPUF) latex was accordingly synthesized by graft reaction of perfluorohexyl ethyl alcohol and hyperbranched polyurethane (HBPU), which was previously obtained from interaction between hydroxyl-terminated hyperbranched polymer and PU prepolymer manufactured via the acetone process, as well as using neutralization, adding water, and high-speed stirring operations. We characterized the resultants and investigated its surface properties by IR, NMR, TEM, XRD, TGA, DSC, FE-SEM, AFM, XPS, and contact angle measurements, etc. IR and NMR tests confirmed that the fluorinated fragments had been grafted onto the tail end of HBPU. TEM, XRD, DSC, and FE-SEM results all accounted for the fact that there were multi-crystals in PU, HBPU and HBPUF. TGA results showed that thermal stabilities of the PU, HBPU, and HBPUF latex films were enhanced in turn. XPS and AFM analyses demonstrated that the fluorine-containing segments from the HBPUF terminals were prone to migrate and enrich on the film-air surface of the HBPUF latex film, which made water contact angle and water absorption of the HBPUF film be as 113.9° and 11.1%, respectively, compared to those of the PU film (77.8° and 136.2%). This research indicates that water resistance of the PU film can be efficiently enhanced by fluorinated polyurethane with novel fluoroalkyl-terminated hyperbranched structure.

The participation of outer membrane proteins in the bacterial sensitivity to nanosilver

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Anna Kędziora

2016-06-01

Full Text Available The presented study is to analyze the participation of outer membrane proteins of Gram- negative bacteria in sensitivity to silver nanomaterials. The mechanism of interaction of silver with the bacterial cell is best described in this group of microorganisms. There are several theories regarding the effectiveness of antimicrobial ions and nanosilver, and at the indicated differences in the way they work. Outer membrane proteins of Gram-negative bacteria are involved in the procurement of silver from the environment and contribute to the development mechanisms of resistance to nanometals. They are measurable parameter in the field of cell phenotypic response to the presence of Gram-negative bacteria in the environment silver nanoforms: its properties, chemical composition, content or times of action. Proteomic methods (including two dimensional electrophoresis and MALDI‑TOF MS are therefore relevant techniques for determining the susceptibility of bacteria to silver and the changes taking place in the outer membrane under the influence: uptime/exposure and physical and chemical parameters of silver nanomaterials. Many products containing nanosilver is still in the research phase in terms of physico‑chemical characteristics and biological activity, others have been already implemented in many industries. During the very fast nanotechnology developing and introduction to the market products based on the nanosilver the bacterial answer to nanosilver is needed.

(Biodegradable Ionomeric Polyurethanes Based on Xanthan: Synthesis, Properties, and Structure

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T. V. Travinskaya

2017-01-01

Full Text Available New (biodegradable environmentally friendly film-forming ionomeric polyurethanes (IPU based on renewable biotechnological polysaccharide xanthan (Xa have been obtained. The influence of the component composition on the colloidal-chemical and physic-mechanical properties of IPU/Xa and based films, as well as the change of their properties under the influence of environmental factors, have been studied. The results of IR-, PMS-, DMA-, and X-ray scattering study indicate that incorporation of Xa into the polyurethane chain initiates the formation of a new polymer structure different from the structure of the pure IPU (matrix: an amorphous polymer-polymer microdomain has occurred as a result of the chemical interaction of Xa and IPU. It predetermines the degradation of the IPU/Xa films as a whole, unlike the mixed polymer systems, and plays a key role in the improvement of material performance. The results of acid, alkaline hydrolysis, and incubation into the soil indicate the increase of the intensity of degradation processes occurring in the IPU/Xa in comparison with the pure IPU. It has been shown that the introduction of Xa not only imparts the biodegradability property to polyurethane, but also improves the mechanical properties.

Polyurethane spray coating of aluminum wire bonds to prevent corrosion and suppress resonant oscillations

CERN Document Server

INSPIRE-00092738; Kurth, Matthew; Boyd, Rusty

2016-01-01

Unencapsulated aluminum wedge wire bonds are common in particle physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent source of tracking-detector failure. Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorentz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of polyurethane-coated wire bonds and their resistance to periodic Lorentz forces are under study for use in a future High Luminosity Large Hadron Collider detector such as the ATLAS Inner Tracker upgrade.

The γ-radiation induced grafting of unsaturated segmented polyurethanes with N-vinyl pyrrolidone

International Nuclear Information System (INIS)

Egboh, S.H.; George, M.H.; Barrie, J.A.

1984-01-01

Linear unsaturated segmented polyurethanes have been modified by hydrophilic grafting at 40 deg C with N-vinyl pyrrolidone, in N,N-dimethylformamide as solvent, using 60 Cobalt γ-irradiation. Graft copolymers were isolated from homopolymers by selective solvent extraction using a Soxhlet apparatus. The effects of reaction time, total dose, temperature and monomer concentration, on the graft yields have been examined. Relatively high irradiation doses were avoided during the grafting experiments to prevent possible degradation of the segmented polyurethanes and gelation of the homopolymer, poly(N-vinyl pyrrolidone). The ungrafted and grafted copolymers were characterized, and the graft copolymers were shown to be more thermally stable than the original polyurethanes, by thermogravimetric analysis. An explanation for the observed variation of the graft yields with some of the experimental variables is suggested. (author)

Polydopamine Particle-Filled Shape-Memory Polyurethane Composites with Fast Near-Infrared Light Responsibility.

Science.gov (United States)

Yang, Li; Tong, Rui; Wang, Zhanhua; Xia, Hesheng

2018-03-25

A new kind of fast near-infrared (NIR) light-responsive shape-memory polymer composites was prepared by introducing polydopamine particles (PDAPs) into commercial shape-memory polyurethane (SMPU). The toughness and strength of the polydopamine-particle-filled polyurethane composites (SMPU-PDAPs) were significantly enhanced with the addition of PDAPs due to the strong interface interaction between PDAPs and polyurethane segments. Owing to the outstanding photothermal effect of PDAPs, the composites exhibit a rapid light-responsive shape-memory process in 60 s with a PDAPs content of 0.01 wt%. Due to the excellent dispersion and convenient preparation method, PDAPs have great potential to be used as high-efficiency and environmentally friendly fillers to obtain novel photoactive functional polymer composites. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Systematic review of the effectiveness of polyurethane-coated compared with textured silicone implants in breast surgery.

Science.gov (United States)

Duxbury, Paula J; Harvey, James R

2016-04-01

Silicone gel implants are used worldwide for breast augmentation and breast reconstruction. Textured silicone implants are the most commonly placed implant, but polyurethane-coated implants are increasingly being used in an attempt to ameliorate the long-term complications associated with implant insertion. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Electronic searches of MEDLINE, EMBASE, the Cochrane Library and www.ClinicalTrials.gov were undertaken in March 2014 using keywords. Following data extraction, 18 studies were included in the review, including four core studies of textured silicone implants and five studies reporting outcomes for polyurethane-coated silicone implants. There are no clear data reporting revision rates in patients treated with polyurethane implants. In the primary reconstructive setting, capsular contracture rates with silicone implants are 10-15% at 6 years, whilst studies of polyurethane implants report rates of 1.8-3.4%. In the primary augmentation setting, core studies show a capsular contracture rate of 2-15% at 6 years compared with 0.4-1% in polyurethane-coated implants; however, the polyurethane studies are limited by their design and poor follow-up. The use of polyurethane implants should be considered a safe alternative to textured silicone implants. It is likely that an implant surface does influence short- and long-term outcomes; however, the extent of any benefit cannot be determined from the available evidence base. Future implant studies should target the short- and long-term benefits of implant surfacing by procedure with defined outcome measures; a head-to-head comparison would help clarify outcomes. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Synthesis and Physicochemical Behaviour of Polyurethane-Multiwalled Carbon Nanotubes Nanocomposites Based on Renewable Castor Oil Polyols

Directory of Open Access Journals (Sweden)

Alaa Ali

2014-01-01

Full Text Available Polyurethanes (PUs are high performance materials, with vast industrial and engineering applications. In this research, effects of Multiwalled Carbon Nanotubes (MWCNTs on physicochemical properties of Castor Oil based Polyurethanes (COPUs were studied. MWCNTs were added in different weight percentages (0% to 1% wt in a castor oil based polyurethane (COPUs-MWCNTs nanocomposites. The composition, structure, and morphology of polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission scanning electron microscopy (FESEM, and element detection by energy dispersive spectroscopy (EDX analysis, respectively. Thermal stability was studied by thermogravimetric analysis (TGA. Barrier properties and surface area studies were investigated by nitrogen permeability machine and BET technique. Mechanical properties were calculated by tensile universal testing machine. Results showed well dispersed MWCNTs in polyurethane matrix at different weight percentages. The best results were obtained with 0.3 wt% of MWCNTs in the composite. Surface area studies revealed presence of very few pores which is in a good agreement with barrier permeability, reduced up to ~68% in 1 wt% and ~70% in 0.5 wt% of MWCNTs in polymer matrix, with respect to pure COPUs samples.

The Effects of Aluminium Hydroxide and Magnesium Hydroxide on the Mechanical Properties of Thermoplastic Polyurethane Materials

Directory of Open Access Journals (Sweden)

Erkin Akdoğan

2015-12-01

Full Text Available Thermoplastic polyurethane materials are widely used in automotive, clothing, electrical and electronics, medical, construction, machine industry due to excellent physical and chemical properties. Thermoplastic polyurethane materials combustion and resistance to high temperature characteristics are poor. Additives and fillers are added into the polyurethane matrix to improve those properties. Particularly adding these agents as a flame retardant are affect mechanical properties of polyurethane materials. Therefore, it is important to determinate the mechanical properties of these materials. In this study, 5% by weight of the thermoplastic polyurethane material, aluminium tri hydroxide (ATH, (Al2O3 3H2O and magnesium hydroxide (MgOH, (Mg(OH2 were added. Ammonium polyphosphate (APP as an intumescent flame retardant with inorganic flame retardants were added to increase the flame resistance of produced composite structure. Tensile test, tear test, hardness and Izod impact tests were made and compared of those produced composites. As a result of experiments the addition of ATH has lowered the tensile strength and tear strength contrast to this the addition of MgOH has improved those properties. Hardness and Izod impact test results were showed that both of the additives have no negative effect.

Flexible optical fiber sensor based on polyurethane

DEFF Research Database (Denmark)

Kaysir, Md Rejvi; Stefani, Alessio; Lwin, Richard

Polyurethane (PU) based hollow core fibers are investigated as optical sensors. The flexibility of PU fibers makes it suitable for sensing mechanical perturbations. We fabricated a PU fiber using the fiber drawing method, characterized the fiber and experimentally demonstrated a simple way...... to measure deformation, in the form of applied pressure....

Polyurethane adhesives in flat roofs

OpenAIRE

Bogárová Markéta; Stodůlka Jindřich; Šuhajda Karel

2017-01-01

It is necessary to stabilize individual layers of flat roofs, mainly because of wind suction. Apart from anchoring and surcharge, these layers can be secured by bonding. At present gluing is an indispensable and widely used stabilization method. On our market we can found many types of adhesives, most widely used are based on polyurethane. This paper focuses on problematic about stabilization thermal insulation from expanded polystyrene to vapor barrier from bitumen. One of the main issues is...

Microbial degradation of polyurethane, polyester polyurethanes and polyether polyurethanes.

Science.gov (United States)

Nakajima-Kambe, T; Shigeno-Akutsu, Y; Nomura, N; Onuma, F; Nakahara, T

1999-02-01

Polyurethane (PUR) is a polymer derived from the condensation of polyisocyanate and polyol and it is widely used as a base material in various industries. PUR, in particular, polyester PUR, is known to be vulnerable to microbial attack. Recently, environmental pollution by plastic wastes has become a serious issue and polyester PUR had attracted attention because of its biodegradability. There are many reports on the degradation of polyester PUR by microorganisms, especially by fungi. Microbial degradation of polyester PUR is thought to be mainly due to the hydrolysis of ester bonds by esterases. Recently, polyester-PUR-degrading enzymes have been purified and their characteristics reported. Among them, a solid-polyester-PUR-degrading enzyme (PUR esterase) derived from Comamonas acidovorans TB-35 had unique characteristics. This enzyme has a hydrophobic PUR-surface-binding domain and a catalytic domain, and the surface-binding domain was considered as being essential for PUR degradation. This hydrophobic surface-binding domain is also observed in other solid-polyester-degrading enzymes such as poly(hydroxyalkanoate) (PHA) depolymerases. There was no significant homology between the amino acid sequence of PUR esterase and that of PHA depolymerases, except in the hydrophobic surface-binding region. Thus, PUR esterase and PHA depolymerase are probably different in terms of their evolutionary origin and it is possible that PUR esterases come to be classified as a new solid-polyester-degrading enzyme family.

Bio-based polyurethane prepared from Kraft lignin and modified castor oil

Directory of Open Access Journals (Sweden)

L. B. Tavares

2016-11-01

Full Text Available Current challenges highlight the need for polymer research using renewable natural sources as a substitute for petroleum-based polymers. The use of polyols obtained from renewable sources combined with the reuse of industrial residues such as lignin is an important agent in this process. Different compositions of polyurethane-type materials were prepared by combining technical Kraft lignin (TKL with castor oil (CO or modified castor oil (MCO1 and MCO2 to increase their reactivity towards diphenylmethane diisocyanate (MDI. The results indicate that lignin increases the glass transition temperature, the crosslinking density and improves the ultimate stress especially for those prepared from MCO2 and 30% lignin content from 8.2 MPa (lignin free to 23.5 MPa. Scanning electron microscopy (SEM micrographs of rupture surface after uniaxial tensile tests show ductile-to-brittle transition. The results show the possibility to develop polyurethane-type materials, varying technical grade Kraft lignin content, which cover a wide range of mechanical properties (from large elastic/low Young modulus to brittle/high Young modulus polyurethanes.

Binding of [125I]iodipine to parathyroid cell membranes: Evidence of a dihydropyridine-sensitive calcium channel

International Nuclear Information System (INIS)

Jones, J.I.; Fitzpatrick, L.A.

1990-01-01

The parathyroid cell is unusual, in that an increase in extracellular calcium concentrations inhibits PTH release. Calcium channels are glycoproteins that span cell membranes and allow entry of extracellular calcium into cells. We have demonstrated that the calcium channel agonist (+)202-791, which opens calcium channels, inhibits PTH release and that the antagonist (-)202-791, which closes calcium channels, stimulates PTH release. To identify the calcium channels responsible for these effects, we used a radioligand that specifically binds to calcium channels. Bovine parathyroid cell membranes were prepared and incubated under reduced lighting with [125I] iodipine (SA, 2000 Ci/mmol), which recognizes 1,4-dihydropyridine-sensitive calcium channels. Bound ligand was separated from free ligand by rapid filtration through Whatman GF/B filters. Nonspecific binding was measured by the inclusion of nifedipine at 10 microM. Specific binding represented approximately 40% of the total binding. The optimal temperature for [125I] iodipine binding was 4 C, and binding reached equilibrium by 30 min. The equilibrium dissociation constant (Kd) was approximately 550 pM, and the maximum number of binding sites was 780 fmol/mg protein. Both the calcium channel agonist (+)202-791 and antagonist (-)202-791 competitively inhibited [125I] iodipine binding, with 50% inhibition concentrations of 20 and 300 nM, respectively. These data indicate the presence of dihydropyridine-sensitive calcium channels on parathyroid cell membranes

Alternative castor oil-based polyurethane adhesive used in the production of plywood

Directory of Open Access Journals (Sweden)

Fabricio Moura Dias

2004-09-01

Full Text Available Plywood is normally produced with urea-formaldehyde and/or phenol-formaldehyde adhesives. However, the former is considerably toxic and environmentally damaging, while the latter is expensive, thus motivating the search for alternative raw materials in plywood production. The castor oil-based polyurethane adhesive developed at the São Carlos Institute of Chemistry, University of São Paulo, is an environmentally friendly vegetal oil-based polymer that is harmless to humans. The wood species Eucalyptus grandis offers favorable properties for plywood the manufacture. The study reported on here involved the use of castor oil-based polyurethane adhesive to produce plywood with Eucalyptus grandis layers. The plywood's performance was evaluated based on the results of physical and mechanical tests recommended by the Brazilian code, ABNT. Tests results showed higher values than those reported in the literature and recommended by the ABNT, indicating that the castor oil-based polyurethane adhesive is a promising glue for the manufacture of plywood.

Influence of polyols on properties of bio-based polyurethanes

Indian Academy of Sciences (India)

resources for the preparation of polyols required for the polyurethane industry. Among the vegetable oils, cardanol a meta-substituted phenol obtained (Kumar et al 2002) from ... High ortho-multinuclear cardanol–formaldehyde resin was.

BONE REGENERATION AFTER DEMINERALIZED BONE MATRIX AND CASTOR OIL (RICINUS COMMUNIS) POLYURETHANE IMPLANTATION

Science.gov (United States)

Leite, Fábio Renato Manzolli; Ramalho, Lizeti Toledo de Oliveira

2008-01-01

Innocuous biocompatible materials have been searched to repair or reconstruct bone defects. Their goal is to restore the function of live or dead tissues. This study compared connective tissue and bone reaction when exposed to demineralized bovine bone matrix and a polyurethane resin derived from castor bean (Ricinus communis). Forty-five rats were assigned to 3 groups of 15 animals (control, bovine bone and polyurethane). A cylindrical defect was created on mandible base and filled with bovine bone matrix and the polyurethane. Control group received no treatment. Analyses were performed after 15, 45 and 60 days (5 animals each). Histological analysis revealed connective tissue tolerance to bovine bone with local inflammatory response similar to that of the control group. After 15 days, all groups demonstrated similar outcomes, with mild inflammatory reaction, probably due to the surgical procedure rather than to the material. In the polymer group, after 60 days, scarce multinucleated cells could still be observed. In general, all groups showed good stability and osteogenic connective tissue with blood vessels into the surgical area. The results suggest biocompatibility of both materials, seen by their integration into rat mandible. Moreover, the polyurethane seems to be an alternative in bone reconstruction and it is an inexhaustible source of biomaterial. PMID:19089203

Bio-based polyurethane for tissue engineering applications: How hydroxyapatite nanoparticles influence the structure, thermal and biological behavior of polyurethane composites.

Science.gov (United States)

Gabriel, Laís P; Santos, Maria Elizabeth M Dos; Jardini, André L; Bastos, Gilmara N T; Dias, Carmen G B T; Webster, Thomas J; Maciel Filho, Rubens

2017-01-01

In this work, thermoset polyurethane composites were prepared by the addition of hydroxyapatite nanoparticles using the reactants polyol polyether and an aliphatic diisocyanate. The polyol employed in this study was extracted from the Euterpe oleracea Mart. seeds from the Amazon Region of Brazil. The influence of hydroxyapatite nanoparticles on the structure and morphology of the composites was studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), the structure was evaluated by Fourier transform infrared spectroscopy (FT-IR), thermal properties were analyzed by thermogravimetry analysis (TGA), and biological properties were studied by in vitro and in vivo studies. It was found that the addition of HA nanoparticles promoted fibroblast adhesion while in vivo investigations with histology confirmed that the composites promoted connective tissue adherence and did not induce inflammation. In this manner, this study supports the further investigation of bio-based, polyurethane/hydroxyapatite composites as biocompatible scaffolds for numerous tissue engineering applications. Copyright © 2016 Elsevier Inc. All rights reserved.

Mechanical and thermal properties of castor oil polyurethane bone cement after gamma irradiation

International Nuclear Information System (INIS)

Azevedo, E.C.; Chierice, G.O.; Claro Neto, S.; Lepiesnki, C.M.; Nascimento, E.M.

2009-01-01

Polyurethanes from castor oil are being employed as bone cement in medical applications. In this work the thermal and mechanical properties of gamma irradiated polyurethanes derivative from castor oil were investigated by instrumented indentation, thermogravimetry and scanning electron microscopy. A slightly increase in hardness is observed only for doses as high as 100 kGy. Thermal analysis indicates stability at human body temperature. The glass transition temperature has small changes after gamma irradiation. (author)

Alteration in lipid composition of plasma membranes of sensitive and resistant Guerin carcinoma cells due to the action of free and liposomal form of cisplatin.

Science.gov (United States)

Naleskina, L A; Todor, I N; Nosko, M M; Lukianova, N Y; Pivnyuk, V M; Chekhun, V F

2013-09-01

To study in vivo changes of lipid composition of plasma membranes of sensitive and resistant to cisplatin Guerin carcinoma cells under influence of free and liposomal cisplatin forms. The isolation of plasma membranes from parental (sensitive) and resistant to cisplatin Guerin carcinoma cells was by differential ultracentrifugation in sucrose density gradient. Lipids were detected by method of thin-layer chromatography. It was determined that more effective action of cisplatin liposomal form on resistant cells is associated with essential abnormalities of conformation of plasma membrane due to change of lipid components and architectonics of rafts. It results in the increase of membrane fluidity. Reconstructions in lipid composition of plasma membranes of cisplatin-resistant Guerin carcinoma cells provide more intensive delivery of drug into the cells, increase of its concentration and more effective interaction with cellular structural elements.

Nasolacrimal Polyurethane Stent: Complications with CT Correlation

International Nuclear Information System (INIS)

Pinto, Isabel T.; Paul, Laura; Grande, Carlos

1998-01-01

Purpose: To evaluate initial results in patients with epiphora secondary to obstruction of the nasolacrimal duct treated by placement of a polyurethane stent, and to discuss the technical problems and complications arising during the procedure, with visualization of the anatomy of the drainage apparatus using computed tomography (CT). Methods: We inserted 20 polyurethane Song stents under fluoroscopic guidance after dacryocystography in 19 patients with grade 3-4 epiphora caused by idiopathic obstruction of the nasolacrimal duct. CT scans were obtained following stent placement in all patients. Results: We focus on the technical problems and complications that arose during these procedures. During negotiation of the guidewire past the obstruction at the level of the junction of the duct with the lacrimal sac, the guidewire created a false passage in a posterior suborbital direction in two cases and towards the posterior midline in another. In all cases the guidewire was withdrawn and reinserted through the proper anatomic route without further difficulty or complications. In two cases the stent was improperly positioned wholly or partially outside the nasolacrimal system (one medially, one posteriorly). In one case the stent was removed and reinserted; in the other it remains in place and functional. CT was performed in all these cases to ensure proper anatomic alignment and determine what had gone wrong. The epiphora was completely resolved in 13 cases and partially relieved in four; there were three cases of stent obstruction. Epistaxis of short duration (1 hr) occurred in seven patients and headache in one. Conclusions: Treatment of epiphora with polyurethane stents is a technique that is well tolerated by patients and achieves a high success rate, yet problems in placement may be encountered. Though no major consequences for patients are involved, cognizance of such difficulties is important to avoid incorrect positioning of stents

A unique photofunction of YVO4:Bi3+,Eu3+ nanophosphor: Photoluminescent indication for photochemical decomposition of polyurethane

International Nuclear Information System (INIS)

Hara, Hiroki; Takeshita, Satoru; Isobe, Tetsuhiko; Sawayama, Tomohiro; Niikura, Seiji

2013-01-01

Highlights: ► A composite film of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor and polyurethane was prepared. ► The composite film exhibits a unique photophysicochemical behavior. ► The nanophosphor shows red photoluminescence under near-UV light irradiation. ► The nanophosphor also acts as a photooxidative decomposer of polyurethane. ► Luminescent intensity becomes an indicator for the decomposition of polyurethane. -- Abstract: We have developed a transparent composite film consisting of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor and polyurethane resin which exhibits unique photophysicochemical behavior. The nanophosphor shows red photoluminescence through f–f transitions of Eu 3+ under near-UV irradiation. The emission intensity drops to half of the initial value after continuous irradiation for 23 h. As shown by electron spin resonance spectroscopy, this decrease in the emission intensity is caused by the formation of V 4+ defects. In addition, thermal analysis and Fourier transform infrared spectroscopy show that the amount of the organic species in the film decreases from 58 to 25 wt% after 23 h. These results indicate that the nanophosphor promotes photooxidative decomposition of the polyurethane resin, while some of the V 5+ ions in YVO 4 are converted to V 4+ ions by photoreduction. Prolonged irradiation for 96 h leads to complete decomposition of the polyurethane and the disappearance of the V 4+ defects, resulting in the recovery of the emission intensity. These findings suggest that the photoluminescence of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor can be used to detect the photooxidative decomposition of polyurethane

UV and gamma irradiation effects on surface properties of polyurethane derivative from castor oil

Energy Technology Data Exchange (ETDEWEB)

Azevedo, Elaine C.; Nascimento, Eduardo M., E-mail: helunica@yahoo.com.br [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Chierice, Gilberto O.; Claro Neto, Salvador [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Lepienski, Carlos M. [Universidade Federal do Parana (UFPR), Curitiba (Brazil)

2013-07-01

Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induce by radiation, were observed by atomic force microscopy. The polyurethane derivative from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PY increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, by not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect. (author)

Thermal, crystallinity and morphological studies of the filled RBD palm kernel oil polyurethane foam

International Nuclear Information System (INIS)

Khairiah Badri; Sahrim Ahmad; Sarani Zakaria

2000-01-01

The synthesis of RBD palm kernel oil (PKO) polyurethane polyol and the polyurethane foam has well been documented. However, less study has been put in discovering the thermal properties and crystallinity of the foam. It is also an initiative to investigate the effect of oil palm empty fruit bunch (EFB) and sorbitol as fillers in the polyurethane (PU) foam to these properties. Thermogravimetric (TGA) investigation of the PKO PU foam was performed to study their decompositions. The semi-crystalline nature of EFB-filled PU was confirmed by x-ray diffratogram and DSC thermogram of glass transition temperature, T g . The x-ray diffraction (XRD) study of the unfilled PU showed a broad amorphous halo, indicative of absence of crystallinity in the polymer, which has been explained as due to strong hydrogen bonding in the hard phase. Overall crystallinity decreases with an increase in the polyester content in agreement with the XRD results. The crystallinity however, increases with the inclusion of EFB in the polyurethane system. This study was followed by the observation of the surface morphologies of the PKO PU foam with and without fillers. The scanning electron micrographs verified the finding on the improved k-factor values. (Author)

UV and gamma irradiation effects on surface properties of polyurethane derivative from castor oil

International Nuclear Information System (INIS)

Azevedo, Elaine C.; Nascimento, Eduardo M.; Chierice, Gilberto O.; Claro Neto, Salvador

2013-01-01

Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induce by radiation, were observed by atomic force microscopy. The polyurethane derivative from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PY increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, by not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect. (author)

Electrospun polyacrylonitrile/polyurethane composite nanofibrous separator with electrochemical performance for high power lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Zainab, Ghazala [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Xianfeng, E-mail: wxf@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China); Yu, Jianyong [Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China); Zhai, Yunyun; Ahmed Babar, Aijaz; Xiao, Ke [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Ding, Bin, E-mail: binding@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Key Laboratory of High Performance Fibers & Products, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Nanofibers Research Center, Modern Textile Institute, Donghua University, Shanghai 200051 (China)

2016-10-01

Lithium ion batteries (LIBs) for high performance require separators with auspicious reliability and safety. Keeping LIBs reliability and safety in view, microporous polyacrylonitrile (PAN)/polyurethane (PU) nonwoven composite separator have been developed by electrospinning technique. The physical, electrochemical and thermal properties of the PAN/PU separator were characterized. Improved ionic conductivity up to 2.07 S cm{sup −1}, high mechanical strength (10.38 MPa) and good anodic stability up to 5.10 V are key outcomes of resultant membranes. Additionally, high thermal stability displaying only 4% dimensional change after 0.5 h long exposure to 170 °C in an oven, which could be valuable addition towards the safety of LIBs. Comparing to commercialized polypropylene based separators, resulting membranes offered improved internal short-circuit protection function, offering better rate capability and enhanced capacity retention under same observation conditions. These fascinating characteristics endow these renewable composite nonwovens as promising separators for high power LIBs battery. - Highlights: • The PAN/PU based separators were prepared by multi-needle electrospinning technique. • The electrospun separators displays good mechanical properties and thermal stability. • These separators exhibit good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection. • Nanofibrous composite nonwoven possesses stable cyclic performance which give rise to acceptable battery performances.

78 FR 55641 - Polyurethane-Type Polymers; Tolerance Exemption

Science.gov (United States)

2013-09-11

...-Type Polymers; Tolerance Exemption AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule... polymers produced by the reaction of either 1,6-hexanediisocyanate; 2,4,4-trimethyl-1,6-hexanediisocyanate... (also known as polyurethane-type polymers), when used as an inert ingredient in a pesticide chemical...

Effect of the average soft-segment length on the morphology and properties of segmented polyurethane nanocomposites

International Nuclear Information System (INIS)

Finnigan, Bradley; Halley, Peter; Jack, Kevin; McDowell, Alasdair; Truss, Rowan; Casey, Phil; Knott, Robert; Martin, Darren

2006-01-01

Two organically modified layered silicates (with small and large diameters) were incorporated into three segmented polyurethanes with various degrees of microphase separation. Microphase separation increased with the molecular weight of the poly(hexamethylene oxide) soft segment. The molecular weight of the soft segment did not influence the amount of polyurethane intercalating the interlayer spacing. Small-angle neutron scattering and differential scanning calorimetry data indicated that the layered silicates did not affect the microphase morphology of any host polymer, regardless of the particle diameter. The stiffness enhancement on filler addition increased as the microphase separation of the polyurethane decreased, presumably because a greater number of urethane linkages were available to interact with the filler. For comparison, the small nanofiller was introduced into a polyurethane with a poly(tetramethylene oxide) soft segment, and a significant increase in the tensile strength and a sharper upturn in the stress-strain curve resulted. No such improvement occurred in the host polymers with poly(hexamethylene oxide) soft segments. It is proposed that the nanocomposite containing the more hydrophilic and mobile poly(tetramethylene oxide) soft segment is capable of greater secondary bonding between the polyurethane chains and the organosilicate surface, resulting in improved stress transfer to the filler and reduced molecular slippage.

Electric Conductivity and Dielectric-Breakdown Behavior for Polyurethane Magnetic Elastomers.

Science.gov (United States)

Sasaki, Shuhei; Tsujiei, Yuri; Kawai, Mika; Mitsumata, Tetsu

2017-02-23

The electric-voltage dependence of the electric conductivity for cross-linked and un-cross-linked magnetic elastomers was measured at various magnetic fields, and the effect of cross-linking on the electric conductivity and the dielectric-breakdown behavior was investigated. The electric conductivity for un-cross-linked elastomers at low voltages was independent of magnetic fields and the volume fraction of magnetic particles, indicating the electric conduction in the polyurethane matrix. At high voltages, the electric conductivity increased with the magnetic field, showing the electric conduction via chains of magnetic particles. On the other hand, the electric conductivity at low voltages for cross-linked elastomers with volume fractions below 0.06 was independent of the magnetic field, suggesting the electric conduction in the polyurethane matrix. At volume fractions above 0.14, the electric conductivity increased with the magnetic field, suggesting the electric conduction via chains of magnetic particles. At high voltages, the electric conductivity for cross-linked elastomers with a volume fraction of 0.02 was independent of the magnetic field, indicating the electric conduction through the polyurethane matrix. At volume fractions above 0.06, the electric conductivity suddenly increased at a critical voltage, exhibiting the dielectric breakdown at the bound layer of magnetic particles and/or the discontinuous part between chains.

Polyurethanes irradiation by accelerated electrons: molecular and supramolecular evolution, incidence on the extractable and biomedical implications

International Nuclear Information System (INIS)

Guignot, C.

2002-11-01

Face to the development of radiosterilization and polymers medical devices it was wished to study the behavior of polyurethanes under accelerated electrons in oxidizing atmosphere. This study has been made to reveal the physico chemical and organisational modifications of polyurethanes for a medical use. (N.C.)

Effect of Reinforced Hybrid Palm Shells on Mechanical Properties of Polyurethane-Jute Woven/ Vinyl Ester Sandwich Board

International Nuclear Information System (INIS)

Cheng, T.S.; Nurul Ain Nanyan; Lan, D.N.U.; Leng, T.P.

2014-01-01

A natural fiber sandwich was constructed from palm shells/polyurethane core and jute woven/vinyl ester face sheets by the in-situ sandwich process (core and panel prepared simultaneously). The polyurethane sandwich core was reinforced by hybrid shell systems of dried palm shell (DPS) and palm kernel shell (PKS) (50P-50D, 25P-75D), and single shell system of PKS (100P) as well as 20 phr empty fruit bunch (EFB) based on hundred part of polyurethane. The sandwich face sheets are prepared by using two jute woven layers and impregnated by vinyl ester. Interlocking between DPS and polyurethane matrix was formed, which hence enhanced the mechanical properties. The interfacial adhesion between DPS, PKS, and EFB with the polyurethane binder played the important role to achieve high mechanical properties. It was found that hybrid shells exhibited high reinforcement for sandwich's performance resulting better compression (50P-50D) and flexural (25P-75D) properties. The single shell 100P showed only improvement on flexural modulus.The fracture surface morphology of sandwich under mechanical test was performed by using optical microscopy. (author)

Effects of polyurethane matrices on fungal tannase and gallic acid production under solid state culture

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The influence of the physical structure of polyurethane matrix as a support in a solid state culture in tannase production and gallic acid accumulation by Aspergillus niger Aa-20 was evaluated. Three different polyurethane matrices were used as the support: continuous, semi-discontinuous and discontinuous. The highest tannase production at 2479.59 U/L during the first 12 h of culture was obtained using the discontinuous matrix. The gallic acid was accumulated at 7.64 g/L at the discontinuous matrix. The results show that the discontinuous matrix of polyurethane is better for tannase production and gallic acid accumulation in a solid state culture bioprocess than the continuous and semi-discontinuous matrices.

The use of polyurethane materials in the surgery of the spine: a review.

Science.gov (United States)

St John, Kenneth R

2014-12-01

The spine contains intervertebral discs and the interspinous and longitudinal ligaments. These structures are elastomeric or viscoelastic in their mechanical properties and serve to allow and control the movement of the bony elements of the spine. The use of metallic or hard polymeric devices to replace the intervertebral discs and the creation of fusion masses to replace discs and/or vertebral bodies changes the load transfer characteristics of the spine and the range of motion of segments of the spine. The purpose of the study was to survey the literature, regulatory information available on the Web, and industry-reported device development found on the Web to ascertain the usage and outcomes of the use of polyurethane polymers in the design and clinical use of devices for spine surgery. A systematic review of the available information from all sources concerning the subject materials' usage in spinal devices was conducted. A search of the peer-reviewed literature combining spinal surgery with polyurethane or specific types and trade names of medical polyurethanes was performed. Additionally, information available on the Food and Drug Administration Web site and for corporate Web sites was reviewed in an attempt to identify pertinent information. The review captured devices that are in testing or have entered clinical practice that use elastomeric polyurethane polymers as disc replacements, dynamic stabilization of spinal movement, or motion limitation to relieve nerve root compression and pain and as complete a listing as possible of such devices that have been designed or tested but appear to no longer be pursued. This review summarizes the available information about the uses to which polyurethanes have been tested or are being used in spinal surgery. The use of polyurethanes in medicine has expanded as modifications to the stability of the polymers in the physiological environment have been improved. The potential for the use of elastomeric materials to more

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

International Nuclear Information System (INIS)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D.; DeYoung, Paul A.; Blum, Arlene; Stapleton, Heather M.; Peaslee, Graham F.

2015-01-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

Energy Technology Data Exchange (ETDEWEB)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D. [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States); DeYoung, Paul A. [Department of Physics, Hope College, 27 Graves Place, Holland, MI 49423 (United States); Blum, Arlene [Green Science Policy Institute, Box 5455, Berkeley, CA 94705 (United States); Stapleton, Heather M. [Nicholas School of the Environment, Duke University, LSRC Box 90328, Durham, NC 27708 (United States); Peaslee, Graham F., E-mail: peaslee@hope.edu [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States)

2015-09-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams.

Synthesis and characterization of bio-based polyurethane from ...

Indian Academy of Sciences (India)

Benzoylated tannin prepared by benzoylation of cashewnut husk tannin, was treated with hexame-thylenediisocyanate in the presence of 1,4-butanediol as an extender to prepare thermosetting polyurethane. The sample was characterized using FT–IR and 13C NMR spectra. Thermal, morphological, physico-chemical and ...

Novel polycarbonate-based polyurethane elastomers: composition–property relationship

Czech Academy of Sciences Publication Activity Database

Špírková, Milena; Pavličevic, J.; Strachota, Adam; Poreba, Rafal; Bera, O.; Kaprálková, Ludmila; Baldrian, Josef; Šlouf, Miroslav; Lazić, N.; Budinski-Simendic, J.

2011-01-01

Roč. 47, č. 5 (2011), s. 959-972 ISSN 0014-3057 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * polycarbonate diol * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.739, year: 2011

Highly sensitive MOS photodetector with wide band responsivity assisted by nanoporous anodic aluminum oxide membrane.

Science.gov (United States)

Chen, Yungting; Cheng, Tzuhuan; Cheng, Chungliang; Wang, Chunhsiung; Chen, Chihwei; Wei, Chihming; Chen, Yangfang

2010-01-04

A new approach for developing highly sensitive MOS photodetector based on the assistance of anodic aluminum oxide (AAO) membrane is proposed, fabricated, and characterized. It enables the photodetector with the tunability of not only the intensity but also the range of the response. Under a forward bias, the response of the MOS photodetector with AAO membrane covers the visible as well as infrared spectrum; however, under a reverse bias, the near-infrared light around Si band edge dominates the photoresponse. Unlike general MOS photodetectors which only work under a reverse bias, our MOS photodetectors can work even under a forward bias, and the responsivity at the optical communication wavelength of 850nm can reach up to 0.24 A/W with an external quantum efficiency (EQE) of 35%. Moreover, the response shows a large enhancement factor of 10 times at 1050 nm under a reverse bias of 0.5V comparing with the device without AAO membrane. The underlying mechanism for the novel properties of the newly designed device has been proposed.

Synthesis of Polyurethane/Silica Modified Epoxy Polymer Based on 1,3-Propanediol for Coating Application

Directory of Open Access Journals (Sweden)

Lutviasari Nuraini

2017-11-01

Full Text Available Studies on the synthesis of polyurethane/silica modified epoxy polymer using 1,3-propanediol has been conducted. Synthesis of polymers made by reaction of tolonate and 1,3-propanediol (ratio NCO/OH=2.5 as the building blocks of polyurethane with diglycidyl ether bisphenol A (DGEBA epoxy and catalyst dibutyltin dilaurate (DBTL.The total weight of the polyurethane used was 20% (w/w of the total epoxy. Based on Fourier Transform Infrared (FTIR and 1H-Nuclear Magnetic Resonance (1H-NMR spectra indicated the existence of a new bond that is formed from the reaction of isocyanate group and hydroxyl group, where the hydroxyl groups derived from epoxy and 1,3-propanediol. The addition of silica (5, 10, and 15% w/w to epoxy into the epoxy-modified polyurethane has been carried out through sol-gel reaction of tetraethyl orthosilicate (TEOS. The isocyanate conversion rate for the addition of silica 5, 10, and 15% are 95.69; 100, and 100%, respectively. The morphology and element identification by Scanning Electron Microscopy/Energy Dispersive X-Ray Analysis (SEM/EDX, showed that Si element has been successfully added in the polymer. From the tensile strength and elongation analysis, also thermal stability analysis using Thermal Gravimetric Analyzer (TGA, the increase of silica amount into the polyurethane modified epoxy did not significantly affect to thermal properties, but decrease the tensile strength of the polymer.

Development of novel biocompatible hybrid nanocomposites based on polyurethane-silica prepared by sol gel process

Energy Technology Data Exchange (ETDEWEB)

Rashti, Ali [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Yahyaei, Hossein [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Firoozi, Saman [Department of Tissue Engineering & Regenerative Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ramezani, Sara [Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Rahiminejad, Ali [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Karimi, Roya [Department of Tissue Engineering and Applied Cell Science, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Farzaneh, Khadijeh [Tehran Heart Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mohseni, Mohsen [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ghanbari, Hossein, E-mail: hghanbari@tums.ac.ir [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Tehran Heart Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Medical Biomaterials Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2016-12-01

Due to high biocompatibility, polyurethane has found many applications, particularly in development of biomedical devices. A new nanocomposite based on thermoset polyurethane and silica nanoparticles was synthesized using sol-gel method. Sol-gel process was fulfilled in two acidic and basic conditions by using tetraethylorthosilicate (TEOS) and trimethoxyisocyanatesilane as precursors. The hybrid films characterized for mechanical and surface properties using tensile strength, contact angle, ATR-FTIR and scanning electron microscopy. Biocompatibility and cytotoxicity of the hybrids were assessed using standard MTT, LDH and TUNEL assays. The results revealed that incorporation of silica nanoparticles was significantly improved tensile strength and mechanical properties of the hybrids. Based on the contact angle results, silica nanoparticles increased hydrophilicity of the hybrids. Biocompatibility by using human lung epithelial cell line (MRC-5) demonstrated that the hybrids were significantly less cytotoxic compared to pristine polymer as tested by MTT and LDH assays. TUNEL assay revealed no signs of apoptosis in all tested samples. The results of this study demonstrated that incorporation of silica nanoparticles into polyurethane lead to the enhancement of biocompatibility, indicating that these hybrids could potentially be used in biomedical field in particular as a new coating for medical implants. - Highlights: • Nanocomposites based on polyurethane and nanosilica prepared by sol-gel method fabricated • Addition of inorganic phase improved mechanical properties. • Nanosilica prepared by sol-gel method increased hydrophilicity. • By adding nanosilica to polyurethane biocompatibility increased significantly.

Preparation and characterization of plasticized palm-based polyurethane solid polymer electrolyte

Energy Technology Data Exchange (ETDEWEB)

Daud, Farah Nadia; Ahmad, Azizan; Badri, Khairiah Haji [School of Chemical Science and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)

2013-11-27

Palm-based polyurethane solid polymer electrolyte was prepared via prepolymerization method between palm kernel oil based polyols (PKO-p) and 2,4’-diphenylmethane diisocyanate (2,4’-MDI) in acetone at room temperature with the vary amount of lithium trifuoromethanesulfonate (LiCF{sub 3}SO{sub 3}) salt and polyethylene glycol (PEG). The film was analyzed using attenuated total reflection infrared (ATR-IR) spectroscopy, electrochemical impedance spectroscopy (EIS) and X-ray diffractometry (XRD). EIS result indicated ionic conductivity obtained with 30 wt% LiCF3SO3 increased to 6.55 × 10{sup −6} S cm{sup −1} when 10 wt.% of plasticizer was added into the system. FTIR analysis showed the interaction between lithium ions and amine (-N-H) at 3600–3100 cm{sup −1}, carbonyl (-C=O) at 1750–1650 cm{sup −1} and ether (-C-O-C-) at 1150–1000 cm{sup −1} of the polyurethane forming polymer-salt complexes. The XRD result confirmed that LiCF{sub 3}SO{sub 3} salt completely dissociated within the polyurethane film with the absence of crystalline peaks of LiCF{sub 3}SO{sub 3}.

Preparation and characterization of plasticized palm-based polyurethane solid polymer electrolyte

International Nuclear Information System (INIS)

Daud, Farah Nadia; Ahmad, Azizan; Badri, Khairiah Haji

2013-01-01

Palm-based polyurethane solid polymer electrolyte was prepared via prepolymerization method between palm kernel oil based polyols (PKO-p) and 2,4’-diphenylmethane diisocyanate (2,4’-MDI) in acetone at room temperature with the vary amount of lithium trifuoromethanesulfonate (LiCF 3 SO 3 ) salt and polyethylene glycol (PEG). The film was analyzed using attenuated total reflection infrared (ATR-IR) spectroscopy, electrochemical impedance spectroscopy (EIS) and X-ray diffractometry (XRD). EIS result indicated ionic conductivity obtained with 30 wt% LiCF3SO3 increased to 6.55 × 10 −6 S cm −1 when 10 wt.% of plasticizer was added into the system. FTIR analysis showed the interaction between lithium ions and amine (-N-H) at 3600–3100 cm −1 , carbonyl (-C=O) at 1750–1650 cm −1 and ether (-C-O-C-) at 1150–1000 cm −1 of the polyurethane forming polymer-salt complexes. The XRD result confirmed that LiCF 3 SO 3 salt completely dissociated within the polyurethane film with the absence of crystalline peaks of LiCF 3 SO 3

Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

Energy Technology Data Exchange (ETDEWEB)

Xu, Yurun; Chen, Dajun, E-mail: cdj@dhu.edu.cn

2017-07-01

Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

International Nuclear Information System (INIS)

Xu, Yurun; Chen, Dajun

2017-01-01

Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

Thermal properties of a sandwich construction insulated with Polyurethane (DC-System)

DEFF Research Database (Denmark)

Jensen, Rasmus Lund; Dreau, Jerome Le

Rigid polyurethane foam (PUR) is a good thermal insulation product for buildings, mainly due to its low thermal conductivity (λ ≈ 20 mW/m.K), low permeability to water and stability over time. The other types of insulation products available on the market have a significantly higher thermal...... conductivity: + 50% for expanded polystyrene (λ ≈ 30 mW/m.K), + 75% for mineral wools (λ ≈ 35 mW/m.K), etc. Despite its low thermal conductivity, polyurethane foam (PUR) is not much used as insulation material for walls because of its low resistance to fire. The most common PUR boards are classified C-s2-d0...

Experimental Investigation of Polyurethane Camouflage Coating Using Dynamic Mechanical Analysis

National Research Council Canada - National Science Library

Crawford, Dawn

1999-01-01

.... The current polyurethane solvent-based (SOL) formulation, used as a chemical-agent-resistant camouflage top coat on all military tactical vehicles, was investigated, along with newly developed water-reducible (WR...

Development of bacterially resistant polyurethane for coating medical devices

International Nuclear Information System (INIS)

Roohpour, Nima; Moshaverinia, Alireza; Wasikiewicz, Jaroslaw M; Paul, Deepen; Vadgama, Pankaj; Wilks, Mark; Millar, Michael

2012-01-01

Polyurethanes have been widely used in medicine for coating and packaging implantable and other medical devices. Polyether-urethanes, in particular, have superior mechanical properties and are biocompatible, but in common with other medical materials they are susceptible to microbial film formation. In this study, polyether-urethane was end-capped with silver lactate and silver sulfadiazine functional groups to produce a bacterially resistant polymer without sacrificing the useful mechanical properties of the polyether-polyurethane. The silver ions were covalently incorporated into the polymer during chain extension of the prepolymer. The functionalized polymers were structurally characterized by light scattering, electron microscopy, NMR, FTIR and Raman spectroscopy. Mechanical properties, hydrophilicity, in vitro stability and antibacterial action of polymers were also investigated. Results indicate that both silver salts were successfully incorporated into the polymer structure without significant effect on mechanical properties, whilst conferring acceptable bacterial resistance.

Synthesis and characterization of castor oil based polyurethane ...

Indian Academy of Sciences (India)

Unknown

Abstract. A series of interpenetrating polymer networks (IPNs) of castor oil based polyurethane/polyacrylo- nitrile (PU/PAN: 80/20, 60/40, 50/50, 40/60 and 20/80) were synthesized by condensation reaction of castor oil with methylene diisocyanate and acrylonitrile, employing benzoyl peroxide (BPO) and ethylene glycol ...

Utilization of natural oils for decomposition of polyurethanes

Czech Academy of Sciences Publication Activity Database

Beneš, Hynek; Černá, R.; Ďuračková, Andrea; Látalová, Petra

2012-01-01

Roč. 20, č. 1 (2012), s. 175-185 ISSN 1566-2543 R&D Projects: GA MPO 2A-2TP1/135 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane * oleochemical polyol * chemical recycling Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.495, year: 2012

Improved lignin polyurethane properties with Lewis acid treatment.

Science.gov (United States)

Chung, Hoyong; Washburn, Newell R

2012-06-27

Chemical modification strategies to improve the mechanical properties of lignin-based polyurethanes are presented. We hypothesized that treatment of lignin with Lewis acids would increase the concentration of hydroxyl groups available to react with diisocyanate monomers. Under the conditions used, hydrogen bromide-catalyzed modification resulted in a 28% increase in hydroxyl group content. Associated increases in hydrophilicity of solvent-cast thin films were also recorded as evidenced by decreases in water contact angle. Polyurethanes were then prepared by first preparing a prepolymer based on mixtures of toluene-2,4-diisocyanate (TDI) and unmodified or modified lignin, then polymerization was completed through addition of polyethylene glycol (PEG), resulting in mass ratios of TDI:lignin:PEG of 43:17:40 in the compositions investigated here. The mixture of TDI and unmodified lignin resulted in a lignin powder at the bottom of the liquid, suggesting it did not react directly with TDI. However, a homogeneous solution resulted when TDI and the hydrogen bromide-treated lignin were mixed, suggesting demethylation indeed increased reactivity and resulted in better integration of lignin into the urethane network. Significant improvements in mechanical properties of modified lignin polyurethanes were observed, with a 6.5-fold increase in modulus, which were attributed to better integration of the modified lignin into the covalent polymer network due to the higher concentration of hydroxyl groups. This research indicates that chemical modification strategies can lead to significant improvements in the properties of lignin-based polymeric materials using a higher fraction of an inexpensive lignin monomer from renewable resources and a lower fraction an expensive, petroleum-derived isocyanate monomer to achieve the required material properties.

Blended Polyurethane and Tropoelastin as a Novel Class of Biologically Interactive Elastomer

Science.gov (United States)

Wise, Steven G.; Liu, Hongjuan; Yeo, Giselle C.; Michael, Praveesuda L.; Chan, Alex H.P.; Ngo, Alan K.Y.; Bilek, Marcela M.M.; Bao, Shisan

2016-01-01

Polyurethanes are versatile elastomers but suffer from biological limitations such as poor control over cell attachment and the associated disadvantages of increased fibrosis. We address this problem by presenting a novel strategy that retains elasticity while modulating biological performance. We describe a new biomaterial that comprises a blend of synthetic and natural elastomers: the biostable polyurethane Elast-Eon and the recombinant human tropoelastin protein. We demonstrate that the hybrid constructs yield a class of coblended elastomers with unique physical properties. Hybrid constructs displayed higher elasticity and linear stress–strain responses over more than threefold strain. The hybrid materials showed increased overall porosity and swelling in comparison to polyurethane alone, facilitating enhanced cellular interactions. In vitro, human dermal fibroblasts showed enhanced proliferation, while in vivo, following subcutaneous implantation in mice, hybrid scaffolds displayed a reduced fibrotic response and tunable degradation rate. To our knowledge, this is the first example of a blend of synthetic and natural elastomers and is a promising approach for generating tailored bioactive scaffolds for tissue repair. PMID:26857114

Effect of γ-radiation sterilization on the stability of polyurethane potting compounds based on castor oil/SMDI and caprolactone polyol/SMDI, used for hollow fibre haemodialyzer

International Nuclear Information System (INIS)

Jayabalan, M.; Lizymol, P.P.

1997-01-01

Stability of polyurethane potting compounds based on castor oil/SMDI and caprolactone polyol/SMDI in repeated gamma radiation sterilization was studied. Radiation-induced degradation and leaching of low molecular weight fragments are higher in castor oil based polyurethane than in caprolactone polyol based polyurethane. For castor oil and caprolactone polyol based polyurethanes degradation increases up to 5 Mrad dose of sterilization. Further increase of dose of sterilization decreases leaching in caprolactone polyol based polyurethane which has resulted from secondary reactions leading to crosslinking. In the case of castor oil based polyurethane such crosslinks undergo cleavage at 10 Mrad dose of sterilization. (author)

40 CFR 63.1297 - Standards for slabstock flexible polyurethane foam production-HAP ABA emissions from the...

Science.gov (United States)

2010-07-01

... polyurethane foam production-HAP ABA emissions from the production line. 63.1297 Section 63.1297 Protection of... foam production—HAP ABA emissions from the production line. (a) Each owner or operator of a new or... § 63.1293(a)(1) shall control HAP ABA emissions from the slabstock polyurethane foam production line in...

Radiation-induced changes affecting polyester based polyurethane binder

Science.gov (United States)

Pierpoint, Sujita Basi

The application of thermoplastic polyurethane elastomers as binders in the high energy explosives particularly when used in weapons presents a significantly complex and challenging problem due to the impact of the aging of this polymer on the useful service life of the explosive. In this work, the effects of radiation on the aging of the polyester based polyurethane were investigated using both electron beam and gamma irradiation at various dose rates in the presence and absence of oxygen. It was found by means of GPC that, in the presence and absence of oxygen, the poly (ester urethane) primarily undergoes cross-linking, by means of a carbon-centered secondary alkyl radical. It was also concluded that the polymer partially undergoes scission of the backbone of the main chain at C-O, N-C, and C-C bonds. Substantial changes in the conditions of irradiation and in dose levels did not affect the cross-linking and scission yields. Experiments were also performed with EPR spectroscopy for the purpose of identifying the initial carbon-centered free radicals and for studying the decay mechanisms of these radicals. It was found that the carbon-centered radical which is produced via C-C scission (primary alkyl radical) is rapidly converted to a long-lived allylic species at higher temperatures; more than 80% radicals are converted to allyl species in 2.5 hours. In the presence of oxygen, the allyl radical undergoes a fast reaction to produce a peroxyl radical; this radical decays with a 1.7 hour half-life by pseudo first-order kinetics to negligible levels in 13 hours. FTIR measurements were conducted to identify the radiation-induced changes to the functional groups in the polyester polyurethane. These measurements show an increase in carbonyl, amine and carboxylic groups as a result of reaction of H atoms with R-C-O·, ·NH-R and R-COO·. The FTIR results also demonstrate the production of the unsaturation resulting from hydrogen atom transfer during intrachain conversion

Polyurethanes elastomers with amide chain extenders of uniform length

NARCIS (Netherlands)

van der Schuur, J.M.; Noordover, B.A.J.; Noordover, Bart; Gaymans, R.J.

2006-01-01

Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

Membranes as sensitive targets in thymocyte apoptosis

International Nuclear Information System (INIS)

Ramakrishnan, N.; McClain, D.E.; Catravas, G.N.

1993-01-01

The role of cellular membranes in thymocyte apoptosis has been examined. Trolox, a water soluble analogue of vitamin E and inhibitor of membrane damage, inhibits DNA fragmentation in thymocytes exposed to γ-radiation, and is most effective in inhibiting DNA fragmentation when added to cells within 30 min post-irradiation. Exposure to trolox only during irradiation did not prevent DNA fragmentation. Incubation of the irradiated cell suspension with trolox for 2h post-irradiation was sufficient to prevent DNA fragmentation measured at 24 h in irradiated cells, suggesting that trolox irreversibly inhibits a cellular lesion required for apoptosis. The induction of DNA fragmentation appears to be related to a concurrent, pronounced flow of Ca 2+ into the cell. At 3 h post-irradiation the amount of Ca 2+ in irradiated thymocytes was more than twice that of unirradiated thymocytes. Trolox treatment completely blocked the radiation-induced influx of Ca 2+ into the thymocytes. These results suggest that membrane damage is a critical lesion involved in DNA fragmentation in thymocyte apoptosis. (author)

Preconcentration of traces of radionuclides and elements with foamed polyurethane sorbents in the analysis of environmental samples

International Nuclear Information System (INIS)

Palagyi, S.; Braun, T.

1986-01-01

The importance of preconcentration and the permanent need of efficient preconcentrating agents in environmental analysis are pointed out. Foamed polyurethane sorbents draw attention as novel agents in separation chemistry. A survey is presented of recent applications of unloaded and reagent-loaded open-cell type resilient polyurethane foams in the separation and preconcentration of radionuclides from environmental samples, and of the latest uses of these foams in the preconcentration and detection of traces of some, mainly inorganic materials in environmental samples, using radioanalytical techniques. Possible future uses of polyurethane foams in trace element detection in environmental analysis are outlined. (author)

Determination of the topology of endoplasmic reticulum membrane proteins using redox-sensitive green-fluorescence protein fusions.

Science.gov (United States)

Tsachaki, Maria; Birk, Julia; Egert, Aurélie; Odermatt, Alex

2015-07-01

Membrane proteins of the endoplasmic reticulum (ER) are involved in a wide array of essential cellular functions. Identification of the topology of membrane proteins can provide significant insight into their mechanisms of action and biological roles. This is particularly important for membrane enzymes, since their topology determines the subcellular site where a biochemical reaction takes place and the dependence on luminal or cytosolic co-factor pools and substrates. The methods currently available for the determination of topology of proteins are rather laborious and require post-lysis or post-fixation manipulation of cells. In this work, we have developed a simple method for defining intracellular localization and topology of ER membrane proteins in living cells, based on the fusion of the respective protein with redox-sensitive green-fluorescent protein (roGFP). We validated the method and demonstrated that roGFP fusion proteins constitute a reliable tool for the study of ER membrane protein topology, using as control microsomal 11β-hydroxysteroid dehydrogenase (11β-HSD) proteins whose topology has been resolved, and comparing with an independent approach. We then implemented this method to determine the membrane topology of six microsomal members of the 17β-hydroxysteroid dehydrogenase (17β-HSD) family. The results revealed a luminal orientation of the catalytic site for three enzymes, i.e. 17β-HSD6, 7 and 12. Knowledge of the intracellular location of the catalytic site of these enzymes will enable future studies on their biological functions and on the role of the luminal co-factor pool. Copyright © 2015 Elsevier B.V. All rights reserved.

Enhanced therapeutic efficacy of budesonide in experimental colitis with enzyme/pH dual-sensitive polymeric nanoparticles

Directory of Open Access Journals (Sweden)

Naeem M

2015-07-01

Full Text Available Muhammad Naeem, Jiafu Cao, Moonjeong Choi, Woo Seong Kim, Hyung Ryong Moon, Bok Luel Lee, Min-Soo Kim, Yunjin Jung, Jin-Wook Yoo College of Pharmacy, Pusan National University, Busan, South Korea Abstract: Current colon-targeted drug-delivery approaches for colitis therapy often utilize single pH-triggered systems, which are less reliable due to the variation of gut pH in individuals and in disease conditions. Herein, we prepared budesonide-loaded dual-sensitive nanoparticles using enzyme-sensitive azo-polyurethane and pH-sensitive methacrylate copolymer for the treatment of colitis. The therapeutic potential of the enzyme/pH dual-sensitive nanoparticles was evaluated using a rat colitis model and compared to single pH-triggered nanoparticles. Clinical activity scores, colon/body weight ratios, myeloperoxidase activity, and proinflammatory cytokine levels were markedly decreased by dual-sensitive nanoparticles compared to single pH-triggered nanoparticles and budesonide solution. Moreover, dual-sensitive nanoparticles accumulated selectively in inflamed segments of the colon. In addition, dual-sensitive nanoparticle plasma concentrations were lower than single pH-triggered nanoparticles, and no noticeable in vitro or in vivo toxicity was observed. Our results demonstrate that enzyme/pH dual-sensitive nanoparticles are an effective and safe colon-targeted delivery system for colitis therapy. Keywords: azo-polyurethane, methacrylate copolymer, budesonide, colon-targeted nanoparticles, colitis

Hardness measurements of silicon rubber and polyurethane rubber cured by ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.

1995-01-01

This work investigates the hardness of both silicon rubber and polyurethane rubber cured by ionizing radiation. Shore A Hardness is used to characterize the subject elastomers in relation to the crosslinking process. Various formulations of both materials have been investigated in order to achieve the optimum cure conditions desired. A small amount of the curing agent has been incorporated in some formulations in order to reduce the required dose to achieve full cure conditions. Silicon rubber has shown improvements in hardness as absorbed dose is increased, whereas hardness remained constant over a range of absorbed doses for polyurethane rubber

Bio-based rigid polyurethane foam from liquefied products of wood in the presence of polyhydric alcohols

Science.gov (United States)

Zhifeng Zheng; Hui Pan; Yuanbo Huang; Chung Y. Hse

2011-01-01

Rigid polyurethane foams were prepared from the liquefied wood polyols, which was obtained by the liquefaction of southern pine wood in the presence of polyhydric alcohols with sulfuric acid catalyst by using microwave-assistant as an energy source. The properties of liquefied biomass-based polyols and the rigid polyurethane foams were investigated. The results...

A review: fabrication of porous polyurethane scaffolds.

Science.gov (United States)

Janik, H; Marzec, M

2015-03-01

The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages. Copyright © 2014. Published by Elsevier B.V.

The Effect of Reactives Diluents to the Physical Properties of Acrylated Palm Oil Based Polyurethane Coatings

Directory of Open Access Journals (Sweden)

Onn Munirah

2016-01-01

Full Text Available The development of polyurethane with hydroxyl access in a molecule leads to a new alternative of low toxicity green product. Palm oil is one of the major commodities in Malaysia. The potential of palm oil to be used as coatings raw material such as alkyd is limited due to low unsaturated side on fatty acid chains. To overcome this limitation, palm oil was modified through transesterification process to produce polyol. Acrylated isocyanate (urethane oligomer was then grafted onto polyol to produce polyurethane with vinylic ends. The polyurethane was formulated with different cross-linkers (reactive diluents and cured under UV radiation. The effect of three different diluents; monoacrylate, diacrylate and triacrylate on the properties of cured polymer were studied in this research. Fourier Transform Infrared (FTIR, Hydroxyl Value Titration, Gel Content, and Volatile Organic Compound (VOC were used for characterization. Physical testing performed were Pencil Hardness and Pull-Off Adhesion test. Novel palm oil-based polyurethane coatings have been found to have good properties with mono acrylate functionality.

Limitations of predicting in vivo biostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing.

Science.gov (United States)

Padsalgikar, Ajay; Cosgriff-Hernandez, Elizabeth; Gallagher, Genevieve; Touchet, Tyler; Iacob, Ciprian; Mellin, Lisa; Norlin-Weissenrieder, Anna; Runt, James

2015-01-01

Polyurethane biostability has been the subject of intense research since the failure of polyether polyurethane pacemaker leads in the 1980s. Accelerated in vitro testing has been used to isolate degradation mechanisms and predict clinical performance of biomaterials. However, validation that in vitro methods reproduce in vivo degradation is critical to the selection of appropriate tests. High temperature has been proposed as a method to accelerate degradation. However, correlation of such data to in vivo performance is poor for polyurethanes due to the impact of temperature on microstructure. In this study, we characterize the lack of correlation between hydrolytic degradation predicted using a high temperature aging model of a polydimethylsiloxane-based polyurethane and its in vivo performance. Most notably, the predicted molecular weight and tensile property changes from the accelerated aging study did not correlate with clinical explants subjected to human biological stresses in real time through 5 years. Further, DMTA, ATR-FTIR, and SAXS experiments on samples aged for 2 weeks in PBS indicated greater phase separation in samples aged at 85°C compared to those aged at 37°C and unaged controls. These results confirm that microstructural changes occur at high temperatures that do not occur at in vivo temperatures. In addition, water absorption studies demonstrated that water saturation levels increased significantly with temperature. This study highlights that the multiphase morphology of polyurethane precludes the use of temperature accelerated biodegradation for the prediction of clinical performance and provides critical information in designing appropriate in vitro tests for this class of materials. © 2014 Wiley Periodicals, Inc.

Enhancement of antibacterial properties of polyurethanes by chitosan and heparin immobilization

International Nuclear Information System (INIS)

Kara, Filiz; Aksoy, E. Ayse; Yuksekdag, Zehranur; Aksoy, Serpil; Hasirci, Nesrin

2015-01-01

Graphical abstract: - Highlights: • Polyurethane elastomer was synthesized in medical purity. • Chitosan (CH) and heparin (Hep) were immobilized on polyurethane films. • Modification with CH and Hep increased hydrophilicity and surface free energy. • Immobilized films had high antibacterial activity against four bacteria. • Bacterial adhesion significantly decreased on the modified surfaces. - Abstract: Being antibacterial is a required property for the materials used in medical devices and instruments. Polyurethanes (PUs) are one class of polymers widely used in the production of devices that especially come in contact with blood (e.g. heart valves, blood vessels, vascular grafts and catheters). In this study, hexamethylene diisocyanate based polyurethanes (PUh) were synthesized and antibacterial and anti-adhesive properties were added by immobilizing chitosan (CH) and heparin (Hep) on the samples of PUh via a stepwise process. Chemistry and topography of the modified film samples (PUh-CH and PUh-CH-Hep) were examined by Fourier Transform Infrared Spectrophotometry-Attenuated Total Reflectance (FTIR-ATR), Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM), and surface free energy (SFE) values after each step were determined by goniometer. PUh-CH and PUh-CH-Hep samples were found to be antibacterial against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) (both Gram positive) and Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) (both Gram negative) bacteria, and bacterial adhesion results showed a significant decrease in the number of viable bacteria on both modified samples where PUh-CH-Hep was the most effective. The findings of this study show that polymeric surfaces can be effectively modified and converted to be antibacterial by chitosan and heparin immobilization, and presence of both chemicals enhance efficacy against bacteria.

Enhancement of antibacterial properties of polyurethanes by chitosan and heparin immobilization

Energy Technology Data Exchange (ETDEWEB)

Kara, Filiz [Department of Chemistry, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Aksoy, E. Ayse [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, 06100 Ankara (Turkey); Yuksekdag, Zehranur [Biotechnology Laboratory, Department of Biology, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Aksoy, Serpil [Department of Chemistry, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Hasirci, Nesrin, E-mail: nhasirci@metu.edu.tr [BIOMATEN, Center of Excellence in Biomaterials and Tissue Engineering, Middle East Technical University, 06800 Ankara (Turkey); Department of Chemistry, Faculty of Arts and Sciences, Middle East Technical University, 06800 Ankara (Turkey)

2015-12-01

Graphical abstract: - Highlights: • Polyurethane elastomer was synthesized in medical purity. • Chitosan (CH) and heparin (Hep) were immobilized on polyurethane films. • Modification with CH and Hep increased hydrophilicity and surface free energy. • Immobilized films had high antibacterial activity against four bacteria. • Bacterial adhesion significantly decreased on the modified surfaces. - Abstract: Being antibacterial is a required property for the materials used in medical devices and instruments. Polyurethanes (PUs) are one class of polymers widely used in the production of devices that especially come in contact with blood (e.g. heart valves, blood vessels, vascular grafts and catheters). In this study, hexamethylene diisocyanate based polyurethanes (PUh) were synthesized and antibacterial and anti-adhesive properties were added by immobilizing chitosan (CH) and heparin (Hep) on the samples of PUh via a stepwise process. Chemistry and topography of the modified film samples (PUh-CH and PUh-CH-Hep) were examined by Fourier Transform Infrared Spectrophotometry-Attenuated Total Reflectance (FTIR-ATR), Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM), and surface free energy (SFE) values after each step were determined by goniometer. PUh-CH and PUh-CH-Hep samples were found to be antibacterial against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) (both Gram positive) and Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) (both Gram negative) bacteria, and bacterial adhesion results showed a significant decrease in the number of viable bacteria on both modified samples where PUh-CH-Hep was the most effective. The findings of this study show that polymeric surfaces can be effectively modified and converted to be antibacterial by chitosan and heparin immobilization, and presence of both chemicals enhance efficacy against bacteria.

Polycarbonate-based polyurethane elastomers: temperature-dependence of tensile properties

Czech Academy of Sciences Publication Activity Database

Hrdlička, Z.; Kuta, A.; Poreba, Rafal; Špírková, Milena

2014-01-01

Roč. 68, č. 2 (2014), s. 233-238 ISSN 0366-6352 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.468, year: 2014

Characterization studies of lower and non-TDI polyurethane encapsulants

International Nuclear Information System (INIS)

Wilson, M.H.

1993-09-01

Polyurethane prepolymers containing toluene diisocyanate (TDI) are used within the Nuclear Weapons complex for many adhesive and encapsulation applications. As part of a program for minimizing hazards to workers and the environment, TDI will be eliminated. This report presents evaluation of alternative encapsulants

Epoxy polyurethane nanocomposites filled with fullerite

International Nuclear Information System (INIS)

Rozhnova, R.A.; Galatenko, N.A.; Lukashevich, S.A.; Shirokov, O.D.; Levenets', Je.G.

2015-01-01

New nanocomposite materials based on epoxy polyurethane (EPU) containing nanoscale fullerite in its composition are produced. The influence of small impurities of fullerite on physical and mechanical properties of the nanocomposites is established. The effect of a nanofiller and its concentration on the structure and properties of the composite and the ability to biodegradation in vitro is studied. The developed nanocomposites exhibit the biodegradability, and the presence of nanofillers in the EPU facilitates the course of the process

Nitric Oxide-Releasing Silica Nanoparticle-Doped Polyurethane Electrospun Fibers

Science.gov (United States)

Koh, Ahyeon; Carpenter, Alexis W.; Slomberg, Danielle L.; Schoenfisch, Mark H.

2013-01-01

Electrospun polyurethane fibers doped with nitric oxide (NO)-releasing silica particles are presented as novel macromolecular scaffolds with prolonged NO-release and high porosity. Fiber diameter (119–614 nm) and mechanical strength (1.7–34.5 MPa of modulus) were varied by altering polyurethane type and concentration, as well as the NO-releasing particle composition, size, and concentration. The resulting NO-releasing electrospun nanofibers exhibited ~83% porosity with flexible plastic or elastomeric behavior. The use of N-diazeniumdiolate- or S-nitrosothiol-modified particles yielded scaffolds exhibiting a wide range of NO release totals and durations (7.5 nmol mg−1–0.12 μmol mg−1 and 7 h to 2 weeks, respectively). The application of NO-releasing porous materials as coating for subcutaneous implants may improve tissue biocompatibility by mitigating the foreign body response and promoting cell integration. PMID:23915047

Highly Sensitive, Transparent, and Durable Pressure Sensors Based on Sea-Urchin Shaped Metal Nanoparticles.

Science.gov (United States)

Lee, Donghwa; Lee, Hyungjin; Jeong, Youngjun; Ahn, Yumi; Nam, Geonik; Lee, Youngu

2016-11-01

Highly sensitive, transparent, and durable pressure sensors are fabricated using sea-urchin-shaped metal nanoparticles and insulating polyurethane elastomer. The pressure sensors exhibit outstanding sensitivity (2.46 kPa -1 ), superior optical transmittance (84.8% at 550 nm), fast response/relaxation time (30 ms), and excellent operational durability. In addition, the pressure sensors successfully detect minute movements of human muscles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies

Directory of Open Access Journals (Sweden)

Michał Strankowski

2016-01-01

Full Text Available Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO, is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO, to modify the matrix of polyurethane elastomers, by rGO.

Testing of Disposable Protective Garments Against Isocyanate Permeation From Spray Polyurethane Foam Insulation.

Science.gov (United States)

Mellette, Michael P; Bello, Dhimiter; Xue, Yalong; Yost, Michael; Bello, Anila; Woskie, Susan

2018-05-12

Diisocyanates (isocyanates), including methylene diphenyl diisocyanate (MDI), are the primary reactive components of spray polyurethane foam (SPF) insulation. They are potent immune sensitizers and a leading cause of occupational asthma. Skin exposure to isocyanates may lead to both irritant and allergic contact dermatitis and possibly contribute to systemic sensitization. More than sufficient evidence exists to justify the use of protective garments to minimize skin contact with aerosolized and raw isocyanate containing materials during SPF applications. Studies evaluating the permeation of protective garments following exposure to SPF insulation do not currently exist. To conduct permeation testing under controlled conditions to assess the effectiveness of common protective gloves and coveralls during SPF applications using realistic SPF product formulations. Five common disposable garment materials [disposable latex gloves (0.07 mm thickness), nitrile gloves (0.07 mm), vinyl gloves (0.07 mm), polypropylene coveralls (0.13 mm) and Tyvek coveralls (0.13 mm)] were selected for testing. These materials were cut into small pieces and assembled into a permeation test cell system and coated with a two-part slow-rise spray polyurethane foam insulation. Glass fiber filters (GFF) pretreated with 1-(9-anthracenylmethyl)piperazine) (MAP) were used underneath the garment to collect permeating isocyanates. GFF filters were collected at predetermined test intervals between 0.75 and 20.00 min and subsequently analyzed using liquid chromatography-tandem mass spectrometry. For each garment material, we assessed (i) the cumulative concentration of total isocyanate, including phenyl isocyanate and three MDI isomers, that effectively permeated the material over the test time; (ii) estimated breakthrough detection time, average permeation rate, and standardized breakthrough time; from which (iii) recommendations were developed for the use of similar protective garments following

Gamma radiation effect on sisal / polyurethane composites without coupling agents

Energy Technology Data Exchange (ETDEWEB)

Vasco, Marina Cardoso; Claro Neto, Salvador; Nascimento, Eduardo Mauro; Azevedo, Elaine, E-mail: marina.mcv@gmail.com [University of Patras (Greece); Universidade de Sao Paulo (USP) Sao Carlos, SP (Brazil); Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

2017-04-15

Natural fibers and polyurethane based composites may present chemical bonding between the components of the polymer and the lignin of the fiber. The incidence of radiation can cause degradation of the polymeric material and alter its mechanical properties. The objective of this study was to obtain and characterize cold pressed composites from polyurethane derived from castor oil and sisal fibers, without coupling agents, through thermogravimetric and mechanical tests, before and after the incidence of 25 kGy dose of gamma radiation. Woven composites that were not irradiated had maximum values of 4.40 GPa for flexural elastic modulus on three point flexural test and dispersed fiber composite that were not irradiated had maximum values of 2.25 GPa. These materials are adequate for use in non-structural applications in radiotherapy and radiodiagnostic rooms. (author)

Characterization of Functionalized Polyurethane Foam for Lead Ion Removal from Water

Directory of Open Access Journals (Sweden)

Subhashini Gunashekar

2014-01-01

Full Text Available Polyurethane foams functionalized with sulfonic acid groups are used in this study to exchange lead (Pb2+ ions from aqueous solutions. Toluene-2, 4-diisocyanate, 2,6-diisocyanate (TDI was reacted with Polypropylene glycol 1200 (PPG in 2 : 1 molar ratio to form a linear prepolymer. The linear prepolymer was further polymerized using N,N-bis(2-hydroxyethyl-2-aminoethanesulfonic acid (BES, which acts both as a chain extender and an ion-exchanger for Pb2+ ions. The functionalized polyurethane foam was characterized by Fourier transform infrared spectroscopy (FTIR, gel permeation chromatography (GPC, scanning electron microscopy (SEM, and energy dispersive X-ray spectroscopy (EDX. The Pb2+ ion exchange capacity was determined using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS. The maximum Pb2+ ion exchange capacity of the foam was found to be 51 ppb/g from a 100 ppb Pb2+ solution over a period of two hours. In addition, pH analysis was carried out on the foam composition with the best Pb2+ ion removal capacity. The pH results based on two-hour exposures showed that the functionalized polyurethane foam performed better at lower pH levels.

A High Sensitivity IDC-Electronic Tongue Using Dielectric/Sensing Membranes with Solvatochromic Dyes

Directory of Open Access Journals (Sweden)

Md. Rajibur Rahaman Khan

2016-05-01

Full Text Available In this paper, an electronic tongue/taste sensor array containing different interdigitated capacitor (IDC sensing elements to detect different types of tastes, such as sweetness (glucose, saltiness (NaCl, sourness (HCl, bitterness (quinine-HCl, and umami (monosodium glutamate is proposed. We present for the first time an IDC electronic tongue using sensing membranes containing solvatochromic dyes. The proposed highly sensitive (30.64 mV/decade sensitivity IDC electronic tongue has fast response and recovery times of about 6 s and 5 s, respectively, with extremely stable responses, and is capable of linear sensing performance (R2 ≈ 0.985 correlation coefficient over the wide dynamic range of 1 µM to 1 M. The designed IDC electronic tongue offers excellent reproducibility, with a relative standard deviation (RSD of about 0.029. The proposed device was found to have better sensing performance than potentiometric-, cascoded compatible lateral bipolar transistor (C-CLBT-, Electronic Tongue (SA402-, and fiber-optic-based taste sensing systems in what concerns dynamic range width, response time, sensitivity, and linearity. Finally, we applied principal component analysis (PCA to distinguish between various kinds of taste in mixed taste compounds.

Determination of effective thermal conductivity for polyurethane foam by use of fractal method

Institute of Scientific and Technical Information of China (English)

SHI Mingheng; LI Xiaochuan; CHEN Yongping

2006-01-01

The microstructure of polyurethane foam is disordered, which influences the foam heat conduction process significantly. In this paper foam structure is described by using the local area fractal dimension in a certain small range of length scales. An equivalent element cell is constructed based on the local fractal dimensions along the directions parallel and transverse to the heat flux. By use of fractal void fraction a simplified heat conduction model is proposed to calculate the effective thermal conductivity of polyurethane foam. The predicted effective thermal conductivity agrees well with the experimental data.

Sorption of Triangular Silver Nanoplates on Polyurethane Foam

Science.gov (United States)

Furletov, A. A.; Apyari, V. V.; Garshev, A. V.; Volkov, P. A.; Tolmacheva, V. V.; Dmitrienko, S. G.

2018-02-01

The sorption of triangular silver nanoplates on polyurethane foam is investigated as a procedure for creating a nanocomposite sensing material for subsequent use in optical means of chemical analysis. Triangular silver nanoplates are synthesized and characterized, and a simple sorption technique for the formation of a composite material based on these nanoplates is proposed.

Synthesis and characterization of castor oil-based polyurethane

Indian Academy of Sciences (India)

Polyurethane (PU) based on polyol, derived from castor oil has been synthesized and characterized for potential use as a base material for electrolytes. Transesterification process of castor oil formed a polyol with hydroxyl value of 190 mg KOH g–1 and molecular weight of 2786 g mol–1. The polyols together with 4 ...

Synthesis and properties of ionic polyurethane dispersions: influence of polyol molecular weight

International Nuclear Information System (INIS)

Valipour Ebrahimi, M.; Barikani, M.; Mohammad Seyed Mohaghegh, S.

2006-01-01

A series of water dispersible polyurethanes containing carboxylate anion as the hydrophilic pendant group were prepared from toluene diisocyanate (TDI), 1,4- butanediol (1,4-BDO), dimethylol propionic acid and different molecular weight of polytetramethylene glycol . IR Spectroscopy was used to check the end of polymerization reaction and characterization of polymer. The effect of polytetramethylene glycol molecular weight was studied on the particle size distribution, contact angle, and mechanical and thermal properties of the emulsion-cast films. Average particle size of prepared polyurethane emulsions decreases with increasing the polytetramethylene glycol molecular weight. Tensile strength and hardness decrease and elongation-at-break and contact angle increase with increase of the polytetramethylene glycol molecular weight. Thermal property and thermal stability are also effected by variation of polytetramethylene glycol molecular weight. The thermal stability increases with increasing polytetramethylene glycol molecular weight. Glass transition temperature (T g ) moved toward the lower temperatures by increasing molecular weight of the polyol. Decrease in T g and tensile properties are interpreted in terms of the decrease in hard segments and the increase in chain flexibility and phase separation in high molecular weight polytetramethylene glycol based polyurethane

SOLAR SAIL PROPULSION SENSITIVITY TO MEMBRANE SHAPE AND OPTICAL PROPERTIES USING THE SOLAR VECTORING EVALUATION TOOL (SVET)

Science.gov (United States)

Ewing, Anthony

2005-01-01

Solar sail propulsive performance is dependent on sail membrane optical properties and on sail membrane shape. Assumptions of an ideal sail (flat, perfect reflector) can result in errors which can affect spacecraft control, trajectory analyses, and overall evaluation of solar sail performance. A MATLAB(R) program has been developed to generate sail shape point cloud files for two square-architecture solar sail designs. Simple parabolic profiles are assumed for sail shape under solar pressure loading. These files are then input into the Solar Vectoring Evaluation Tool (SVET) software to determine the propulsive force vector, center of pressure, and moments about the sail body axes as a function of sail shape and optical properties. Also, the impact of the center-line angle, due to non-perfect optical properties, is addressed since this constrains sail force vector cone angle and is often overlooked when assuming ideal-reflector membranes. Preliminary sensitivity analysis using these tools aids in determining the key geometric and optical parameters that drive solar sail propulsive performance.

Unidirectional fibers and polyurethane elastomer matrix based composites synthesis and properties. Ph.D. Thesis

Science.gov (United States)

Chakar, A.

1984-01-01

A study of the properties and manufacturing techniques for long-fiber reinforced elastomeric composites for flexible and damping structural materials is presented. Attention is given to the usage of polyurethane in the matrix to obtain plastic elastomeric matrices and vitreous transition temperatures which vary from -80 C to 10 C, as well as assure good fiber adhesion. Various polyurethane formulations synthesized from diisocyanate prepolymers are examined in terms of mechanical and thermal properties. The principal reinforcing fiber selected is a unidirectional glass cloth.

Polyurethane foam for roadway stabilization NH route 129, Loudon, NH.

Science.gov (United States)

2016-12-12

This report summarizes the evaluation of the performance of polyurethane foam as a method of roadway : stabilization for a rural roadway experiencing substantial frost heaving. : NHDOT is responsible for many roads which have evolved from gravel road...

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

International Nuclear Information System (INIS)

Raja, Mohan; Shanmugharaj, A.M.; Ryu, Sung Hun; Subha, J.

2011-01-01

Highlights: → Polyurethane based on pristine and metal (Ag and Cu) nanoparticle decorated CNTs nanocomposites are prepared through melt blending process. → The electrical, mechanical, dynamic mechanical, thermal conductivity and electro active shape memory properties of the PU nanocomposites were investigated. → The influence of metal nanoparticle decorated CNTs showed significant improvement in their all properties to compare to pristine CNTs. → Electro active shape memory studies of the PU/M-CNTs nanocomposites reveal extraordinary recoverability of its shape at lower applied dc voltages. - Abstract: Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.

The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

International Nuclear Information System (INIS)

Yu, Ya-Jen; Hearon, Keith; Maitland, Duncan J; Wilson, Thomas S

2011-01-01

The effect of moisture absorption on the glass transition temperature (T g ) and the stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood-contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To the best of our knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the T g of the foam, with a maximum water uptake shifting the T g from 67 to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h

Structures and Properties of Polyurethanes. Part II,

Science.gov (United States)

1979-03-23

effect was observed for polymethyl methacrylate (222, 2721. The polyol, which contain fluorine , decrease adhesion, in spite DOC = 79011112 PAGE S4% of...small differences in the hardness of films on the basis of the fluorine -bearing polyol and generally accepted polyol. Is investigated the etfect ot...polyurethane, to rigid surface. DOC 79011112 P A * S The effect of the solvent, utilized for obtaining the varnish , on adhesion is investigated in

Fracture Toughness Evaluation of Space Shuttle External Tank Thermal Protection System Polyurethane Foam Insulation Materials

Science.gov (United States)

McGill, Preston; Wells, Doug; Morgan, Kristin

2006-01-01

Experimental evaluation of the basic fracture properties of Thermal Protection System (TPS) polyurethane foam insulation materials was conducted to validate the methodology used in estimating critical defect sizes in TPS applications on the Space Shuttle External Fuel Tank. The polyurethane foam found on the External Tank (ET) is manufactured by mixing liquid constituents and allowing them to react and expand upwards - a process which creates component cells that are generally elongated in the foam rise direction and gives rise to mechanical anisotropy. Similarly, the application of successive foam layers to the ET produces cohesive foam interfaces (knitlines) which may lead to local variations in mechanical properties. This study reports the fracture toughness of BX-265, NCFI 24-124, and PDL-1034 closed-cell polyurethane foam as a function of ambient and cryogenic temperatures and knitline/cellular orientation at ambient pressure.

The Acoustical Properties of the Polyurethane Concrete Made of Oyster Shell Waste Comparing Other Concretes as Architectural Design Components

Science.gov (United States)

Setyowati, Erni; Hardiman, Gagoek; Purwanto

2018-02-01

This research aims to determine the acoustical properties of concrete material made of polyurethane and oyster shell waste as both fine aggregate and coarse aggregate comparing to other concrete mortar. Architecture needs aesthetics materials, so the innovation in architectural material should be driven through the efforts of research on materials for building designs. The DOE methods was used by mixing cement, oyster shell, sands, and polyurethane by composition of 160 ml:40 ml:100 ml: 120 ml respectively. Refer to the results of previous research, then cement consumption is reduced up to 20% to keep the concept of green material. This study compared three different compositions of mortars, namely portland cement concrete with gravel (PCG), polyurethane concrete of oyster shell (PCO) and concrete with plastics aggregate (PCP). The methods of acoustical tests were conducted refer to the ASTM E413-04 standard. The research results showed that polyurethane concrete with oyster shell waste aggregate has absorption coefficient 0.52 and STL 63 dB and has a more beautiful appearance when it was pressed into moulding. It can be concluded that polyurethane concrete with oyster shell aggregate (PCO) is well implemented in architectural acoustics-components.

Preparation and Characterization of Liquid Crystalline Polyurethane/Al2O3/Epoxy Resin Composites for Electronic Packaging

Directory of Open Access Journals (Sweden)

Shaorong Lu

2012-01-01

Full Text Available Liquid crystalline polyurethane (LCPU/Al2O3/epoxy resin composites were prepared by using LCPU as modifier. The mechanical properties, thermal stability, and electrical properties of the LCPU/Al2O3/epoxy resin composites were investigated systematically. The thermal oxidation analysis indicated that LCPU/Al2O3/epoxy resin composites can sustain higher thermal decomposition temperature. Meanwhile, coefficient of thermal expansion (CTE was also found to decrease with addition of LCPU and nano-Al2O3.

Structure, properties and application of a novel low-glossed waterborne polyurethane

International Nuclear Information System (INIS)

Li, Jianjun; Zheng, Wen; Zeng, Wenbo; Zhang, Dongqiao; Peng, Xiaohong

2014-01-01

Waterborne polyurethane (WPU) with low gloss was prepared successfully and used as surface modifier to adjust the gloss of leather. The structure and morphology of the WPU films were characterized by Fourier transform infrared spectrometer (FTIR), Atomic force microscope (AFM) and Scanning electron microscope (SEM). Then the factors affecting the gloss, light transmittance and water absorption of WPU films including varieties and amount of chain extenders, n NCO /n OH molar ratio and 2-[(2-aminoethyl)amino]ethyl sulfonic acid sodium content.etc were studied. Results showed that the WPU film possessed a broad particle size distribution combined with a relatively large particle size. This kind of novel WPU would be widely used in polyvinyl chloride, polyurethane synthetic leather surface.

Investigation on Thermal Properties of Kenaf Fibre Reinforced Polyurethane Bio-Composites

Science.gov (United States)

Athmalingam, Mathan; Vicki, W. V.

2018-01-01

This research focuses on the effect of Kenaf fibre on thermal properties of Polyurethane (PU) reinforced kenaf bio-composites. The samples were prepared using the polymer casting method with different percentages of kenaf fibre content (5 wt%, 10 wt%, 15 wt%). The thermal properties of Kenaf/PU bio-composite are determined through the Thermogravimetric Analysis and Differential Scanning Calorimeter test. The TGA results revealed that 10 wt% Kenaf/PU bio-composite appeared to be more stable. DSC results show that the glass transition temperature (Tg) value of 10 wt% Kenaf/PU composite is significant to pure polyurethane. It can be said that the thermal stability of 10 wt% Kenaf/PU bio-composite exhibits higher thermal stability compared to other samples.

Thermoplastic polyurethane and multi-walled carbon nanotubes nanocomposites for electrostatic dissipation

International Nuclear Information System (INIS)

Lavall, Rodrigo L.; Sales, Juliana A. de; Borges, Raquel S.; Calado, Hallen D. R.; Machado, Jose C.; Windmoeller, Dario; Silva, Glaura G.; Lacerda, Rodrigo G.; Ladeira, Luiz O.

2010-01-01

Polyurethane/multi-walled carbon nanotube (MWCNT) nanocomposites have been prepared with nanotube concentrations between 0.01 wt% and 1 wt%. MWCNT as-synthesized samples with ∼74 nm diameter and ∼7 mm length were introduced by solution processing in the polyurethane matrix. Scanning electron microscopy (SEM) images demonstrated good dispersion and adhesion of the CNTs to the polymeric matrix. The C=O stretching band showed evidence of perturbation of the hydrogen interaction between urethanic moieties in the nanocomposites as compared to pure TPU. Differential scanning calorimetry and positron annihilation lifetime spectroscopy measurements allowed the detection of glass transition displacement with carbon nanotube addition. Furthermore, the electrical conductivity of the nanocomposites was significantly increased with the addition of CNT. (author)

Gamma radiation effect on sisal / polyurethane composites without coupling agents

Directory of Open Access Journals (Sweden)

Marina Cardoso Vasco

Full Text Available Abstract Natural fibers and polyurethane based composites may present chemical bonding between the components of the polymer and the lignin of the fiber. The incidence of radiation can cause degradation of the polymeric material and alter its mechanical properties. The objective of this study was to obtain and characterize cold pressed composites from polyurethane derived from castor oil and sisal fibers, without coupling agents, through thermogravimetric and mechanical tests, before and after the incidence of 25 kGy dose of gamma radiation. Woven composites that were not irradiated had maximum values of 4.40 GPa for flexural elastic modulus on three point flexural test and dispersed fiber composite that were not irradiated had maximum values of 2.25 GPa. These materials are adequate for use in non-structural applications in radiotherapy and radiodiagnostic rooms.

Development of a gelatin-based polyurethane vascular graft by spray, phase-inversion technology

International Nuclear Information System (INIS)

Losi, Paola; Al Kayal, Tamer; Briganti, Enrica; Volpi, Silvia; Soldani, Giorgio; Mancuso, Luisa; Cao, Giacomo; Celi, Simona; Gualerzi, Alice

2015-01-01

The capacity of a composite vascular graft constituting polyurethane (PU) and gelatin to support cell growth was investigated using human mesenchymal stem cells (hMSCs). Gelatin-based polyurethane grafts were fabricated by co-spraying polyurethane and gelatin using a spray, phase-inversion technique. Graft microstructure was investigated by light and scanning electron microscopy. Uniaxial tensile tests were performed to assess the grafts’ mechanical properties in longitudinal and circumferential directions. hMSCs obtained from bone marrow aspirate were seeded onto flat graft samples. After 24, 48, and 72 h of incubation, cell morphology was evaluated by Giemsa staining and cell viability was calculated by XTT assay. SEM analysis evidenced that PU samples display a microporous structure, whereas the gelatin-based PU samples show a fibrillar appearance. The presence of cross-linked gelatin produced a significant increase of ultimate tensile strength and ultimate elongation in circumferential directions compared to PU material. Qualitative analysis of hMSC adhesion onto the grafts revealed remarkable differences between gelatin-based PU and control graft. hMSCs grown onto gelatin-based PU graft form a monolayer that reached confluence at 72 h, whereas cells seeded onto the control graft were not able to undergo appropriate spreading. hMSCs grown onto gelatin-based PU graft showed significantly higher viability than cells seeded onto bare PU at all time points. In conclusion, a composite vascular graft was successfully manufactured by simultaneous co-spraying of a synthetic polymer and a protein to obtain a scaffold that combines the mechanical characteristics of polyurethanes with the favorable cell interaction features of gelatin. (paper)

Response to fire, thermal insulation and acoustic performance of rigid polyurethane agglomerates with addition of natural fiber

Directory of Open Access Journals (Sweden)

Marcos Vinicius Rizzo

2015-03-01

Full Text Available This paper aims to reuse rigid polyurethane waste in the preparation of composites with the addition of banana fibers and cellulose in order to qualify the acoustic performance, thermal insulation and reaction to fire the material with the addition of 7% of polysulfone. Agglomerated with 100% of polyurethane and either with 20% of banana fiber or 20% of cellulose were characterized in the sound transmission loss, thermal conductivity and reaction to fire, take into account variations in the granulometry of the solid polyurethane and type of pressing. Natural fiber composites had lower thermal conductivity, higher acoustic insulation in medium frequencies and the addition of polysulfone delayed the total time of firing the material.

Biodegradation polyurethane derived from vegetable oil irradiated with gamma rays 25 kGy and 100 kGy

International Nuclear Information System (INIS)

Santos, Antonia M. dos; Claro Neto, Salvador; Azevedo, Elaine C. de

2011-01-01

The environment requires polymers that can be degraded by the action of microorganisms. In this work was studied the biodegradation of polyurethane samples derived from vegetable oil (castor oil), which were irradiated with gamma rays 25 kGy and 100 kGy compared with the same polyurethane without being irradiated. Biodegradation of polyurethane was carried out in culture medium containing the fungus Aspergillus niger by 146 days and the result was evaluated using the technique of thermogravimetric analysis, where there was a change of behavior of the curves TGA / DTG occurred indicating that chemical modifications of molecules present in the structure of the polymer chain, thus confirming that the material has undergone the action of microorganisms. (author)

Antimicrobial polyurethane coatings based on ionic liquid quaternary ammonium compounds

NARCIS (Netherlands)

Yagci, M.B.; Bolca, S.; Heuts, J.P.A.; Ming, W.; With, de G.

2011-01-01

The antimicrobial effect of ionic liquids (ILs) as comonomers in polyurethane surface coatings was investigated. Ionic liquid-containing coatings were prepared from a hydroxyl end-capped liquid oligoester and a triisocyanate crosslinker. Three different commercially available hydroxyl end-capped

WEATHERING DEGRADATION OF A POLYURETHANE COATING. (R828081E01)

Science.gov (United States)

The degradation of polyurethane topcoat over a chromate pigmented epoxy primer was examined by atomic force microscopy (AFM), scanning electronic microscopy (SEM), X-ray photo-electron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR) after the coated pane...

Physicochemical and Biological Investigation of Different Structures of Carbon Coatings Deposited onto Polyurethane

Directory of Open Access Journals (Sweden)

Witold Kaczorowski

2016-01-01

Full Text Available The aim of this study was to examine the thrombogenic properties of polyurethane that was surface modified with carbon coatings. Physicochemical properties of manufactured coatings were investigated using transmission electron microscopy (TEM, atomic force microscopy (AFM, X-ray Photoelectron Spectroscopy (XPS, Raman spectroscopy and contact angle measurement methods. Samples were examined by the Impact-R method evaluating the level of platelets activation and adhesion of particular blood cell elements. The analysis of antimicrobial resistance against E. coli colonization and viability of endothelial cells showed that polyurethane modified with use of carbon layers constituted an interesting solution for biomedical application.

Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

International Nuclear Information System (INIS)

Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

2009-01-01

Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

Study of the morphology exhibited by linear segmented polyurethanes during shape memory cycles

International Nuclear Information System (INIS)

Pereira, I.M.; Orefice, R.L.

2009-01-01

By using small-angle X-ray, this study aims to identify the role of the morphological structures of linear segmented thermoplastic polyurethane during shape memory cycle. A deformed specimen was placed on a heating stage mounted at the beamline; the shape recovery was measured during 20min. Furthermore, to study the influence of the temperature during recover, the specimens were subjected to different thermo-cycle. In each condition, the phase morphology and composition were investigated. Recovery process was separated into three stages. Bulk incompatibility and entropic recovery were the two controlling features for determining the final polyurethane morphology. (author)

Sorption of oil in the polyurethane from oil or castor oil; Sorcao de oleo no poliuretano derivado do petroleo ou do oleo de mamona

Energy Technology Data Exchange (ETDEWEB)

Florentino, Wagner M; Goulart, Shane A.S.; Mulinari, Daniella R. [Centro Universitario de Volta Redonda (UniFOA), Volta Redonda, RJ (Brazil)], e-mail: wagner-can@hotmail.com

2011-07-01

The oil outpouring has caused serious environmental problems. To minimize this damage polyurethane foams have been used. In this work, the use of polyurethane from oil and castor oil, in different polyol/diisocyanate mass ratios, to absorb oil was evaluated. Results revealed that the proportion of polyol and diisocyanate influenced in the sorption capacity and the polyurethane from castor oil presented greater sorption capacity. Of this way, can say that the polyurethane from oil can be replaced by castor oil, contributing to sustainable development. (author)

pH Optimum of Hemagglutinin-Mediated Membrane Fusion Determines Sensitivity of Influenza A Viruses to the Interferon-Induced Antiviral State and IFITMs.

Science.gov (United States)

Gerlach, Thomas; Hensen, Luca; Matrosovich, Tatyana; Bergmann, Janina; Winkler, Michael; Peteranderl, Christin; Klenk, Hans-Dieter; Weber, Friedemann; Herold, Susanne; Pöhlmann, Stefan; Matrosovich, Mikhail

2017-06-01

The replication and pathogenicity of influenza A viruses (IAVs) critically depend on their ability to tolerate the antiviral interferon (IFN) response. To determine a potential role for the IAV hemagglutinin (HA) in viral sensitivity to IFN, we studied the restriction of IAV infection in IFN-β-treated human epithelial cells by using 2:6 recombinant IAVs that shared six gene segments of A/Puerto Rico/8/1934 virus (PR8) and contained HAs and neuraminidases of representative avian, human, and zoonotic H5N1 and H7N9 viruses. In A549 and Calu-3 cells, viruses displaying a higher pH optimum of HA-mediated membrane fusion, H5N1-PR8 and H7N9-PR8, were less sensitive to the IFN-induced antiviral state than their counterparts with HAs from duck and human viruses, which fused at a lower pH. The association between a high pH optimum of fusion and reduced IFN sensitivity was confirmed by using HA point mutants of A/Hong Kong/1/1968-PR8 that differed solely by their fusion properties. Furthermore, similar effects of the viral fusion pH on IFN sensitivity were observed in experiments with (i) primary human type II alveolar epithelial cells and differentiated cultures of human airway epithelial cells, (ii) nonrecombinant zoonotic and pandemic IAVs, and (iii) preparations of IFN-α and IFN-λ1. A higher pH of membrane fusion and reduced sensitivity to IFN correlated with lower restriction of the viruses in MDCK cells stably expressing the IFN-inducible transmembrane proteins IFITM2 and IFITM3, which are known to inhibit viral fusion. Our results reveal that the pH optimum of HA-driven membrane fusion of IAVs is a determinant of their sensitivity to IFN and IFITM proteins. IMPORTANCE The IFN system constitutes an important innate defense against viral infection. Substantial information is available on how IAVs avoid detection by sensors of the IFN system and disable IFN signaling pathways. Much less is known about the ability of IAVs to tolerate the antiviral activity of IFN

Polyurethane as a base for a family of tissue equivalent materials

International Nuclear Information System (INIS)

Griffith, R.V.

1980-01-01

Recent experience gained in the selection of tissue equivalent materials for the construction of whole body counting phantoms has shown that commercially available polyurethane can be used as a base for a variety of tissue equivalent materials. Tissues simulated include lung, adipose, muscle, cartilage and rib bone. When selecting tissue equivalent materials it is important to understand what tissue properties must be simulated. Materials that simply simulate the linear attenuation of low energy photons for example, are not very likely to simulate neutron interaction properties accurately. With this in mind, we have developed more than one simulation composition for a given tissue, depending on the purpose to which the simulant is to be applied. Simple simulation of linear attenuation can be achieved by addition of carefully measured amounts of higher Z material, such as calcium carbonate to the polyurethane. However, the simulation necessary for medical scanning purposes, or for use in mixed radiation fields requires more complex formulations to yield proper material density, hydrogen and nitrogen content, electron density, and effective atomic number. Though polyurethane has limitations for simulation of tissues that differ markedly from its inherent composition (such as compacted bone), it is safe and easily used in modestly equipped laboratories. The simulants are durable and generally flexible. They can also be easily cast in irregular shapes to simulate specific organ geometries. (author)

Cardiomyocyte behavior on biodegradable polyurethane/gold nanocomposite scaffolds under electrical stimulation

Energy Technology Data Exchange (ETDEWEB)

Ganji, Yasaman [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Institute for Materials Science, Dept. Biocompatible Nanomaterials, University of Kiel, Kaiserstr. 2, D-24143 Kiel (Germany); Li, Qian [Institute for Materials Science, Dept. Biocompatible Nanomaterials, University of Kiel, Kaiserstr. 2, D-24143 Kiel (Germany); Quabius, Elgar Susanne [Dept. of Otorhinolaryngology, Head and Neck Surgery, University of Kiel, Arnold-Heller-Str. 3, Building 27, D-24105 Kiel (Germany); Institute of Immunology, University of Kiel, Arnold-Heller-Str. 3, Building 17, D-24105 Kiel (Germany); Böttner, Martina [Department of Anatomy, University of Kiel, Otto-Hahn-Platz 8, 24118 Kiel (Germany); Selhuber-Unkel, Christine, E-mail: cse@tf.uni-kiel.de [Institute for Materials Science, Dept. Biocompatible Nanomaterials, University of Kiel, Kaiserstr. 2, D-24143 Kiel (Germany); Kasra, Mehran [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran (Iran, Islamic Republic of)

2016-02-01

Following a myocardial infarction (MI), cardiomyocytes are replaced by scar tissue, which decreases ventricular contractile function. Tissue engineering is a promising approach to regenerate such damaged cardiomyocyte tissue. Engineered cardiac patches can be fabricated by seeding a high density of cardiac cells onto a synthetic or natural porous polymer. In this study, nanocomposite scaffolds made of gold nanotubes/nanowires incorporated into biodegradable castor oil-based polyurethane were employed to make micro-porous scaffolds. H9C2 cardiomyocyte cells were cultured on the scaffolds for one day, and electrical stimulation was applied to improve cell communication and interaction in neighboring pores. Cells on scaffolds were examined by fluorescence microscopy and scanning electron microscopy, revealing that the combination of scaffold design and electrical stimulation significantly increased cell confluency of H9C2 cells on the scaffolds. Furthermore, we showed that the gene expression levels of Nkx2.5, atrial natriuretic peptide (ANF) and natriuretic peptide precursor B (NPPB), which are functional genes of the myocardium, were up-regulated by the incorporation of gold nanotubes/nanowires into the polyurethane scaffolds, in particular after electrical stimulation. - Highlights: • Biodegradable polyurethane/gold nanocomposites for cardiomyocyte adhesion are proposed. • The nanocomposite scaffolds are porous and electrical stimulation enhances cell adhesion. • Expression levels of functional myocardium genes were upregulated after electrical stimulation.

Preparation and characterization of polyurethane - Fe powder composites

Czech Academy of Sciences Publication Activity Database

Špírková, Milena; Bureš, R.; Fáberová, M.; Trchová, Miroslava; Strachota, Adam; Kaprálková, Ludmila

2011-01-01

Roč. 11, 3/4 (2011), s. 290-299 ISSN 1335-8987 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethanes * polybutadiene diol * Fe powder Subject RIV: CD - Macromolecular Chemistry http://www.imr.saske.sk/pmp/issue/3-4-2011/PMP_Vol11_No3-4_p_290-299.pdf

Design and milling manufacture of polyurethane custom contoured cushions for wheelchair users.

Science.gov (United States)

da Silva, Fabio Pinto; Beretta, Elisa Marangon; Prestes, Rafael Cavalli; Kindlein Junior, Wilson

2011-01-01

The design of custom contoured cushions manufactured in flexible polyurethane foams is an option to improve positioning and comfort for people with disabilities that spend most of the day seated in the same position. These surfaces increase the contact area between the seat and the user. This fact contributes to minimise the local pressures that can generate problems like decubitus ulcers. The present research aims at establishing development routes for custom cushion production to wheelchair users. This study also contributes to the investigation of Computer Numerical Control (CNC) machining of flexible polyurethane foams. The proposed route to obtain the customised seat began with acquiring the user's contour in adequate posture through plaster cast. To collect the surface geometry, the cast was three-dimensionally scanned and manipulated in CAD/CAM software. CNC milling parameters such as tools, spindle speeds and feed rates to machine flexible polyurethane foams were tested. These parameters were analysed regarding the surface quality. The best parameters were then tested in a customised seat. The possible dimensional changes generated during foam cutting were analysed through 3D scanning. Also, the customised seat pressure and temperature distribution was tested. The best parameters found for foams with a density of 50kg/cm(3) were high spindle speeds (24000 rpm) and feed rates between 2400-4000mm/min. Those parameters did not generate significant deformities in the machined cushions. The custom contoured cushion satisfactorily increased the contact area between wheelchair and user, as it distributed pressure and heat evenly. Through this study it was possible to define routes for the development and manufacturing of customised seats using direct CNC milling in flexible polyurethane foams. It also showed that custom contoured cushions efficiently distribute pressure and temperature, which is believed to minimise tissue lesions such as pressure ulcers.

A novel electrospun polyurethane nanofibre membrane - production parameters and suitability for wastewater (WW) treatment

Czech Academy of Sciences Publication Activity Database

Lev, J.; Holba, Marek; Došek, M.; Kalhotka, L.; Mikula, Přemysl; Kimmer, D.

2014-01-01

Roč. 69, č. 7 (2014), s. 1496-1501 ISSN 0273-1223 R&D Projects: GA TA ČR TA01010356 Institutional support: RVO:67985939 Keywords : bacteria * pathogen removal * membrane filtration Subject RIV: EF - Botanics Impact factor: 1.106, year: 2014

Structural Engineering for High Sensitivity, Ultrathin Pressure Sensors Based on Wrinkled Graphene and Anodic Aluminum Oxide Membrane.

Science.gov (United States)

Chen, Wenjun; Gui, Xuchun; Liang, Binghao; Yang, Rongliang; Zheng, Yongjia; Zhao, Chengchun; Li, Xinming; Zhu, Hai; Tang, Zikang

2017-07-19

Nature-motivated pressure sensors have been greatly important components integrated into flexible electronics and applied in artificial intelligence. Here, we report a high sensitivity, ultrathin, and transparent pressure sensor based on wrinkled graphene prepared by a facile liquid-phase shrink method. Two pieces of wrinkled graphene are face to face assembled into a pressure sensor, in which a porous anodic aluminum oxide (AAO) membrane with the thickness of only 200 nm was used to insulate the two layers of graphene. The pressure sensor exhibits ultrahigh operating sensitivity (6.92 kPa -1 ), resulting from the insulation in its inactive state and conduction under compression. Formation of current pathways is attributed to the contact of graphene wrinkles through the pores of AAO membrane. In addition, the pressure sensor is also an on/off and energy saving device, due to the complete isolation between the two graphene layers when the sensor is not subjected to any pressure. We believe that our high-performance pressure sensor is an ideal candidate for integration in flexible electronics, but also paves the way for other 2D materials to be involved in the fabrication of pressure sensors.

Pullout strength of bone-patellar tendon-bone allograft bone plugs: a comparison of cadaver tibia and rigid polyurethane foam.

Science.gov (United States)

Barber, F Alan

2013-09-01

To compare the load-to-failure pullout strength of bone-patellar tendon-bone (BPTB) allografts in human cadaver tibias and rigid polyurethane foam blocks. Twenty BPTB allografts were trimmed creating 25 mm × 10 mm × 10 mm tibial plugs. Ten-millimeter tunnels were drilled in 10 human cadaver tibias and 10 rigid polyurethane foam blocks. The BPTB anterior cruciate ligament allografts were inserted into these tunnels and secured with metal interference screws, with placement of 10 of each type in each material. After preloading (10 N), cyclic loading (500 cycles, 10 to 150 N at 200 mm/min) and load-to-failure testing (200 mm/min) were performed. The endpoints were ultimate failure load, cyclic loading elongation, and failure mode. No difference in ultimate failure load existed between grafts inserted into rigid polyurethane foam blocks (705 N) and those in cadaver tibias (669 N) (P = .69). The mean rigid polyurethane foam block elongation (0.211 mm) was less than that in tibial bone (0.470 mm) (P = .038), with a smaller standard deviation (0.07 mm for foam) than tibial bone (0.34 mm). All BPTB grafts successfully completed 500 cycles. The rigid polyurethane foam block showed less variation in test results than human cadaver tibias. Rigid polyurethane foam blocks provide an acceptable substitute for human cadaver bone tibia for biomechanical testing of BPTB allografts and offer near-equivalent results. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Extraction of ruthenium thiocyanate and its separation from rhodium by polyurethane foam

International Nuclear Information System (INIS)

Al-Bazi, S.J.; Chow, A.

1984-01-01

Conditions for the formation and extraction of the thiocyanate complex of ruthenium are reported. Distribution coefficients of more than 10 4 and a capacity of about 0.24 mole per kg of foam were obtained. The effect of the chloride salts of various univalent cations on the extraction of Ru(SCN) 6 3- indicated that the efficiency of ruthenium extraction depends on how well the cation fits into the polyether segment of the polyurethane foam, which agrees with the 'cation-chelation' mechanism. The separation of ruthenium and rhodium indicated that more than 95% of the rhodium remained in the aqueous phase and about 95% of the ruthenium was retained by the polyurethane foam and could be easily recovered. (author)

Synthesis and surface characterization of electroactive conducting polymers and polyurethane coatings

Science.gov (United States)

Vang, Chur Kalec

The direct electrodeposition of electroactive conducting polymers (ECPs) on active metals such as iron, steel, and aluminum is complicated by the concomitant metal oxidation that occurs at the positive potentials required for polymer formation. In the case of aluminum and its alloys, the oxide layer that forms is an insulator that blocks electron transfer and impedes polymer formation and deposition. As a result, only patchy, nonuniform polymer films are obtained. Electron transfer mediation is a well-known technique for overcoming kinetic limitations of electron transfer at metal electrodes. In this dissertation, we report the use of electron transfer mediation for the direct electrodeposition of polypyrrole onto aluminum and onto Al 2024-T3 alloy. The first few chapters focus on the electrochemistry and use of Tiron RTM (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) as the mediator. Electroactive conductive polymers (ECPs) were also being investigated for corrosion protection of Al alloys, with a view toward replacement of chromate-based coating systems. The use of electrochemical methods clearly indicated that the electrodeposited Ppy coatings had altered the corrosion behavior of the Al alloy. Degradation mechanisms for self-priming (unicoat), high-gloss, and fluorinated polyurethane aircraft coatings exposed to QUV/H2O radiation were carried out using linear and step-scan photoacoustic (S2-PA) FTIR spectroscopy (Chapters 7--9). FTIR spectroscopic analysis indicated that, as the depth of sampling increased from film-air to film-substrate, an increase of free carbonyl components was observed. These free carbonyl groups are indicative of polyurethane components. Exposure of the polyurethane coating to prolonged periods of extreme weathering conditions indicated a loss of both polyurethane/polyurea components at the air interface, which has lead to an increase of disordered hydrogen-bonding formations. Contact angle measurement further indicated that as

Sensitivity of Hollow Fiber Spacesuit Water Membrane Evaporator Systems to Potable Water Constituents, Contaminants and Air Bubbles

Science.gov (United States)

Bue, Grant C.; Trevino, Luis A.; Fritts, Sharon; Tsioulos, Gus

2008-01-01

The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning and compares the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source. Some of the impurities in potable water are volatile, such as the organics, while others, such as the metals and inorganic ions are nonvolatile. The non-volatile constituents will concentrate in the SWME as evaporated water from the loop is replaced by the feedwater. At some point in the SWME mission lifecycle as the concentrations of the non-volatiles increase, the solubility limits of one or more of the constituents may be reached. The resulting presence of precipitate in the coolant water may begin to plug pores and tube channels and affect the SWME performance. Sensitivity to macroparticles, lunar dust simulant, and air bubbles will also be investigated.

Extraction of Mo, W and Tc with polyurethane foam and with cyclic polyether from SCN-/HC1 medium

International Nuclear Information System (INIS)

Caletka, R.; Hausbeck, R.; Krivan, V.

1986-01-01

The extraction of molybdenum, tungsten and technetium by polyether-based polyurethane foam and by a cyclic polyether from aqueous thiocyanate solutions is described. The influence of the reductants stannous chloride and ascorbic acid has also been studied. The possibilites of the polyurethane foam for preconcentration and determination of molybdenum are discussed. (author)

Design of Xylose-Based Semisynthetic Polyurethane Tissue Adhesives with Enhanced Bioactivity Properties.

Science.gov (United States)

Balcioglu, Sevgi; Parlakpinar, Hakan; Vardi, Nigar; Denkbas, Emir Baki; Karaaslan, Merve Goksin; Gulgen, Selam; Taslidere, Elif; Koytepe, Suleyman; Ates, Burhan

2016-02-01

Developing biocompatible tissue adhesives with high adhesion properties is a highly desired goal of the tissue engineering due to adverse effects of the sutures. Therefore, our work involves synthesis, characterization, adhesion properties, protein adsorption, in vitro biodegradation, in vitro and in vivo biocompatibility properties of xylose-based semisynthetic polyurethane (NPU-PEG-X) bioadhesives. Xylose-based semisynthetic polyurethanes were developed by the reaction among 4,4'-methylenebis(cyclohexyl isocyanate) (MCI), xylose and polyethylene glycol 200 (PEG). Synthesized polyurethanes (PUs) showed good thermal stability and high adhesion strength. The highest values in adhesion strength were measured as 415.0 ± 48.8 and 94.0 ± 2.8 kPa for aluminum substrate and muscle tissue in 15% xylose containing PUs (NPU-PEG-X-15%), respectively. The biodegradation of NPU-PEG-X-15% was also determined as 19.96 ± 1.04% after 8 weeks of incubation. Relative cell viability of xylose containing PU was above 86%. Moreover, 10% xylose containing NPU-PEG-X (NPU-PEG-X-10%) sample has favorable tissue response, and inflammatory reaction between 1 and 6 weeks implantation period. With high adhesiveness and biocompatibility properties, NPU-PEG-X can be used in the medical field as supporting materials for preventing the fluid leakage after abdominal surgery or wound closure.

Hollow Fiber Space Water Membrane Evaporator Flight Prototype Design and Testing

Science.gov (United States)

Bue, Grant C.; Makinen, Janice; Vogel, Mtthew; Honas, Matt; Dillon, Paul; Colunga, Aaron; Truong, Lily; Porwitz, Darwin; Tsioulos, Gus

2011-01-01

The spacesuit water membrane evaporator (SWME) is being developed to perform thermal control for advanced spacesuits and to take advantage of recent advances in micropore membrane technology. This results in a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. The current design was based on a previous design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape. This was developed into a full-scale prototype consisting of 14,300 tube bundled into 30 stacks, each of which is formed into a chevron shape and separated by spacers and organized into three sectors of 10 nested stacks. The new design replaced metal components with plastic ones, eliminated the spacers, and has a custom built flight like backpressure valve mounted on the side of the SWME housing to reduce backpressure when fully open. A number of tests were performed in order to improve the strength of the polyurethane header that holds the fibers in place while the system is pressurized. Vacuum chamber testing showed similar heat rejection as a function of inlet water temperature and water vapor backpressure was similar to the previous design. Other tests pushed the limits of tolerance to freezing and showed suitability to reject heat in a Mars pressure environment with and without a sweep gas. Tolerance to contamination by constituents expected to be found in potable water produced by distillation processes was tested in a conventional way by allowing constituents to accumulate in the coolant as evaporation occurs. For this purpose, the SWME cartridge has endured an equivalent of 30 EVAs exposure and demonstrated acceptable performance decline.

Recycling Waste Polyurethane as a Carbon Resource in Ironmaking ...

African Journals Online (AJOL)

Globally, major avenues available for dealing with waste Poly-Urethane (PU) are disposal at landfill sites and incineration. However, PU contains high levels of carbon and hydrogen that can be recovered for use as reductant in metal extraction processes. In this work the use of post-consumer PU as reductant for the ...

The Abrasive Wear Resistance of the Segmented Linear Polyurethane Elastomers Based on a Variety of Polyols as Soft Segments

Directory of Open Access Journals (Sweden)

Konrad Kwiatkowski

2017-12-01

Full Text Available The presented results make an original contribution to the development of knowledge on the prediction and/or modeling of the abrasive wear properties of polyurethanes. A series of segmented linear polyurethane elastomers (PUR—In which the hard segments consist of 4,4′-methylene bis(phenylisocyanate and 1,4-butanodiol, whilst polyether, polycarbonate, or polyester polyols constitute the soft segments—Were synthesized and characterized. The hardness and wear performance as functions of the variable chemical composition of polyurethane elastomers were evaluated in order to define the relationship between studied factors. The microstructure was characterized in detail, including analysis of the hydrogen bonding by Fourier transformed infrared (FT-IR spectroscopy and the phase structure by X-ray scattering (WAXS and differential scanning calorimetry (DSC methods. The presented studies provide the key features of the polymer composition affecting the abrasive resistance as well as attempts to explain the origin of the differences in the polyurethane elastomers’ performance.

Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

Science.gov (United States)

Asefnejad, Azadeh; Khorasani, Mohammad Taghi; Behnamghader, Aliasghar; Farsadzadeh, Babak; Bonakdar, Shahin

2011-01-01

Background Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid–liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50–300 μm, and porosities of 64%–83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. PMID:22072874

Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams

OpenAIRE

Bogusław Czupryński; Joanna Liszkowska; Joanna Paciorek-Sadowska

2014-01-01

The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR) foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis...

Castor oil polyurethane as a coating option for spent nuclear fuel disposal containment

Energy Technology Data Exchange (ETDEWEB)

Mortley, A.; Bonin, H.W.; Bui, V.T. [Dept. of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario (Canada)

2009-07-01

Castor oil polyurethane (COPU) coatings are being proposed as an additional barrier in the design of the copper containers to store spent nuclear fuel in Canada. The present work investigates the variation in the physicomechanical properties of two COPUs, based on an aliphatic and aromatic diisocyanate, as a function of ionizing radiation dose and dose rate. The changes in physicomechanical properties have shown that radiation, regardless of dose rate and isocyanate structure, increases the values of the modulus and the ultimate tensile strength when compared with those of the unirradiated samples, with aromatic based polyurethanes being more susceptible to variation than aliphatic based ones. (author)

Castor oil polyurethane as a coating option for spent nuclear fuel disposal containment

International Nuclear Information System (INIS)

Mortley, A.; Bonin, H.W.; Bui, V.T.

2009-01-01

Castor oil polyurethane (COPU) coatings are being proposed as an additional barrier in the design of the copper containers to store spent nuclear fuel in Canada. The present work investigates the variation in the physicomechanical properties of two COPUs, based on an aliphatic and aromatic diisocyanate, as a function of ionizing radiation dose and dose rate. The changes in physicomechanical properties have shown that radiation, regardless of dose rate and isocyanate structure, increases the values of the modulus and the ultimate tensile strength when compared with those of the unirradiated samples, with aromatic based polyurethanes being more susceptible to variation than aliphatic based ones. (author)

Nanocrystalline cellulose as an eco-friendly reinforcing additive to polyurethane coating for augmented anticorrosive behavior.

Science.gov (United States)

Abd El-Fattah, M; Hasan, Abdulraheim M A; Keshawy, Mohamed; El Saeed, Ashraf M; Aboelenien, Ossama M

2018-03-01

Nanocrystalline cellulose (NCC) and micro-powdered cellulose (MPC) were extracted from rice straw by mechanical and alkali treatment methods, then characterized via infrared spectroscopy and dynamic light scattering. A series of polyurethane nanocrystalline cellulose composite (PNCCC) and polyurethane micro-powdered cellulose composite (PMPCC) coatings were prepared with various loading levels of NCC and MPC from 0.5 to 2.0 wt.%, and the coatings were applied onto the pretreated mild steel substrate at room temperature. The results showed that the NCC and MPC influenced positively the studied properties of the polyurethane coating; furthermore the most pronounced anticorrosive properties were obtained at 1 wt.% NCC and MPC, as confirmed by open circuit potential (OCP) study, electrochemical impedance spectroscopy (EIS) study and salt spray test. However, the optimum enhancement of mechanical properties was found at 1.5 wt.% loading level, after which further loading of NCC and MPC led to the reduction in the mechanical properties. Copyright © 2018 Elsevier Ltd. All rights reserved.

Preparation, characterization and infrared emissivity study of helical polyurethane-SiO2 core-shell composite

International Nuclear Information System (INIS)

Wang Zhiqiang; Zhou Yuming; Yao Qingzhao; Sun Yanqing

2009-01-01

Helical polyurethane-SiO 2 (HPU-SiO 2 ) core-shell composite was prepared after surface modification of SiO 2 nanoparticles. HPU-SiO 2 was characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet (UV) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicate that the helical polyurethane has been successfully grafted onto the surfaces of the modified SiO 2 . HPU-SiO 2 composite exhibits clearly core-shell structure. The ultraviolet absorption and crystallizability of HPU-SiO 2 are changed due to the shell of helical polyurethane, which possesses regular single-handed conformation and inter-chain hydrogen bonds. The infrared emissivity of HPU-SiO 2 was also investigated. The result indicates that the interfacial interactions between organic shell and inorganic core induce the infrared emissivity value being reduced from 0.781 for SiO 2 to 0.503 for HPU-SiO 2 .

Gamma radiation effects on mechanical properties and morphology of a polyurethane derivate from castor oil

Science.gov (United States)

Azevedo, Elaine Cristina; Orivaldo Chierice, Gilberto; Claro Neto, Salvador; Scheidegger Soboll, Daniel; Mauro Nascimento, Eduardo; Lepienski, Carlos Mauricio

2011-03-01

In this study, an adhesive of a polyurethane derivate from castor oil was irradiated with gamma radiation from a 60Co source, at doses from 0.2 to 25 kGy. This adhesive polyurethane is considered for use in hospital furniture because it does not liberate dangerous solvents. Hardness and elastic modulus were measured by instrumented indentation with a pyramidal Berkovich indenter, using loads from 0.08-40 mN with a nanoindenter XP. The instrumented indentation hardness was 110 MPa for an untreated sample, increasing to 124 MPa after irradiation with 25 kGy, at penetration depths of about 5 μm. The increases in elastic modulus induced by radiation were less pronounced. This polyurethane is naturally cross-linked and the relative modifications in the hardness are attributed to an additional cross-linking process induced by radiation. X-ray diffraction indicates a slight increase in crystallinity. The roughness measured by atomic force microscopy increases after gamma irradiation.

Preparation and characterization of polyurethane microcapsules containing functional oil

Energy Technology Data Exchange (ETDEWEB)

Kim, I.H.; Seo, J.B.; Kim, Y.J. [Sungkyunkwan University, Suwon (Korea)

2002-05-01

Polyurethane microcapsules containing functional oil (citronella oil) were successfully prepared by conventional interfacial polymerization of tolulene 2,4-diisocyanate (TDI) and ethylene glycol (EG) and characterized by Fourier transform (FT-IR) spectroscopy, Ultraviolet spectroscopy, particle size analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of polymerization variables such as surfactant concentration and agitation speed, on the particle size and particle size distribution were investigated. FT-IR spectroscopic data showed that citronella oil was successfully encapsulated in the microcapsule. Thermogravimetric analysis data showed that the microcapsule was thermally stable up to 220 deg. C. The controlled release of the citronella oil present in the microcapsule core in a methanol medium was demonstrated by ultraviolet spectroscopy, showing that the amount of released citronella oil was increased with increasing time. It was observed that the amount of released citronella oil was increased with increasing stirring speed and emulsifier concentration in the microcapsule preparation step. Polyurethane microcapsules containing citronella oil showed excellent anti-moth property. (author). 28 refs., 1 tab., 12 figs.

Very low drift and high sensitivity of nanocrystal-TiO2 sensing membrane on pH-ISFET fabricated by CMOS compatible process

International Nuclear Information System (INIS)

Bunjongpru, W.; Sungthong, A.; Porntheeraphat, S.; Rayanasukha, Y.; Pankiew, A.; Jeamsaksiri, W.; Srisuwan, A.; Chaisriratanakul, W.; Chaowicharat, E.; Klunngien, N.; Hruanun, C.; Poyai, A.; Nukeaw, J.

2013-01-01

High sensitivity and very low drift rate pH sensors are successfully prepared by using nanocrystal-TiO 2 as sensing membrane of ion sensitive field effect transistor (ISFET) device fabricated via CMOS process. This paper describes the physical properties and sensing characteristics of the TiO 2 membrane prepared by annealing Ti and TiN thin films that deposited on SiO 2 /p-Si substrates through reactive DC magnetron sputtering system. The X-ray diffraction, scanning electron microscopy and Auger electron spectroscopy were used to investigate the structural and morphological features of deposited films after they had been subjected to annealing at various temperatures. The experimental results are interpreted in terms of the effects of amorphous-to-crystalline phase transition and subsequent oxidation of the annealed films. The electrolyte–insulator–semiconductor (EIS) device incorporating Ti-O-N membrane that had been obtained by annealing of TiN thin film at 850 °C exhibited a higher sensitivity (57 mV/pH), a higher linearity (1), a lower hysteresis voltage (1 mV in the pH cycle of 7 → 4 → 7 → 10 → 7), and a smaller drift rate (0.246 mV/h) than did those devices prepared at the other annealing temperatures. Furthermore, this pH-sensing device fabrication process is fully compatible with CMOS fabrication process technology.

Modeling the compliance of polyurethane nanofiber tubes for artificial common bile duct

Science.gov (United States)

Moazeni, Najmeh; Vadood, Morteza; Semnani, Dariush; Hasani, Hossein

2018-02-01

The common bile duct is one of the body’s most sensitive organs and a polyurethane nanofiber tube can be used as a prosthetic of the common bile duct. The compliance is one of the most important properties of prosthetic which should be adequately compliant as long as possible to keep the behavioral integrity of prosthetic. In the present paper, the prosthetic compliance was measured and modeled using regression method and artificial neural network (ANN) based on the electrospinning process parameters such as polymer concentration, voltage, tip-to-collector distance and flow rate. Whereas, the ANN model contains different parameters affecting on the prediction accuracy directly, the genetic algorithm (GA) was used to optimize the ANN parameters. Finally, it was observed that the optimized ANN model by GA can predict the compliance with high accuracy (mean absolute percentage error = 8.57%). Moreover, the contribution of variables on the compliance was investigated through relative importance analysis and the optimum values of parameters for ideal compliance were determined.

Evaluation of Inulin Replacing Chitosan in a Polyurethane/Polysaccharide Material for Pb2+ Removal.

Science.gov (United States)

Hernández-Martínez, Angel Ramon; Molina, Gustavo A; Jiménez-Hernández, Luis Fernando; Oskam, Adrian Hendrik; Fonseca, Gerardo; Estevez, Miriam

2017-11-29

Downstream waste from industry and other industrial processes could increase concentration of heavy metals in water. These pollutants are commonly removed by adsorption because it is an effective and economical method. Previously, we reported adsorption capacity of a chitosan/polyurethane/titanium dioxide (TiO₂) composite for three ions in a dynamic wastewater system. There, increasing the chitosan concentration in composite increased the cation removal as well; however, for ratios higher than 50% of chitosan/TiO₂, the manufacturing cost increased significantly. In this work, we address the manufacturing cost problem by proposing a new formulation of the composite. Our hypothesis is that inulin could replace chitosan in the composite formulation, either wholly or in part. In this exploratory research, three blends were prepared with a polyurethane matrix using inulin or/and chitosan. Adsorption was evaluated using a colorimetric method and the Langmuir and Freundlich models. Fourier-transform infrared spectroscopy (FTIR) spectra, scanning electron microscopy (SEM) micrographs, differential scanning calorimetry and thermogravimetric analysis curves were obtained to characterize blends. Results indicate that blends are suitable for toxic materials removal (specifically lead II, Pb 2+ ). Material characterization indicates that polysaccharides were distributed in polyurethane's external part, thus improving adsorption. Thermal degradation of materials was found above 200 °C. Comparing the blends data, inulin could replace chitosan in part and thereby improve the cost efficiency and scalability of the production process of the polyurethane based-adsorbent. Further research with different inulin/chitosan ratios in the adsorbent and experiments with a dynamic system are justified.

Effect of the incorporation of chitosan on the physico-chemical, mechanical properties and biological activity on a mixture of polycaprolactone and polyurethanes obtained from castor oil.

Science.gov (United States)

Arévalo, Fabian; Uscategui, Yomaira L; Diaz, Luis; Cobo, Martha; Valero, Manuel F

2016-11-01

In the present study, polyurethane materials were obtained from castor oil, polycaprolactone and isophorone diisocyanate by incorporating different concentrations of chitosan (0.5, 1.0 and 2.0% w/w) as an additive to improve the mechanical properties and the biological activity of polyurethanes. The polyurethanes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, stress/strain fracture tests and swelling analysis, and the hydrophilic character of the surface was determined by contact angle trials. The objectives of the study were to evaluate the effect of the incorporation of chitosan on the changes of the physico-chemical and mechanical properties and the in vitro biological activity of the polyurethanes. It was found that the incorporation of chitosan enhances the ultimate tensile strength of the polyurethanes and does not affect the strain at fracture in polyurethanes with 5% w/w of polycaprolactone and concentrations of chitosan ranging from 0 to 2% w/w. In addition, PCL5-Q-PU formulations and their degradation products did not affect cell viability of L929 mouse fibroblast and 3T3, respectively. Polyurethane formulations showed antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria. The results of this study have highlighted the potential biomedical application of this polyurethanes related to soft and cardiovascular tissues. © The Author(s) 2016.

Thermal and mechanical properties of multiple-component aliphatic degradable polyurethanes

Czech Academy of Sciences Publication Activity Database

Poreba, Rafal; Kredatusová, Jana; Hodan, Jiří; Serkis, Magdalena; Špírková, Milena

2015-01-01

Roč. 132, č. 16 (2015), 41872_1-41872_12 ISSN 0021-8995 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : differential scanning calorimetry * mechanical properties * polyurethanes Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.866, year: 2015

Use of porous polyurethanes for meniscal reconstruction and meniscal prostheses

NARCIS (Netherlands)

deGroot, JH; deVrijer, R; Pennings, AJ; Veth, RPH; Jansen, HWB

In the past, porous materials made of an aromatic polyurethane (PU) were successfully used for meniscal reconstruction in dogs. Since aromatic PUs yield very toxic fragments upon degradation, a linear PU was synthesized by curing a poly(epsilon-caprolactone) and 1,4-trans-cyclohexane diisocyanate I

The small angle neutron scattering study on the segmented polyurethane

International Nuclear Information System (INIS)

Sudirman; Gunawan; Prasetyo, S.M.; Karo Karo, A.; Lahagu, I.M.; Darwinto, Tri

1999-01-01

The distance between hard segment (HS) and soft segment (SS) of segmented polyurethane have been determined using the Small Angle Neutron Scattering (SANS) technique. The segmented Polyurethanes (SPU) are linear multiblock copolymers, which include elastomer thermoplastic. SPU consist of hard segment and soft segment, each has tendency to make a group with similar type to form a domain. The soft segments used were polypropylene glycol (PPG) and 4,4 diphenylmethane diisocyanate (MDI), while l,4 butanediol (BD) was used as hard segment. The characteristic of SPU depends on its phase structure which is affected by several factors, such as type of chemical formula and the composition of the HS and SS, solvent as well as the synthesizing process. The samples used in this study were SPU56 and SPU68. Based on the appearance of SANS profile, it was obtained that domain distances are 12.32 nm for the SPU56 and 19 nm for the SPU68. (author)

Permeation of lysosomal membranes in the course of photo-sensitization with methylene blue and hematoporphyrin: study by cellular microspectrofluorometry

International Nuclear Information System (INIS)

Santus, R.; Kohen, C.; Kohen, E.; Morliere, P.; Dubertret, L.; Tocci, P.M.

1983-01-01

The photodynamically-induced liberation of lysosomal enzymes using β-galactosidase as marker for the lysosomal enzymes has been studied by microspectrofluorometry on mouse L cells. Similar studies have been carried out using N-acetyl-β-glucosaminidase as marker for the lysosomal enzymes of human fibroblasts. The high sensitivity of the fluorescence detection makes it possible to use 4-methylumbelliferyl substrates for the enzymes contained in a single cell. Methylene blue and hematoporphyrin readily incorporate into both cells and upon excitation, sensitize lysosomal membrane damages, leading to enzyme release accompanying strong morphological changes. (author)

An experimental study of dynamic behaviour of graphite-polycarbonatediol polyurethane composites for protective coatings

Science.gov (United States)

Gómez, C. M.; Culebras, M.; Cantarero, A.; Redondo-Foj, B.; Ortiz-Serna, P.; Carsí, M.; Sanchis, M. J.

2013-06-01

Segmented polycarbonatediol polyurethane (PUPH) has been synthesized and modified with different amounts of graphite conductive filler (from 0 to 50 wt%). Thermal and dynamical thermal analysis of the composites clearly indicates changes in the polyurethane relaxations upon addition of graphite. Broadband dielectric spectroscopy has been used to study the dielectric properties of the (PUPH) and one composite in the frequency range from 10-2 to 107 Hz and in the temperature window of -140 to 170 °C. Relaxation processes associated with different molecular motions and conductivity phenomena (Maxwell-Wagner-Sillars and electrode polarization) are discussed and related to the graphite content.

Polyurethane spray coating of aluminum wire bonds to prevent corrosion and suppress resonant oscillations

CERN Document Server

Izen, Joseph; The ATLAS collaboration; Kurth, Matthew Glenn

2015-01-01

Unencapsulated aluminum wedge wire bonds are common in particle-physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent, source of tracking detector failure Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorenz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of PU-coated wire bonds and their resistance to periodic Lorenz forces will be described.

Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

Directory of Open Access Journals (Sweden)

Asefnejad A

2011-10-01

Full Text Available Azadeh Asefnejad1, Mohammad Taghi Khorasani2, Aliasghar Behnamghader3, Babak Farsadzadeh1, Shahin Bonakdar4 1Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Iran Polymers and Petrochemical Institute, Tehran, Iran; 3Materials and Energy Research Center, Tehran, Iran; 4National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran Background: Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods: In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid–liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results: Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50–300 µm, and porosities of 64%–83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion: These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. Keywords: polyurethane, tissue engineering, biodegradable, fibroblast cells

Flexible magnetic polyurethane/Fe{sub 2}O{sub 3} nanoparticles as organic-inorganic nanocomposites for biomedical applications: Properties and cell behavior

Energy Technology Data Exchange (ETDEWEB)

Shahrousvand, Mohsen [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of); Hoseinian, Monireh Sadat [Department of Medical Nanotechnology, Faculty of Advanced Sciences and Technology, Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS), Tehran (Iran, Islamic Republic of); Ghollasi, Marzieh [Department of Cell & Molecular Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran (Iran, Islamic Republic of); Karbalaeimahdi, Ali [Nanobiotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Salimi, Ali, E-mail: salimiali@bmsu.ac.ir [Nanobiotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Tabar, Fatemeh Ahmadi [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of)

2017-05-01

Nowadays, the discovery of cell behaviors and their responses in communication with the stem cell niches and/or microenvironments are one of the major topics in tissue engineering and regenerative medicine. In this study, incorporated organic-inorganic polyurethane (PU) nanocomposites were prepared for better understanding of cell signaling and the effect of magnetite nanoparticles on cell proliferation and cell responses. The properties of PU-IONs were evaluated by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic-force microscopy (AFM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). The presence of the iron oxide nanoparticles (IONs) affects on the properties of polyurethane nanocomposites such as bulk morphology, mechanical, electrochemical, and biological properties. The electrical conductivity and hydrophilicity of PU-IONs were improved by increasing the magnetite nanoparticles; therefore water absorption, biodegradation and cell viability were changed. The biocompatibility of PU-IONs was investigated by MTT assay, cell attachment and cell staining. According to the results, the magnetite polyurethane nanocomposites could be a potential choice for cell therapy and tissue engineering, especially nerve repair. - Highlights: • Biodegradable and biocompatible incorporated organic-inorganic polyurethane (PU) nanocomposites were prepared. • The hydrophilicity of polyurethane/iron oxide nanocomposites (PU-IONs) was improved by increasing of magnetite nanoparticles. • The magnetite nanocomposites showed greater electrical conductivity and surface roughness in contrast to neat polyurethane. • The PU-IONs nanocomposites had suitable cell viability and hold promising potential for tissue engineering applications.

Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

DEFF Research Database (Denmark)

Bagatolli, Luis

2015-01-01

of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting...... comparative studies. This chapter presents a short historical overview about these fluorescent reporters, discusses on different models proposed to explain their sensitivity to membrane hydration, and includes relevant examples from experiments performed in artificial and biological membranes....

Improved Lignin Polyurethane Properties with Lewis Acid Treatment

OpenAIRE

Chung, Hoyong; Washburn, Newell R.

2012-01-01

Chemical modification strategies to improve the mechanical properties of lignin-based polyurethanes are presented. We hypothesized that treatment of lignin with Lewis acids would increase the concentration of hydroxyl groups available to react with diisocyanate monomers. Under the conditions used, hydrogen bromide-catalyzed modification resulted in a 28% increase in hydroxyl group content. Associated increases in hydrophilicity of solvent-cast thin films were also recorded as evidenced by ...

Preparation of carbon quantum dots based high photostability luminescent membranes.

Science.gov (United States)

Zhao, Jinxing; Liu, Cui; Li, Yunchuan; Liang, Jiyuan; Liu, Jiyan; Qian, Tonghui; Ding, Jianjun; Cao, Yuan-Cheng

2017-06-01

Urethane acrylate (UA) was used to prepare carbon quantum dots (C-dots) luminescent membranes and the resultants were examined with FT-IR, mechanical strength, scanning electron microscope (SEM) and quantum yields (QYs). FT-IR results showed the polyurethane acrylate (PUA) prepolymer -C = C-vibration at 1101 cm -1 disappeared but there was strong vibration at1687cm -1 which was contributed from the-C = O groups in cross-linking PUA. Mechanical strength results showed that the different quantity of C-dots loadings and UV-curing time affect the strength. SEM observations on the cross-sections of the membranes are uniform and have no structural defects, which prove that the C-dots are compatible with the water-soluble PUA resin. The C-dot loading was increased from 0 to 1 g, the maximum tensile stress was nearly 2.67 MPa, but the tensile strain was decreased from 23.4% to 15.1% and 7.2% respectively. QYs results showed that the C-dots in the membrane were stable after 120 h continuous irradiation. Therefore, the C-dots photoluminescent film is the promising material for the flexible devices in the future applications. Copyright © 2016 John Wiley & Sons, Ltd.

In vitro studies on the effect of physical cross-linking on the biological performance of aliphatic poly(urethane urea) for blood contact applications.

Science.gov (United States)

Thomas, V; Kumari, T V; Jayabalan, M

2001-01-01

The effect of physical cross-linking in candidate cycloaliphatic and hydrophobic poly(urethane urea) (4,4'-methylenebis(cyclohexylisocyanate), H(12)MDI/hydroxy-terminated polybutadiene, HTPBD/hexamethylenediamine, HDA) and poly(ether urethane urea)s (H(12)MDI/HTPBD-PTMG/HDA) on the in vitro calcification and blood-material interaction was studied. All the candidate poly(urethane urea)s and poly(ether urethane urea)s elicit acceptable hemolytic activity, cytocompatibility, calcification, and blood compatibility in vitro. The studies on blood-material interaction reveal that the present poly(urethane urea)s are superior to polystyrene microtiter plates which were used for the studies on blood-material interaction. The present investigation reveals the influence of physical cross-link density on biological interaction differently with poly(urethane urea) and poly(ether urethane urea)s. The higher the physical cross-link density in the poly(urethane urea)s, the higher the calcification and consumption of WBC in whole blood. On the other hand, the higher the physical cross-link density in the poly(ether urethane urea)s, the lesser the calcification and consumption of WBC in whole blood. However a reverse of the above trend has been observed with the platelet consumption in the poly(urethane urea)s and poly(ether urethane urea)s.

Synthesis, characterization and fluorescence performance of a waterborne polyurethane-based polymeric dye

Energy Technology Data Exchange (ETDEWEB)

Xianhai, Hu, E-mail: hxyh@aiai.edu.cn [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); School of Materials and Chemical Engineering, Building Energy Efficiency Research Institute, Anhui University of Architecture, Hefei 230022 (China); Zhang, Xingyuan, E-mail: zxym@ustc.edu.cn [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Liu, Jin [School of Materials and Chemical Engineering, Building Energy Efficiency Research Institute, Anhui University of Architecture, Hefei 230022 (China); Dai, Jiabing [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China)

2013-10-15

A novel anionic waterborne polyurethane-based fluorescent dye WPU-DV26 was synthesized by incorporating the molecular structure of disperse violet 26 (DV26) into the polyurethane chain. The structure of WPU-DV26 was confirmed by means of Fourier transform infrared spectroscopy and UV–vis absorption analysis. Comparing to the UV–vis spectrum of DV26, WPU-DV26 showed a hypsochromic shift from the absorption maxima of 518, 558, 609 nm to 510, 548, 586 nm, respectively. WPU-DV26 can form stable latex in water. The number average molecular weight and its distribution index, and average latex particle size for WPU-DV26 were determined to be 2.33×10{sup 4}, 1.36 and 80 nm, respectively. The improved thermal stability of WPU-DV26 can be attributed to the embedded anthraquinone unit of DV26. It was found that both the intensity and stability of the fluorescence of WPU-DV26 latex were improved significantly compared with those of DV26. -- Highlights: ► A waterborne polyurethane-based polymeric dye was synthesized. ► The fluorescence intensity of WPU-DV26 emulsion was enhanced greatly compared with that of DV26. ► The fluorescence stability of WPU-DV26 emulsion was fine not only for long term storage but also for fluorescence quencher.

Synthesis and characterization of gold nanotube/nanowire–polyurethane composite based on castor oil and polyethylene glycol

International Nuclear Information System (INIS)

Ganji, Yasaman; Kasra, Mehran; Salahshour Kordestani, Soheila; Bagheri Hariri, Mohiedin

2014-01-01

Gold nanotubes/nanowires (GNT/NW) were synthesized by using the template-assisted electrodeposition technique and mixed with castor oil–polyethylene glycol based polyurethane (PU) to fabricate porous composite scaffolds for biomedical application. 100 and 50 ppm of GNT/NW were used to synthesize composites. The composite scaffolds were characterized by Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscopy. Cell attachment on polyurethane–GNT/NW composites was investigated using fat-derived mesenchymal stem cells. Addition of 50 or 100 ppm GNT/NW had significant effects on thermal, mechanical, and cell attachment of polyurethane. Higher crosslink density and better cell attachment and proliferation were observed in polyurethane containing 50 ppm GNT/NW. The results revealed that GNT/NW formed hydrogen bonding with the polyurethane matrix and improved the thermomechanical properties of nanocomposites. Compared with pure PU, better cellular attachment on polyurethane–GNT/NW composites was observed resulting from the improved surface properties of composites. - Highlights: • Polyurethane–gold nanotubes/nanowires (GNT/NWs) composites were synthesized. • Tan δ, E′ and E″ were increased upon addition of 50 ppm of GNT/NW. • Better cell attachment was observed in composites containing 50 ppm of GNT/NW. • GNT/NWs can make a bridge between the pores of the porous polymeric scaffolds. • GNT/NWs increased the crosslink density of the polymeric matrix

Synthesis and characterization of gold nanotube/nanowire–polyurethane composite based on castor oil and polyethylene glycol

Energy Technology Data Exchange (ETDEWEB)

Ganji, Yasaman, E-mail: y.ganji@aut.ac.ir [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave., Tehran (Iran, Islamic Republic of); Kasra, Mehran, E-mail: mkasra@aut.ac.ir [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave., Tehran (Iran, Islamic Republic of); Salahshour Kordestani, Soheila, E-mail: s.kordestani@aut.ac.ir [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave., Tehran (Iran, Islamic Republic of); Bagheri Hariri, Mohiedin, E-mail: mohibagheri@gmail.com [Materials Science and Engineering Department, Sharif University of Technology, Azadi Ave., Tehran (Iran, Islamic Republic of)

2014-09-01

Gold nanotubes/nanowires (GNT/NW) were synthesized by using the template-assisted electrodeposition technique and mixed with castor oil–polyethylene glycol based polyurethane (PU) to fabricate porous composite scaffolds for biomedical application. 100 and 50 ppm of GNT/NW were used to synthesize composites. The composite scaffolds were characterized by Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, and scanning electron microscopy. Cell attachment on polyurethane–GNT/NW composites was investigated using fat-derived mesenchymal stem cells. Addition of 50 or 100 ppm GNT/NW had significant effects on thermal, mechanical, and cell attachment of polyurethane. Higher crosslink density and better cell attachment and proliferation were observed in polyurethane containing 50 ppm GNT/NW. The results revealed that GNT/NW formed hydrogen bonding with the polyurethane matrix and improved the thermomechanical properties of nanocomposites. Compared with pure PU, better cellular attachment on polyurethane–GNT/NW composites was observed resulting from the improved surface properties of composites. - Highlights: • Polyurethane–gold nanotubes/nanowires (GNT/NWs) composites were synthesized. • Tan δ, E′ and E″ were increased upon addition of 50 ppm of GNT/NW. • Better cell attachment was observed in composites containing 50 ppm of GNT/NW. • GNT/NWs can make a bridge between the pores of the porous polymeric scaffolds. • GNT/NWs increased the crosslink density of the polymeric matrix.

Thermal assault and polyurethane foam-evaluating protective mechanisms

International Nuclear Information System (INIS)

Williamson, C.L.; Iams, Z.L.

2004-01-01

Rigid polyurethane foam utilizes a variety of mechanisms to mitigate the thermal assault of a ''regulatory burn''. Polymer specific heat and foam k-factor are of limited usefulness in predicting payload protection. Properly formulated rigid polyurethane foam provides additional safeguards by employing ablative mechanisms which are effective even when the foam has been crushed or fractured as a result of trauma. The dissociative transitions from polymer to gas and char, and the gas transport of heat from inside the package out into the environment are also thermal mitigators. Additionally, the in-situ production of an intumescent, insulative, carbonaceous char, confers thermal protection even when a package's outer steel skin has been breached. In this test program, 19 liter, ''Five gallon'' steel pails are exposed on one end to the flame of an ''Oil Burner'' as described in the US Federal Aviation Administration (FAA) ''Aircraft Materials Fire Test Handbook''. When burning 2 diesel at a nominal rate of 8.39 kg (18.5 pounds)/hr, the burner generates a high emissivity flame that impinges on the pail face with the thermal intensity of a full scale pool-fire environment. Results of these tests, TGA and MDSC analysis on the subject foams are reported, and their relevance to full size packages and pool fires are discussed

Membrane fusion by VAMP3 and plasma membrane t-SNAREs

International Nuclear Information System (INIS)

Hu Chuan; Hardee, Deborah; Minnear, Fred

2007-01-01

Pairing of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins on vesicles (v-SNAREs) and SNARE proteins on target membranes (t-SNAREs) mediates intracellular membrane fusion. VAMP3/cellubrevin is a v-SNARE that resides in recycling endosomes and endosome-derived transport vesicles. VAMP3 has been implicated in recycling of transferrin receptors, secretion of α-granules in platelets, and membrane trafficking during cell migration. Using a cell fusion assay, we examined membrane fusion capacity of the ternary complexes formed by VAMP3 and plasma membrane t-SNAREs syntaxin1, syntaxin4, SNAP-23 and SNAP-25. VAMP3 forms fusogenic pairing with t-SNARE complexes syntaxin1/SNAP-25, syntaxin1/SNAP-23 and syntaxin4/SNAP-25, but not with syntaxin4/SNAP-23. Deletion of the N-terminal domain of syntaxin4 enhanced membrane fusion more than two fold, indicating that the N-terminal domain negatively regulates membrane fusion. Differential membrane fusion capacities of the ternary v-/t-SNARE complexes suggest that transport vesicles containing VAMP3 have distinct membrane fusion kinetics with domains of the plasma membrane that present different t-SNARE proteins

One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification

International Nuclear Information System (INIS)

Pant, Hem Raj; Kim, Han Joo; Joshi, Mahesh Kumar; Pant, Bishweshwar; Park, Chan Hee; Kim, Jeong In; Hui, K.S.; Kim, Cheol Sang

2014-01-01

Highlights: • A single mat having varieties of performance for water treatment is simply introduced. • Cost effective Ag-doped fly ash/PU nanofibers are fabricated in one-step. • Solvent reduction of AgNO 3 could produce Ag-loaded spider-web nets. • Size of Ag NPs on fiber surface can be controlled by controlling stirring time. • Fabrication of nanocomposite using pollutant material to control other pollutents. -- Abstract: A stable silver-doped fly ash/polyurathene (Ag-FA/PU) nanocomposite multifunctional membrane is prepared by a facile one-step electrospinning process using fly ash particles (FAPs). Colloidal solution of PU with FAPs and Ag metal precursor was subjected to fabricate nanocomposite spider-web-like membrane using electrospinning process. Presence of N,N-dimethylformamide (solvent of PU) led to reduce silver nitrate into Ag NPs. Incorporation of Ag NPs and FAPs through electrospun PU fibers is proven through electron microscopy and spectroscopic techniques. Presence of these NPs on PU nanofibers introduces several potential physicochemical properties such as spider-web-like nano-neeting for NPs separation, enhanced absorption capacity to remove carcinogenic arsenic (As) and toxic organic dyes, and antibacterial properties with reduce bio-fouling for membrane filter application. Preliminary observations used for above-mentioned applications for water treatment showed that it will be an economically and environmentally friendly nonwoven matrix for water purification. This simple approach highlights new avenues about the utilization of one pollutant material to control other pollutants in scalable and inexpensive ways

One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification

Energy Technology Data Exchange (ETDEWEB)

Pant, Hem Raj, E-mail: hempant@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Engineering Science and Humanities, Institute of Engineering, Pulchowk Campus, Tribhuvan University, Kathmandu (Nepal); Kim, Han Joo [Division of Mechanical Design Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Joshi, Mahesh Kumar; Pant, Bishweshwar; Park, Chan Hee; Kim, Jeong In [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2014-01-15

Highlights: • A single mat having varieties of performance for water treatment is simply introduced. • Cost effective Ag-doped fly ash/PU nanofibers are fabricated in one-step. • Solvent reduction of AgNO{sub 3} could produce Ag-loaded spider-web nets. • Size of Ag NPs on fiber surface can be controlled by controlling stirring time. • Fabrication of nanocomposite using pollutant material to control other pollutents. -- Abstract: A stable silver-doped fly ash/polyurathene (Ag-FA/PU) nanocomposite multifunctional membrane is prepared by a facile one-step electrospinning process using fly ash particles (FAPs). Colloidal solution of PU with FAPs and Ag metal precursor was subjected to fabricate nanocomposite spider-web-like membrane using electrospinning process. Presence of N,N-dimethylformamide (solvent of PU) led to reduce silver nitrate into Ag NPs. Incorporation of Ag NPs and FAPs through electrospun PU fibers is proven through electron microscopy and spectroscopic techniques. Presence of these NPs on PU nanofibers introduces several potential physicochemical properties such as spider-web-like nano-neeting for NPs separation, enhanced absorption capacity to remove carcinogenic arsenic (As) and toxic organic dyes, and antibacterial properties with reduce bio-fouling for membrane filter application. Preliminary observations used for above-mentioned applications for water treatment showed that it will be an economically and environmentally friendly nonwoven matrix for water purification. This simple approach highlights new avenues about the utilization of one pollutant material to control other pollutants in scalable and inexpensive ways.

Injectable Biodegradable Polyurethane Scaffolds with Release of Platelet-derived Growth Factor for Tissue Repair and Regeneration

Science.gov (United States)

Hafeman, Andrea E.; Li, Bing; Yoshii, Toshitaka; Zienkiewicz, Katarzyna; Davidson, Jeffrey M.; Guelcher, Scott A.

2013-01-01

Purpose The purpose of this work was to investigate the effects of triisocyanate composition on the biological and mechanical properties of biodegradable, injectable polyurethane scaffolds for bone and soft tissue engineering. Methods Scaffolds were synthesized using reactive liquid molding techniques, and were characterized in vivo in a rat subcutaneous model. Porosity, dynamic mechanical properties, degradation rate, and release of growth factors were also measured. Results Polyurethane scaffolds were elastomers with tunable damping properties and degradation rates, and they supported cellular infiltration and generation of new tissue. The scaffolds showed a two-stage release profile of platelet-derived growth factor, characterized by a 75% burst release within the first 24 h and slower release thereafter. Conclusions Biodegradable polyurethanes synthesized from triisocyanates exhibited tunable and superior mechanical properties compared to materials synthesized from lysine diisocyanates. Due to their injectability, biocompatibility, tunable degradation, and potential for release of growth factors, these materials are potentially promising therapies for tissue engineering. PMID:18516665

Naloxone-sensitive, haloperidol-sensitive, [3H](+)SKF-10047-binding protein partially purified from rat liver and rat brain membranes: an opioid/sigma receptor?

Science.gov (United States)

Tsao, L I; Su, T P

1997-02-01

A naloxone-sensitive, haloperidol-sensitive, [3H](+)SKF-10047-binding protein was partially purified from rat liver and rat brain membranes in an affinity chromatography originally designed to purify sigma receptors. Detergent-solubilized extracts from membranes were adsorbed to Sephadex G-25 resin containing an affinity ligand for sigma receptors: N-(2- 3,4-dichlorophenyl]ethyl)-N-(6-aminohexyl)-(2-[1-pyrrolidinyl]) ethylamine (DAPE). After eluting the resin with haloperidol, a protein that bound [3H](+)SKF-10047 was detected in the eluates. However, the protein was not the sigma receptor. [3H](+)SKF-10047 binding to the protein was inhibited by the following compounds in the order of decreasing potency: (+)pentazocine > (-) pentazocine > (+/-)cyclazocine > (-)morphine > (-)naloxone > haloperidol > (+)SKF-10047 > DADLE > (-)SKF-10047. Further, the prototypic sigma receptor ligands, such as 1,3-di-o-tolylguanidine (DTG), (+)3-PPP, and progesterone, bound poorly to the protein. Tryptic digestion and heat treatment of the affinity-purified protein abolished radioligand binding. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS/PAGE) of the partially-purified protein from the liver revealed a major diffuse band with a molecular mass of 31 kDa, a polypeptide of 65 kDa, and another polypeptide of > 97 kDa. This study demonstrates the existence of a novel protein in the rat liver and rat brain which binds opioids, benzomorphans, and haloperidol with namomolar affinity. The protein resembles the opioid/sigma receptor originally proposed by Martin et al. [(1976): J. Pharmacol. Exp. Ther., 197:517-532.]. A high degree of purification of this protein has been achieved in the present study.

Development of electroactive nanofibers based on thermoplastic polyurethane and poly(o-ethoxyaniline) for biological applications.

Science.gov (United States)

Cruz, Karina Ferreira Noronha; Formaggio, Daniela Maria Ducatti; Tada, Dayane Batista; Cristovan, Fernando Henrique; Guerrini, Lilia Müller

2017-02-01

Electroactive nanofibers based on thermoplastic polyurethane (TPU) and poly(alkoxy anilines) produced by electrospinning has been explored for biomaterials applications. The thermoplastic polyurethane is a biocompatible polymer with good mechanical properties. The production of TPU nanofibers requires the application of high voltage during electrospinning in order to prepare uniform mats due to its weak ability to elongate during the process. To overcome this limitation, a conductive polymer can be incorporated to the process, allowing generates mats without defects. In this study, poly(o-ethoxyaniline) POEA doped with dodecylbenzene sulfonic acid (DBSA) was blended with thermoplastic polyurethane (TPU) by solution method. Films were produced by casting and nanofibers were prepared by electrospinning. The effect of the POEA on morphology, distribution of diameter and cell viability of the nanofibers was evaluated. The results demonstrated that the incorporation of POEA in TPU provided to the mats a suitable morphology for cellular growth. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 601-607, 2017. © 2016 Wiley Periodicals, Inc.

Validation of an experimental polyurethane model for biomechanical studies on implant supported prosthesis - tension tests

Directory of Open Access Journals (Sweden)

Mariane Miyashiro

2011-06-01

Full Text Available OBJECTIVES: The complexity and heterogeneity of human bone, as well as ethical issues, frequently hinder the development of clinical trials. The purpose of this in vitro study was to determine the modulus of elasticity of a polyurethane isotropic experimental model via tension tests, comparing the results to those reported in the literature for mandibular bone, in order to validate the use of such a model in lieu of mandibular bone in biomechanical studies. MATERIAL AND METHODS: Forty-five polyurethane test specimens were divided into 3 groups of 15 specimens each, according to the ratio (A/B of polyurethane reagents (PU-1: 1/0.5, PU-2: 1/1, PU-3: 1/1.5. RESULTS: Tension tests were performed in each experimental group and the modulus of elasticity values found were 192.98 MPa (SD=57.20 for PU-1, 347.90 MPa (SD=109.54 for PU-2 and 304.64 MPa (SD=25.48 for PU-3. CONCLUSION: The concentration of choice for building the experimental model was 1/1.

Dosimetric properties of new formulation of PRESAGE® with tin organometal catalyst: Development of sensitivity and stability to megavoltage energy.

Science.gov (United States)

Khezerloo, Davood; Nedaie, Hassan Ali; Takavar, Abbas; Zirak, Alireza; Farhood, Bagher; Banaee, Nooshin; Alidokht, Eisa

2018-01-01

Tin-base catalyst is one of the widely used organometallic catalysts in polyurethane technology. The purpose of this study was to evaluate the effect of tin organometallic catalyst in the radiation response and radiological properties of a new formula of PRESAGE ® . In the study, two types of PRESAGE were fabricated. A very little amount of dibutyltindillaurate (DBTDL) (0.07% weight) was used as a catalyst in the fabrication of new PRESAGE (i.e., PRESAGE with catalyst), which components were: 93.93% weight polyurethane, 5% weight tetrachloride, and 1% weight leucomalachite green (LMG). For PRESAGE without catalyst, 94% weight polyurethane, 4% weight tetrachloride, and 2% weight LMG were used. Radiochromic response and postirradiation stability of PRESAGEs were determined. Also, radiological characteristics of PRESAGEs, such as mass density, electron density, mass attenuation coefficient, and mass stopping power in different photon energies were assessed and compared with water. The absorption peak of new PRESAGE compared to PRESAGE without catalyst was observed without change. Sensitivity of new PRESAGE was higher than PRESAGE without catalyst and its stability after the first 1 h was relatively constant. Also, Mass attenuation coefficient of new PRESAGE in energy ranges catalyst in very low concentration can be used in fabrication of radiochromic polymer gel to achieve high sensitivity and stability as well as good radiological properties in the megavoltage photon beam.

Engineering a segmented dual-reservoir polyurethane intravaginal ring for simultaneous prevention of HIV transmission and unwanted pregnancy.

Directory of Open Access Journals (Sweden)

Justin T Clark

Full Text Available The HIV/AIDS pandemic and its impact on women prompt the investigation of prevention strategies to interrupt sexual transmission of HIV. Long-acting drug delivery systems that simultaneously protect womenfrom sexual transmission of HIV and unwanted pregnancy could be important tools in combating the pandemic. We describe the design, in silico, in vitro and in vivo evaluation of a dual-reservoir intravaginal ring that delivers the HIV-1 reverse transcriptase inhibitor tenofovir and the contraceptive levonorgestrel for 90 days. Two polyether urethanes with two different hard segment volume fractions were used to make coaxial extruded reservoir segments with a 100 µm thick rate controlling membrane and a diameter of 5.5 mm that contain 1.3 wt% levonorgestrel. A new mechanistic diffusion model accurately described the levonorgestrel burst release in early time points and pseudo-steady state behavior at later time points. As previously described, tenofovir was formulated as a glycerol paste and filled into a hydrophilic polyurethane, hollow tube reservoir that was melt-sealed by induction welding. These tenofovir-eluting segments and 2 cm long coaxially extruded levonorgestrel eluting segments were joined by induction welding to form rings that released an average of 7.5 mg tenofovir and 21 µg levonorgestrel per day in vitro for 90 days. Levonorgestrel segments placed intravaginally in rabbits resulted in sustained, dose-dependent levels of levonorgestrel in plasma and cervical tissue for 90 days. Polyurethane caps placed between segments successfully prevented diffusion of levonorgestrel into the tenofovir-releasing segment during storage.Hydrated rings endured between 152 N and 354 N tensile load before failure during uniaxial extension testing. In summary, this system represents a significant advance in vaginal drug delivery technology, and is the first in a new class of long-acting multipurpose prevention drug delivery systems.

Synthesis and characterization of polyurethane/CdS-SiO 2 nanocomposites via ultrasonic process

Science.gov (United States)

Chen, Jing; Zhou, Yu-Ming; Nan, Qiu-Li; Ye, Xiao-Yun; Sun, Yan-Qing; Wang, Zhi-Qiang; Zhang, Shi-Ming

2008-12-01

In this study, the high-intensity ultrasound was applied in the preparation of chiral polyurethane/CdS-SiO 2 nanocomposites. The polyurethane/CdS-SiO 2 nanocomposites were analyzed by powder X-ray diffraction, thermogravimetric analysis (TGA), TEM and SEM. The results indicated that the heat stability of the nanocomposites was improved in the presence of CdS-SiO 2 core-shell nanoparticles. The infrared emissivity (8-14 μm) study revealed that the nanocomposites possessed much lower infrared values compared with those of the neat polymers and nanoparticles, respectively. A possible mechanism of ultrasonic induced composite reaction was proposed based on the experimental results.

Synthesis and characterization of polyurethane/CdS-SiO2 nanocomposites via ultrasonic process

International Nuclear Information System (INIS)

Chen Jing; Zhou Yuming; Nan Qiuli; Ye Xiaoyun; Sun Yanqing; Wang Zhiqiang; Zhang Shiming

2008-01-01

In this study, the high-intensity ultrasound was applied in the preparation of chiral polyurethane/CdS-SiO 2 nanocomposites. The polyurethane/CdS-SiO 2 nanocomposites were analyzed by powder X-ray diffraction, thermogravimetric analysis (TGA), TEM and SEM. The results indicated that the heat stability of the nanocomposites was improved in the presence of CdS-SiO 2 core-shell nanoparticles. The infrared emissivity (8-14 μm) study revealed that the nanocomposites possessed much lower infrared values compared with those of the neat polymers and nanoparticles, respectively. A possible mechanism of ultrasonic induced composite reaction was proposed based on the experimental results.

Effect of silica nanoparticles on polyurethane foaming process and foam properties

International Nuclear Information System (INIS)

Francés, A B; Bañón, M V Navarro

2014-01-01

Flexible polyurethane foams (FPUF) are commonly used as cushioning material in upholstered products made on several industrial sectors: furniture, automotive seating, bedding, etc. Polyurethane is a high molecular weight polymer based on the reaction between a hydroxyl group (polyol) and isocyanate. The density, flowability, compressive, tensile or shearing strength, the thermal and dimensional stability, combustibility, and other properties can be adjusted by the addition of several additives. Nanomaterials offer a wide range of possibilities to obtain nanocomposites with specific properties. The combination of FPUF with silica nanoparticles could develop nanocomposite materials with unique properties: improved mechanical and thermal properties, gas permeability, and fire retardancy. However, as silica particles are at least partially surface-terminated with Si-OH groups, it was suspected that the silica could interfere in the reaction of poyurethane formation.The objective of this study was to investigate the enhancement of thermal and mechanical properties of FPUF by the incorporation of different types of silica and determining the influence thereof during the foaming process. Flexible polyurethane foams with different loading mass fraction of silica nanoparticles (0-1% wt) and different types of silica (non treated and modified silica) were synthesized. PU/SiO 2 nanocomposites were characterized by FTIR spectroscopy, TGA, and measurements of apparent density, resilience and determination of compression set. Addition of silica nanoparticles influences negatively in the density and compression set of the foams. However, resilience and thermal stability of the foams are improved. Silica nanoparticles do not affect to the chemical structure of the foams although they interfere in the blowing reaction

Castor Oil Based Polyurethanes: Synthesis and Characterization

Science.gov (United States)

Macalino, AD; Salen, VA; Reyes, LQ

2017-09-01

In this study, polyurethanes based on castor oil and 1,6-hexamethylene diisocyanate (HMDI) were synthesized with varying weight ratio of the castor oil and HMDI. The formation of urethane linkages was verified through the use of a fourier transform infrared spectroscopy (FTIR). The hydrophilicity of the films was evaluated through the use of a contact angle meter and it was found that the contact angle of all the films were below 90 degrees which confirms their hydrophilicity. The thermal stability of the PU films were studies through the use of a thermal gravimetric analyzer and found that all of the polyurethane films exhibited two weight loss events at elevated temperatures wherein the first weight loss event was observed to occur at 285°C to 384°C while the second weight loss event was observed at around 521°C to 551°C. The hardness, elastic modulus, and tensile elongation of the PU films were determined by using a universal testing machine (UTM) where it was found out that the hardness and the elastic modulus of the film is directly proportional with HMDI loading while the tensile elongation is inversely proportional to it. Lastly, it was known through the swelling studies of the PU films that it does not swell, this is due to the presence of unreacted triglycerides in the material, which prevents water from permeating to the films.