New approaches to the CL-20/HMX cocrystal a less sensitive high power explosive

OpenAIRE

Herrmannsdörfer, Dirk; Herrmann, Michael; Heintz, Thomas

2015-01-01

Understanding the kinetic and thermodynamic of the formation of the 2:1 cocrystal of CL-20 and HMX is a key factor to optimize crystallization procedures in regard to time and material efficiency as well as crystal purity. Here we describe the temperature and polymorph dependency of the solvent-mediated cocrystallization of HMX and CL-20 in 2-propanol as well as the solubility curves of CL-20 and HMX in acetone/2-propanol mixtures and acetonitrile/2-propanol mixtures at room temperature. The ...

Analysis of compaction shock interactions during DDT of low density HMX

Science.gov (United States)

Rao, Pratap T.; Gonthier, Keith A.

2017-01-01

Deflagration-to-Detonation Transition (DDT) in confined, low density granular HMX occurs by a complex mechanism that involves compaction shock interactions within the material. Piston driven DDT experiments indicate that detonation is abruptly triggered by the interaction of a strong combustion-supported secondary shock and a piston-supported primary (input) shock, where the nature of the interaction depends on initial packing density and primary shock strength. These interactions influence transition by affecting dissipative heating within the microstructure during pore collapse. Inert meso-scale simulations of successive shock loading of low density HMX are performed to examine how dissipation and hot-spot formation are affected by the initial density, and the primary and secondary shock strengths. This information is used to formulate an ignition and burn model for low density HMX that accounts for the effect of shock densensitization on burn. Preliminary DDT predictions are presented that illustrate how primary shock strength affects the transition mechanism.

Theoretical insight into the solvent effect of H2O and formamide on the cooperativity effect in HMX complex.

Science.gov (United States)

Meng, Rui-Hong; Cao, Xiong; Hu, Shuang-Qi; Hu, Li-Shuang

2017-08-01

The cooperativity effects of the H-bonding interactions in HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane)∙∙∙HMX∙∙∙FA (formamide), HMX∙∙∙HMX∙∙∙H 2 O and HMX∙∙∙HMX∙∙∙HMX complexes involving the chair and chair-chair HMX are investigated by using the ONIOM2 (CAM-B3LYP/6-31++G(d,p):PM3) and ONIOM2 (M06-2X/6-31++G(d,p):PM3) methods. The solvent effect of FA or H 2 O on the cooperativity effect in HMX∙∙∙HMX∙∙∙HMX are evaluated by the integral equation formalism polarized continuum model. The results show that the cooperativity and anti-cooperativity effects are not notable in all the systems. Although the effect of solvation on the binding energy of ternary system HMX∙∙∙HMX∙∙∙HMX is not large, that on the cooperativity of H-bonds is notable, which leads to the mutually strengthened H-bonding interaction in solution. This is perhaps the reason for the formation of different conformation of HMX in different solvent. Surface electrostatic potential and reduced density gradient are used to reveal the nature of the solvent effect on cooperativity effect in HMX∙∙∙HMX∙∙∙HMX. Graphical abstract RDG isosurface and electrostatic potential surface of HMX∙∙∙HMX∙∙∙HMX.

Performance of mesophilic anaerobic granules for removal of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from aqueous solution

International Nuclear Information System (INIS)

An Chunjiang; He Yanling; Huang Guohe; Liu Yonghong

2010-01-01

The performance of mesophilic anaerobic granules to degrade octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was investigated under various conditions. The results of batch experiments showed that anaerobic granules were capable of removing HMX from aqueous solution with high efficiency. Both biotic and abiotic mechanisms contributed to the removal of HMX by anaerobic granules under mesophilic conditions. Adsorption appeared to play a significant role in the abiotic process. Furthermore, HMX could be biodegraded by anaerobic granules as the sole substrate. After 16 days of incubation, 99.04% and 96.42% of total HMX could be removed by 1 g VSS/L acclimated and unacclimated granules, respectively. Vancomycin, an inhibitor of acetogenic bacteria, caused a significant inhibition of HMX biotransformation, while 2-bromoethanesulfonic acid, an inhibitor of methanogenic bacteria, only resulted in a slight decrease of metabolic activity. The presence of the glucose, as a suitable electron donor and carbon source, was found to enhance the degradation of HMX by anaerobic granules. Our study showed that sulfate had little adverse effects on biotransformation of HMX by anaerobic granules. However, nitrate had significant inhibitory effect on the extent of HMX removal especially in the initial period. This study offered good prospects of using high-rate anaerobic technology in the treatment of munition wastewater.

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Science.gov (United States)

Pal, Anirban; Picu, Catalin R.

2018-06-01

HMX (cyclotetramethylene tetranitramine) is an energetic material which releases substantial amounts of energy upon decomposition. The role of defects and deformation in causing reaction initiation was discussed in the literature but remains insufficiently understood. In this work, we identify, using computational methods, the slip systems which are potentially active in β-HMX and rank them in terms of their propensity for slip. To this end, we develop first a tentative ranking based on the degree of steric hindrance associated with slip. This is quantified using a geometric analog of the γ-surface. Further, we use atomistic models to compute the Peierls–Nabarro (PN) stress for the motion of dislocations in the slip systems with smallest degree of steric hindrance. A complex mechanical behavior is observed, including strong slip asymmetry, twinning and cleavage. The five systems with the lowest PN stress are (011)[01\\bar{1}], (011)[100], (101)[010], (101)[10\\bar{1}] and (021)[100]. We conclude that the material has enough slip systems available for supporting a generalized state of plastic strain provided the twinning system (101)[10\\bar{1}] is taken into consideration and that the resolved shear stress is at least 260 MPa.

High-Pressure Behaviour of β-HMX Crystal Studied by DFT-LDA

International Nuclear Information System (INIS)

Dan, Lian; Lai-Yu, Lu; Dong-Qing, Wei; Qing-Ming, Zhang; Zi-Zheng, Gong; Yong-Xin, Guo

2008-01-01

Density functional theory (DFT) with local density approximation (LDA) is employed to study the structural and electronic properties of the high explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under high pressure compression up to 40 GPa. Pressure dependences of the cell volume, lattice constants, and molecular geometry of solid β-HMX are presented and discussed. It is found that N-N and N-C bonds are subject to significant change. This may implies that these bonds may be related to the sensitivity. The band gap is calculated and plotted as a function of pressure. Compared the experimental results with other theoretical works we find that LDA gives good results

Pressure Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

Energy Technology Data Exchange (ETDEWEB)

Glascoe, E A; Zaug, J M; Burnham, A K

2009-05-29

The effect of pressure on the thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low to moderate pressures (i.e. between ambient pressure and 1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure enhanced autocatalysis whereas the deceleration at high pressures is attributed pressure inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both {beta} and {delta} phase HMX are sensitive to pressure in the thermally induced decomposition kinetics.

Deletion of a conserved regulatory element required for Hmx1 expression in craniofacial mesenchyme in the dumbo rat: a newly identified cause of congenital ear malformation

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Lely A. Quina

2012-11-01

Hmx1 is a homeodomain transcription factor expressed in the developing eye, peripheral ganglia, and branchial arches of avian and mammalian embryos. Recent studies have identified a loss-of-function allele at the HMX1 locus as the causative mutation in the oculo-auricular syndrome (OAS in humans, characterized by ear and eye malformations. The mouse dumbo (dmbo mutation, with similar effects on ear and eye development, also results from a loss-of-function mutation in the Hmx1 gene. A recessive dmbo mutation causing ear malformation in rats has been mapped to the chromosomal region containing the Hmx1 gene, but the nature of the causative allele is unknown. Here we show that dumbo rats and mice exhibit similar neonatal ear and eye phenotypes. In midgestation embryos, dumbo rats show a specific loss of Hmx1 expression in neural-crest-derived craniofacial mesenchyme (CM, whereas Hmx1 is expressed normally in retinal progenitors, sensory ganglia and in CM, which is derived from mesoderm. High-throughput resequencing of 1 Mb of rat chromosome 14 from dmbo/dmbo rats, encompassing the Hmx1 locus, reveals numerous divergences from the rat genomic reference sequence, but no coding changes in Hmx1. Fine genetic mapping narrows the dmbo critical region to an interval of ∼410 kb immediately downstream of the Hmx1 transcription unit. Further sequence analysis of this region reveals a 5777-bp deletion located ∼80 kb downstream in dmbo/dmbo rats that is not apparent in 137 other rat strains. The dmbo deletion region contains a highly conserved domain of ∼500 bp, which is a candidate distal enhancer and which exhibits a similar relationship to Hmx genes in all vertebrate species for which data are available. We conclude that the rat dumbo phenotype is likely to result from loss of function of an ultraconserved enhancer specifically regulating Hmx1 expression in neural-crest-derived CM. Dysregulation of Hmx1 expression is thus a candidate mechanism for congenital ear

Compaction of granular HMX: P-α porosity model in CTH hydrocode

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K. S. Mahon

2015-12-01

Full Text Available Compaction waves traveling through porous cyclotetramethylene-tetranitramine (HMX are computationally modeled using the Eulerian hydrocode CTH and validated with gas gun experimental data. The method employed use of a newly generated set of P-α parameters for granular HMX in a Mie-Gruneisen equation of state. The P-α model adds a separate parameter to differentiate between the volume changes of a solid material due to compression from the volume change due to compaction, void collapse in a granular material. Computational results are compared via five validation schema for two different initial-porosity experiments. These schema include stress measurements, velocity rise times and arrival times, elastic sound speeds though the material and final compaction densities for a series of two different percent Theoretical Maximum Density (TMD HMX sets of experimental data. There is a good agreement between the simulations and the experimental gas gun data with the largest source of error being an 11% overestimate of the peak stress which may be due to impedance mismatch on the experimental gauge interface. Determination of these P-α parameters are important as they enable modeling of porosity and are a vital first step in modeling of precursory hotspots, caused by hydrodynamic collapse of void regions or grain interactions, prior to deflagration to detonation transition of granular explosives.

Modeling compaction-induced energy dissipation of granular HMX

Energy Technology Data Exchange (ETDEWEB)

Gonthier, K.A. [Lamar Univ., Beaumont, TX (US). Dept. of Mechanical Engineering; Menikoff, R.; Son, S.F.; Asay, B.W. [Los Alamos National Lab., NM (US)

1998-12-31

A thermodynamically consistent model is developed for the compaction of granular solids. The model is an extension of the single phase limit of two-phase continuum models used to describe Deflagration-to-Detonation Transition (DDT) experiments. The focus is on the energetics and dissipation of the compaction process. Changes in volume fraction are partitioned into reversible and irreversible components. Unlike conventional DDT models, the model is applicable from the quasi-static to dynamic compaction regimes for elastic, plastic, or brittle materials. When applied to the compaction of granular HMX (a brittle material), the model predicts results commensurate with experiments including stress relaxation, hysteresis, and energy dissipation. The model provides a suitable starting point for the development of thermal energy localization sub-scale models based on compaction-induced dissipation.

Oblique impact and friction of HMX and/or TATB-based PBXs

Science.gov (United States)

Picart, Didier; Junqua-Moullet, Alexandra

2017-06-01

Transportation, handling, vibrations can lead to moderate compressive but dynamic loadings requiring the characterization of the safety of PBXs submitted to such scenarios. Knowing that ignition can occur at a lower critical height during a fall on an inclined surface than a normal impact, the attention is focused in this paper on the heating due to the friction between PBXs and surfaces. A lot of experiments have been made using free-falling samples in vertical drop configurations on inclined targets or pendulum (skid) drop configurations (Green et al. 1971; Randolph et al. 1976). Data obtained on our HMX and/or TATB-based plastic-bonded explosives using pendulum drop configurations will be detailed. Evaluation of the heating due to friction requires the determination of the tangential projectile/target relative displacement and the contact pressure. The pressure is related to the normal force during the impact and the evolving contact surface, the latter being evaluated using a series of normal impacts. The aim of our paper is to compare the experimental diameter of the contact zones to (i) the classical Hertz's theory of contacting elastic solids and (ii) a spring-mass description of the impact. Data and models are then used to evaluate the increase of the temperature at the projectile/target interface for our explosives. We highlight the experimental bias which has already been attributed to the grits used to mimic the roughness of the surfaces.

Deflagration to Detonation Transition (DDT) Simulations of HMX Powder Using the HERMES Model

Science.gov (United States)

White, Bradley; Reaugh, John; Tringe, Joseph

2017-06-01

We performed computer simulations of DDT experiments with Class I HMX powder using the HERMES model (High Explosive Response to MEchanical Stimulus) in ALE3D. Parameters for the model were fitted to the limited available mechanical property data of the low-density powder, and to the Shock to Detonation Transition (SDT) test results. The DDT tests were carried out in steel-capped polycarbonate tubes. This arrangement permits direct observation of the event using both flash X-ray radiography and high speed camera imaging, and provides a stringent test of the model. We found the calculated detonation transition to be qualitatively similar to experiment. Through simulation we also explored the effects of confinement strength, the HMX particle size distribution and porosity on the computed detonation transition location. This work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344.

Nano-CL-20/HMX Cocrystal Explosive for Significantly Reduced Mechanical Sensitivity

OpenAIRE

An, Chongwei; Li, Hequn; Ye, Baoyun; Wang, Jingyu

2017-01-01

Spray drying method was used to prepare cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX). Raw materials and cocrystals were characterized using scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, Raman spectroscopy, and Fourier transform infrared spectroscopy. Impact and friction sensitivity of cocrystals were tested and analyzed. Results show that, after preparation by spray drying method, microparticles were sph...

Vibrational Spectrum of HMX at CO2 Laser Wavelengths: A Combined DRIFT and LPAS Study

Directory of Open Access Journals (Sweden)

A. Puiu

2012-01-01

Full Text Available The vibrational spectrum of solid standard HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine was investigated. Two spectroscopic techniques were adopted for their different sensitivity and resolution. A preliminary survey of the absorption bands of the compound was performed in the 8000–400 cm−1 spectral range by employing the diffuse reflectance infrared Fourier transform (DRIFT technique at room temperature. The high-resolution line spectrum of HMX was obtained in the 9.2–10.8 μm spectral range by laser photoacoustic spectroscopy (LPAS method, using a line tuneable 10 W stabilised cw CO2 laser light source. By comparing the data collected with the two techniques in the common frequency range, a very good agreement was observed.

Theoretical insight into the binding energy and detonation performance of ε-, γ-, β-CL-20 cocrystals with β-HMX, FOX-7, and DMF in different molar ratios, as well as electrostatic potential.

Science.gov (United States)

Feng, Rui-Zhi; Zhang, Shu-Hai; Ren, Fu-de; Gou, Rui-Jun; Gao, Li

2016-06-01

Molecular dynamics method was employed to study the binding energies on the selected crystal planes of the ε-, γ-, β-conformation 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (ε-, γ-, β-CL-20) cocrystal explosives with 1,1-diamino-2,2-dinitroethylene (FOX-7), 1,3,5,7-tetranitro- 1,3,5,7-tetrazacyclooctane with β-conformation (β-HMX) and N,N-dimethylformamide (DMF) in different molar ratios. The oxygen balance, density, detonation velocity, detonation pressure, and surface electrostatic potential were analyzed. The results indicate that the binding energies E b (*) and stabilities are in the order of 1:1 > 2:1 > 3:1 > 5:1 > 8:1 (CL-20:FOX-7/β-HMX/DMF). The values of E b (*) and stabilities of the energetic-nonenergetic CL-20/DMF cocrystals are far larger than those of the energetic-energetic CL-20/FOX-7 and CL-20/β-HMX, and those of CL-20/β-HMX are the smallest. For CL-20/FOX-7 and CL-20/β-HMX, the largest E b (*) appears in the cocrystals with the 1:1, 1:2 or 1:3 molar ratio, and the stabilities of the cocrystals with the excess ratio of CL-20 are weaker than those in the cocrystals with the excess ratio of FOX-7 or β-HMX. In CL-20/FOX-7, CL-20 prefers adopting the γ-form, and ε-CL-20 is the preference in CL-20/β-HMX, and ε-CL-20 and β-CL-20 can be found in CL-20/DMF. The CL-20/FOX-7 and CL-20/β-HMX cocrystals with low molar ratios can meet the requirements of low sensitive high energetic materials. Surface electrostatic potential reveals the nature of the sensitivity change upon the cocrystal formation. Graphical Abstract MD method was employed to study the binding energies on the selected crystal planes in the ε-, γ-, β-CL-20 cocrystals with FOX-7, β-HMX and DMF in different molar ratios. Surface electrostatic potential reveals the nature of the sensitivity change in cocrystals.

Expansion of the HMX-1 Flight Envelope With the EDU-5/P Laser Eye Protection Spectacles

National Research Council Canada - National Science Library

Penhallegon, William

2004-01-01

...) takeoffs and landings. Flight testing determined that fit, internal and external lighting conditions, aircrew experience, and aircrafi type are important factors in determining the suitability of the EDU-iIP in HMX-I plafforms...

Small Scale Characterization of the Presence of the Explosive Octahydro-1,3,5,7-tetranitro- 1,3,5,7 tetrazocine (HMX) Near Former Naval Sites on Vieques Island, Puerto Rico

Science.gov (United States)

Simmons, C. C.; Carvalho-Knighton, K. M.; Pyrtle, A. J.

2007-12-01

Octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX) is a synthetic energetic compounds that has been commonly used in military munitions. The presence and movement of HMX through the environment is of growing concern because of potential civilian exposure and impacts on human health. HMX remains in the environment unreactive with little degradation. It can be transported great distances in water thus having the possibility for migrating into groundwater. The former naval sites in Vieques were used for weapons training and housed several disposal sites. Previous studies around these sites indicate the presence of radioactive materials produced through thermal fission, such as Cs-137. Since HMX was primarily used to implode fissionable materials in nuclear devices, evaluating the release of HMX and consequent movement through the environment at these sites is essential. Surface water and soil samples as well as core and pore water samples were collected from two sites in Vieques; Kiani Lagoon and Mosquito Bay. All samples were extracted using EPA method 8330 and analyzed using RP-HPLC analysis with a C-18 column. HMX was undetected in samples collected from both Kiani Lagoon and Mosquito Bay. The development of a model that studies the flow rates and fate of water runoff in these areas of interest, coupled with data on groundwater testing inside the actual former naval facilities, is being explored for further sample collection and analysis.

Measurement and reactive burn modeling of the shock to detonation transition for the HMX based explosive LX-14

Science.gov (United States)

Jones, J. D.; Ma, Xia; Clements, B. E.; Gibson, L. L.; Gustavsen, R. L.

2017-06-01

Gas-gun driven plate-impact techniques were used to study the shock to detonation transition in LX-14 (95.5 weight % HMX, 4.5 weight % estane binder). The transition was recorded using embedded electromagnetic particle velocity gauges. Initial shock pressures, P, ranged from 2.5 to 8 GPa and the resulting distances to detonation, xD, were in the range 1.9 to 14 mm. Numerical simulations using the SURF reactive burn scheme coupled with a linear US -up / Mie-Grueneisen equation of state for the reactant and a JWL equation of state for the products, match the experimental data well. Comparison of simulation with experiment as well as the ``best fit'' parameter set for the simulations is presented.

Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

Science.gov (United States)

Springer, H. K.; Tarver, C. M.; Bastea, S.

2017-01-01

The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

Ignition and Growth Modeling of Detonating LX-04 (85% HMX / 15% VITON) Using New and Previously Obtained Experimental Data

Science.gov (United States)

Tarver, Craig

2017-06-01

An Ignition and Growth reactive flow model for detonating LX-04 (85% HMX / 15% Viton) was developed using new and previously obtained experimental data on: cylinder test expansion; wave curvature; failure diameter; and laser interferometric copper and tantalum foil free surface velocities and LiF interface particle velocity histories. A reaction product JWL EOS generated by the CHEETAH code compared favorably with the existing, well normalized LX-04 product JWL when both were used with the Ignition and Growth model. Good agreement with all existing experimental data was obtained. Keywords: LX-04, HMX, detonation, Ignition and Growth PACS:82.33.Vx, 82.40.Fp This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Human health risks from TNT, RDX, and HMX in environmental media and consideration of the US Regulatory Environment

International Nuclear Information System (INIS)

Daniels, J.I.; Knezovich, J.P.

1994-12-01

Although the most economical method for disposing of unwanted energetic high explosives [HEs; e.g., 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-triazine (RDX, also known as Cyclonite), and octahydro-1,3,5,7-tetrazocine (HMX, also known as Octogen)] involves open burning and open or underground detonation [OB/O(U)D]; federal, state, and even local government agencies in the United States (U.S.) are implementing stricter environmental regulations that eventually may prevent such activities. These stricter regulations will promote alternative technologies that are designed to be environmentally benign. However, past HE-waste disposal practices at manufacturing and fabrication facilities in the U.S. have included uncontrolled OB/O(U)D, as well as direct surface discharge of HE-contaminated waste water, resulting in contaminated environmental media (e.g., ground water, soil, and perhaps even edible vegetation) near residential areas. Using TNT, RDX, and HMX as examples, this paper describes how risk-based standards for HEs can be derived that account for potential multimedia exposures (associated with contaminated air, water, food, and soil) by individuals near a contaminated site, and used to (1) protect public health and safety; (2)prevent limited resources from being dedicated to unnecessary cleanup activities; and (3) identify the most cost-effective, practical, and environmentally benign technologies suitable for integrating with the handling of the large quantity of high explosives scheduled for demilitarization

Experimental Studies on Improved Plastic Bonded Explosives Materials (PBXs for Controlled Fragmentation Warheads

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Elsharkawy Karim

2017-01-01

Full Text Available This paper describes formulations of plastic bonded explosives (PBXs based on three highly brisant explosives, namely 1,3,5-trinitro-1,3,5-triazinane (RDX, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX and pentaerythritoltetranitrate (PETN with polyurethane (PU based on Glycidyl azide polymer (GAP as an energetic binder in comparison with composition-B, which used in the fragmentation warheads. The sensitivity and performance properties of different types of PBXs were evaluated by experimental results of prepared selected PBX compositions. Casting technique was used to prepare the selected compositions containing 14% PU based on GAP. It has been observed that the brisance of the PBX based on HMX was higher than that of comp-B by 21.3 %, the detonation velocity showed a remarkable increase of the order of 8480 (m/s while that of comp-B was 7638 (m/s. A controlled fragmentation warhead with an outer grooving warhead case of dimensions 100x35x4 mm was used and arena test was carried out to determine the lethal zone of the fragmentation warhead. The lethal zone obtained from arena test for PBX composition based on HMX named PBXHG4 was higher than that based on RDX or PETN, and than that of comp-B by 40%.

Deflagration to detonation experiments in granular HMX

Energy Technology Data Exchange (ETDEWEB)

Burnside, N.J.; Son, S.F.; Asay, B.W.; Dickson, P.M.

1998-03-01

In this paper the authors report on continuing work involving a series of deflagration-to-detonation transition (DDT) experiments in which they study the piston-initiated DDT of heavily confined granular cyclotetramethylenetetranitramine (HMX). These experiments were designed to he useful in model development and evaluation. A main focus of these experiments is the effect of density on the DDT event. Particle size distribution and morphology are carefully characterized. In this paper they present recent surface area analysis. Earlier studies demonstrated extensive fracturing and agglomeration in samples at densities as low as 75% TMD as evidenced by dramatic decreases in particle size distribution due to mild stimulus. This is qualitatively confirmed with SEM images and quantitatively studied with gas absorption surface area analysis. Also, in this paper they present initial results using a microwave interferometer technique. Dynamic calibration of the technique was performed, a 35 GHz signal is used to increase resolution, and the system has been designed to be inexpensive for repeated experiments. The distance to where deformation of the inner wall begins for various densities is reported. This result is compared with the microwave interferometer measurements.

Changes in Blow-Off Velocity Observed in Two Explosives at the Threshold for Sustained Ignition Using the Modified Gap Test

Science.gov (United States)

Lee, R. J.; Forbes, J. W.; Tasker, D. G.; Orme, R. S.

2009-12-01

The Modified Gap Test was used to quantify different levels of partial reaction for various input stresses. This test configuration has been historically useful in highlighting thresholds for first reaction, sustained ignition, and detonation. Two different HMX based compositions were studied; a cast-cured composition with 87% HMX and a pressed composition with 92% HMX. Each explosive was prepared from large industrially produced batches consisting of different unreactive polymeric binder systems. Short samples (50.8 mm in diameter and 12.7 mm thick) were shock loaded using the standard large-scale gap test donor system. Product-cloud blow-off velocities at the opposite end of the sample were measured using a high-speed digital-camera. Velocity versus input pres sure plots provided changes in reactivity that had developed by the 12.7 mm run distance. Results appear consistent for the lower input stresses. In contrast, the results varied widely in a range of input stresses around the transition to detonation in both explosives. These results indicate that both explosives are subject to large variation in blow-off velocity in a range of input stresses near the threshold for prompt detonation. This is explained by localized variations of HMX particle size and density in industrially prepared samples. Approved for public release, Distribution unlimited, IHDIV Log No. 09-108.

Final report for SERDP WP-2209 Replacement melt-castable formulations for Composition B

Energy Technology Data Exchange (ETDEWEB)

Leonard, Philip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Francois, Elizabeth Green [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-05-19

During this project we investigated a number of energetic materials both old and new and determined that most of them were unsuitable due to safety or sensitivity reasons. Unsuccessful coformulants include TNAZ and BNFF for volatility reasons, and DAAF due to thermal compatibility issues. The powerful explosive HMX became a focus of the work in later stages as it conferred excellent power while being commonly available in well-regulated particle size lots and is chemically compatible in the melt with many coformulants. Ultimately three preferred formulations emerged from this work: a formulation tested on large scale by ARDEC involving PrNQ and HMX; a formulation tested at ARDEC and LANL using a nitrate salt eutectic and HMX; a formulation tested at LANL using LLM-201 and HMX.

Combustion synthesis and catalytic activity of LaCoO{sub 3} for HMX thermal decomposition

Energy Technology Data Exchange (ETDEWEB)

Wei, Zhi-Xian; Chi, Ying-Nan [Department of Chemistry, Institute for Chemical Physics, Beijing Institute of Technology (China); Hu, Chang-Wen [State Key Laboratory of Explosion Science, Technology Beijing Institute of Technology, Beijing (China); Liu, Hai-Yan [Department of Chemistry, Science Institute, North China University, Taiyuan, Shanxi (China)

2009-10-15

Perovskite-type LaCoO{sub 3} was prepared by stearic acid solution combustion method and characterized by XRD, DSC-TG, and XPS techniques. The catalytic activities of LaCoO{sub 3} for HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) thermal decomposition were investigated. The as-prepared LaCoO{sub 3} shows higher activity than the calcined one. This could be due to higher concentration of surface-adsorbed oxygen and hydroxyl species as well as higher BET surface area of the as-prepared LaCoO{sub 3}. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Mechanical and chemical responses of low-velocity impacted RDX and HMX explosive powders

Science.gov (United States)

Wu, Yanqing; Guo, Hongfu; Huang, Fenglei; Bao, Xiaowei; Explosion; damage Team

2017-06-01

The experimental analyses of mechanical and chemical responses of RDX and HMX particles were performed based on the optimized drop-weight experimental system equipped with the High-Speed Camera (HSC). It has been found that Jetting phenomenon observed by HSC is the result of the energy released by gaseous products, which push the pulverized or melted explosives to splash radially. Jetting is the only and the most obvious difference between reactive and inert particles prior to combustion so that jetting can be regarded as the sign of ignition. Area expansion velocity, jetting velocity, and flame propagation velocity have been estimated via image processing, making it possible to characterize mechanical deformation and violence of reaction of each stage. Hot-spots coalescence promotes flame propagation whose velocity reflects the violence of deflagration reaction. Jetting appearance time can be used to determine time-to-ignition more accurately than other ways. For RDX, molten phase plays an important role to the formation of the hot-spots. Multiple particles experienced more severe burning reactions than an individual particle. China National Nature Science Foundation (11572045), ``Science Challenging Program'' (JCKY2016212A501),opening fund from Safety ammunition research and Development Center (RMC2015B03).

Study of nano-nitramine explosives: preparation, sensitivity and application

Directory of Open Access Journals (Sweden)

Jie Liu

2014-06-01

Full Text Available Nano-nitramine explosives (RDX, HMX, CL-20 are produced on a bi-directional grinding mill. The scanning electron microscope (SEM observations show that the prepared particles are semi-spherical, and the narrow size distributions are characterized using the laser particle size analyzer. Compared with the micron-sized samples, the nano-products show obvious decrease in friction and impact sensitivities. In the case of shock sensitivities, nano-products have lower values by 59.9% (RDX, 56.4% (HMX, and 58.1% (CL-20, respectively. When nano-RDX and nano-HMX are used in plastic bonded explosives (PBX as alternative materials of micron-sized particles, their shock sensitivities are significantly decreased by 24.5% (RDX and 22.9% (HMX, and their detonation velocities are increased by about 1.7%. Therefore, it is expected to promote the application of nano-nitramine explosives in PBXs and composite modified double-based propellants (CMDBs so that some of their properties would be improved.

Microstructure Deformation and Fracture Mechanism of Highly Filled Polymer Composites under Large Tensile Deformation

International Nuclear Information System (INIS)

Tao Zhangjiang; Ping Songdan; Mei Zhang; Cheng Zhaipeng

2013-01-01

The microstructure deformation and fracture mechanisms of particulate-filled polymer composites were studied based on microstructure observations in this paper. By using in-situ tensile test system under scanning electron microscopy, three different composites composed of polymer binder filled by three different types of particles, namely Al particles, AP particles and HMX particles, with the same total filler content were tested. The roles of initial microstructure damage and particle type on the microstructure deformation and damage are highlighted. The results show that microstructure damage starts with the growth of the initial microvoids within the binders or along the binder/particle interfaces. With the increase of strain, the microstructure damages including debonding at the particle/binder interface and tearing of the binder lead to microvoid coalescence, and finally cause an abrupt fracture of the samples. Coarse particles lead to an increase of debonding at the particle/binder interface both in the initial state and during the loading process, and angular particles promote interface debonding during the loading process.

A thermodynamically based definition of fast verses slow heating in secondary explosives

Science.gov (United States)

Henson, Bryan; Smilowitz, Laura

2013-06-01

The thermal response of energetic materials is often categorized according to the rate of heating as either fast or slow, e.g. slow cook-off. Such categorizations have most often followed some operational rationale, without a material based definition. We have spent several years demonstrating that for the energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) a single mechanism of thermal response reproduces times to ignition independent of rate or means of heating over the entire range of thermal response. HMX is unique in that bulk melting is rarely observed in either thermal ignition or combustion. We have recently discovered a means of expressing this mechanism for HMX in a reduced form applicable to many secondary explosives. We will show that with this mechanism a natural definition of fast versus slow rates of heating emerges, related to the rate of melting, and we use this to illustrate why HMX does not exhibit melting, and why a number of other secondary explosives do, and require the two separate categories.

Shock initiation sensitivity and Hugoniot-based equation of state of Composition B obtained using in situ electromagnetic gauging

International Nuclear Information System (INIS)

Gibson, L L; Bartram, B D; Sheffield, S A; Gustavsen, R L; Brown, G W; Sandstrom, M M; Giambra, A M; Dattelbaum, D M; Handley, C A

2014-01-01

A series of gas gun-driven plate impact experiments were performed on vacuum melt-cast Composition B to obtain new Hugoniot states and shock sensitivity (run-distance-to-detonation) information. The Comp B (ρ 0 = 1.713 g/cm 3 ) consisted of 59.5% RDX, 39.5% TNT, and 1% wax, with ∼ 6.5% HMX in the RDX. The measured Hugoniot states were found to be consistent with earlier reports, with the compressibility on the shock adiabat softer than that of a 63% RDX material reported by Marsh.[4] The shock sensitivity was found to be more sensitive (shorter run distance to detonation at a given shock input condition) than earlier reports for Comp B-3 and a lower density (1.68-1.69 g/cm 3 ) Comp B formulation. The reactive flow during the shock-to-detonation transition was marked by heterogeneous, hot spot-driven growth both in and behind the leading shock front.

Gas gun experiments and numerical simulations on the HMX-based explosive PBX 9501 in the overdriven 30 to 120 GPa pressure regime

Science.gov (United States)

Pittman, E. R.; Gustavsen, R. L.; Hagelberg, C. R.; Schmidt, J. H.

2017-06-01

The focus of this set of experiments is the development of data on the Hugoniot for the overdriven products equation of state (EOS) of PBX 9501 (95 weight % HMX, 5 weight % plastic binder) and to extend data from which current computational EOS models draw. This series of shots was conducted using the two-stage gas-guns at Los Alamos and aimed to gather data in the 30 to 120 GPa pressure regime. Experiments were simulated using FLAG, a Langrangian multiphysics code, using a one-dimensional setup which employs the Wescott Stewart Davis (WSD) reactive burn model. Prior to this study, data did not extend above 90 GPa, so the new data allowed the model to be re-evaluated. A comparison of the simulations with the experimental data shows that the model fits well below 80 GPa. However, the model did not fall within the error bars of the data for higher pressures. This is an indication that the PBX 9501 overdriven EOS products model could be modified to better match the data.

Examining the effects of microstructure and loading on the shock initiation of HMX with mesoscale simulations

Science.gov (United States)

Springer, H. Keo; Tarver, Craig; Bastea, Sorin

2015-06-01

We perform reactive mesoscale simulations to study shock initiation in HMX over a range of pore morphologies and sizes, porosities, and loading conditions in order to improve our understanding of structure-performance relationships. These relationships are important because they guide the development of advanced macroscale models incorporating hot spot mechanisms and the optimization of novel energetic material microstructures. Mesoscale simulations are performed using the multiphysics hydrocode, ALE3D. Spherical, elliptical, polygonal, and crack-like pore geometries 0.1, 1, 10, and 100 microns in size and 2, 5, 10, and 14% porosity are explored. Loading conditions are realized with shock pressures of 6, 10, 20, 38, and 50 GPa. A Cheetah-based tabular model, including temperature-dependent heat capacity, is used for the unreacted and the product equation-of-state. Also, in-line Cheetah is used to probe chemical species evolution. The influence of microstructure and shock loading on shock-to-detonation-transition run distance, reaction rate and product gas species evolution are discussed. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344. This work is funded by the Joint DoD-DOE Munitions Program.

Synthesis of 14C-Labelled Octahydor-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (HMx0 and 15N-Isotopic Hexahyrro-1,3,5-Trinitro-1,3,5-Triazine (RDX) for use in Microcosm Experiments

National Research Council Canada - National Science Library

Ampleman, G

2000-01-01

Within the framework of an R & D project on bioremediation of soils contaminated with energetic compounds, the biodegradation of energetic nitramine products such as octogen (HMX) and hexogen (RDX) is under study...

Hot spot formation and chemical reaction initiation in shocked HMX crystals with nanovoids: a large-scale reactive molecular dynamics study.

Science.gov (United States)

Zhou, Tingting; Lou, Jianfeng; Zhang, Yangeng; Song, Huajie; Huang, Fenglei

2016-07-14

We report million-atom reactive molecular dynamic simulations of shock initiation of β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well as chemical reaction initiation are observed which depend on the void size and impact strength. For an impact velocity of 1 km s(-1) and a void radius of 4 nm, the void collapse process includes three stages; the dominant mechanism is the convergence of upstream molecules toward the centerline and the downstream surface of the void forming flowing molecules. Hot spot formation also undergoes three stages, and the principal mechanism is kinetic energy transforming to thermal energy due to the collision of flowing molecules on the downstream surface. The high temperature of the hot spot initiates a local chemical reaction, and the breakage of the N-NO2 bond plays the key role in the initial reaction mechanism. The impact strength and void size have noticeable effects on the shock dynamical process, resulting in a variation of the predominant mechanisms leading to void collapse and hot spot formation. Larger voids or stronger shocks result in more intense hot spots and, thus, more violent chemical reactions, promoting more reaction channels and generating more reaction products in a shorter duration. The reaction products are mainly concentrated in the developed hot spot, indicating that the chemical reactivity of the hmx crystal is greatly enhanced by void collapse. The detailed information derived from this study can aid a thorough understanding of the role of void collapse in hot spot formation and the chemical reaction initiation of explosives.

Role of additives in combustion waves and effect on stable combustion limit of double-base propellants

Energy Technology Data Exchange (ETDEWEB)

Kubota, N [Japan Defence Agency, Tachikawa. 3. Research Center

1978-12-01

The effect of additives on the flame structures and the burning rates of double-base propellants have been examined by means of photographic observations and temperature profile measurements. The additives used for this study are lead salicylate (PbSa, 2%), nickel (Ni, 1%), ammonium perchlorate (AP, 30%), and cyclotetramethylene tetranitramine (HMX, 30%). The addition of PbSa increases the burning rate, but does not improve the flame temperature characteristics. The addition of Ni increases the flame temperature significantly at pressures below 30 atm. The Ni acts as a catalyst to promote the flame reaction while it does not act as a burning rate modifier. The additions of AP and HMX increase the thermal performance of the propellant system, however, the HMX does not improve the stable combustion limit of the rocket motor at low pressures. The addition of Ni or AP is found to increase the flame temperature at pressures below 30 atm, and the stable combustion limits is lowered to below 3 atm.

Wood-based composite materials : panel products, glued-laminated timber, structural composite lumber, and wood-nonwood composite materials

Science.gov (United States)

Nicole M. Stark; Zhiyong Cai; Charles Carll

2010-01-01

This chapter gives an overview of the general types and composition of wood-based composite products and the materials and processes used to manufacture them. It describes conventional wood-based composite panels and structural composite materials intended for general construction, interior use, or both. This chapter also describes wood–nonwood composites. Mechanical...

Rocket propellants with reduced smoke and high burning rates

Energy Technology Data Exchange (ETDEWEB)

Menke, K.; Eisele, S. [Fraunhofer-Institut fuer Chemische Technologie (ICT), Pfinztal-Berghausen (Germany)

1997-07-01

Rocket propellants with reduced smoke and high burning rates recommend themselves for use in a rocket motor for high accelerating tactical missiles. They serve for an improved camouflage on the battle field and may enable guidance control due to the higher transmission of their rocket plume compared to traditional aluminized composite propellants. In this contribution the material based ranges of performance and properties of three non aluminized rocket propellants will be introduced and compared to each other. The selected formulations based on AP/HTPB; AP/PU/TMETN and AP/HMX/GAP/TMETN have roughly the same specific impulse of I{sub SP}=2430 Ns/kg at 70:1 expansion ratio. The burning rates in the pressure range from 10-18 MPa vary from to 26-33 mm/s for the AP/HTPB propellant, 52-68 mm/s for the formulation based on AP/PU/TMETN and 28-39 mm/s for the propellant based on AP/HMX/GAP. With 58% and 20% AP-contents the propellants with nitrate ester plasticizers create a much smaller secondary signature than the AP/HTPB representative containing 85% AP. Their disadvantage, however, is the connection of high performance to a high level of energetic plasticizer. For this reason, the very fast burning propellant based on AP/PU/TMETN is endowed with a low elastic modulus and is limited to a grain configuration which isn`t exposed too much to the fast and turbulent airstream. The mechanical properties of the AP/HMX/GAP-propellant are as good or better as those of the AP/HTPB propellant. The first one exhibits the same performance and burn rates as the composite representative but produces only one fifth of HCl exhaust. For this reason it is recommended for missile applications, which must have high accelerating power together with a significantly reduced plume signature and smoke production. (orig.) [Deutsch] Rauchreduzierte Festtreibstoffe mit hohen Abbrandgeschwindigkeiten bieten sich fuer den Antrieb hochbeschleunigender taktischer Flugkoerper an, da sie gegenueber

Nanocellulose based polymer composite for acoustical materials

Science.gov (United States)

Farid, Mohammad; Purniawan, Agung; Susanti, Diah; Priyono, Slamet; Ardhyananta, Hosta; Rahmasita, Mutia E.

2018-04-01

Natural fibers are biodegradable materials that are innovatively and widely used for composite reinforcement in automotive components. Nanocellulose derived from natural fibers oil palm empty bunches have properties that are remarkable for use as a composite reinforcement. However, there have not been many investigations related to the use of nanocellulose-based composites for wideband sound absorption materials. The specimens of nanocellulose-based polyester composite were prepared using a spray method. An impedance tube method was used to measure the sound absorption coefficient of this composite material. To reveal the characteristics of the nanocellulose-based polyester composite material, SEM (scanning electron microscope), TEM (Transmission Electron Microscope), FTIR (Fourier Transform Infra Red), TGA (Thermogravimetric Analysis), and density tests were performed. Sound absorption test results showed the average value of sound absorption coefficient of 0.36 to 0,46 for frequency between 500 and 4000 Hz indicating that this nanocellulose-based polyester composite materials had a tendency to wideband sound absorption materials and potentially used as automotive interior materials.

Composites Similarity Analysis Method Based on Knowledge Set in Composites Quality Control

OpenAIRE

Li Haifeng

2016-01-01

Composites similarity analysis is an important link of composites review, it can not only to declare composites review rechecking, still help composites applicants promptly have the research content relevant progress and avoid duplication. This paper mainly studies the composites similarity model in composites review. With the actual experience of composites management, based on the author’s knowledge set theory, paper analyzes deeply knowledge set representation of composites knowledge, impr...

Processing and characterization of bio-based composites

Science.gov (United States)

Lu, Hong

Much research has focused on bio-based composites as a potential material to replace petroleum-based plastics. Considering the high price of Polyhydroxyalkanoates (PHAs), PHA/ Distiller's Dried Grains with Solubles (DDGS) composite is a promising economical and high-performance biodegradable material. In this paper, we discuss the effect of DDGS on PHA composites in balancing cost with material performance. Poly (lactic acid) PLA/DDGS composite is another excellent biodegradable composite, although as a bio-based polymer its degradation time is relatively long. The goal of this research is therefore to accelerate the degradation process for this material. Both bio-based composites were extruded through a twin-screw microcompounder, and the two materials were uniformly mixed. The morphology of the samples was examined using a Scanning Electron Microscope (SEM); thermal stability was determined with a Thermal Gravimetric Analyzer (TGA); other thermal properties were studied using Differential Scanning Calorimetry (DSC) and a Dynamic Mechanical Analyzer (DMA). Viscoelastic properties were also evaluated using a Rheometer.

Macro-Fiber Composite Based Transduction

Science.gov (United States)

2016-03-01

substrate Material properties of single crystal macro fiber composite actuators for active twist rotor blades Park, Jae-Sang (Seoul National...Passive Smart Structures and Integrated Systems 2007 Material properties of single crystal macro fiber composite actuators for active twist rotor ...19b. TELEPHONE NUMBER (Include area code) 10-03-20 16 Final Report 01 Jan 2013 - 31 Dec 2015 Macro-Fiber Composite Based Transduction N000-14-13-1-0212

Composite Techniques Based Color Image Compression

Directory of Open Access Journals (Sweden)

Zainab Ibrahim Abood

2017-03-01

Full Text Available Compression for color image is now necessary for transmission and storage in the data bases since the color gives a pleasing nature and natural for any object, so three composite techniques based color image compression is implemented to achieve image with high compression, no loss in original image, better performance and good image quality. These techniques are composite stationary wavelet technique (S, composite wavelet technique (W and composite multi-wavelet technique (M. For the high energy sub-band of the 3rd level of each composite transform in each composite technique, the compression parameters are calculated. The best composite transform among the 27 types is the three levels of multi-wavelet transform (MMM in M technique which has the highest values of energy (En and compression ratio (CR and least values of bit per pixel (bpp, time (T and rate distortion R(D. Also the values of the compression parameters of the color image are nearly the same as the average values of the compression parameters of the three bands of the same image.

Correlation between Composition and Properties of Composite Material Based on Scrap Tires

OpenAIRE

Mālers, L; Plēsuma, R; Ločmele, L; Kalniņš, M

2010-01-01

Purpose of present work is to investigate mechanical and insulation properties of the composite material based on scrap tires and polyurethane-type binder in correlation with composition of composite material. The studies of material’s hardness must be considered as an express-method for estimation of the selected mechanical properties (E and ccompressive stress) of the composite material without direct experimental testing of given parameters. It was shown that composite material must be r...

Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

Directory of Open Access Journals (Sweden)

Hamid Kermanshah

2016-01-01

Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite. In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations .

Improvement in energy release properties of boron-based propellant by oxidant coating

Energy Technology Data Exchange (ETDEWEB)

Liang, Daolun; Liu, Jianzhong, E-mail: jzliu@zju.edu.cn; Chen, Binghong; Zhou, Junhu; Cen, Kefa

2016-08-20

Highlights: • NH{sub 4}ClO{sub 4}, KNO{sub 3}, KClO{sub 4} and HMX coated B were used to prepare propellant samples. • FTIR, XRD and SEM were used for the microstructure analysis of the prepared B. • Thermal oxidation and combustion characteristics of the propellants were studied. • HMX coating was the most beneficial to the energy release of the samples. - Abstract: The energy release properties of a propellant can be improved by coating boron (B) particles with oxidants. In the study, B was coated with four different oxidants, namely, NH{sub 4}ClO{sub 4}, KNO{sub 3}, LiClO{sub 4}, and cyclotetramethylenetetranitramine (HMX), and the corresponding propellant samples were prepared. First, the structural and morphological analyses of the pretreated B were carried out. Then, the thermal analysis and laser ignition experiments of the propellant samples were carried out. Coating with NH{sub 4}ClO{sub 4} showed a better performance than mechanical mixing with the same component. Coating with KNO{sub 3} efficiently improved the ignition characteristics of the samples. Coating with LiClO{sub 4} was the most beneficial in reducing the degree of difficulty of B oxidation. Coating with HMX was the most beneficial in the heat release of the samples. The KNO{sub 3}-coated sample had a very high combustion intensity in the beginning, but then it rapidly became weak. Large amounts of sparks were ejected during the combustion of the LiClO{sub 4}-coated sample. The HMX-coated sample had the longest self-sustaining combustion time (4332 ms) and the highest average combustion temperature (1163.92 °C).

Some analytical methods for explosives: Part 2

Energy Technology Data Exchange (ETDEWEB)

Selig, W.

1965-12-08

This report is the second compilation of methods for analyzing explosives. All the methods were developed for routine performance by techniques, and an attempt has therefore been made to keep them as simple as possible. Methods are presented for analyzing plastic-bonded explosives based on sym-cyclomethylenetetra-nitramine (HMX), based on viton in addition to HMX, and based on pentraerythritol tetranitrate (PETN).

Design of Composite Structures Using Knowledge-Based and Case Based Reasoning

Science.gov (United States)

Lambright, Jonathan Paul

1996-01-01

A method of using knowledge based and case based reasoning to assist designers during conceptual design tasks of composite structures was proposed. The cooperative use of heuristics, procedural knowledge, and previous similar design cases suggests a potential reduction in design cycle time and ultimately product lead time. The hypothesis of this work is that the design process of composite structures can be improved by using Case-Based Reasoning (CBR) and Knowledge-Based (KB) reasoning in the early design stages. The technique of using knowledge-based and case-based reasoning facilitates the gathering of disparate information into one location that is easily and readily available. The method suggests that the inclusion of downstream life-cycle issues into the conceptual design phase reduces potential of defective, and sub-optimal composite structures. Three industry experts were interviewed extensively. The experts provided design rules, previous design cases, and test problems. A Knowledge Based Reasoning system was developed using the CLIPS (C Language Interpretive Procedural System) environment and a Case Based Reasoning System was developed using the Design Memory Utility For Sharing Experiences (MUSE) xviii environment. A Design Characteristic State (DCS) was used to document the design specifications, constraints, and problem areas using attribute-value pair relationships. The DCS provided consistent design information between the knowledge base and case base. Results indicated that the use of knowledge based and case based reasoning provided a robust design environment for composite structures. The knowledge base provided design guidance from well defined rules and procedural knowledge. The case base provided suggestions on design and manufacturing techniques based on previous similar designs and warnings of potential problems and pitfalls. The case base complemented the knowledge base and extended the problem solving capability beyond the existence of

Formulation and properties of ADN/GAP propellants

Energy Technology Data Exchange (ETDEWEB)

Menke, Klaus; Heintz, Thomas; Schweikert, Wenka; Keicher, Thomas; Krause, Horst [Fraunhofer-Institut fuer Chemische Technologie ICT, Pfinztal (Germany)

2009-06-15

In this contribution two ways are described, how it is possible to achieve perfectly cured and processible propellants with prilled ADN, low amounts of HMX 5{mu}m mps and a binder system based on GAP diole and GAP triole oligomers with and without TMETN as a nitrate ester plasticizer. It was shown how it will be possible to suppress the strongly gas forming reaction between ADN and reactive isocyanates by a mixture of stabilizers. In this way it was possible to create minimum smoke ADN/HMX/GAP/TMETN propellants cured with the triisocyanate N100. In the second part an unconventional binder system based on the 1.3 dipolar cycloaddition reaction of azido groups with acetylene compounds forming 1,2,3-triazole heterocyclic rings has been applied for ADN/GAP and AP/GAP propellants. Together with small parts of HMX formulations with ADN/HMX/GAP and the corresponding AP/HMX/GAP exhibit high thermodynamic performance, are easily processible, and cure successfully at 60 C. Their basic properties consisting of burning behavior and mechanical properties, at ambient temperature, chemical stability, and sensitivity have been investigated and are compared to each other. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Metal-composite adhesion based on diazonium chemistry.

Science.gov (United States)

Oweis, Yara; Alageel, Omar; Kozak, Paige; Abdallah, Mohamed-Nur; Retrouvey, Jean-Marc; Cerruti, Marta; Tamimi, Faleh

2017-11-01

Composite resins do not adhere well to dental alloys. This weak bond can result in failure at the composite-metal interface in fixed dental prostheses and orthodontic brackets. The aim of this study was to develop a new adhesive, based on diazonium chemistry, to facilitate chemical bonding between dental alloys and composite resin. Samples of two types of dental alloys, stainless steel and cobalt chromium were primed with a diazonium layer in order to create a surface coating favorable for composite adhesion. Untreated metal samples served as controls. The surface chemical composition of the treated and untreated samples was analyzed by X-ray photoelectron spectroscopy (XPS) and the tensile strength of the bond with composite resin was measured. The diazonium adhesive was also tested for shear bond strength between stainless steel orthodontic brackets and teeth. XPS confirmed the presence of a diazonium coating on the treated metals. The coating significantly increased the tensile and shear bond strengths by three and four folds respectively between the treated alloys and composite resin. diazonium chemistry can be used to develop composite adhesives for dental alloys. Diazonium adhesion can effectively achieve a strong chemical bond between dental alloys and composite resin. This technology can be used for composite repair of fractured crowns, for crown cementation with resin based cements, and for bracket bonding. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

REST based service composition

DEFF Research Database (Denmark)

Grönvall, Erik; Ingstrup, Mads; Pløger, Morten

2011-01-01

This paper presents an ongoing work developing and testing a Service Composition framework based upon the REST architecture named SECREST. A minimalistic approach have been favored instead of a creating a complete infrastructure. One focus has been on the system's interaction model. Indeed, an aim...

Development of a self-compacting gypsum-based lightweight composite

NARCIS (Netherlands)

Yu, Q.; Brouwers, H.J.H.

2012-01-01

This article addresses experiments and theories of a self-compacting gypsum-based lightweight composite (SGLC). A ß-hemihydrate is used as binder and lightweight aggregate (LWA, 0–2 mm in different size ranges) is used as aggregate into this composite. The mix of the new composite is designed based

Studies of the laser-induced fluorescence of explosives and explosive compositions.

Energy Technology Data Exchange (ETDEWEB)

Hargis, Philip Joseph, Jr. (,; .); Thorne, Lawrence R.; Phifer, Carol Celeste; Parmeter, John Ethan; Schmitt, Randal L.

2006-10-01

Continuing use of explosives by terrorists throughout the world has led to great interest in explosives detection technology, especially in technologies that have potential for standoff detection. This LDRD was undertaken in order to investigate the possible detection of explosive particulates at safe standoff distances in an attempt to identify vehicles that might contain large vehicle bombs (LVBs). The explosives investigated have included the common homogeneous or molecular explosives, 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclonite or hexogen (RDX), octogen (HMX), and the heterogeneous explosive, ammonium nitrate/fuel oil (ANFO), and its components. We have investigated standard excited/dispersed fluorescence, laser-excited prompt and delayed dispersed fluorescence using excitation wavelengths of 266 and 355 nm, the effects of polarization of the laser excitation light, and fluorescence imaging microscopy using 365- and 470-nm excitation. The four nitro-based, homogeneous explosives (TNT, PETN, RDX, and HMX) exhibit virtually no native fluorescence, but do exhibit quenching effects of varying magnitude when adsorbed on fluorescing surfaces. Ammonium nitrate and fuel oil mixtures fluoresce primarily due to the fuel oil, and, in some cases, due to the presence of hydrophobic coatings on ammonium nitrate prill or impurities in the ammonium nitrate itself. Pure ammonium nitrate shows no detectable fluorescence. These results are of scientific interest, but they provide little hope for the use of UV-excited fluorescence as a technique to perform safe standoff detection of adsorbed explosive particulates under real-world conditions with a useful degree of reliability.

Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites

Directory of Open Access Journals (Sweden)

Drago Skrtic

2009-11-01

Full Text Available Our studies of amorphous calcium phosphate (ACP-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/remineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and

Biosensors Based on Ultrathin Film Composite Membranes

Science.gov (United States)

1994-01-25

composite membranes should have a number C •’ of potential advantages including fast response time, simplicity of construction, and applicability to a number...The support membrane for the ultrathin film composite was an Anopore ( Alltech Associates) microporous alumina filter, these membranes are 55 Pm thick...constant 02 concentration in this solution. Finally, one of the most important potential advantage of a sensor based on an ultrathin film composite

A comparative evaluation of microleakage of restorations using silorane-based dental composite and methacrylate-based dental composites in Class II cavities: An in vitro study

Directory of Open Access Journals (Sweden)

Jambai Sampath Kumar Sivakumar

2016-01-01

Full Text Available Aim: The aim of this in vitro study was to evaluate and compare the microleakage of restorations using low shrinkage silorane-based dental composite and methacrylate-based dental composites in Class II cavity at the occlusal and gingival margins. Materials and Methods: Sixty mandibular molars were collected and divided into three experimental groups and one negative control group. Class II slot cavity was prepared on the mesial surface. Experimental groups were restored with Group I: silorane-based microhybrid composite, Group II: methacrylate-based nanohybrid composite, and Group III: Methacrylate-based microhybrid composite, respectively. Group IV: negative control. The samples were thermocycled, root apices were sealed with sticky wax and coated with nail varnish except 1 mm around the restoration. This was followed by immersion in 2% Rhodamine-B dye solution under vacuum at room temperature for 24 h. Then, the samples were sectioned longitudinally in the mesiodistal direction and evaluated under stereomicroscope ×40 magnification. Scoring was done according to the depth of dye penetration in to the cavity. Statistical analysis of the data was done. Results: The results were that no statistically significant difference in the microleakage at the occlusal margin for all the restorative materials, whereas at the gingival margin, silorane-based microhybrid composite showed less microleakage than the methacrylate-based nano- and micro-hybrid composites. Conclusion: In general, silorane-based microhybrid composite had less microleakage among the other materials used in this in vitro study.

Characterization of fabricated cobalt-based alloy/nano bioactive glass composites

Energy Technology Data Exchange (ETDEWEB)

Bafandeh, Mohammad Reza, E-mail: mr.bafandeh@gmail.com [Department of Materials Science and Engineering, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Gharahkhani, Raziyeh; Fathi, Mohammad Hossein [Department of Materials Engineering, Isfahan University of Technology (IUT), Isfahan 84156-83111 (Iran, Islamic Republic of)

2016-12-01

In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4 weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1 week immersion in SBF. After 2 weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4 weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications. - Highlights: • Co-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared. • In order to study their bioactivity, composite samples were immersed in SBF solution for 1 to 4 weeks. • Immersion in SBF accompanied with precipitation of hydroxyapatite on surface of samples. • Prepared composite samples unlike cobalt-based alloy were bioactive.

Characterization of fabricated cobalt-based alloy/nano bioactive glass composites

International Nuclear Information System (INIS)

Bafandeh, Mohammad Reza; Gharahkhani, Raziyeh; Fathi, Mohammad Hossein

2016-01-01

In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4 weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1 week immersion in SBF. After 2 weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4 weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications. - Highlights: • Co-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared. • In order to study their bioactivity, composite samples were immersed in SBF solution for 1 to 4 weeks. • Immersion in SBF accompanied with precipitation of hydroxyapatite on surface of samples. • Prepared composite samples unlike cobalt-based alloy were bioactive.

Mechanical properties of wood-based composite materials

Science.gov (United States)

Zhiyong Cai; Robert J. Ross

2010-01-01

The term composite is used to describe any wood material bonded together with adhesives. The current product mix ranges from fiberboard to laminated beams and components. In this chapter, wood-based composite materials are classified into the following categories: panel products (plywood, oriented strandboard (OSB), particleboard, fiberboard, medium-density fiberboard...

A composite material based on recycled tires

Science.gov (United States)

Malers, L.; Plesuma, R.; Locmele, L.

2009-01-01

The present study is devoted to the elaboration and investigation of a composite material based on mechanically grinded recycled tires and a polymer binder. The correlation between the content of the binder, some technological parameters, and material properties of the composite was clarified. The apparent density, the compressive stress at a 10% strain, the compressive elastic modulus in static and cyclic loadings, and the insulating properties (acoustic and thermal) were the parameters of special interest of the present investigation. It is found that a purposeful variation of material composition and some technological parameters leads to multifunctional composite materials with different and predictable mechanical and insulation properties.

Graphene-Based Composites as Cathode Materials for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Libao Chen

2013-01-01

Full Text Available Owing to the superior mechanical, thermal, and electrical properties, graphene was a perfect candidate to improve the performance of lithium ion batteries. Herein, we review the recent advances in graphene-based composites and their application as cathode materials for lithium ion batteries. We focus on the synthesis methods of graphene-based composites and the superior electrochemical performance of graphene-based composites as cathode materials for lithium ion batteries.

Quasi-dynamic pressure and temperature

International Nuclear Information System (INIS)

Zaug, J M.; Farber, D L; Blosch, L L; Craig, I M; Hansen, D W; Aracne-Ruddle, C M; Shuh, D K

1998-01-01

The phase transformation of(beta)-HMX ( and lt; 0.5% RDX) to the(delta) phase has been studied for over twenty years and more recently with an optically sensitive second harmonic generation technique. Shock studies of the plastic binder composites of HMX have indicated that the transition is perhaps irreversible, a result that concurs with the static pressure results published by F. Goetz et al.[l] in 1978. However the stability field favors the(beta) polymorph over(delta) as pressure is increased (up to 5.4 GPa) along any sensible isotherm. In this experiment strict control of pressure and temperature is maintained while x-ray and optical diagnostics are applied to monitor the conformational dynamics of HMX. Unlike the temperature induced(beta) - and gt;(delta) transition, the pressure induced is heterogeneous in nature. The room pressure and temperature(delta) - and gt;(beta) transition is not immediate although it seems to occur over tens of hours. Transition points and kinetics are path dependent and so this paper describes our work in progress

Structural Acoustic Physics Based Modeling of Curved Composite Shells

Science.gov (United States)

2017-09-19

NUWC-NPT Technical Report 12,236 19 September 2017 Structural Acoustic Physics -Based Modeling of Curved Composite Shells Rachel E. Hesse...SUBTITLE Structural Acoustic Physics -Based Modeling of Curved Composite Shells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...study was to use physics -based modeling (PBM) to investigate wave propagations through curved shells that are subjected to acoustic excitation. An

Sustainable hemp-based composites for the building industry application

Science.gov (United States)

Schwarzova, Ivana; Stevulova, Nadezda; Junak, Jozef; Hospodarova, Viola

2017-07-01

Sustainability goals are essential driving principles for the development of innovative materials in the building industry. Natural plant (e.g. hemp) fibers represent an attractive alternative as reinforcing material due to its good properties and sustainability prerequisites. In this study, hemp-based composite materials, designed for building application as non-load bearing material, providing both thermal insulation and physico-mechanical properties, are presented. Composite materials were produced by bonding hemp hurds with a novel inorganic binder (MgO-based cement) and then were characterized in terms of physical properties (bulk density, water absorption), thermal properties (thermal conductivity) and mechanical properties (compressive and tensile strength). The composites exhibited promising physical, thermal and mechanical characteristics, generally comparable to commercially available products. In addition, the hemp-based composites have the advantage of a significantly low environmental impact (thanks to the nature of both the dispersed and the binding phase) and no negative effects on human health. All things considered, the composite materials seem like very promising materials for the building industry application.

Reduced sensitivity RDX obtained from bachmann RDX

Energy Technology Data Exchange (ETDEWEB)

Spyckerelle, Christian; Eck, Genevieve [EURENCO France, Sorgues Plant 1928 route d' Avignon, BP 311, 84706 Sorgues Cedex (France); Sjoeberg, Per; Amneus, Anna-Maria [EURENCO Sweden, SE-69186 Karlskoga (Sweden)

2008-02-15

In recent years much interest has been generated in a quality of reduced sensitivity RDX (RS-RDX), like I-RDX {sup registered} which, when incorporated in cast cure and even pressable plastic bonded explosives (PBX compositions), can confer reduced shock sensitivity as measured through gap test. At crystal level, lot of work has been done to try to determine which property or properties may explain the behaviour of the corresponding cast PBX composition. But up to now, and despite an international inter-laboratory comparison (Round Robin) of seven lots of RDX from five different manufacturers conducted from 2003 to 2005, even if some techniques lead to interesting results, there is no dedicated specification to apply to RS-RDX. This quality (I-RDX {sup registered}) has proved to retain its low sensitivity even after ageing, which does not seem to be the case for standard RDX produced by the Bachmann process (when re-crystallized under I-RDX conditions in order to obtain RS-RDX). It has been shown that the higher sensitivity of RDX produced by the Bachmann process, or the evolution of sensitivity after ageing of RS-RDX produced from Bachmann RDX may be linked to the presence of octogen (HMX) during the crystallization process. In order to check such hypothesis, low HMX content RDX produced by the Bachmann process has been prepared and evaluated in cast PBX composition (PBX N 109). Results of the characterization of such quality of RDX and its evaluation in cast PBX composition as well as ageing behaviour are presented and discussed; there are indications that removal of HMX from Bachmann RDX may lead to RS-RDX, which retains its RS character even after ageing. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

Fracture resistance of premolar teeth restored with silorane-based or dimethacrylate-based composite resins.

Science.gov (United States)

Akbarian, Golsa; Ameri, Hamideh; Chasteen, Joseph E; Ghavamnasiri, Marjaneh

2014-01-01

To restore posterior teeth using low-shrinkage composite to minimize microleakage. To compare the fracture resistance of mesio-occlusal-distal (MOD) cavity preparations restored with either low-shrinkage composite or with dimethacrylate-based composite in conjunction with cavity liners and without them. The null hypothesis of the study is that there are no differences in either fracture resistance or fracture mode between the silorane group and dimethacrylate groups with and without the use of cavity liners. Sixty maxillary premolars were divided into six groups of 10. MOD cavities were prepared in four groups: F: posterior composite (Filtek P60); GF: 0.5-mm Glass Ionomer (Fuji LC) + posterior composite; FF: 0.5-mm flowable composite (Filtek Supreme XT) + posterior composite; and S: low-shrinkage composite (Filtek P90). Negative (N) and positive (P) control groups consisted of unrestored and sound teeth, respectively. The specimens were thermocycled and loaded. Data were analyzed using analysis of variance, Tukey, and chi-square tests (α = 0.05). Groups FF (1643.09 ± 187/80 N) and GF (1596.80 ± 163/93 N) (p = 0.06 > 0.05) were statistically identical, although less than group P (1742/33 ± 110/08 N), but still demonstrated greater fracture resistance than the other groups. The fracture resistance of group S (1434/69 ± 107/62 N) was identical to GF and FF (p = 0.06 > 0.05). The fracture resistance of F (1353/19 ± 233/90 N) was less than GF and FF, and statistically identical to S (p = 0.87 > 0.05). Silorane-based composite showed a resistance to fracture similar to methacrylate-based composite restorations regardless of whether cavity liners were used. The findings of this study support the selection of silorane-based composite for the restoration of maxillary premolars with standardized Class II cavity preparations in order to strengthen the resistance to fracture to the same extent as do dimethacrylate

Enhancing durability of wood-based composites with nanotechnology

Science.gov (United States)

Carol Clausen

2012-01-01

Wood protection systems are needed for engineered composite products that are susceptible to moisture and biodeterioration. Protection systems using nano-materials are being developed to enhance the durability of wood-based composites through improved resistance to biodeterioration, reduced environmental impact from chemical leaching, and improved resistance to...

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications

Science.gov (United States)

Bao, Xiaohua; Memon, Shazim Ali; Yang, Haibin; Dong, Zhijun; Cui, Hongzhi

2017-01-01

Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural–functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs). Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles. PMID:28772823

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications

Directory of Open Access Journals (Sweden)

Xiaohua Bao

2017-04-01

Full Text Available Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural–functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs. Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles.

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications.

Science.gov (United States)

Bao, Xiaohua; Memon, Shazim Ali; Yang, Haibin; Dong, Zhijun; Cui, Hongzhi

2017-04-27

Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural-functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs). Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles.

Colloidal-based additive manufacturing of bio-inspired composites

Science.gov (United States)

Studart, Andre R.

Composite materials in nature exhibit heterogeneous architectures that are tuned to fulfill the functional demands of the surrounding environment. Examples range from the cellulose-based organic structure of plants to highly mineralized collagen-based skeletal parts like bone and teeth. Because they are often utilized to combine opposing properties such as strength and low-density or stiffness and wear resistance, the heterogeneous architecture of natural materials can potentially address several of the technical limitations of artificial homogeneous composites. However, current man-made manufacturing technologies do not allow for the level of composition and fiber orientation control found in natural heterogeneous systems. In this talk, I will present two additive manufacturing technologies recently developed in our group to build composites with exquisite architectures only rivaled by structures made by living organisms in nature. Since the proposed techniques utilize colloidal suspensions as feedstock, understanding the physics underlying the stability, assembly and rheology of the printing inks is key to predict and control the architecture of manufactured parts. Our results will show that additive manufacturing routes offer a new exciting pathway for the fabrication of biologically-inspired composite materials with unprecedented architectures and functionalities.

Repairability of CAD/CAM high-density PMMA- and composite-based polymers.

Science.gov (United States)

Wiegand, Annette; Stucki, Lukas; Hoffmann, Robin; Attin, Thomas; Stawarczyk, Bogna

2015-11-01

The study aimed to analyse the shear bond strength of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA)- and composite-based polymer materials repaired with a conventional methacrylate-based composite after different surface pretreatments. Each 48 specimens was prepared from six different CAD/CAM polymer materials (Ambarino high-class, artBloc Temp, CAD-Temp, Lava Ultimate, Telio CAD, Everest C-Temp) and a conventional dimethacrylate-based composite (Filtek Supreme XTE, control) and aged by thermal cycling (5000 cycles, 5-55 °C). The surfaces were left untreated or were pretreated by mechanical roughening, aluminium oxide air abrasion or silica coating/silanization (each subgroup n = 12). The surfaces were further conditioned with an etch&rinse adhesive (OptiBond FL) before the repair composite (Filtek Supreme XTE) was adhered to the surface. After further thermal cycling, shear bond strength was tested, and failure modes were assessed. Shear bond strength was statistically analysed by two- and one-way ANOVAs and Weibull statistics, failure mode by chi(2) test (p ≤ 0.05). Shear bond strength was highest for silica coating/silanization > aluminium oxide air abrasion = mechanical roughening > no surface pretreatment. Independently of the repair pretreatment, highest bond strength values were observed in the control group and for the composite-based Everest C-Temp and Ambarino high-class, while PMMA-based materials (artBloc Temp, CAD-Temp and Telio CAD) presented significantly lowest values. For all materials, repair without any surface pretreatment resulted in adhesive failures only, which mostly were reduced when surface pretreatment was performed. Repair of CAD/CAM high-density polymers requires surface pretreatment prior to adhesive and composite application. However, four out of six of the tested CAD/CAM materials did not achieve the repair bond strength of a conventional dimethacrylate-based

Repair Strength in Simulated Restorations of Methacrylate- or Silorane-Based Composite Resins.

Science.gov (United States)

Consani, Rafael Leonardo Xediek; Marinho, Tatiane; Bacchi, Atais; Caldas, Ricardo Armini; Feitosa, Victor Pinheiro; Pfeifer, Carmem Silvia

2016-01-01

The study verified the bond strength in simulated dental restorations of silorane- or methacrylate-based composites repaired with methacrylate-based composite. Methacrylate- (P60) or silorane-based (P90) composites were used associated with adhesive (Adper Single Bond 2). Twenty-four hemi-hourglass-shaped samples were repaired with each composite (n=12). Samples were divided according to groups: G1= P60 + Adper Single Bond 2+ P60; G2= P60 + Adper Single Bond 2 + P60 + thermocycling; G3= P90 + Adper Single Bond 2 + P60; and G4= P90 + Adper Single Bond 2 + P60 + thermocycling. G1 and G3 were submitted to tensile test 24 h after repair procedure, and G2 and G4 after submitted to 5,000 thermocycles at 5 and 55 ?#61616;C for 30 s in each bath. Tensile bond strength test was accomplished in an universal testing machine at crosshead speed of 0.5 mm/min. Data (MPa) were analyzed by two-way ANOVA and Tukey's test (5%). Sample failure pattern (adhesive, cohesive in resin or mixed) was evaluated by stereomicroscope at 30?#61655; and images were obtained in SEM. Bond strength values of methacrylate-based composite samples repaired with methacrylate-based composite (G1 and G2) were greater than for silorane-based samples (G3 and G4). Thermocycling decreased the bond strength values for both composites. All groups showed predominance of adhesive failures and no cohesive failure in composite resin was observed. In conclusion, higher bond strength values were observed in methacrylate-based resin samples and greater percentage of adhesive failures in silorane-based resin samples, both composites repaired with methacrylate-based resin.

Sisal organosolv pulp as reinforcement for cement based composites

Directory of Open Access Journals (Sweden)

Ana Paula Joaquim

2009-09-01

Full Text Available The present work describes non-conventional sisal (Agave sisalana chemical (organosolv pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

Zinc-based electrolyte compositions, and related electrochemical processes and articles

Science.gov (United States)

Kniajanski, Sergei; Soloveichik, Grigorii Lev

2018-02-20

An aqueous electrolyte composition is described, including a zinc salt based on zinc acetate or zinc glocolate. The saturation concentration of zinc in the electrolyte composition is in the range of about 2.5M to about 3.5M. The composition also contains at least one salt of a monovalent cation. The molar ratio of zinc to the monovalent cation is about 1:2. An aqueous zinc electroplating bath, containing the aqueous electrolyte composition, is also disclosed, along with a method for the electrochemical deposition of zinc onto a substrate surface, using the electroplating bath. Related flow batteries are also described, including a catholyte, as well as an anolyte based on the aqueous electrolyte composition, with a membrane between the catholyte and the anolyte.

Oxidation resistance coating for niobium base structural composites

International Nuclear Information System (INIS)

Tabaru, T.; Shobu, K.; Kim, J.H.; Hirai, H.; Hanada, S.

2003-01-01

Oxidation behavior of Al-rich Mo(Si,Al) 2 base alloys, which is a candidate material for the oxidation resistance coating on Nb base structural composites, were investigated by thermogravimetry. The Mo(Si,Al) 2 base alloys containing Mo 5 (Si,Al) 3 up to about 10 vol% exhibits excellent oxidation resistance at temperatures ranging from 780 to 1580 K, particularly at 1580 K due to continuous Al 2 O 3 layer development. To evaluate the applicability of the Mo(Si,Al) 2 base coating, plasma spraying on Nb base composites were undertaken. However, interface reaction layer was found to form during the following heat treatment. Preparation of Mo(Si,Al) 2 /Al 2 O 3 /Nb layered structures via powder metallurgical process was attempted to preclude diffusion reaction between coating and substrate. (orig.)

Base hydrolysis and hydrothermal processing of PBX-9404

International Nuclear Information System (INIS)

Flesner, R.L.; Spontarelli, T.; Dell'Orco, P.C.; Sanchez, J.A.

1994-01-01

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, the authors examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. They also examined products from the subsequent hydrothermal treatment of the base hydrolysate. The gases produced from hydrolysis of PBX-9404 are ammonia, nitrous oxide, and nitrogen. Major aqueous products are sodium formate, acetate, nitrate, and nitrite, but not all carbon products have been identified. Hydrothermal processing of base hydrolysate destroyed up to 98% of the organic carbon in solution, and higher destruction efficiencies are possible. Major gas products detected from hydrothermal processing were nitrogen and nitrous oxide

Analysis of microstructure-dependent shock dissipation and hot-spot formation in granular metalized explosive

Science.gov (United States)

Chakravarthy, Sunada; Gonthier, Keith A.

2016-07-01

Variations in the microstructure of granular explosives (i.e., particle packing density, size, shape, and composition) can affect their shock sensitivity by altering thermomechanical fields at the particle-scale during pore collapse within shocks. If the deformation rate is fast, hot-spots can form, ignite, and interact, resulting in burn at the macro-scale. In this study, a two-dimensional finite and discrete element technique is used to simulate and examine shock-induced dissipation and hot-spot formation within low density explosives (68%-84% theoretical maximum density (TMD)) consisting of large ensembles of HMX (C4H8N8O8) and aluminum (Al) particles (size ˜ 60 -360 μm). Emphasis is placed on identifying how the inclusion of Al influences effective shock dissipation and hot-spot fields relative to equivalent ensembles of neat/pure HMX for shocks that are sufficiently strong to eliminate porosity. Spatially distributed hot-spot fields are characterized by their number density and area fraction enabling their dynamics to be described in terms of nucleation, growth, and agglomeration-dominated phases with increasing shock strength. For fixed shock particle speed, predictions indicate that decreasing packing density enhances shock dissipation and hot-spot formation, and that the inclusion of Al increases dissipation relative to neat HMX by pressure enhanced compaction resulting in fewer but larger HMX hot-spots. Ensembles having bimodal particle sizes are shown to significantly affect hot-spot dynamics by altering the spatial distribution of hot-spots behind shocks.

Ontology-based composition and matching for dynamic service coordination

OpenAIRE

Pahl, Claus; Gacitua-Decar, Veronica; Wang, MingXue; Yapa Bandara, Kosala

2011-01-01

Service engineering needs to address integration problems allowing services to collaborate and coordinate. The need to address dynamic automated changes - caused by on-demand environments and changing requirements - can be addressed through service coordination based on ontology-based composition and matching techniques. Our solution to composition and matching utilises a service coordination space that acts as a passive infrastructure for collaboration. We discuss the information models an...

Development of antifriction composites based on polypyromellitimide matrix

Energy Technology Data Exchange (ETDEWEB)

Olifirov, L.K., E-mail: M80786@yandex.ru [National University of Science and Technology «MISIS» (Russian Federation); Kaloshkin, S.D.; Tcherdyntsev, V.V. [National University of Science and Technology «MISIS» (Russian Federation); Danilov, V.D. [Blagonravov Institute of Machines Science of Russian Academy of Sciences (Russian Federation)

2014-02-15

Highlights: • Polypyromellitimide powder from waste of production polyimide films were obtained. • Structure of polypyromellitimide strongly changes after high energy ball milling. • Addition of commercial polyimide powder improve moldability of polypyromellitimide. • Polypyromellitimide based composites show good tribological properties in dry friction mode. -- Abstract: A method of polypyromellitimide powder production from PM-A film was proposed and a possibility of fabricating bulk composites based on polypyromellitimide matrix was investigated. The powders were prepared by the treatment of PM-A films in a planetary ball mill. The compositions based on polypyromellitimide containing additives of Al{sub 65}Cu{sub 23}Fe{sub 12} quasicrystals, graphite, polytetrafluoroethylene and PI-PR-20 polyimide were prepared by the solid-state mixing in an IKA M20 batch mill. The bulk samples were fabricated by the compression molding technique. Thus produced materials were characterized by using the methods of sieve analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, dynamo-mechanical analysis and tribological tests. It was found that the PM-A polypyromellitimide powder had a low sinterability and, therefore, the bulk samples of unfilled PM-A and also the composites based on PM-A containing additives of Al{sub 65}Cu{sub 23}Fe{sub 12} quasicrystals, graphite and polytetrafluoroethylene exhibited a high brittleness and show unstable behavior in the tribological tests. It was found that an addition of 15 wt.% PI-PR-20 polyimide improved the sinterability of PM-A and also provides excellent antifriction properties.

Pyrotechnic countermeasures: IV. Radiometric performance of a sulphur-based Flare composition

Energy Technology Data Exchange (ETDEWEB)

Koch, Ernst-Christian [NATO Munitions Safety Information Analysis Center (MSIAC), Brussels (Belgium)

2008-10-15

Radiometric performance of a sulphur-based flare composition has been investigated. Composition comprising sulphur, potassium perchlorate and antimony sulphide has acceptable band ratio but an order of magnitude weaker spectral efficiency than typical carbon-based compositions. The use of other sulphur compounds with potential for increased performance is discussed. For part III see Ref. [1]. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

Fracture strength and fatigue resistance of dental resin-based composites

NARCIS (Netherlands)

Keulemans, F.; Palav, P.; Aboushelib, M.M.N.; van Dalen, A.; Kleverlaan, C.J.; Feilzer, A.J.

2009-01-01

Objectives: The aim of this study was to evaluate in vitro the influence of fiber-reinforcement on the fracture strength and fatigue resistance of resin-based composites. Methods: One hundred rectangular bar-shaped specimens (2 mm × 2 mm × 25 mm) made of resin-based composite were prepared in a

Soy-based fillers for thermoset composites

Science.gov (United States)

Watt, Paula

Considerable work has been done with bio-based fillers in thermoplastics. Wood dust has been used for decades in wood plastic composites in conjunction with recycled high HDPE and PET. In recent years rapidly renewable fillers derived from dried distillery grains and from wood have been introduced commercially for thermoset polymers. These fillers provide bio-content and weight reduction to thermoset molding compounds but issues with moisture absorption and polymerization inhibition have limited their commercial acceptance. The intent of this research was to develop a bio-based filler suitable for thermoset composites. This filler would provide a low density alternative to mined mineral filler, such as CaCO3 or clay. Composites made with these fillers would be lighter in weight, which is desirable for many markets, particularly transportation. Cost parity to the mineral fillers, on a volume basis, was desirable and the use of green chemistry principles was a key objective of the project. This work provides a basis from which further development of modified soy flours as fillers for thermoset composites will continue. Biomass has been evaluated as fillers for thermoset composites since the early 1980s but failed to gain commercial acceptance due to excessive water absorption and inhibition issues with free radical curing. Biomass, with a large percentage of carbohydrates, are very hydrophilic due to their abundance of hydroxyl groups, while biomass, high in lignin, resulted in inhibition of the free radical cure of the unsaturated styrenated polyester matrix systems. Generally protein use as a filler is not desirable due to its food value. Torrefaction has proved to be a good, cost effective, process to reduce hydrophilicity of high cellulose feedstock. Surprising, however, some levels of torrefaction were found to induce the inhibition effect of the filler. Scientific inquiry into this problem proved that aromatics form during the torrefaction process and can

A State of the Art Review- Methods to Evaluate Electrical Performance of Composite Cross-arms and Composite-based Pylons

DEFF Research Database (Denmark)

Wang, Qian; Bak, Claus Leth; Silva, Filipe Miguel Faria da

2016-01-01

A novel uni-body composite pylon has been proposed for 400 kV transmission lines with advantages of compacted size, friendly looking and cost competitiveness. As its configuration is quite different from the traditional lattice pylon, its electrical performance needs in-depth investigation...... and evaluation, for which electrical testing methods are essential. However, as research on composite-based pylons is still in initial stage, leaving international standards and theoretical analysis on this topic very limited, effective testing methods to evaluate the fully composite pylon’s electrical...... performance need to be studied. This paper sums up experience and key advances on testing methods to evaluate electrical performance of composite cross-arms and composite-based pylons. Based on state of the art review, several feasible testing methods that can be used to verify the feasibility of the novel...

Development of Polymethylmethacrylate Based Composite for Gas Sensing Application

OpenAIRE

Devikala, S.; Kamaraj, P.

2011-01-01

Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring and process control. Conductive polymer composites have various industrial applications. The composite prepared by mixing carbon black with polymethylmethacrylate (PMMA) has very good gas sensing applications. The gas sensors based on carbon nanotube/polymer, ceramic and metal oxide composites such as epoxy, polyimide, PMMA / Barium titanate and tin oxide have also been developed. In t...

The effect of chemical composition and granulation of Fe - based fillers on properties of metal resinous composite

International Nuclear Information System (INIS)

Janecki, J.; Dasiewicz, J.; Pawelec, Z.

2000-01-01

In this paper the authors present metal-resinous composites with Fe based fillers of various element constitution and granulation. The analysis of influence of filler type on coefficient of linear thermal expansion of composite materials was performed. Friction and wear tests (composite-bronze and composite-steel pairs) were carried out. It was stated that the thinner granulation of main filler has a positive effect on coefficient of linear thermal expansion and friction/wear characteristics. The presence of copper, nickel and molybdenum in the filler is beneficial for some properties of the composite. (author)

Innovative energy absorbing devices based on composite tubes

Science.gov (United States)

Tiwari, Chandrashekhar

Analytical and experimental study of innovative load limiting and energy absorbing devices are presented here. The devices are based on composite tubes and can be categorized in to two groups based upon the energy absorbing mechanisms exhibited by them, namely: foam crushing and foam fracturing. The device based on foam crushing as the energy absorbing mechanism is composed of light weight elastic-plastic foam filling inside an angle ply composite tube. The tube is tailored to have a high Poisson’s ratio (>20). Upon being loaded the device experiences large transverse contraction resulting in rapid decrease in diameter. At a certain axial load the foam core begins to crush and energy is dissipated. This device is termed as crush tube device. The device based upon foam shear fracture as the energy absorbing mechanism involves an elastic-plastic core foam in annulus of two concentric extension-twist coupled composite tubes with opposite angles of fibers. The core foam is bonded to the inner and outer tube walls. Upon being loaded axially, the tubes twist in opposite directions and fracture the core foam in out of plane shear and thus dissipate the energy stored. The device is termed as sandwich core device (SCD). The devices exhibit variations in force-displacement characteristics with changes in design and material parameters, resulting in wide range of energy absorption capabilities. A flexible matrix composite system was selected, which was composed of high stiffness carbon fibers as reinforcements in relatively low stiffness polyurethane matrix, based upon large strain to failure capabilities and large beneficial elastic couplings. Linear and non-linear analytical models were developed encapsulating large deformation theory of the laminated composite shells (using non-linear strain energy formulation) to the fracture mechanics of core foam and elastic-plastic deformation theory of the foam filling. The non-linear model is capable of including material and

Treatment of groundwater contaminated with low levels of military munitions

International Nuclear Information System (INIS)

Bricka, R.M.; Sharp, W.

1993-01-01

The site of interest is a military base that was established in the late 1800s. In its early history this facility was used as a powder depot to fill projectiles with miximite (a propellant). Since World War I, this facility was used to produce artillery ammunition, bombs, high explosives, pyrotechnics and other ordinances. Weapons production at this facility has ceased, but as a result of the past activities at this facility, contaminants are migrating into the groundwater. One source of drinking water for this installation is a screened well in a stratified-drift aquifer system at a depth of 75-85 feet below land surface. In the 1980s sampling of this well revealed low level contamination of trichloroethylene (TCE), RDX and HMX. TCE levels exceeded drinking water standards and an air stripping column was installed to remove the TCE. RDX and HMX, concentrations were below drinking water standards. Health Advisory (HA) levels for RDX and HMX were published by the U.S. Environmental Protection Agency (USEPA) in November 1988. The lifetime HA levels are 2 ppb and 400 ppb for RDX and HMX, respectively (McLellan et al. 1988a, and McLellan et al. 1988b). It is expected that continuous withdrawals from this well will increase RDX and HMX concentrations. In addition, it is believed that future USEPA regulations will adapt the HA as a drinking water standard. This study was initiated in an effort to have an appropriate cost effective technology ready to meet any such standard. RDX and HMX RDX and HMX are military explosives. RDX (Hexahydro-l,3,5-trinitro-l,3,5-triazine) is a code name for Research Department Explosive. This explosive is described as a white crystalline solid with about 1.3 times the explosive power of trinitrotoluene (TNT). RDX is classified as a EPA Group C compound: Possible Human Carcinogen (McLellan et. al. 1988a). HMX (Octahydro-1, 3, 5, 7- tetranitro-l, 3, 5, 7-tetrazocine) is a code name for High Melting Explosive. This explosive is described as a

Sustainable Bio-Aggregate-Based Composites Containing Hemp Hurds and Alternative Binder

Directory of Open Access Journals (Sweden)

Nadezda Stevulova

2018-02-01

Full Text Available This experimental study was focused on the application of a surface-modified hemp- hurds aggregate into composites using an alternative binder of MgO-cement. This paper presents the results of the comparative study of the parameters (chemical and physico-chemical modification, and hardening time affecting the physical (density, thermal conductivity coefficient and water-absorption behavior and mechanical properties (compressive strength of the bio-aggregate-based composite. A test of the parameters of the bio-composite samples showed some differences, which were determined by the chemical and surface properties of the modified filler, and which affected the mechanisms of hardening. The bulk density values of the hemp hurd composites hardened for 28 days place this material in the lightweight category of composites. The values of water absorption and the thermal conductivity coefficient of bio-composites decreased, and the strength parameter increased with an increase in the hardening time. The lower values of compressive strength, water absorption, and thermal conductivity coefficient (except for the ethylenediaminetetraacetic-acid-treated filler were observed in composites based on fillers chemically treated with NaOH and Ca(OH2 compared to referential composites (based on original hemp hurds. This is related to changes in the chemical composition of hemp hurds after chemical modification. The composites with ultrasound-treated hemp hurds had the greatest strengths at each hardening time. This is related to pulping the bundles of fibers and forming a larger surface area for bonding in the matrix.

Bidirectional current-voltage converters based on magnetostrictive/piezoelectric composites

NARCIS (Netherlands)

Jia, Y.; Or, S.W.; Chan, H.L.W.; Jiao, J.; Luo, H.; Van der Zwaag, S.

2009-01-01

We report a power supply-free, bidirectional electric current-voltage converter based on a coil-wound laminated composite of magnetostrictive alloy and piezoelectric crystal. An electric current applied to the coil induces a magnetic field, resulting in an electric voltage from the composite due to

Additives for cement compositions based on modified peat

Energy Technology Data Exchange (ETDEWEB)

Kopanitsa, Natalya, E-mail: kopanitsa@mail.ru; Sarkisov, Yurij, E-mail: sarkisov@tsuab.ru; Gorshkova, Aleksandra, E-mail: kasatkina.alexandra@gmail.com; Demyanenko, Olga, E-mail: angel-n@sibmail.com [Tomsk State University of Architecture and Building, 2, Solyanaya sq., Tomsk, 634003 (Russian Federation)

2016-01-15

High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

Strengthening Masonry Arches with Lime-Based Mortar Composite

Directory of Open Access Journals (Sweden)

Valerio Alecci

2017-06-01

Full Text Available In recent decades, many strengthening interventions on masonry elements were performed by using fiber reinforced polymers (FRPs. These advanced materials proved to be effective to increase the load-carrying capacity of masonry elements and to improve their structural behavior, avoiding the most critical failure modes. Despite the advantages of this technique compared to more traditional methods, FRP systems have disadvantages related to their low resistance to high temperatures, impossibility of application on wet surfaces, low permeability, and poor compatibility with masonry supports. Therefore, composite materials made of a fiber textile embedded in an inorganic matrix were recently proposed as alternatives to FRPs for strengthening historic masonry constructions. These composite materials are easier to install, have higher resistance to high temperatures, and permit higher vapor permeability than FRPs. The inorganic matrix is frequently a cement-based mortar, and the composite materials made of a fiber textile embedded in a cement-based mortar are usually identified as FRCM (fabric reinforced cementitious matrix composites. More recently, the use of natural lime mortar as an inorganic matrix has been proposed as an alternative to cement-based mortars when historic compatibility with the substrate is strictly required, as in case of restoration of historic buildings. In this paper, the effectiveness of a fabric made of basalt fibers embedded in lime mortar matrix (Basalt-FRLM for the strengthening of masonry arches is investigated. An experimental investigation was performed on 1:2 scaled brick masonry arches strengthened at the extrados with a layer of Basalt-FRLM and tested under vertical load. The results obtained are compared with previous results obtained by the authors by testing masonry arches strengthened at their extrados with FRCM and FRP composites. This investigation highlights the effectiveness of Basalt-FRLM in increasing load

The effect of explosive percentage on underwater explosion energy release of hexanitrohexaazaisowurtzitane and octogen based aluminized explosives

Directory of Open Access Journals (Sweden)

Qingjie Jiao

2018-03-01

Full Text Available To control the explosion energy output by optimizing explosive components is a key requirement in a number of different application areas. The effect of different Al/O Ratio on underwater explosion of aluminized explosives has been studied detailedly. However, the effect of explosive percentage in the same Al/O Ratio is rarely researched, especially for Hexanitrohexaazaisowurtzitane (CL-20 based aluminized explosives. In this study, we performed the underwater explosion experiments with 1.2-kilogram explosives in order to investigate the explosion energy released from CL-20 and Octogen (HMX based aluminized explosives. The percentage of the explosive varied from 5% to 30% and it is shown that: the shockwave peak pressure (pm grows gradually; shock wave energy (Es continues increasing, bubble energy (Eb increases then decreases peaking at 15% for both formulas, and the total energy (E and energy release rate (η peak at 20% for CL-20 and 15% for HMX. This paper outlines the physical mechanism of Eb change under the influence of an aluminium initial reaction temperature and reaction active detonation product percentage coupling. The result shows that CL-20 is superior as a new high explosive and has promising application prospects in the regulation of explosive energy output for underwater explosives.

The effect of explosive percentage on underwater explosion energy release of hexanitrohexaazaisowurtzitane and octogen based aluminized explosives

Science.gov (United States)

Jiao, Qingjie; Wang, Qiushi; Nie, Jianxin; Guo, Xueyong; Zhang, Wei; Fan, Wenqi

2018-03-01

To control the explosion energy output by optimizing explosive components is a key requirement in a number of different application areas. The effect of different Al/O Ratio on underwater explosion of aluminized explosives has been studied detailedly. However, the effect of explosive percentage in the same Al/O Ratio is rarely researched, especially for Hexanitrohexaazaisowurtzitane (CL-20) based aluminized explosives. In this study, we performed the underwater explosion experiments with 1.2-kilogram explosives in order to investigate the explosion energy released from CL-20 and Octogen (HMX) based aluminized explosives. The percentage of the explosive varied from 5% to 30% and it is shown that: the shockwave peak pressure (pm) grows gradually; shock wave energy (Es) continues increasing, bubble energy (Eb) increases then decreases peaking at 15% for both formulas, and the total energy (E) and energy release rate (η) peak at 20% for CL-20 and 15% for HMX. This paper outlines the physical mechanism of Eb change under the influence of an aluminium initial reaction temperature and reaction active detonation product percentage coupling. The result shows that CL-20 is superior as a new high explosive and has promising application prospects in the regulation of explosive energy output for underwater explosives.

Hybrid welding of carbon-fiber reinforced epoxy based composites

NARCIS (Netherlands)

Lionetto, Francesca; De Nicolas Morillas, M.; Pappadà, Silvio; Buccoliero, Giuseppe; Fernandez Villegas, I.; Maffezzoli, Alfonso

2018-01-01

The approach for joining thermosetting matrix composites (TSCs) proposed in this study is based on the use of a low melting co-cured thermoplastic film, added as a last ply in the stacking sequence of the composite laminate. During curing, the thermoplastic film partially penetrates in the first

Toward Improved Fidelity of Thermal Explosion Simulations

Energy Technology Data Exchange (ETDEWEB)

Nichols, A L; Becker, R; Howard, W M; Wemhoff, A

2009-07-17

We will present results of an effort to improve the thermal/chemical/mechanical modeling of HMX based explosive like LX04 and LX10 for thermal cook-off. The original HMX model and analysis scheme were developed by Yoh et.al. for use in the ALE3D modeling framework. The current results were built to remedy the deficiencies of that original model. We concentrated our efforts in four areas. The first area was addition of porosity to the chemical material model framework in ALE3D that is used to model the HMX explosive formulation. This is needed to handle the roughly 2% porosity in solid explosives. The second area was the improvement of the HMX reaction network, which included the inclusion of a reactive phase change model base on work by Henson et.al. The third area required adding early decomposition gas species to the CHEETAH material database to develop more accurate equations of state for gaseous intermediates and products. Finally, it was necessary to improve the implicit mechanics module in ALE3D to more naturally handle the long time scales associated with thermal cook-off. The application of the resulting framework to the analysis of the Scaled Thermal Explosion (STEX) experiments will be discussed.

Development of Polymethylmethacrylate Based Composite for Gas Sensing Application

Directory of Open Access Journals (Sweden)

S. Devikala

2011-01-01

Full Text Available Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring and process control. Conductive polymer composites have various industrial applications. The composite prepared by mixing carbon black with polymethylmethacrylate (PMMA has very good gas sensing applications. The gas sensors based on carbon nanotube/polymer, ceramic and metal oxide composites such as epoxy, polyimide, PMMA / Barium titanate and tin oxide have also been developed. In the present work, a new composite has been prepared by using PMMA and ammonium dihydrogen phosphate (ADP. The PMMA/Ammonium dihydrogen phosphate (PMADP composites PMADP 1 and PMADP 2 were characterized by using Powder XRD. The thick films of the composite on glass plates were prepared by using a spin coating unit at 9000 rpm. The application of the thick film as gas sensor has been studied between 0 and 2000 seconds. The results reveal that the thick film of PMADP composite can function as a very good gas sensor.

Graph-Based Semantic Web Service Composition for Healthcare Data Integration.

Science.gov (United States)

Arch-Int, Ngamnij; Arch-Int, Somjit; Sonsilphong, Suphachoke; Wanchai, Paweena

2017-01-01

Within the numerous and heterogeneous web services offered through different sources, automatic web services composition is the most convenient method for building complex business processes that permit invocation of multiple existing atomic services. The current solutions in functional web services composition lack autonomous queries of semantic matches within the parameters of web services, which are necessary in the composition of large-scale related services. In this paper, we propose a graph-based Semantic Web Services composition system consisting of two subsystems: management time and run time. The management-time subsystem is responsible for dependency graph preparation in which a dependency graph of related services is generated automatically according to the proposed semantic matchmaking rules. The run-time subsystem is responsible for discovering the potential web services and nonredundant web services composition of a user's query using a graph-based searching algorithm. The proposed approach was applied to healthcare data integration in different health organizations and was evaluated according to two aspects: execution time measurement and correctness measurement.

Anhydrous proton conductor based on composites of PEO and ATMP

International Nuclear Information System (INIS)

Sun Baoying; Qiu Xinping; Zhu Wentao

2011-01-01

A new type anhydrous PEM material based on Poly (ethylene oxide) (PEO)/Amino Trimethylene Phosphonic Acid (ATMP) composite was prepared. In this study, PEO assumed to 'grab' protons via hydrogen bond between PEO and ATMP. Based on this point, the PEO/ATMP composites were prepared firstly as the preliminary study to verify this proton conducting system. Then, PVDF was added to enhance the membrane's stability. The PVDF/PEO/ATMP composite membranes were thermally stable up to 200 o C in the studied composition ranges. The membrane had relatively compact structure by SEM images. Proton conductivity of 59% PVDF/29% PEO/12% ATMP was up to 6.71 x 10 -3 S cm -1 at 86 o C after doping with 7.9 wt% phosphoric acid without extra humidification.

[Aging of silorane- and methacrylate-based composite resins: effects on color and translucency].

Science.gov (United States)

Liu, Chang; Pan, Jie; Lin, Hong; Shen, Song

2015-10-01

To evaluate the color stability and translucency of silorane-based low shrinkage composite after in vitro aging procedures of thermal cycling and water storage respectively, and to compare with those of conventional methacrylate-based posterior composite. Three light-cured composite resins, dimethacrylate-based composite A (Filtek™ Z350), B (Filtek™ P60) and silorane-based composite C (Filtek™ P90), were tested in this study. Ten specimens (10 mm in diameter, 1 mm in height) of each composite were prepared. The ten specimens in each group were then divided into two subgroups (n = 5). One subgroup underwent thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 10 000 cycles] and the other was stored in 37 C° distilled water for 180 days. With a spectrophotometer, the CIE L * a * b * parameters of the specimens were tested before and after artificial aging against white, medium grey and black backgrounds, respectively. △E, TP and △TP were calculated and data were analyzed using independent-samples t test and partial analysis (P composite showed color alteration above the clinically acceptable levels (△E > 3.3), and also showed higher △E with a statistically significant difference in comparison with the other composites (B and C) (P composite C showed more alteration compared with composite B (P composite underwent greater alteration with regard to color stability and translucency.

Fabrication of tungsten wire reinforced nickel-base alloy composites

Science.gov (United States)

Brentnall, W. D.; Toth, I. J.

1974-01-01

Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

ROMP-based polymer composites and biorenewable rubbers

Energy Technology Data Exchange (ETDEWEB)

Jeong, Wonje [Iowa State Univ., Ames, IA (United States)

2009-01-01

This research is divided into two related topics. In the first topic, the synthesis and characterization of novel composite materials reinforced with MWCNTs by ring-opening metathesis polymerization (ROMP) is reported for two ROMP based monomers: dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene (ENB). Homogeneous dispersion of MWCNTs in the polymer matrices is achieved by grafting norbornene moieties onto the nanotube surface. For the DCPD-based system, the investigation of mechanical properties of the composites shows a remarkable increase of tensile toughness with just 0.4 wt % of functionalized MWCNTs (f-MWCNTs). To our knowledge, this represents the highest toughness enhancement efficiency in thermosetting composites ever reported. DMA results show that there is a general increase of thermal stability (rg) with the addition of f-MWCNTs, which means that covalently bonded f-MWCNTs can reduce the local chain mobility of the matrix by interfacial interactions. The ENB system also shows significant enhancement of the toughness using just 0.8 wt % f-MWCNTs. These results indicate that the ROMP approach for polyENB is also very effective. The second topic is an investigation of the biorenewable rubbers synthesized by the tandem ROMP and cationic polymerization. The resin consists of a norbornenyl-modified linseed oil and a norbornene diester. Characterization of the bio-based rubbers includes dynamic mechanical analysis, tensile testing, and thermogravimetric analysis. The experimental results show that there is a decrease in glass transition temperature and slight increase of elongation with increased diester loading.

Ceria Based Composite Membranes for Oxygen Separation

DEFF Research Database (Denmark)

Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas

2014-01-01

Mixed ionic-electronic conducting membranes for oxygen gas separation are attracting a lot of interest due to their promising potential for the pure oxygen and the syngas production. Apart from the need for a sufficiently high oxygen permeation fluxes, the prolonged stability of these membranes...... under the large oxygen potential gradients at elevated temperatures is decisive for the future applications. The gadolinium doped cerium oxide (CGO) based composite membranes are considered as promising candidates due to inherent stability of CGO phase. The CGO matrix is a main oxygen ion transporter......; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated...

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres.

Science.gov (United States)

Ozakar Ilday, Nurcan; Celik, Neslihan; Bayindir, Yusuf Ziya; Seven, Nilgün

2014-06-01

The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Radiation-resistant composite scintillators based on GSO and GPS grains

Energy Technology Data Exchange (ETDEWEB)

Boyarintsev, A.Yu. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Galunov, N.Z. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); V.N. Karasin Kharkov National University, 4 Svobody Sq., 61022 Kharkiv (Ukraine); Gerasymov, Ia.V.; Karavaeva, N.L. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Krech, A.V., E-mail: AntonKrech@gmail.com [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Levchuk, L.G.; Popov, V.F. [National Science Center, Kharkov Institute of Physics and Technology, 1 Akademicheskaya Str., 61108 Kharkiv (Ukraine); Sidletskiy, O.Ts. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine); Sorokin, P.V. [National Science Center, Kharkov Institute of Physics and Technology, 1 Akademicheskaya Str., 61108 Kharkiv (Ukraine); Tarasenko, O.A. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, 60 Nauki Avenue, 61001 Kharkiv (Ukraine)

2017-01-01

The effect of irradiation on the scintillation light output, optical transmittance, and luminescent spectra of composite scintillators based on grains of single crystals Gd{sub 2}SiO{sub 5}:Ce (GSO) and Gd{sub 2}Si{sub 2}O{sub 7}:Ce (GPS) is studied. The dielectric gel Sylgard-184 is the base and the binder for the grains inside the composite scintillator. The paper presents and analyzes the results obtained for the scintillators exposed by 10 MeV electrons from the linear electron accelerator at room temperature. The exposure doses D≤250 Mrad. The dose rate is 0.2 or 1500 Mrad/h. The study has shown that the composite scintillators based on the grains of GSO and GPS are radiation-resistant over the range of the irradiation.

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)

Problem-Based Composition: The Practical Side

Science.gov (United States)

Beckelhimer, Lisa; Hundemer, Ronald; Sharp, Judith; Zipfel, William

2007-01-01

For several years a number of instructors at the University of Cincinnati have experimented with the concept of problem-based learning (PBL) in their composition courses. The concept, rooted as it is in Socratic method and the hands-on problem-solving advocated by John Dewey, is not new, and though some of its applications may call for adjustments…

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

Anhydrous proton conductor based on composites of PEO and ATMP

Energy Technology Data Exchange (ETDEWEB)

Sun Baoying [Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Qiu Xinping, E-mail: qiuxp@tsinghua.edu.c [Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Zhu Wentao [Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 (China)

2011-04-15

A new type anhydrous PEM material based on Poly (ethylene oxide) (PEO)/Amino Trimethylene Phosphonic Acid (ATMP) composite was prepared. In this study, PEO assumed to 'grab' protons via hydrogen bond between PEO and ATMP. Based on this point, the PEO/ATMP composites were prepared firstly as the preliminary study to verify this proton conducting system. Then, PVDF was added to enhance the membrane's stability. The PVDF/PEO/ATMP composite membranes were thermally stable up to 200 {sup o}C in the studied composition ranges. The membrane had relatively compact structure by SEM images. Proton conductivity of 59% PVDF/29% PEO/12% ATMP was up to 6.71 x 10 {sup -3} S cm{sup -1} at 86 {sup o}C after doping with 7.9 wt% phosphoric acid without extra humidification.

Un Cours de composition francaise par ordinateur (A Computer-Based Course in French Composition).

Science.gov (United States)

Landes, Anne; Kaplan, Alice

1988-01-01

The origins, organization, and methods of a Columbia University course offering computer-based instruction in French composition are outlined, and the progress of four individual students is described. (MSE)

Manufacturing Technology of Composite Materials-Principles of Modification of Polymer Composite Materials Technology Based on Polytetrafluoroethylene.

Science.gov (United States)

Panda, Anton; Dyadyura, Kostiantyn; Valíček, Jan; Harničárová, Marta; Zajac, Jozef; Modrák, Vladimír; Pandová, Iveta; Vrábel, Peter; Nováková-Marcinčínová, Ema; Pavelek, Zdeněk

2017-03-31

The results of the investigations into the technological formation of new wear-resistant polymer composites based on polytetrafluoroethylene (PTFE) filled with disperse synthetic and natural compounds are presented. The efficiency of using PTFE composites reinforced with carbon fibers depends on many factors, which influence the significant improvement of physicomechanical characteristics. The results of this research allow stating that interfacial and surface phenomena of the polymer-solid interface and composition play a decisive role in PTFE composites properties. Fillers hinder the relative movement of the PTFE molecules past one another and, in this way, reduce creep or deformation of the parts, reducing the wear rate of parts used in dynamic applications as well as the coefficient of thermal expansion. The necessary structural parameters of such polymer composites are provided by regimes of process equipment.

Chemical microsensors based on polymer fiber composites

Science.gov (United States)

Kessick, Royal F.; Levit, Natalia; Tepper, Gary C.

2005-05-01

There is an urgent need for new chemical sensors for defense and security applications. In particular, sensors are required that can provide higher sensitivity and faster response in the field than existing baseline technologies. We have been developing a new solid-state chemical sensor technology based on microscale polymer composite fiber arrays. The fibers consist of an insulating polymer doped with conducting particles and are electrospun directly onto the surface of an interdigitated microelectrode. The concentration of the conducting particles within the fiber is controlled and is near the percolation threshold. Thus, the electrical resistance of the polymer fiber composite is very sensitive to volumetric changes produced in the polymer by vapor absorption. Preliminary results are presented on the fabrication and testing of the new microsensor. The objective is to take advantage of the very high surface to volume ratio, low thermal mass and linear geometry of the composite fibers to produce sensors exhibiting an extremely high vapor sensitivity and rapid response. The simplicity and low cost of a resistance-based chemical microsensor makes this sensing approach an attractive alternative to devices requiring RF electronics or time-of-flight analysis. Potential applications of this technology include battlespace awareness, homeland security, environmental surveillance, medical diagnostics and food process monitoring.

Bio-based polyurethane composite foams with inorganic fillers studied by thermogravimetry

International Nuclear Information System (INIS)

Hatakeyema, Hyoe; Tanamachi, Noriko; Matsumura, Hiroshi; Hirose, Shigeo; Hatakeyama, Tatsuko

2005-01-01

Bio-based polyurethane (PU) composite foams filled with various inorganic fillers, such as barium sulfate (BaSO 4 ), calcium carbonate (CaCO 3 ) and talc were prepared using polyols, such as diethylene glycol, triethylene glycol and polyethylene glycol (molecular weight ca. 200) containing molasses and lignin. Reactive hydroxyl groups in plant components and above polyols were used as reaction sites. Morphological observation of fracture surface of composites was carried out by scanning electron microscopy. Thermal properties of bio-based PU composites were examined by thermogravimetry. It was found that the above composites decompose in two stages reflecting decomposition of organic components. Decomposition temperature increased with increasing filler content, when plant components were homogenously mixed with inorganic fillers. Activation energy calculated by Ozawa-Wall-Flynn method was ca. 150 kJ mol -1 . The durability of composites was predicted using kinetic data. Calculated values indicate that composites with fillers are more durable than that of those without fillers at a moderate temperature region

Shape memory-based tunable resistivity of polymer composites

Energy Technology Data Exchange (ETDEWEB)

Luo, Hongsheng, E-mail: hongshengluo@163.com [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Zhou, Xingdong; Ma, Yuanyuan [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Yi, Guobin, E-mail: ygb116@163.com [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Cheng, Xiaoling [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Zhu, Yong [Shanghai Hiend Polyurethane Inc., No. 389, Jinshan District, Shanghai (China); Zu, Xihong; Zhang, Nanjun; Huang, Binghao; Yu, Lifang [Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China)

2016-02-15

Graphical abstract: Hybrid nanofillers of the CNTs and AgNPs were embedded into a shape memory polyurethane. The composites exhibited tunable conduction, which could be facially tailored by the compositions and the thermal–mechanical programming. - Highlights: • Electrically conductive polymer composites in bi-layer structure were fabricated. • The CNTs/AgNPs layer had influence on the mechanics and thermal transitions. • The conductivity could be facially tailored via a thermo-mechanical programming. • The AgNPs contents enlarged the gauge factor of the resistivity–strain curves. • Tunneling theory was suitable for simulating the strain-dependent behaviors. - Abstract: A conductive composite in bi-layer structure was fabricated by embedding hybrid nanofillers, namely carbon nanotubes (CNTs) and silver nanoparticles (AgNPs), into a shape memory polyurethane (SMPU). The CNT/AgNP-SMPU composites exhibited a novel tunable conductivity which could be facially tailored in wide range via the compositions or a specifically designed thermo-mechanical shape memory programming. The morphologies of the conductive fillers and the composites were investigated by scanning electron microscope (SEM). The mechanical and thermal measurements were performed by tensile tests and differential scanning calorimetry (DSC). By virtue of a specifically explored shape memory programming, the composites were stretched and fixed into different temporary states. The electrical resistivity (R{sub s}) varied accordingly, which was able to be stabilized along with the shape fixing. Theoretical prediction based upon the tunneling model was performed. The R{sub s}–strain curves of the composites with different compositions were well fitted. Furthermore, the relative resistivity and the Gauge factor along with the elongation were calculated. The influence of the compositions on the strain-dependent R{sub s} was disclosed. The findings provided a new avenue to tailor the conductivity

A 24-month evaluation of amalgam and resin-based composite restorations

DEFF Research Database (Denmark)

McCracken, Michael S; Gordan, Valeria V; Litaker, Mark S

2013-01-01

Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from The National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations.......Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from The National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations....

Developing a composite based elliptic spring for automotive applications

International Nuclear Information System (INIS)

Talib, Abdul Rahim Abu; Ali, Aidy; Goudah, G.; Lah, Nur Azida Che; Golestaneh, A.F.

2010-01-01

An automotive suspension system is designed to provide both safety and comfort for the vehicle occupants. In this study, finite element models were developed to optimize the material and geometry of the composite elliptical spring based on the spring rate, log life and shear stress parameters. The influence of the ellipticity ratio on the performance of woven roving-wrapped composite elliptical springs was investigated both experimentally and numerically. The study demonstrated that composite elliptical springs can be used for light and heavy trucks with substantial weight reduction. The results showed that the ellipticity ratio significantly influenced the design parameters. Composite elliptic springs with ellipticity ratios of a/b = 2 had the optimum spring parameters.

Automated geospatial Web Services composition based on geodata quality requirements

Science.gov (United States)

Cruz, Sérgio A. B.; Monteiro, Antonio M. V.; Santos, Rafael

2012-10-01

Service-Oriented Architecture and Web Services technologies improve the performance of activities involved in geospatial analysis with a distributed computing architecture. However, the design of the geospatial analysis process on this platform, by combining component Web Services, presents some open issues. The automated construction of these compositions represents an important research topic. Some approaches to solving this problem are based on AI planning methods coupled with semantic service descriptions. This work presents a new approach using AI planning methods to improve the robustness of the produced geospatial Web Services composition. For this purpose, we use semantic descriptions of geospatial data quality requirements in a rule-based form. These rules allow the semantic annotation of geospatial data and, coupled with the conditional planning method, this approach represents more precisely the situations of nonconformities with geodata quality that may occur during the execution of the Web Service composition. The service compositions produced by this method are more robust, thus improving process reliability when working with a composition of chained geospatial Web Services.

An assembly sequence planning method based on composite algorithm

Directory of Open Access Journals (Sweden)

Enfu LIU

2016-02-01

Full Text Available To solve the combination explosion problem and the blind searching problem in assembly sequence planning of complex products, an assembly sequence planning method based on composite algorithm is proposed. In the composite algorithm, a sufficient number of feasible assembly sequences are generated using formalization reasoning algorithm as the initial population of genetic algorithm. Then fuzzy knowledge of assembly is integrated into the planning process of genetic algorithm and ant algorithm to get the accurate solution. At last, an example is conducted to verify the feasibility of composite algorithm.

Highly sensitive strain sensors based on fragmentized carbon nanotube/polydimethylsiloxane composites

Science.gov (United States)

Gao, Yang; Fang, Xiaoliang; Tan, Jianping; Lu, Ting; Pan, Likun; Xuan, Fuzhen

2018-06-01

Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human–machine interfaces, etc. In this research, a type of high performance strain sensors has been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF composite particles during mechanical deformation, which causes significant resistance change in the strain sensors. The strain sensors can differentiate mechanical stimuli and monitor various human body motions, such as bending of the fingers, human breathing, and blood pulsing.

Manufacturing Technology of Composite Materials—Principles of Modification of Polymer Composite Materials Technology Based on Polytetrafluoroethylene

Directory of Open Access Journals (Sweden)

Anton Panda

2017-03-01

Full Text Available The results of the investigations into the technological formation of new wear-resistant polymer composites based on polytetrafluoroethylene (PTFE filled with disperse synthetic and natural compounds are presented. The efficiency of using PTFE composites reinforced with carbon fibers depends on many factors, which influence the significant improvement of physicomechanical characteristics. The results of this research allow stating that interfacial and surface phenomena of the polymer–solid interface and composition play a decisive role in PTFE composites properties. Fillers hinder the relative movement of the PTFE molecules past one another and, in this way, reduce creep or deformation of the parts, reducing the wear rate of parts used in dynamic applications as well as the coefficient of thermal expansion. The necessary structural parameters of such polymer composites are provided by regimes of process equipment.

Surface roughness comparison of methacrylate and silorane-based composite resins after 40% hydrogen peroxide application

Directory of Open Access Journals (Sweden)

Rori Sasmita

2018-01-01

Full Text Available The change of the tooth colour could be restored with bleaching. The tooth bleaching will affects the surface roughness of the composite resins. Recently, the material basis for composite resins has developed, among others are methacrylate-based and silorane based composite resins. The objective of this study was to distinguish the surface roughness value of methacrylate-based composite resin and silorane based composite resins. This research was quasi-experimental. The sample used in this study were methacrylate and silorane based composite resins in discs form, with the size of 6 mm and the thickness of 3 mm, manufactured into 20 specimens and divided into 2 groups. The control group was immersed in the artificial saliva, and the treatment group was applied with 40% hydrogen peroxide. The result of the experiment analyzed using unpaired sample t-test showed significant differences in the average value of the surface roughness after the application of 40% hydrogen peroxide. The average value of methacrylate and silorane based composite resins were 2.744 μm and 3.417 μm, respectively. There was a difference in the surface roughness of methacrylate and silorane based composite resin compounds after the application of 40% hydrogen peroxide. The surface roughness value of the silorane-based composite resin was higher than the methacrylate-based.

Dual light-activated microfluidic pumps based on an optopiezoelectric composite

International Nuclear Information System (INIS)

Wang, Hsin-Hu; Lee, Chih-Kung; Hsu, Yu-Hsiang; Wu, Ting-Jui; Cheng, I-Chun; Lin, Shih-Jue; Gu, Jen-Tau

2017-01-01

In this paper, a new type of microfluidic pump that can be activated and controlled by a masked light source is presented. The actuation of this micropump is based on an optopiezoelectric composite. This composite is constructed by having one of the electrodes of a piezoelectric PVDF (polyvinylidene fluoride) polymer replaced by a layer of TiOPc (titanyl phthalocyanine) photoconductive coating and an ITO (indium-tin-oxide) transparent electrode. This layer of photoconductive electrode provides the capability to activate multiple locations of this optopiezoelectric composite independently using a masked light source and a single voltage source. To verify the feasibility of this concept, dual light-activated microfluidic pumps based on this optopiezoelectric composite are implemented and studied. Experimental results verify that two microfluidic pumps can be created by one optopiezoelectric composite and that each pump can be optically turned on and off independently or be turned on simultaneously. These results suggest that integrating an optopiezoelectric composite into a lab-on-a-chip system can reduce the size and the number of driving units significantly, since every operation can be done optically and only one driving source is needed. The equivalent circuit, design, and implementation of dual light-activated optopiezoelectric micropumps are discussed in this paper. (paper)

The magnetoelectric coupling effect in multiferroic composites based on PZT–ferrite

International Nuclear Information System (INIS)

Bartkowska, J.A.

2015-01-01

In the multiferroic materials, the dielectric and magnetic properties are closely correlated through the coupling interaction between the ferroelectric and magnetic order. We attempted to determine the values of magnetoelectric coupling coefficient, from the temperature dependences of the dielectric permittivity for the ferroelectric–ferromagnetic composite PZT–ferrite type, namely PSZTC–NiZn and PBZTN–NiZn. The main component of the ferroelectric–ferromagnetic composite was PZT type powder (with ferroelectric properties), which was synthesized using sintering of a mixture of simple oxides in solid phase. The second element of the ferroelectric–ferromagnetic composite was the ferrite powder (with ferromagnetic properties). Ferrite powder was synthesized using calcination. Next, the mixed components were synthesized using sintering of the mixture of simple oxides in a solid phase (compaction by a free sintering method). The temperature dependences of the dielectric permittivity (ε) for the different frequencies and for both multiferroic composites were investigated. Based on dielectric measurements and theoretical considerations, the values of the magnetoelectric coupling coefficient were specified. - Highlights: • The magnetoelectric effect at two different ferroelectric–ferromagnetic composites based on a PZT and nickel–zinc ferrite. • Multiferroics composite incorporate both ferroelectric and magnetic phases. • The mechanism of the magnetoelectric coupling between ferroelectric and magnetic properties, in multiferroic composites, is caused by the strain. • The determination of the magnetoelectric coupling coefficient based on a theoretical model and the measurements of dielectric permittivity

The magnetoelectric coupling effect in multiferroic composites based on PZT–ferrite

Energy Technology Data Exchange (ETDEWEB)

Bartkowska, J.A., E-mail: joanna.bartkowska@us.edu.pl

2015-01-15

In the multiferroic materials, the dielectric and magnetic properties are closely correlated through the coupling interaction between the ferroelectric and magnetic order. We attempted to determine the values of magnetoelectric coupling coefficient, from the temperature dependences of the dielectric permittivity for the ferroelectric–ferromagnetic composite PZT–ferrite type, namely PSZTC–NiZn and PBZTN–NiZn. The main component of the ferroelectric–ferromagnetic composite was PZT type powder (with ferroelectric properties), which was synthesized using sintering of a mixture of simple oxides in solid phase. The second element of the ferroelectric–ferromagnetic composite was the ferrite powder (with ferromagnetic properties). Ferrite powder was synthesized using calcination. Next, the mixed components were synthesized using sintering of the mixture of simple oxides in a solid phase (compaction by a free sintering method). The temperature dependences of the dielectric permittivity (ε) for the different frequencies and for both multiferroic composites were investigated. Based on dielectric measurements and theoretical considerations, the values of the magnetoelectric coupling coefficient were specified. - Highlights: • The magnetoelectric effect at two different ferroelectric–ferromagnetic composites based on a PZT and nickel–zinc ferrite. • Multiferroics composite incorporate both ferroelectric and magnetic phases. • The mechanism of the magnetoelectric coupling between ferroelectric and magnetic properties, in multiferroic composites, is caused by the strain. • The determination of the magnetoelectric coupling coefficient based on a theoretical model and the measurements of dielectric permittivity.

Highly sensitive strain sensors based on fragmentized carbon nanotube/polydimethylsiloxane composites.

Science.gov (United States)

Gao, Yang; Fang, Xiaoliang; Tan, Jianping; Lu, Ting; Pan, Likun; Xuan, Fuzhen

2018-06-08

Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human-machine interfaces, etc. In this research, a type of high performance strain sensors has been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF sensors is ascribed to the sliding of individual fragmentized-CNT/PDMS-composite particles during mechanical deformation, which causes significant resistance change in the strain sensors. The strain sensors can differentiate mechanical stimuli and monitor various human body motions, such as bending of the fingers, human breathing, and blood pulsing.

Supercapacitors based on flexible graphene/polyaniline nanofiber composite films.

Science.gov (United States)

Wu, Qiong; Xu, Yuxi; Yao, Zhiyi; Liu, Anran; Shi, Gaoquan

2010-04-27

Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 x 10(2) S m(-1)) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g(-1)) at a discharge rate of 0.3 A g(-1). They also exhibited greatly improved electrochemical stability and rate performances.

Tungsten-based composite materials for fusion reactor shields

International Nuclear Information System (INIS)

Greenspan, E.; Karni, Y.

1985-01-01

Composite tungsten-based materials were recently proposed for the heavy constituent of compact fusion reactor shields. These composite materials will enable the incorporation of tungsten - the most efficient nonfissionable inelastic scattering (as well as good neutron absorbing and very good photon attenuating) material - in the shield in a relatively cheap way and without introducing voids (so as to enable minimizing the shield thickness). It is proposed that these goals be achieved by bonding tungsten powder, which is significantly cheaper than high-density tungsten, with a material having the following properties: good shielding ability and relatively low cost and ease of fabrication. The purpose of this work is to study the effectiveness of the composite materials as a function of their composition, and to estimate the economic benefit that might be gained by the use of these materials. Two materials are being considered for the binder: copper, second to tungsten in its shielding ability, and iron (or stainless steel), the common fusion reactor shield heavy constituent

Phase Change Insulation for Energy Efficiency Based on Wax-Halloysite Composites

International Nuclear Information System (INIS)

Zhao, Yafei; Thapa, Suvhashis; Weiss, Leland; Lvov, Yuri

2014-01-01

Phase change materials (PCMs) have gained extensive attention in thermal energy storage. Wax can be used as a PCM in solar storage but it has low thermal conductivity. Introducing 10% halloysite admixed into wax yields a novel composite (wax-halloysite) which has a thermal conductivity of 0.5 W/mK. To increase the base conductivity, graphite and carbon nanotubes were added into the PCM composite improving its thermal energy storage. Thermal conductivity of wax-halloysite-graphite (45/45/10%) composite showed increased conductivity of 1.4 W/mK (3 times higher than the base wax-halloysite composite). Wax- halloysite-graphite-carbon nanotubes (45/45/5/5%) composite showed conductivity of 0.85 W/mK while maintaining the original shape perfectly until 91 °C (above the original wax melting point). Thermal conductivity can be further increased with higher doping of carbon nanotubes. This new composites are promising heat storage material due to good thermal stability, high thermal/electricity conductivity and ability to preserve its shape during phase transitions

Structure and properties of compositions based on petroleum sulfonic acids

Energy Technology Data Exchange (ETDEWEB)

Tutorskii, I.A.; Sultanova, A.S.; Belkina, E.V.; Fomin, A.G. [Lomonosov Academy of Fine Chemical Technology, Moscow (Russian Federation)

1995-03-01

Colloidal characteristics of compositions based on petroleum sulfonic acids were studied. Neutralized heavy oil residue exhibits surface-active properties and contains an ultradisperse filler. Analysis of the compositions by size-exclusion-chromatography shows deep structural changes in the heavy acid residue upon neutralization with calcium carbonate.

Tungsten wire-nickel base alloy composite development

Science.gov (United States)

Brentnall, W. D.; Moracz, D. J.

1976-01-01

Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W-Hf-C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/square meters (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics.

Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR Ceramifiable Composites

Directory of Open Access Journals (Sweden)

Rafał Anyszka

2016-07-01

Full Text Available Ceramifiable styrene-butadiene (SBR-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.

THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

Directory of Open Access Journals (Sweden)

Romildo Dias Tolêdo Filho

1999-08-01

Full Text Available ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre reinforced, cement based matrices is reported and experimental data are provided to illustrate the performance of sisal fibre reinforced cement composites. A brief description on the use of these composite materials as building products has been included. The influence of sisal fibres on the development of plastic shrinkage in the pre-hardened state, on tensile, compressive and bending strength in the hardened state of mortar mixes is discussed. Creep and drying shrinkage of the composites and the durability of natural fibres in cement based matrices are of particular interest and are also highlighted. The results show that the composites reinforced with sisal fibres are reliable materials to be used in practice for the production of structural elements to be used in rural and civil construction. This material could be a substitute asbestos-cement composite, which is a serious hazard to human and animal health and is prohibited in industrialized countries. The

Evaluation of Thermal and Thermomechanical Behaviour of Bio-Based Polyamide 11 Based Composites Reinforced with Lignocellulosic Fibres

Directory of Open Access Journals (Sweden)

Helena Oliver-Ortega

2017-10-01

Full Text Available In this work, polyamide 11 (PA11 and stone ground wood fibres (SGW were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of PA11-based composites were studied. Natural fibres have lower degradation temperatures than PA11, thus, composites showed lower onset degradation temperatures than PA11, as well. The thermal transition and the semi-crystalline structure of the composites were similar to PA11. On the other hand, when SGW was submitted to an annealing treatment, the composites prepared with these fibres increased its crystallinity, with increasing fibre contents, compared to PA11. The differences between the glass transition temperatures of annealed and untreated composites decreased with the fibre contents. Thus, the fibres had a higher impact in the composites mechanical behaviour than on the mobility of the amorphous phase. The crystalline structure of PA11 and PA11-SGW composites, after annealing, was transformed to α’ more stable phase, without any negative impact on the properties of the fibres.

X-ray based micromechanical finite element modeling of composite materials

DEFF Research Database (Denmark)

Mikkelsen, Lars Pilgaard; Emerson, Monica Jane; Jespersen, Kristine Munk

2016-01-01

This is a study of a uni-directional non-crimp fabric reinforced epoxy composite material typically used as the load carrying laminate in wind turbine blades. Based on a 3D xray tomography scan, the bundle and fibre/matrix structure of the composite is segmented. This segmentation is used...

Characterization of composite materials based on cement-ceramic powder blended binder

Science.gov (United States)

Kulovaná, Tereza; Pavlík, Zbyšek

2016-06-01

Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

Science.gov (United States)

Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

2017-08-01

Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

Preparation and Properties of Silver Nanowire-Based Transparent Conductive Composite Films

Science.gov (United States)

Tian, Ji-Li; Zhang, Hua-Yu; Wang, Hai-Jun

2016-06-01

Silver nanowire-based transparent conductive composite films with different structures were successfully prepared using various methods, including liquid polyol, magnetron sputtering and spin coating. The experimental results revealed that the optical transmittance of all different structural composite films decreased slightly (1-3%) compared to pure films. However, the electrical conductivity of all composite films had a great improvement. Under the condition that the optical transmittance was greater than 78% over the wavelength range of 400-800 nm, the AgNW/PVA/AgNW film became a conductor, while the AZO/AgNW/AZO film and the ITO/AgNW/ITO film showed 88.9% and 94% reductions, respectively, for the sheet resistance compared with pure films. In addition, applying a suitable mechanical pressure can improve the conductivity of AgNW-based composite films.

Thermal analysis and microstructure of hexaperrite based magnet composite with natural rubber matrix

International Nuclear Information System (INIS)

Sudirman; Ridwan; Jamilah; Trijono, Waluyo

2000-01-01

Thermal and microstructure analyse of hexa ferrite based on composite magnets with natural rubber matrix have been done to investigate their performance. Such magnets play an important role in the toy and house-hold industries because of their suitable magnetic properties, low cost, lightness and flexibility. The composite magnets were synthesized by blending the ferrite powder and natural rubber at composition 30%-70% rubber volume. The microstructure and thermal behaviour of the composite were examined by using SEM and OTA/TGA. The result show that the natural rubber swelling is optimally at 181,17 o C, which is the recommended top condition for blending. The performance magnet composite is limited by the change of natural rubber properties which decompose at temperature around 400 o C. In the decomposition process, the natural rubber molecule trapped in a composite system based on BaM is more difficult are more compared to the composite system based on SrM because the BaM system particle microstructure and its distribution more homogeneous

On the elastic properties of carbon nanotube-based composites: modelling and characterization

CERN Document Server

Thostenson, E T

2003-01-01

The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon nanotube strongly influences the overall properties of the composite. The focus of this research is to develop a fundamental understanding of the structure/size influence of carbon nanotubes on the elastic properties of nanotube-based composites. Towards this end, the nanoscale structure and elastic properties of a model composite system of aligned multi-walled carbon nanotubes embedded in a polystyrene matrix were characterized, and a micromechanical approach for modelling of short fibre composites was modified to account for the structure of the nanotube reinforcement to predict the elastic modulus of the nanocomposite as a function of the constituent properties, reinforcement geometry and nanot...

Effect of preheat repetition on color stability of methacrylate- and silorane-based composite resins.

Science.gov (United States)

Abed Kahnamouei, Mehdi; Gholizadeh, Sarah; Rikhtegaran, Sahand; Daneshpooy, Mehdi; Kimyai, Soodabeh; Alizadeh Oskoee, Parnian; Rezaei, Yashar

2017-01-01

Background. The aim of this study was to investigate the effect of preheating methacrylate- and silorane-based composite resins on their color stability up to 40 times at 55‒60°C. Methods. Seventy-six methacrylate and silorane-based composite resin samples, with a diameter of 10 mm and a height of 2 mm, were divided into 4 groups (n=19). After the samples were prepared, their color parameters were determined using a reflective spectrophotometer. The composite resin samples were separately stored in a solution of tea for 40 consecutive days. Then the samples underwent a color determination procedure again using a spectrophotometer and color changes were recorded. Finally two-way ANOVA was used to study the effect of composite temperature on its staining (Pcomposite resin samples compared to non-heated samples at P=0.005 and P=0.029 for silorane-based and Z250 composite resin samples, respectively. Results. Both composite resin type (P=0.014) and preheating (Pcomposite resin samples, up to 55‒60°C for 40 rounds, resulted in more color changes compared with unheated composite resin samples. After storage in a solution of tea the color change rate in the composite resin samples of silorane-based was higher than the Z250 composite resin samples.

Ignition criterion for heterogeneous energetic materials based on hotspot size-temperature threshold

Science.gov (United States)

Barua, A.; Kim, S.; Horie, Y.; Zhou, M.

2013-02-01

A criterion for the ignition of granular explosives (GXs) and polymer-bonded explosives (PBXs) under shock and non-shock loading is developed. The formulation is based on integration of a quantification of the distributions of the sizes and locations of hotspots in loading events using a cohesive finite element method (CFEM) developed recently and the characterization by Tarver et al. [C. M. Tarver et al., "Critical conditions for impact- and shock-induced hot spots in solid explosives," J. Phys. Chem. 100, 5794-5799 (1996)] of the critical size-temperature threshold of hotspots required for chemical ignition of solid explosives. The criterion, along with the CFEM capability to quantify the thermal-mechanical behavior of GXs and PBXs, allows the critical impact velocity for ignition, time to ignition, and critical input energy at ignition to be determined as functions of material composition, microstructure, and loading conditions. The applicability of the relation between the critical input energy (E) and impact velocity of James [H. R. James, "An extension to the critical energy criterion used to predict shock initiation thresholds," Propellants, Explos., Pyrotech. 21, 8-13 (1996)] for shock loading is examined, leading to a modified interpretation, which is sensitive to microstructure and loading condition. As an application, numerical studies are undertaken to evaluate the ignition threshold of granular high melting point eXplosive, octahydro-1,3,5,7-tetranitro-1,2,3,5-tetrazocine (HMX) and HMX/Estane PBX under loading with impact velocities up to 350 ms-1 and strain rates up to 105 s-1. Results show that, for the GX, the time to criticality (tc) is strongly influenced by initial porosity, but is insensitive to grain size. Analyses also lead to a quantification of the differences between the responses of the GXs and PBXs in terms of critical impact velocity for ignition, time to ignition, and critical input energy at ignition. Since the framework permits

Fabrication of polypeptide-based piezoelectric composite polymer film

International Nuclear Information System (INIS)

Farrar, Dawnielle; West, James E.; Busch-Vishniac, Ilene J.; Yu, Seungju M.

2008-01-01

A new class of molecular composite piezoelectric material was produced by simultaneous poling and curing of a homogeneous solution comprising poly(γ-benzyl α,L-glutamate) and methylmethacrylate via corona discharge methods. This film exhibited high piezoelectricity (d 33 = 23 pC N -1 ), and its mechanical characteristics (modulus = 450 MPa) were similar to those of low molecular weight poly(methylmethacrylate). As it is produced via solution-based fabrication processes, the composite film is conducive to miniaturization for small sensors with integrated electronics, and could also potentially be used in piezoelectric coating applications

Micro-tribological properties of hydroxyapatite-based composites in dry sliding

International Nuclear Information System (INIS)

Lu, Zhi; Liu, Yong; Liu, Bowei; Liu, Meiling

2013-01-01

Highlights: ► The micro-tribological properties of HA-based composites were investigated. ► The micro-scale test is greatly benefits to the analyses of the wear mechanism. ► A higher speed benefits the formation of the lubricating layer, when high in Cu. ► With increasing Cu, the wear mechanism shift from abrasive wear to adhesive wear. - Abstract: The micro-tribological properties of hydroxyapatite-based composites sliding against alumina balls were investigated by a ball-on-block tribometer. Surface properties of the HA-based composites were measured and examined by using atomic force microscopy and scanning electron microscopy. Running-in behavior during sliding tests was studied as a function of surface properties. The effects of copper fibers, initial surface roughness, and sliding velocity on the friction coefficient and the wear resistance were discussed. Results show that a lubricant layer benefits the tribological properties of the composites. With the increasing of Cu, the lubricant layer is more stable, and resistant to increase of the sliding velocity. At a Cu content of 15%, the wear curve is very stable even at a velocity of 900 rpm. The wear mechanism also changes from abrasive wear to adhesive wear. A model was quoted to describe the relationship between the wear resistant and the load

On possibility of fabrication of monolith composite materials on niobium carbide base

International Nuclear Information System (INIS)

Ploshkin, V.V.; Ul'yanina, I.Yu.; Filonenko, V.P.

1984-01-01

An attempt was made to fabricate the composite material on niobium carbide base possessing the elevated heat resistance, erosion and chemical resistance in special media, as well as capable of withstanding sufficient thermal shocks. Powder of niobium carbide of 10 μm fraction was used as base material, the powder of pure copper of 10...12 μm fraction - as binder. It was shown that samples of composite mateiral on niobium carbide base fabricated by the method of hydrostatic pressing possessed the minimal porosity as compared to samples fabricated by usual methods of powder metallurgy. The basic phases of composite material-copper and niobium carbide - distribute uniformly over sample cross-section and don't interact with each other under any conditions. The fabricated composite material possesses sufficient thermal shock resistance and isn't subjected to brittle fracture

Poly(lactic acid Composites Containing Carbon-Based Nanomaterials: A Review

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Carolina Gonçalves

2017-07-01

Full Text Available Poly(lactic acid (PLA is a green alternative to petrochemical commodity plastics, used in packaging, agricultural products, disposable materials, textiles, and automotive composites. It is also approved by regulatory authorities for several biomedical applications. However, for some uses it is required that some of its properties be improved, namely in terms of thermo-mechanical and electrical performance. The incorporation of nanofillers is a common approach to attain this goal. The outstanding properties of carbon-based nanomaterials (CBN have caused a surge in research works dealing with PLA/CBN composites. The available information is compiled and reviewed, focusing on PLA/CNT (carbon nanotubes and PLA/GBM (graphene-based materials composites. The production methods, and the effects of CBN loading on PLA properties, namely mechanical, thermal, electrical, and biological, are discussed.

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.

New biodegradable air-entraining admixture based on LAS for cement-based composites

International Nuclear Information System (INIS)

Mendes, J.C.; Moro, T.K.; Dias, L.S.; Campos, P.A.M.; Silva, G.J.B.; Peixoto, R.A.F.; Cury, A.A.

2016-01-01

The active principle of Air Entraining Admixtures (AEA) are surfactants, analogously to washing up liquids. Washing up (or dishwashing) liquids are widely available products, relatively inexpensive, non-toxic and biodegradable, thus presenting smaller environmental impact. Therefore, the present work proposes the use of a biodegradable surfactant comprised in washing up liquids, Linear Alkylbenzene Sulfonate (LAS), as sustainable air entraining agent for cement-based composites. In this sense, a performance evaluation of the proposed AEA is carried out, by comparing the properties of mortars with proposed AEA, commercial AEA and ones without any admixture. Through the physical, mechanical and microstructural analysis, it was possible to determine the efficiency of the proposed AEA, as well as its optimum range of dosage. As a result, we seek to contribute to the technical development of cement-based composites in Brazil and in the world. (author)

Compositional descriptor-based recommender system for the materials discovery

Science.gov (United States)

Seko, Atsuto; Hayashi, Hiroyuki; Tanaka, Isao

2018-06-01

Structures and properties of many inorganic compounds have been collected historically. However, it only covers a very small portion of possible inorganic crystals, which implies the presence of numerous currently unknown compounds. A powerful machine-learning strategy is mandatory to discover new inorganic compounds from all chemical combinations. Herein we propose a descriptor-based recommender-system approach to estimate the relevance of chemical compositions where crystals can be formed [i.e., chemically relevant compositions (CRCs)]. In addition to data-driven compositional similarity used in the literature, the use of compositional descriptors as a prior knowledge is helpful for the discovery of new compounds. We validate our recommender systems in two ways. First, one database is used to construct a model, while another is used for the validation. Second, we estimate the phase stability for compounds at expected CRCs using density functional theory calculations.

Size and Base Composition of RNA in Supercoiled Plasmid DNA

Science.gov (United States)

Williams, Peter H.; Boyer, Herbert W.; Helinski, Donald R.

1973-01-01

The average size and base composition of the covalently integrated RNA segment in supercoiled ColE1 DNA synthesized in Escherichia coli in the presence of chloramphenicol (CM-ColE1 DNA) have been determined by two independent methods. The two approaches yielded similar results, indicating that the RNA segment in CM-ColE1 DNA contains GMP at the 5′ end and comprises on the average 25 to 26 ribonucleotides with a base composition of 10-11 G, 3 A, 5-6 C, and 6-7 U. PMID:4359488

SORPTION AND SOLUBILITY OF LOW-SHRINKAGE RESIN-BASED DENTAL COMPOSITES

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Sevda Yantcheva

2016-04-01

Full Text Available Background: Resin-based composites are well-established restorative materials. However, these materials may absorb significant amounts of water when exposed to aqueous environments. Sorption and solubility are affecting composite restorations by two different mechanisms; the first is the up taking of water producing an increased weight and the second is the dissolution of materials in water, leading to a weight reduction of the final conditioned samples. Objective: To measure the water sorption and solubility of different low-shrinkage resin-based composites. Six materials were selected: Filtek P60, Filtek Ultimate, SonicFill, Filtek Silorane, Kalore and Venus Diamond. Materials and methods: Five disc specimens were prepared of each material and polymerized with diode light-curing unit. Water sorption and solubility of the different materials were were calculated by means of weighting the samples before and after water immersion and desiccation. Data were statistically analyzed using Shapiro-Wilk One Way Analysis of Variance followed by the Holm-Sidak comparison test . Results: There were significant differences (p<=0.001 between materials regarding sorption and solubility. Regarding sorption F. Silorane showed lowest values, followed by SonicFill, without significant difference between them. Statistical significant differences exist between F. Silorane and F.P60, F. Ultimate, Kalore. Significant differences exist between SonicFill and F. Ultimate. F.Silorane (-0.018 and Kalore (-0.010 showed lowest values of solubility but there were marginal difference among all composites investigated. Conclusions: 1.The material with lowest values of sorption and solubility was F.Silorane. 2. The attained sorption and solubility values for composites are influenced by the differences in resin matrix composition and filler contend. 3. Modifications of dimethacrylate matrix did not minimize significantly sorption and solubility of composites. 4. Besides water

The potential of wood-based composite poles

Science.gov (United States)

Todd F. Shupe; Cheng Piao; Chung Y. Hse

2009-01-01

Wood-based composite utility poles are receiving increasing attention in the North American pole market. This interest is being driven by many increasing factors such as increasing: (1) disposal costs of solid wood poles, (2) liability and environmental concerns with traditional means of disposal of solid wood poles, (3) cost and concerns of long-term...

Fe-based composite materials with improved mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Werniewicz, Katarzyna [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland); Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland)

2008-07-01

Following a previous study by the authors two new compositions (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 91}C{sub 9} and (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} have been developed with the aim of improving the ductility of Fe{sub 65.5}Cr{sub 4}Mo{sub 4}Ga{sub 4}P{sub 12}C{sub 5}B{sub 5.5} bulk metallic glass (BMG). In contrast to the alloys in that study, the recently prepared Fe-based materials are Ga-free. It was expected that the variations in the composition will lead to the changes in the phase formation and, hence, in the mechanical response of the investigated alloys. It was recognized that in-situ formed Fe-based composites show superior plasticity ({epsilon}{sub pl}{approx}37%) for the alloy with lower C content and ({epsilon}{sub pl}{approx}4%) for the alloy with higher C content compared to monolithic glass ({epsilon}{sub pl}{approx}0.2%). Furthermore, on the basis of present as well as previous investigations it has been shown that the Ga addition is beneficial for the plasticity of these Fe-based alloys. It was observed that the (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} alloy exhibits a significantly smaller fracture strain ({epsilon}{sub f}{approx}5%) compared to its Ga-containing counterpart ({epsilon}{sub f}{approx}16%). Therefore, it can be concluded that appropriate alloying additions are crucial in enhancing the mechanical properties of the complex Fe-based materials developed here.

Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

Science.gov (United States)

Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

2015-12-01

The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

A Process Mining Based Service Composition Approach for Mobile Information Systems

Directory of Open Access Journals (Sweden)

Chengxi Huang

2017-01-01

Full Text Available Due to the growing trend in applying big data and cloud computing technologies in information systems, it is becoming an important issue to handle the connection between large scale of data and the associated business processes in the Internet of Everything (IoE environment. Service composition as a widely used phase in system development has some limits when the complexity of relationship among data increases. Considering the expanding scale and the variety of devices in mobile information systems, a process mining based service composition approach is proposed in this paper in order to improve the adaptiveness and efficiency of compositions. Firstly, a preprocessing is conducted to extract existing service execution information from server-side logs. Then process mining algorithms are applied to discover the overall event sequence with preprocessed data. After that, a scene-based service composition is applied to aggregate scene information and relocate services of the system. Finally, a case study that applied the work in mobile medical application proves that the approach is practical and valuable in improving service composition adaptiveness and efficiency.

Room temperature humidity sensor based on polyaniline-tungsten disulfide composite

Science.gov (United States)

Manjunatha, S.; Chethan, B.; Ravikiran, Y. T.; Machappa, T.

2018-05-01

Polyaniline-tungsten disulfide (PANI-WS2) composite was synthesized using in situ polymerization technique by adding finely grinded powder of WS2 during the polymerization of aniline. Field emission scanning electron microscopy (FESEM) images showed the granular morphology with porous nature. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of carbon, nitrogen, chlorine of PANI, tungsten and sulfur elements of WS2. Humidity sensing property of the composite was investigated by plotting change in its resistance with different relative humidity environments ranging from 10 to 97% RH. Decrease in resistance of the composite was observed with increase in relative humidity. Maximum sensing response of the composite was found to be 88.46%. Response and recovery times of the composite at 97%RH were fair enough to fabricate a sensor based on it. Stability of the composite with respect to the humidity sensing behavior was observed to be unchanged even after two months.

Deuterium isotope effects in condensed-phase thermochemical decomposition reactions of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine

International Nuclear Information System (INIS)

Shackelford, S.A.; Coolidge, M.B.; Goshgarian, B.B.; Loving, B.A.; Rogers, R.N.; Janney, J.L.; Ebinger, M.H.

1985-01-01

The deuterium isotope effect was applied to condensed-phase thermochemical reactions of HMX and HMX-d 8 by using isothermal techniques. Dissimilar deuterium isotope effects revealed a mechanistic dependence of HMX upon different physical states which may singularly predominate in a specific type of thermal event. Solid-state HMX thermochemical decomposition produces a primary deuterium isotope effect (DIE), indicating that covalent C-H bond rupture is the rate-controlling step in this phase. An apparent inverse DIE is displayed by the mixed melt phase and can be attributed to C-H bond contraction during a weakening of molecular lattice forces as the solid HMX liquefies. The liquid-state decomposition rate appears to be controlled by ring C-N bond cleavage as evidenced by a secondary DIE and higher molecular weight products. These results reveal a dependence of the HMX decomposition process on physical state and lead to a broader mechanistic interpretation which explains the seemingly contradictory data found in current literature reviews. 33 references, 9 figures, 5 tables

Experimental Characterization of Aluminum-Based Hybrid Composites Obtained Through Powder Metallurgy

Science.gov (United States)

Marcu, D. F.; Buzatu, M.; Ghica, V. G.; Petrescu, M. I.; Popescu, G.; Niculescu, F.; Iacob, G.

2018-06-01

The paper presents some experimental results concerning fabrication through powder metallurgy (P/M) of aluminum-based hybrid composites - Al/Al2O3/Gr. In order to understand the mechanisms that occur during the P/M processes of obtaining Al/Al2O3/Gr composite, we correlated the physical characteristics with their micro-structural characteristics. The characterization was performed using analysis techniques specific for P/M process, SEM-EDS and XRD analyses. Micro-structural characterization of the composites has revealed fairly uniform distribution this resulting in good properties of the final composite material.

Wettability and interface considerations in advanced heat-resistant Ni-base composites

International Nuclear Information System (INIS)

Asthana, R.; Mileiko, S.T.; Sobczak, N.

2006-01-01

Oxide fiber-reinforced Ni-base composites have long been considered as attractive heat-resistant materials. After several decades of active research, however, interest in these materials began to decline around mid-1990's due chiefly to 1) a lack of manufacturing technology to grow inexpensive single-crystal oxide fibers to be used in structural composites, and 2) fiber strength loss during processing due to chemical interactions with reactive solutes in the matrix. The cost disadvantage has been mitigated to a large extent by the development of innovative fiber fabrication processes such as the Internal Crystallization Method (ICM) that produces monocrystalline oxide fibers in a cost-effective manner. Fiber strength loss has been an equally restrictive issue but recent work has shown that it may be possible to design creep-resistant composites even when fiber surface reconstruction from chemical interactions has degraded the strength of extracted fibers tested outside the matrix. The key issue is the optimization of the composite- and interface structure. Reaction-formed defects may be healed by the matrix (or a suitable coating material) so that the fiber residing in the matrix may exhibit diminished sensitivity to flaws as compared to fibers extracted from the matrix and tested in isolation of the matrix. Generally, the Ni-base/Al 2 O 3 composites exhibit acceptable levels of wettability and interface strength (further improved with the aid of reactive solutes), which are required for elevated-temperature creep-resistance. In order to harness the full potential of these composites, the quality of the interface as manifested in the fiber/matrix wettability, interface composition, interphase morphology, and interface strength must be designed. We identify key issues related to the measurement of contact angle, interface strength, and chemical and structural properties at the fiber/matrix interface in the Ni/alumina composites, and present the current state-of the

Nanoporous Cu-C composites based on carbon-nanotube aerogels

Energy Technology Data Exchange (ETDEWEB)

Charnvanichborikarn, S.; Shin, S. J.; Worsley, M. A.; Tran, I. C.; Willey, T. M.; van Buuren, T.; Felter, T. E.; Colvin, J. D.; Kucheyev, S. O. [LLNL; (Sandia)

2013-11-22

Current synthesis methods of nanoporous Cu–C composites offer limited control of the material composition, structure, and properties, particularly for large Cu loadings of ≳20 wt%. Here, we describe two related approaches to realize novel nanoporous Cu–C composites based on the templating of recently developed carbon-nanotube aerogels (CNT-CAs). Our first approach involves the trapping of Cu nanoparticles while CNT-CAs undergo gelation. This method yields nanofoams with relatively high densities of ≳65 mg cm^-3 for Cu loadings of ≳10 wt%. Our second approach overcomes this limitation by filling the pores of undoped CNT-CA monoliths with an aqueous solution of CuSO₄ followed by (i) freeze-drying to remove water and (ii) thermal decomposition of CuSO₄. With this approach, we demonstrate Cu–C composites with a C matrix density of -25 mg cm^-3 and Cu loadings of up to 70 wt%. These versatile methods could be extended to fabricate other nanoporous metal–carbon composite materials geared for specific applications.

High-Speed Photorefractive Response Capability in Triphenylamine Polymer-Based Composites

Science.gov (United States)

Tsujimura, Sho; Kinashi, Kenji; Sakai, Wataru; Tsutsumi, Naoto

2012-06-01

We present here the poly(4-diphenylamino)styrene (PDAS)-based photorefractive composites with a high-speed response time. PDAS was synthesized as a photoconductive polymer and photorefractive polymeric composite (PPC) films by using triphenylamine (TPA) (or ethylcarbazole, ECZ), 4-homopiperidino-2-fluorobenzylidene malononitrile (FDCST), and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were investigated. The photorefractive quantities of the PDAS-based PPCs were determined by a degenerate four-wave mixing (DFWM) technique. Additionally, the holographic images were recorded through an appropriate PDAS-based PPC. Those holographic images clearly reconstruct the original motion with high-speed quality. The present approach provides a promising candidate for the future application of dynamic holographic displays.

Improvement of acoustical characteristics : wideband bamboo based polymer composite

Science.gov (United States)

Farid, M.; Purniawan, A.; Rasyida, A.; Ramadhani, M.; Komariyah, S.

2017-07-01

Environmental friendly and comfortable materials are desirable for applications in the automobile interior. The objective of this research was to examine and develop bamboo based polymer composites applied to the sound absorption materials of automobile door panels. Morphological analysis of the polyurethane/bamboo powder composite materials was carried out using scanning electron microscope to reveal the microscopic material behavior and followed by the FTIR and TGA testing. The finding demonstrated that this acoustical polymer composite materials provided a potential wideband sound absorption material. The range of frequency can be controlled between 500 and 4000 Hz with an average of sound absorption coefficient around 0.411 and it met to the door panels criteria.

Fabrication and Transport Properties of Manganite-Polyacrylamide-Based Composites

Directory of Open Access Journals (Sweden)

Viorel Sandu

2009-01-01

Full Text Available We present the fabrication and transport properties of a series of composites made of La2/3Sr1/3MnO3 and acrylamide-based copolymers. The most important result is the very narrow transition, of only 27 K, displayed by the peak that appears around the metal-insulator transition of the composites made with poly(acrylamide-vinylacetate. Although the amount of polymer is rather low, different copolymers change drastically the electric transport characteristics.

Electron spectroscopy of rubber and resin-based composites containing 2D carbon

International Nuclear Information System (INIS)

Kaciulis, S.; Mezzi, A.; Balijepalli, S.K.; Lavorgna, M.; Xia, H.S.

2015-01-01

Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D x parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter

Electron spectroscopy of rubber and resin-based composites containing 2D carbon

Energy Technology Data Exchange (ETDEWEB)

Kaciulis, S., E-mail: saulius.kaciulis@ismn.cnr.it [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Mezzi, A.; Balijepalli, S.K. [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Lavorgna, M. [Institute of Polymers, Composites and Biomaterials, IPCB-CNR, P.le Fermi, 80055 Napoli (Italy); Xia, H.S. [State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065 Sichuan (China)

2015-04-30

Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D{sub x} parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter.

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles.

Science.gov (United States)

Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu

2017-04-07

Energy piles-A fairly new renewable energy concept-Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles

Science.gov (United States)

Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu

2017-01-01

Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications. PMID:28772752

Composition-based statistics and translated nucleotide searches: Improving the TBLASTN module of BLAST

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Schäffer Alejandro A

2006-12-01

Full Text Available Abstract Background TBLASTN is a mode of operation for BLAST that aligns protein sequences to a nucleotide database translated in all six frames. We present the first description of the modern implementation of TBLASTN, focusing on new techniques that were used to implement composition-based statistics for translated nucleotide searches. Composition-based statistics use the composition of the sequences being aligned to generate more accurate E-values, which allows for a more accurate distinction between true and false matches. Until recently, composition-based statistics were available only for protein-protein searches. They are now available as a command line option for recent versions of TBLASTN and as an option for TBLASTN on the NCBI BLAST web server. Results We evaluate the statistical and retrieval accuracy of the E-values reported by a baseline version of TBLASTN and by two variants that use different types of composition-based statistics. To test the statistical accuracy of TBLASTN, we ran 1000 searches using scrambled proteins from the mouse genome and a database of human chromosomes. To test retrieval accuracy, we modernize and adapt to translated searches a test set previously used to evaluate the retrieval accuracy of protein-protein searches. We show that composition-based statistics greatly improve the statistical accuracy of TBLASTN, at a small cost to the retrieval accuracy. Conclusion TBLASTN is widely used, as it is common to wish to compare proteins to chromosomes or to libraries of mRNAs. Composition-based statistics improve the statistical accuracy, and therefore the reliability, of TBLASTN results. The algorithms used by TBLASTN are not widely known, and some of the most important are reported here. The data used to test TBLASTN are available for download and may be useful in other studies of translated search algorithms.

Cell-Based Fabrication of Organic/Inorganic Composite Gel Material

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Takayoshi Nakano

2011-01-01

Full Text Available Biomaterials containing components similar to the native biological tissue would have benefits as an implantable scaffold material. To obtain such biomimetic materials, cells may be great contributors because of their crucial roles in synthetic organics. In addition, the synthesized organics—especially those derived from osteogenic differentiated cells—become a place where mineral crystals nucleate and grow even in vitro. Therefore to fabricate an organic/inorganic composite material, which is similar to the biological osteoid tissue, bone marrow derived mesenchymal stem cells (BMSCs were cultured in a 3D fibrin gel in this study. BMSCs secreted bone-related proteins that enhanced the biomineralization within the gel when the cells were cultured with an osteogenic differentiation medium. The compositions of both synthesized matrices and precipitated minerals in the obtained materials altered depending on the cell culture period. The mineral obtained in the 3D gel showed low crystalline hydroxyapatite. The composite materials also showed excellent osteoconductivity with new bone formation when implanted in mice tibiae. Thus, we demonstrated the contributions of cells for fabricating implantable organic/inorganic composite gel materials and a method for controlling the material composition in the gel. This cell-based material fabrication method would be a novel method to fabricate organic/inorganic composite biomimetic materials for bone tissue engineering.

Constitutive modeling of two-phase metallic composites with application to tungsten-based composite 93W–4.9Ni–2.1Fe

International Nuclear Information System (INIS)

Lu, W.R.; Gao, C.Y.; Ke, Y.L.

2014-01-01

The two-phase metallic composites, composed by the metallic particulate reinforcing phase and the metallic matrix phase, have attracted a lot of attention in recent years for their excellent material properties. However, the constitutive modeling of two-phase metallic composites is still lacking currently. Most used models for them are basically oriented for single-phase homogeneous metallic materials, and have not considered the microstructural evolution of the components in the composite. This paper develops a new constitutive model for two-phase metallic composites based on the thermally activated dislocation motion mechanism and the volume fraction evolution. By establishing the relation between microscopic volume fraction and macroscopic state variables (strain, strain rate and temperature), the evolution law of volume fraction during the plastic deformation in two-phase composites is proposed for the first time and introduced into the new model. Then the new model is applied to a typical two-phase tungsten-based composite – 93W–4.9Ni–2.1Fe tungsten heavy alloy. It has been found that our model can effectively describe the plastic deformation behaviors of the tungsten-based composite, because of the introduction of volume fraction evolution and the connecting of macroscopic state variables and micromechanical characteristics in the constitutive model. The model's validation by experimental data indicates that our new model can provide a satisfactory prediction of flow stress for two-phase metallic composites, which is better than conventional single-phase homogeneous constitutive models including the Johnson–Cook (JC), Khan–Huang–Liang (KHL), Nemat-Nasser–Li (NNL), Zerilli–Armstrong (ZA) and Voyiadjis–Abed (VA) models

SiC-Based Composite Materials Obtained by Siliconizing Carbon Matrices

Science.gov (United States)

Shikunov, S. L.; Kurlov, V. N.

2017-12-01

We have developed a method for fabrication of parts of complicated configuration from composite materials based on SiC ceramics, which employs the interaction of silicon melt with the carbon matrix having a certain composition and porosity. For elevating the operating temperatures of ceramic components, we have developed a method for depositing protective silicon-carbide coatings that is based on the interaction of the silicon melt and vapor with carbon obtained during thermal splitting of hydrocarbon molecules. The new structural ceramics are characterized by higher operating temperatures; chemical stability; mechanical strength; thermal shock, wear and radiation resistance; and parameters stability.

Asphaltenes-based polymer nano-composites

Science.gov (United States)

Bowen, III, Daniel E

2013-12-17

Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

Effect of In-Office Carbamide Peroxide-Based Tooth Bleaching System on Wear Resistance of Silorane-Based and Methacrylate-Based Dental Composites

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Masoumeh Hasani Tabatabaei

2016-04-01

Full Text Available Objectives: Several studies have assessed the characteristics and properties of silorane-based composites and adhesive systems. Considering the extensive application of tooth-whitening agents, possible deteriorative effects of tooth bleaching agents on these restorative materials must be studied. The aim of this study was to evaluate the effect of an in-office carbamide peroxide-based tooth bleaching agent on the wear resistance of a silorane-based and a conventional microhybrid dimethyl methacrylate-based dental composite with two different application times.  Materials and Methods: Thirty cylindrical specimens were made of Z250 and P90 dental composite resins (n=15 for each composite. Samples made of each composite were divided into three groups (n=5 for immersion in an in-office bleaching agent (Opalescence® Quick 45% for either three or eight hours or saline solution (control. Wear tests were conducted after bleaching using a pin-on disk apparatus under the load of 40N at a constant sliding speed of 0.5 ms-1 for a sliding distance of 300 m. The samples were weighed before and after the wear test. Repeated measures ANOVA was used to statistically analyze the obtained data (α=0.05.Results: There was a significant decrease in the weight of samples after the wear test (P<0.001. However, no significant difference was found among groups in the mean weight of samples before and after the wear test (P>0.05. Conclusion: Bleaching for three or eight hours using 45% carbamide peroxide had no deteriorative effect on the wear resistance of Z250 and P90 composites.

Novel high-strength Fe-based composite materials with large plasticity

Energy Technology Data Exchange (ETDEWEB)

Werniewicz, Katarzna; Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Siegel, Uwe; Bartusch, Birgit; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering (Poland)

2007-07-01

Among glass-forming alloy systems reported so far, Fe-based bulk metallic glasses play a special role. Compared to other amorphous alloys e.g. Zr-, Ti-based, such glasses show superior mechanical strength. However, due to the general brittleness their wider application as structural materials is strongly restricted. The alternative approach to overcome this defect is to design BMG composites. In this work we present a series of new Fe-Cr-Mo-Ga-(Si,C) composite materials derived from an Fe-Cr-Mo-Ga-C-P-B glassy alloy, with the aim to improve the ductility of this high-strength material. The effect of the composition and the phase formation on the resulting mechanical properties was investigated. It has been found that the formation of a complex microstructure, which essentially consists of soft Ga-rich dendrites embedded in a hard Cr- and Mo-rich matrix, leads to a material with excellent compressive mechanical properties. While the obtained values of true strength are comparable with data reported for Fe-Cr-Mo-Ga-C-P-B BMG, the values of true strain are greatly improved for investigated composites.

Opportunity and development of bio-based composites

Science.gov (United States)

Zhiyong Cai; Jerrold E. Winandy

2005-01-01

Our forests are a naturally renewable resource that has been used as a principal source of bio-energy and building materials for centuries. The rapid growth of world population has now resulted in substantial increases in demand and in consumption of all raw materials. This now provides a unique opportunity of developing new bio-based composites. The 100-year history...

Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

International Nuclear Information System (INIS)

Tan, Y.M.; Lim, S.H.; Tay, B.Y.; Lee, M.W.; Thian, E.S.

2015-01-01

Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology

Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

Energy Technology Data Exchange (ETDEWEB)

Tan, Y.M. [Department of Mechanical Engineering, National University of Singapore (Singapore); Lim, S.H.; Tay, B.Y. [Forming Technology Group, Singapore Institute of Manufacturing Technology (Singapore); Lee, M.W. [Food Innovation and Resource Centre, Singapore Polytechnic (Singapore); Thian, E.S., E-mail: mpetes@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore (Singapore)

2015-09-15

Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.

Hysteresis Compensation of Piezoresistive Carbon Nanotube/Polydimethylsiloxane Composite-Based Force Sensors

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Ji-Sik Kim

2017-01-01

Full Text Available This paper provides a preliminary study on the hysteresis compensation of a piezoresistive silicon-based polymer composite, poly(dimethylsiloxane dispersed with carbon nanotubes (CNTs, to demonstrate its feasibility as a conductive composite (i.e., a force-sensitive resistor for force sensors. In this study, the potential use of the nanotube/polydimethylsiloxane (CNT/PDMS as a force sensor is evaluated for the first time. The experimental results show that the electrical resistance of the CNT/PDMS composite changes in response to sinusoidal loading and static compressive load. The compensated output based on the Duhem hysteresis model shows a linear relationship. This simple hysteresis model can compensate for the nonlinear frequency-dependent hysteresis phenomenon when a dynamic sinusoidal force input is applied.

Dependence of mechanical characteristics from composition and structure and optimization of mechanical fracture energy of polymer composite material based on high-molecular rubbers

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E. Nurullaev

2017-07-01

Full Text Available By means of numerical experiment the authors investigate dependence of conventional rupturing stress and mechanical fracture energy at uniaxial tension from fractional composition of dispersed filler, plasticizer volume fraction in polymer binder, effective density of transverse bonds, applied to development of covering for different purposes and with advanced service life in temperature range from 223 to 323 K. They compare mechanical characteristics of polymer composite materials (PCMs based on high- and low-molecular rubbers. It was shown that rupturing stress of high-molecular rubber-based PCM is of a higher magnitude than the stress of low-molecular rubber-based one at almost invariable rupturing deformation. Numerical simulation by variation of composition parameters and molecular structure enables evaluation of its maximum fracture energy which is 1000 times higher than mechanical fracture energy of similar composites based on low-molecular rubbers.

Mechanical and corrosion behaviors of developed copper-based metal matrix composites

Science.gov (United States)

Singh, Manvandra Kumar; Gautam, Rakesh Kumar; Prakash, Rajiv; Ji, Gopal

2018-03-01

This work investigates mechanical properties and corrosion resistances of cast copper-tungsten carbide (WC) metal matrix composites (MMCs). Copper matrix composites have been developed by stir casting technique. Different sizes of micro and nano particles of WC particles are utilized as reinforcement to prepare two copper-based composites, however, nano size of WC particles are prepared by high-energy ball milling. XRD (X-rays diffraction) characterize the materials for involvement of different phases. The mechanical behavior of composites has been studied by Vickers hardness test and compression test; while the corrosion behavior of developed composites is investigated by electrochemical impedance spectroscopy in 0.5 M H2SO4 solutions. The results show that hardness, compressive strength and corrosion resistance of copper matrix composites are very high in comparison to that of copper matrix, which attributed to the microstructural changes occurred during composite formation. SEM (Scanning electron microscopy) reveals the morphology of the corroded surfaces.

Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review.

Science.gov (United States)

Ma, Lining; Dong, Xinfa; Chen, Mingliang; Zhu, Li; Wang, Chaoxian; Yang, Fenglin; Dong, Yingchao

2017-03-18

Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs)-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined.

Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs-Based Composite Membranes: A Review

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Lining Ma

2017-03-01

Full Text Available Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined.

Effect of Accelerated Artificial Aging on Translucency of Methacrylate and Silorane-Based Composite Resins.

Science.gov (United States)

Shirinzad, Mehdi; Rezaei-Soufi, Loghman; Mirtorabi, Maryam Sadat; Vahdatinia, Farshid

2016-03-01

Composite restorations must have tooth-like optical properties namely color and translucency and maintain them for a long time. This study aimed to compare the effect of accelerated artificial aging (AAA) on the translucency of three methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) and one silorane-based composite resin (Filtek P90). For this in vitro study, 56 composite discs were fabricated (n=14 for each group). Using scanning spectrophotometer, CIE L*a*b* parameters and translucency of each specimen were measured at 24 hours and after AAA for 384 hours. Data were analyzed using one-way ANOVA, Tukey's test and paired t-test at P=0.05 level of significance. The mean (±standard deviation) translucency parameter for Filtek Z250, Filtek Z250XT, Filtek Z350XT and Filtek P90 was 5.67±0.64, 4.59±0.77, 7.87±0.82 and 4.21±0.71 before AAA and 4.25±0.615, 3.53±0.73, 5.94±0.57 and 4.12±0.54 after AAA, respectively. After aging, the translucency of methacrylate-based composites decreased significantly (P0.05). The AAA significantly decreased the translucency of methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) but no change occurred in the translucency of Filtek P90 silorane-based composite.

Mechanical Properties Of 3D-Structure Composites Based On Warp-Knitted Spacer Fabrics

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Chen Si

2015-06-01

Full Text Available In this paper, the mechanical properties (compression and impact behaviours of three-dimension structure (3D-structure composites based on warp-knitted spacer fabrics have been thoroughly investigated. In order to discuss the effect of fabric structural parameters on the mechanical performance of composites, six different types of warp-knitted spacer fabrics having different structural parameters (such as outer layer structure, diameter of spacer yarn, spacer yarn inclination angle and thickness were involved for comparison study. The 3D-structure composites were fabricated based on a flexible polyurethane foam. The produced composites were characterised for compression and impact properties. The findings obtained indicate that the fabric structural parameters have strong influence on the compression and impact responses of 3D-structure composites. Additionally, the impact test carried out on the 3D-structure composites shows that the impact loads do not affect the integrity of composite structure. All the results reveal that the product exhibits promising mechanical performance and its service life can be sustained.

A Two-Stage Composition Method for Danger-Aware Services Based on Context Similarity

Science.gov (United States)

Wang, Junbo; Cheng, Zixue; Jing, Lei; Ota, Kaoru; Kansen, Mizuo

Context-aware systems detect user's physical and social contexts based on sensor networks, and provide services that adapt to the user accordingly. Representing, detecting, and managing the contexts are important issues in context-aware systems. Composition of contexts is a useful method for these works, since it can detect a context by automatically composing small pieces of information to discover service. Danger-aware services are a kind of context-aware services which need description of relations between a user and his/her surrounding objects and between users. However when applying the existing composition methods to danger-aware services, they show the following shortcomings that (1) they have not provided an explicit method for representing composition of multi-user' contexts, (2) there is no flexible reasoning mechanism based on similarity of contexts, so that they can just provide services exactly following the predefined context reasoning rules. Therefore, in this paper, we propose a two-stage composition method based on context similarity to solve the above problems. The first stage is composition of the useful information to represent the context for a single user. The second stage is composition of multi-users' contexts to provide services by considering the relation of users. Finally the danger degree of the detected context is computed by using context similarity between the detected context and the predefined context. Context is dynamically represented based on two-stage composition rules and a Situation theory based Ontology, which combines the advantages of Ontology and Situation theory. We implement the system in an indoor ubiquitous environment, and evaluate the system through two experiments with the support of subjects. The experiment results show the method is effective, and the accuracy of danger detection is acceptable to a danger-aware system.

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles

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Haibin Yang

2017-04-01

Full Text Available Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

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Kaveh Movlaee

2017-11-01

Full Text Available Iron oxide nanostructures (IONs in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (biochemical substances.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

Science.gov (United States)

Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

2017-01-01

Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

Indentation creep behaviors of amorphous Cu-based composite alloys

Science.gov (United States)

Song, Defeng; Ma, Xiangdong; Qian, Linfang

2018-04-01

This work reports the indentation creep behaviors of two Si2Zr3/amorphous Cu-based composite alloys utilizing nanoindentation technique. By analysis with Kelvin model, the retardation spectra of alloys at different positions, detached and attached regions to the intermetallics, were deduced. For the indentation of detached regions to Si2Zr3 intermetallics in both alloys, very similarity in creep displacement can be observed and retardation spectra show a distinct disparity in the second retardation peak. For the indentation of detached regions, the second retardation spectra also display distinct disparity. At both positions, the retardation spectra suggest that Si elements may lead to the relatively dense structure in the amorphous matrix and to form excessive Si2Zr3 intermetallics which may deteriorate the plastic deformation of current Cu-based composite alloys.

Effect of 38% carbamide peroxide on the microleakage of silorane-based versus methacrylate-based composite restorations

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Sedighe Sadat Hashemi Kamangar

2014-08-01

Full Text Available Objectives This study aimed to assess the effect of 38% carbamide peroxide on the microleakage of class V cavities restored with either a silorane-based composite or two methacrylate-based composites. Materials and Methods A total of 96 class V cavities were prepared on the buccal surface of extracted human teeth with both enamel and dentin margins and were randomly assigned into three groups of Filtek P90 (3M-ESPE + P90 system adhesive (3M-ESPE(group A, Filtek Z250 (3M-ESPE + Adper Prompt L-Pop (3M-ESPE(group B and Filtek Z350XT (3M-ESPE + Adper Prompt L-Pop (group C. Half of the teeth were randomly underwent bleaching (38% carbamide peroxide, Day White, Discus Dental, applying for 15 min, twice a day for 14 day while the remaining half (control were not bleached. Dye penetration was measured following immersion in basic fuchsine. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at a level of 0.05. Results No significant differences were found between composites in the control groups in enamel (p = 0.171 or dentin (p = 0.094 margins. After bleaching, microleakage of Z250 (in enamel [p = 0.867] or dentin [p = 0.590] margins and Z350 (in enamel [p = 0.445] or dentin [p = 0.591] margins did not change significantly, but the microleakage of P90 significantly increased in both enamel (p = 0.042 and dentin (p = 0.002 margins. Conclusions No significant differences were noted between the bleached and control subgroups of two methacrylate-based composites in enamel or dentin margins. Microleakage of silorane-based composite significantly increased after bleaching.

Composites Based on Polytetrafluoroethylene and Detonation Nanodiamonds: Filler-Matrix Chemical Interaction and Its Effect on a Composite's Properties

Science.gov (United States)

Koshcheev, A. P.; Perov, A. A.; Gorokhov, P. V.; Zaripov, N. V.; Tereshenkov, A. V.; Khatipov, S. A.

2018-06-01

Specific properties of PTFE composites filled with ultradisperse detonation diamonds (UDDs) with different surface chemistries are studied. It is found for the first time that filler in the form of UDDs affects not only the rate of PTFE thermal decomposition in vacuum pyrolysis, but also the chemical composition of the products of degradation. The wear resistance of UDD/PTFE composites is shown to depend strongly on the UDD surface chemistry. The presence of UDDs in a PTFE composite is found to result in perfluorocarbon telomeres, released as a readily condensable fraction upon composite pyrolysis. The chemical interaction between PTFE and UDDs, characterized by an increase in the rate of gas evolution and a change in the desorbed gas's composition, is found to occur at temperature as low as 380°C. It is shown that the intensity of this interaction depends on the concentration of oxygen-containing surface groups, the efficiency of UDDs in terms of the composite's wear resistance being reduced due to the presence of these groups. Based on the experimental data, a conclusion is reached about the chemical interaction between UDDs and a PTFE matrix, its dependence on the nanodiamond surface chemistry, and its effect on a composite's tribology.

Development and Characterization of Sr-Containing Glass-Ceramic Composites Based on Biogenic Hydroxyapatite

Science.gov (United States)

Kuda, Oleksii; Pinchuk, Nataliia; Bykov, Oleksandr; Tomila, Tamara; Olifan, Olena; Golovkova, Maryna

2018-05-01

Composite materials based on hydroxyapatite are widely used for bone tissue engineering. There is evidence of a positive effect of the presence of strontium in osteoplastic materials in the case of a Ca/Sr certain ratio. To examine the effect of the addition of Sr2+, a study was made by introducing it into the material composition based on biogenic hydroxyapatite and sodium borosilicate glass (50/50% wt.). The strontium was introduced into the composition in an amount of 1% wt. Composite materials were obtained at final sintering temperatures of 780 °C and a sintering time of 1 h. The effect of additions of glass phase and strontium affect changes in the crystal lattice of biogenic hydroxyapatite was investigated with the help of X-ray phase analysis, IR spectroscopy. Also the behavior of composites in vitro in physiological solution was studied.

Designing of the chemical composition of steels basing on the hardenability of constructional steels

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Sitek, W.

2003-01-01

The paper presents the original method of modelling of the relationships between chemical composition of alloy constructional steel and its hardenability, employing neural networks. Basing on the experimental results of the hardenability investigations, which employed Jominy method, the model of the neural networks was developed and fully verified experimentally. The model makes it possible to obtain Jominy hardenability curves basing on the steel chemical composition. The model of neural networks, making it possible to design the steel chemical composition, basing on the known Jominy hardenability curve shape, was developed also and fully verified numerically. (author)

Preparation and Photocatalytic Property of TiO2/Diatomite-Based Porous Ceramics Composite Materials

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Shuilin Zheng

2012-01-01

Full Text Available The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor of TiO2 and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at 550°C, TiO2 thin film loaded on the diatomite-based porous ceramics is anatase TiO2 and average grain size of TiO2 is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.

Nutrient Composition And Organoleptic Attributes Of Gruel Based ...

African Journals Online (AJOL)

The nutrient composition and organoleptic attributes of gruel based on blends of 24-hour fermented wateryam (WY), cocoyam (CY), plantain (PT), african yam- bean (AYB), cowpea (CP), pigeon pea (PP) and corn (C) flour were examined. A batch of each food-grain was picked clean, sun-dried, hammermilled into ...

Development of temperature stable charge based piezoelectric composite quasi-static pressure sensors

NARCIS (Netherlands)

Ende, D.A. van den; Groen, W.A.; Zwaag, S. van der

2010-01-01

In this work piezoelectric composite charge based sensors are developed, aimed at quasi-static pressure sensor or switch type applications. The use of piezoelectric composite materials allows for manufacturing robust devices which can easily be integrated with conventional polymer processing.

Wood-based Tri-Axial Sandwich Composite Materials: Design, Fabrication, Testing, Modeling and Application

Science.gov (United States)

Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

2014-01-01

As the demand for sustainable materials increases, there are unique challenges and opportunities to develop light-weight green composites materials for a wide range of applications. Thus wood-based composite materials from renewable forests may provide options for some niche applications while helping to protect our environment. In this paper, the wood-based tri-axial...

VEST: An Aspect-Based Composition Tool for Real-Time Systems

Science.gov (United States)

2003-01-01

VEST: An Aspect-Based Composition Tool for Real - Time Systems * John A. Stankovic Ruiqing Zhu Ram Poornalingam Chenyang Lu Zhendong Yu Marty Humphrey...Composition Tool for Real - Time Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK...it is obvious that designers of embedded real - time systems face many difficult problems. By working through various product scenarios with avionics

Review of Research Work on Ti-BASED Composite Coatings

Science.gov (United States)

Gabbitas, Brian; Salman, Asma; Zhang, Deliang; Cao, Peng

The service life of industrial components is limited predominantly by Chemical corrosion/mechanical wear. The project is concerned with the investigation of the capability of Ti(Al,O)/Al2O3 coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting. This paper gives a general review on the research work conducted at the University of Waikato on producing and evaluating the titanium/alumina based composite coatings. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO2 powders in two different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity air-fuel (HVAF) technique on H13 steel substrates to produce a Ti(Al,O)/Al2O3 composite coatings. The performance of the coating was assessed in terms of thermal shock resistance and reaction kinetics with molten aluminium. The composite powders and coatings were characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD).

Epoxy based photoresist/carbon nanoparticle composites

DEFF Research Database (Denmark)

Lillemose, Michael; Gammelgaard, Lauge; Richter, Jacob

2008-01-01

We have fabricated composites of SU-8 polymer and three different types of carbon nanoparticles (NPs) using ultrasonic mixing. Structures of composite thin films have been patterned on a characterization chip with standard UV photolithography. Using a four-point bending probe, a well defined stress...... is applied to the composite thin film and we have demonstrated that the composites are piezoresistive. Stable gauge factors of 5-9 have been measured, but we have also observed piezoresistive responses with gauge factors as high as 50. As SU-8 is much softer than silicon and the gauge factor of the composite...

Modeling of the physico-chemical ablation of carbon-based composites

International Nuclear Information System (INIS)

Lachaud, J.

2006-12-01

Carbon-based composites are used in extreme conditions: Tokamaks, re-entry bodies, nozzle throats, plane brakes. Their walls undergo a surface recession, called ablation, mainly due to some gasification phenomena (oxidation or even sublimation). This work is a contribution to the improvement of the understanding of the near-wall material/environment interaction and to its modeling. Some original gasification experiments have been carried out, modeled, and quantitatively analyzed; a complex multi-scale behavior of the materials is observed through their average recession velocity and a surface roughness onset mainly caused by their heterogeneous anisotropic structure. In order to explain these observations, a multi-scale modeling strategy has been set up; it follows the characteristic scales of the composites: nano-scopic (carbon texture), microscopic (fiber, inter-fiber matrix), mesoscopic (yarn, inter-yarn matrix), and macroscopic (homogenized composite) scales. The proposed models notably integrate the local recession of the wall, the heterogeneous gasification reactions, and mass transfer. A numerical simulation tool, based on Monte-Carlo Random Walks with Simplified Marching Cubes for the front tracking, has been implemented, validated, and used to solve these models. Using some numerically validated hypotheses, an analytical solution has been obtained; it provides a comprehensive understanding of ablation phenomena. It provides the effective behavior of the composites from that of their microscopic components through two changes of scale. The results of these phenomenological models have been validated by comparison to the laboratory experiments and applied for the analysis of actual applications. Physics-based criterions are made available for the choice or the fabrication of ideal materials. (author)

Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

NARCIS (Netherlands)

Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

2012-01-01

The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

Science.gov (United States)

Spates, J.J.; Martin, S.J.; Mansure, A.J.

1997-08-26

An acoustic-wave sensor apparatus and method are disclosed. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal microbalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recovery, transport, storage, refining and use of petroleum and petroleum-based products. 7 figs.

Fermentation based carbon nanotube multifunctional bionic composites

Science.gov (United States)

Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

2016-06-01

The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

Mutation exposed: a neutral explanation for extreme base composition of an endosymbiont genome.

Science.gov (United States)

Wernegreen, Jennifer J; Funk, Daniel J

2004-12-01

The influence of neutral mutation pressure versus selection on base composition evolution is a subject of considerable controversy. Yet the present study represents the first explicit population genetic analysis of this issue in prokaryotes, the group in which base composition variation is most dramatic. Here, we explore the impact of mutation and selection on the dynamics of synonymous changes in Buchnera aphidicola, the AT-rich bacterial endosymbiont of aphids. Specifically, we evaluated three forms of evidence. (i) We compared the frequencies of directional base changes (AT-->GC vs. GC-->AT) at synonymous sites within and between Buchnera species, to test for selective preference versus effective neutrality of these mutational categories. Reconstructed mutational changes across a robust intraspecific phylogeny showed a nearly 1:1 AT-->GC:GC-->AT ratio. Likewise, stationarity of base composition among Buchnera species indicated equal rates of AT-->GC and GC-->AT substitutions. The similarity of these patterns within and between species supported the neutral model. (ii) We observed an equivalence of relative per-site AT mutation rate and current AT content at synonymous sites, indicating that base composition is at mutational equilibrium. (iii) We demonstrated statistically greater equality in the frequency of mutational categories in Buchnera than in parallel mammalian studies that documented selection on synonymous sites. Our results indicate that effectively neutral mutational pressure, rather than selection, represents the major force driving base composition evolution in Buchnera. Thus they further corroborate recent evidence for the critical role of reduced N(e) in the molecular evolution of bacterial endosymbionts.

Bidirectional composition on lie groups for gradient-based image alignment.

Science.gov (United States)

Mégret, Rémi; Authesserre, Jean-Baptiste; Berthoumieu, Yannick

2010-09-01

In this paper, a new formulation based on bidirectional composition on Lie groups (BCL) for parametric gradient-based image alignment is presented. Contrary to the conventional approaches, the BCL method takes advantage of the gradients of both template and current image without combining them a priori. Based on this bidirectional formulation, two methods are proposed and their relationship with state-of-the-art gradient based approaches is fully discussed. The first one, i.e., the BCL method, relies on the compositional framework to provide the minimization of the compensated error with respect to an augmented parameter vector. The second one, the projected BCL (PBCL), corresponds to a close approximation of the BCL approach. A comparative study is carried out dealing with computational complexity, convergence rate and frequence of convergence. Numerical experiments using a conventional benchmark show the performance improvement especially for asymmetric levels of noise, which is also discussed from a theoretical point of view.

HAUTO: Automated composition of convergent services based in HTN planning

Directory of Open Access Journals (Sweden)

Armando Ordoñez

2014-01-01

Full Text Available This paper presents HAUTO, a framework able to compose convergent services automatically. HAUTO is based in HTN (hierarchical task networks Automated Planning and is composed of three modules: a request processing module that transforms natural language and context information into a planning instance, the automated composition module based on HTN planning and the execution environment for convergent (Web and telecom services. The integration of a planning component provides two basic functionalities: the possibility of customizing the composition of services using the user context information and a middleware level that integrates the execution of services in high performance telecom environments. Finally, a prototype in environmental early warning management is presented as a test case.

Spectrally based mapping of riverbed composition

Science.gov (United States)

Legleiter, Carl; Stegman, Tobin K.; Overstreet, Brandon T.

2016-01-01

Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader

Mechanical properties of silorane-based and methacrylate-based composite resins after artificial aging.

Science.gov (United States)

de Castro, Denise Tornavoi; Lepri, César Penazzo; Valente, Mariana Lima da Costa; dos Reis, Andréa Cândido

2016-01-01

The aim of this study was to compare the compressive strength of a silorane-based composite resin (Filtek P90) to that of conventional composite resins (Charisma, Filtek Z250, Fill Magic, and NT Premium) before and after accelerated artificial aging (AAA). For each composite resin, 16 cylindrical specimens were prepared and divided into 2 groups. One group underwent analysis of compressive strength in a universal testing machine 24 hours after preparation, and the other was subjected first to 192 hours of AAA and then the compressive strength test. Data were analyzed by analysis of variance, followed by the Tukey HSD post hoc test (α = 0.05). Some statistically significant differences in compressive strength were found among the commercial brands (P aging. Comparison of each material before and after AAA revealed that the aging process did not influence the compressive strength of the tested resins (P = 0.785).

CARBON-CONTAINING COMPOSITES BASED ON METALS

Directory of Open Access Journals (Sweden)

VAGANOV V. E.

2015-10-01

Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

Development of in-situ ZrC reinforced iron based composites for wear resistance applications

International Nuclear Information System (INIS)

Bandyopadhyay, T.K.; Das, K.

2002-01-01

A common objective behind the processing of iron-based composites is to improve the wear resistance of steels by incorporating some reinforcing phases, e.g., carbides and oxides. In the present investigation, iron-based zirconium carbide reinforced composite is produced by the aluminothermic reduction of zircon sand (ZrSiO 4 ) and blue dust (Fe 2 O 3 ) in the presence of carbon. Aluminothermic reduction of blue dust and zircon sand, being highly exothermic in nature, essentially leads to a self-propagating high-temperature synthesis (SHS) of the Fe-ZrC composite. The as-cast composite is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties of the composite and the effect of heat treatment on the microstructure are evaluated. The composite possess sufficient hardness and promising abrasive wear resistance property. The abrasive wear resistance property of the Fe-ZrC composite is compared with that of a M2 grade tool material and it is found to be better than the tool material. The composite also possess good high temperature stability. (author)

Workshop Report: Fundamental Reactions in Solid Propellant Combustion

Science.gov (United States)

1979-05-01

combustion conditions. 6. What effect might a pressure-induced phase transition to a polymorph other than 6- HMX have on the pressure slope break during...pure HMX as well. Nevertheless, it is recommended that the high pressure polymorphs of HMX and RDX be determined. It was also felt that there...plateau burning phenomena E. Solid phase, surface, gas phase reactions F. Phase transitions : melting, vaporization, polymorphs G. Flame

Nitramine Monopropellant Deflagration and General Nonsteady Reacting Rocket Chamber Flows.

Science.gov (United States)

1980-01-01

structure of RDX was also investigated by Harris,2 using X-ray diffraction. 2. The Crystalline Polymorphs of RMX HMX in the solid state exhibits four distinct...deflagration were shown to occur after transition . The critical transition pressure was found to correlate with the mean particle size of HMX and RDX ...Structure ....... ............ 4 2. The Crystalline Polymorphs of HMX ... ....... 5 3. Sublimation, Vaporization and Melting...... 6 C. The Chemical

Development of a metal-based composite actuator

Science.gov (United States)

Asanuma, Hiroshi; Haga, Osamu; Ishii, Toshio; Kurihara, Haruki; Ohira, Junichiro; Hakoda, Genji

2000-06-01

This paper describes a basic concept and elemental developments to realize a metal based composite actuator to be used for smart structures. In this study, CFRP prepreg was laminated on aluminum plate to develop an actuator and this laminate could perform unidirectional actuation. SiC continuous fiber/Al composite thin plate could also be used for form a modified type of actuator instead of using CFRP. As sensors to be embedded in this actuator, the following ones wee developed. (1) A pre-notched optical fiber filament could be embedded in aluminum matrix without fracture by the interphase forming/bonding method with copper insert and could be fractured in it at the notch, which enabled forming of an optical interference type strain sensor. (2) Nickel wire could be uniformly oxidized and embedded in aluminum matrix without fracture, which could successfully work as a temperature sensor and a strain sensor.

Coupling of HDPE/hydroxyapatite composites by silane-based methodologies.

Science.gov (United States)

Sousa, R A; Reis, R L; Cunha, A M; Bevis, M J

2003-06-01

Several coupling treatments based on silane chemicals were investigated for the development of high density (HDPE)/hydroxyapatite (HA) composites. Two HA powders, sintered HA (HAs) and non sintered HA (HAns), were studied in combination with five silanes, namely y-methacryloxy propyltrimethoxy silane (MEMO), 3-(2-aminoethyl)aminopropyltrimethoxy silane (DAMO), vinyltrimethoxy silane (VTMO), 3-aminopropyltriethoxy silane (AMEO) and trimethoxypropyl silane (PTMO). The HA particles were treated by a dipping in method or by spraying with silane solutions. After drying, the treated powders were compounded with HDPE or HDPE with acrylic acid and/or organic peroxide and subsequently compression molded. The tensile test specimens obtained from the molded plates were tensile tested and their fracture surfaces were observed by scanning electron microscopy (SEM). For the sintered HA (HAs) composites, the most effective coupling treatments concerning stiffness are those based on MEMO and AMEO. The low influence of these coupling procedures on strength is believed to be associated to the low volume fraction and the relatively smooth surface of the used HA particles. For the non-sintered HA (HAns) composites, it was possible to improve significantly both the stiffness and the strength. Amino silanes demonstrated to be highly efficient concerning strength enhancement. The higher effectiveness of the coupling treatments for HAns filled composites is attributed to their higher particle surface area, smaller particle size distribution and expected higher chemical reactivity. For both cases, the improvement in mechanical performance after the coupling treatment is consistent with the enhancement in interfacial adhesion observed by SEM.

and O-based composite materials derived from differential ...

Indian Academy of Sciences (India)

Abstract. In this work, we have made an effort to determine whether the effective atomic numbers of H-, C-, N- and O-based composite materials would indeed remain a constant over the energy grid of 280–1200 keV wherein incoherent scattering dominates their interaction with photons. For this purpose, the differential ...

PEDOT-based composites as electrode materials for supercapacitors

International Nuclear Information System (INIS)

Zhao, Zhiheng; Richardson, Georgia F; Meng, Qingshi; Ma, Jun; Zhu, Shenmin; Kuan, Hsu-Chiang

2016-01-01

Poly (3, 4-ethylenedioxythiophene) (denoted PEDOT) already has a brief history of being used as an active material in supercapacitors. It has many advantages such as low-cost, flexibility, and good electrical conductivity and pseudocapacitance. However, the major drawback is low stability, which means an obvious capacitance drop after a certain number of charge–discharge cycles. Another disadvantage is its limited capacitance and this becomes an issue for industrial applications. To solve these problems, there are several approaches including the addition of conducting nanofillers to increase conductivity, and mixing or depositing metal oxide to enhance capacitance. Furthermore, expanding the surface area of PEDOT is one of the main methods to improve its performance in energy storage applications through special processes; for example using a three-dimensional substrate or preparing PEDOT aerogel through freeze drying. This paper reviews recent techniques and outcomes of PEDOT based composites for supercapacitors, as well as detailed calculations about capacitances. Finally, this paper outlines the new direction and recent challenges of PEDOT based composites for supercapacitor applications. (topical review)

ComTrustO: Composite Trust-Based Ontology Framework for Information and Decision Fusion

Science.gov (United States)

2015-07-06

11] presents a methodological approach for ontology management allowing development of extensible ontologies and the mapping from ontologies to...ComTrustO: Composite Trust-based Ontology Framework for Information and Decision Fusion Alessandro Oltramari Carnegie Mellon University Pittsburgh... ontology -based framework for information fusion, as a support system for human decision makers. In particular, we build upon the concept of composite

Are the MDS-UPDRS-based composite scores clinically applicable?

Science.gov (United States)

Makkos, Attila; Kovács, Márton; Aschermann, Zsuzsanna; Harmat, Márk; Janszky, József; Karádi, Kázmér; Kovács, Norbert

2018-02-28

The International Parkinson and Movement Disorder Society-sponsored UPDRS (MDS-UPDRS) is a powerful clinical outcome measure. To evaluate the feasibility of various MDS-UPDRS-based composite scores and determine their minimal clinically important difference threshold values. Overall, 1,113 paired investigations of 452 patients were reviewed implementing three different techniques simultaneously. Based on the ordinal regression modeling, the MDS-UPDRS II+III, MDS-UPDRS I+II+III, and the total score of MDS-UPDRS are clinically applicable outcome measures. Any improvement greater than 4.9 points or any worsening more than 4.2 points on MDS-UPDRS II+III represent a minimal, yet clinically meaningful, change. In reference to MDS-UPDRS I+II+III, the smallest changes considered clinically relevant were 6.7 and 5.2 points for improvement and deterioration, respectively. The thresholds for the total score of MDS-UPDRS were 7.1 points for improvement and 6.3 points for worsening. Our findings support the application of various MDS-UPDRS-based composite scores. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

Dual sensing-actuation artificial muscle based on polypyrrole-carbon nanotube composite

Science.gov (United States)

Schumacher, J.; Otero, Toribio F.; Pascual, Victor H.

2017-04-01

Dual sensing artificial muscles based on conducting polymer are faradaic motors driven by electrochemical reactions, which announce the development of proprioceptive devices. The applicability of different composites has been investigated with the aim to improve the performance. Addition of carbon nanotubes may reduce irreversible reactions. We present the testing of a dual sensing artificial muscle based on a conducting polymer and carbon nanotubes composite. Large bending motions (up to 127 degrees) in aqueous solution and simultaneously sensing abilities of the operation conditions are recorded. The sensing and actuation equations are derived for incorporation into a control system.

Investigation on corrosion and wear behaviors of nanoparticles reinforced Ni-based composite alloying layer

International Nuclear Information System (INIS)

Xu Jiang; Tao Jie; Jiang Shuyun; Xu Zhong

2008-01-01

In order to investigate the role of amorphous SiO 2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO 2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO 2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO 2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of γ-phase and amorphous nano-SiO 2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO 2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the amorphous nano-SiO 2 particles slightly decreased the corrosion resistance of the Ni-Cr-Mo-Cu alloying layer. X-ray photoelectron spectroscopy (XPS) revealed that the passive films formed on the composite alloying consisted of Cr 2 O 3 , MoO 3 , SiO 2 and metallic Ni and Mo. The dry wear test results showed that the composite alloying layer had excellent friction-reduced property, and the wear weight loss of composite alloying layer was less than 60% of that of Ni-Cr-Mo-Cu alloying layer

Microstructure and wear behaviour of FeAl-based composites ...

Indian Academy of Sciences (India)

FeAl-based composites; precipitation; mechanical properties; wear. 1. Introduction. Fe–Al alloys ... ground to 1500 grit and polished with alumina powder. (0.5 μm). ... Alloy-2 (figure 2) consists of cuboid-shaped ZrC (region C), an FeAl matrix ...

Polylactide-based renewable green composites from agricultural residues and their hybrids.

Science.gov (United States)

Nyambo, Calistor; Mohanty, Amar K; Misra, Manjusri

2010-06-14

Agricultural natural fibers like jute, kenaf, sisal, flax, and industrial hemp have been extensively studied in green composites. The continuous supply of biofibers in high volumes to automotive part makers has raised concerns. Because extrusion followed by injection molding drastically reduces the aspect ratio of biofibers, the mechanical performance of injection molded agricultural residue and agricultural fiber-based composites are comparable. Here, the use of inexpensive agricultural residues and their hybrids that are 8-10 times cheaper than agricultural fibers is demonstrated to be a better way of getting sustainable materials with better performance. Green renewable composites from polylactide (PLA), agricultural residues (wheat straw, corn stover, soy stalks, and their hybrids) were successfully prepared through twin-screw extrusion, followed by injection molding. The effect on mechanical properties of varying the wheat straw amount from 10 to 40 wt % in PLA-wheat straw composites was studied. Tensile moduli were compared with theoretical calculations from the rule of mixture (ROM). Combination of agricultural residues as hybrids is proved to reduce the supply chain concerns for injection molded green composites. Densities of the green composites were found to be lower than those of conventional glass fiber composites.

Durability-Based Design Criteria for a Chopped-Glass-Fiber Automotive Structural Composite; TOPICAL

International Nuclear Information System (INIS)

Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

1999-01-01

This report provides recommended durability-based design criteria for a chopped-glass-fiber reinforced polymeric composite for automotive structural applications. The criteria closely follow the framework of an earlier criteria document for a continuous-strand-mat (CSM) glass-fiber reference composite. Together these design criteria demonstrate a framework that can be adapted for future random-glass-fiber composites for automotive structural applications

Some functional properties of composite material based on scrap tires

Science.gov (United States)

Plesuma, Renate; Malers, Laimonis

2013-09-01

The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

Removal of Cu 2+ Ions from Aqueous Medium Using Clinoptilolite/Emeraldine Base Composite

Directory of Open Access Journals (Sweden)

Silviya I. Lavrova

2016-12-01

Full Text Available The aim of this study was to investigate the removal efficiency of in situ synthesized composites consisted of emeraldine base and clinoptilolite on copper ions removal from aqueous medium. Two composite materials (Composite I and Composite II with different quantity of clinoptilolite were synthesised. The influence of the composite dosage, the contact time and the initial copper ions concentration has been studied. The results show that the significant removal of the copper ions becomes at the first minute of the contact between the composite material and the aqueous medium and the longer contact time leads to increasing of the copper ions removal. The removal efficiency at the 1st minute was 57.5% and 77.3% using Composite Iand Composite II, respectively. Maximum removal efficiency of 87.3% and 96.8% was achieved at the same dosage of Composite I and Composite II, respectively, at contact time of 360 minutes and temperature of 24 °C.

Copper infiltrated high speed steels based composites

International Nuclear Information System (INIS)

Madej, M.; Lezanski, J.

2003-01-01

High hardness, mechanical strength, heat resistance and wear resistance of M3/2 high speed steel (HSS) make it an attractive material. Since technological and economical considerations are equally important, infiltration of high-speed steel skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. Attempts have been made to describe the influence of the production process parameters and alloying additives, such as tungsten carbide on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2+10% Wc, M3/2=30% WC. The powders were uniaxially cold compacted in a cylindrical die at 800 MPa. The green compacts were sintered in vacuum at 1150 o C for 60 minutes. Thereby obtained porous skeletons were subsequently infiltrated with cooper, by gravity method, in vacuum furnace at 1150 o C for 15 minutes. (author)

Development of radiation processes wood-polymer composites based on tropical hardwoods

International Nuclear Information System (INIS)

Iya, V.K.; Majali, A.B.

1978-01-01

The wood-polymer composites based on tropical hardwoods were prepared with three monomer systems. Use of chlorinated paraffin oil as an additive imparted fire resistance to the composites and also brought down the gamma dose requirement for total polymerisation. A number of tropical hardwoods can be upgraded by radiation curing, but for cost optimisation, hardwoods with high improvement per unit polymer should be selected. (author)

Composite materials based on high-modulus compounds for additive technology

Science.gov (United States)

Grigoriev, M.; Kotelnikov, N.; Buyakova, S.; Kulkov, S.

2016-07-01

The effect of adding nanocrystalline ZrO2 and submicron TiC to ultrafine Al2O3 on mechanical properties and the microstructure of the composites developed by hot pressing was investigated. It was shown that by means of hot pressing in argon atmosphere at the sintering temperature of 1500 °C one can obtain the composites of Al2O3-ZrO2-TiC with a fine structure and minimal porosity. It was shown that in the material a multi-scale hierarchical structure is formed, which possesses high physical and mechanical properties: the hardness and fracture toughness was 22 GPa and 5.2 MPa*m1/2, respectively. It has been shown that mechanical properties of the composite are better than those of commercial composites based on aluminum oxide (Al2O3, ZTA, Al2O3-TiC) and are comparable to those of silicon nitride.

THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

Directory of Open Access Journals (Sweden)

Zita Iždinská

2010-09-01

Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

Tribological properties of copper-based composites with copper coated NbSe2 and CNT

International Nuclear Information System (INIS)

Chen, Beibei; Yang, Jin; Zhang, Qing; Huang, Hong; Li, Hongping; Tang, Hua; Li, Changsheng

2015-01-01

Graphical abstract: Morphology of copper coated NbSe 2 and CNT; friction coefficient and wear rate of copper-based composites. - Highlights: • NbSe 2 and CNT were coated with copper layers by the means of electroless plating. • The mechanical and tribological properties of copper composites were studied. • The enhancement mechanisms of copper coated NbSe 2 and CNT were proposed. • Copper–copper coated (12 wt.%NbSe 2 –3 wt.%CNT) composite had the best wear resistance. - Abstract: Copper-based composites with copper coated NbSe 2 and/or CNT were fabricated by the powder metallurgy technique. The morphology and phase composition of copper coated NbSe 2 and carbon nanotube (CNT) were observed using high solution transmission electronic microscope (HRTEM), scanning electronic microscope (SEM equipped with EDS) and X-ray diffraction (XRD). The density, hardness, and bending strength of as-prepared copper-based composites were measured, and their tribological properties were investigated using UMT-2 tester. Results indicated that all copper-based composites showed decreased density and bending strength, but increased hardness in comparison with copper matrix. Besides, the incorporation of copper coated NbSe 2 improved the friction-reducing and anti-wear properties of copper matrix. Addition of copper coated CNT greatly enhanced the mechanical and tribological properties. In particular, when the content of copper coated CNT was 3 wt.%, the corresponding composite exhibited the best tribological properties. This was because NbSe 2 was distributed chaotically in matrix, which greatly improved the friction-reducing property of copper, while CNT with superior mechanical strength enhanced the wear resistance by increasing the load-carrying capacity. More importantly, copper layers coated on NbSe 2 and CNT favored the good interfacial combination between fillers and copper matrix showing beneficial effect for the stresses transferring from matrix to fillers

Computational modeling of biodegradable starch based polymer composites

Science.gov (United States)

Joshi, Sachin Sudhakar

2007-12-01

Purpose. The goal of this study is to improve the favorable molecular interactions between starch and PPC by addition of grafting monomers MA and ROM as compatibilizers, which would advance the mechanical properties of starch/PPC composites. Methodology. DFT and semi-empirical methods based calculations were performed on three systems: (a) starch/PPC, (b) starch/PPC-MA, and (c) starch-ROM/PPC. Theoretical computations involved the determination of optimal geometries, binding-energies and vibrational frequencies of the blended polymers. Findings. Calculations performed on five starch/PPC composites revealed hydrogen bond formation as the driving force behind stable composite formation, also confirmed by the negative relative energies of the composites indicating the existence of binding forces between the constituent co-polymers. The interaction between starch and PPC is also confirmed by the computed decrease in stretching CO and OH group frequencies participating in hydrogen bond formation, which agree qualitatively with the experimental values. A three-step mechanism of grafting MA on PPC was proposed to improve the compatibility of PPC with starch. Nine types of 'blends' produced by covalent bond formation between starch and MA-grafted PPC were found to be energetically stable, with blends involving MA grafted at the 'B' and 'C' positions of PPC indicating a binding-energy increase of 6.8 and 6.2 kcal/mol, respectively, as compared to the non-grafted starch/PPC composites. A similar increase in binding-energies was also observed for three types of 'composites' formed by hydrogen bond formation between starch and MA-grafted PPC. Next, grafting of ROM on starch and subsequent blend formation with PPC was studied. All four types of blends formed by the reaction of ROM-grafted starch with PPC were found to be more energetically stable as compared to the starch/PPC composite and starch/PPC-MA composites and blends. A blend of PPC and ROM grafted at the ' �

Tribological characteristics of Si3N4-based composites in unlubricated sliding against steel ball

International Nuclear Information System (INIS)

Liu, C.-C.; Huang, J.-L.

2004-01-01

The dry-sliding wear mechanism of Si 3 N 4 -based composites against AISI-52100 steel ball was studied using a ball-on-disc mode in a reciprocation motion. The addition of TiN particles can increase the fracture toughness of Si 3 N 4 -based composites. The fracture toughness of Si 3 N 4 -based composites played an important role for wear behavior. The Si 3 N 4 -based composites exhibits a small friction and wear coefficient compared to monolithic Si 3 N 4 . Atomic force microscopy (AFM) studies displayed fine wear grooves along the sliding traces. The subsurface deformation shows that the microcrack propagation extends along the TiN/Si 3 N 4 grain interface. The wear mechanisms were determined with scanning electron microscopy, transmission electron microscopy, X-ray diffraction and atomic force microscopy

Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

Institute of Scientific and Technical Information of China (English)

蔡艳芝; 殷小玮; 尹洪峰

2015-01-01

The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

Thermophysical properties of composite fuel based on T grade coal (Alardinskoe deposit) and timber industry wastes

Science.gov (United States)

Yankovsky, S. A.; Tolokolnikov, A. A.; Gubin, V. E.; Slyusarskiy, K. V.; Zenkov, A. V.

2017-09-01

Results of experimental studies of composite fuel thermal decomposition processes based on T grade coal (Alardinskoe deposit) and timber industry wastes (fine wood) are presented. C, H, N, S weight percentage of each component of composite fuel was determined experimentally. It has been established that with an increase in wood concentration up to 50% in composite fuel, its energy characteristics decrease by less than 3.6%, while the yield of fly ash is 39.7%. An effective composite fuel composition has been defined as 50%/50%. Results of performed experimental studies suggest that it is possible to use composite fuels based on coal and wood at thermal power plants.

Improved microstructure of cement-based composites through the addition of rock wool particles

Energy Technology Data Exchange (ETDEWEB)

Lin, Wei-Ting [Dept. of Civil Engineering, National Ilan University, Ilan 26047, Taiwan (China); Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan 32546, Taiwan (China); Cheng, An, E-mail: ancheng@niu.edu.tw [Dept. of Civil Engineering, National Ilan University, Ilan 26047, Taiwan (China); Huang, Ran; Zou, Si-Yu [Dept. of Harbor and River Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China)

2013-10-15

Rock wool is an inorganic fibrous substance produced by steam blasting and cooling molten glass. As with other industrial by-products, rock wool particles can be used as cementitious materials or ultra fine fillers in cement-based composites. This study investigated the microstructure of mortar specimens produced with cement-based composites that include various forms of rock wool particles. It conducted compressive strength testing, rapid chloride penetration tests, X-ray diffraction analysis, thermo-gravimetric analysis, and scanning electronic microscopy to evaluate the macro- and micro-properties of the cement-based composites. Test results indicate that inclusion of rock wool particles in composites improved compressive strength and reduced chloride ion penetration at the age of 91 days due to the reduction of calcium hydroxide content. Microscopic analysis confirms that the use of rock wool particles contributed to the formation of a denser, more compact microstructure within the hardened paste. In addition, X-ray diffraction analysis shows few changes in formation of pozzolanic reaction products and no new hydrations are formed with incorporating rock wool particles. - Highlights: • We report the microstructural characterization of cement-based composites. • Different mixes produced with various rock wool particles have been tested. • The influence of different mixes on macro and micro properties has been discussed. • The macro properties are included compressive strength and permeability. • XRD and SEM observations confirm the pozzolanic reaction in the resulting pastes.

Enhanced electrochemical performances with a copper/xylose-based carbon composite electrode

Science.gov (United States)

Sirisomboonchai, Suchada; Kongparakul, Suwadee; Nueangnoraj, Khanin; Zhang, Haibo; Wei, Lu; Reubroycharoen, Prasert; Guan, Guoqing; Samart, Chanatip

2018-04-01

Copper/carbon (Cu/C) composites were prepared through the simple and environmentally benign hydrothermal carbonization of xylose in the presence of Cu2+ ions. The morphology, specific surface area, phase structure and chemical composition were investigated. Using a three-electrode system in 0.1 M H2SO4 aqueous electrolyte, the Cu/C composite (10 wt% Cu) heat-treated at 600 °C gave the highest specific capacitance (316.2 and 350.1 F g-1 at 0.5 A g-1 and 20 mV s-1, respectively). The addition of Cu was the major factor in improving the electrochemical performance, enhancing the specific capacitance more than 30 times that of the C without Cu. Therefore, the Cu/C composite presented promising results in improving biomass-based C electrodes for supercapacitors.

Reinforcement Learning Based Web Service Compositions for Mobile Business

Science.gov (United States)

Zhou, Juan; Chen, Shouming

In this paper, we propose a new solution to Reactive Web Service Composition, via molding with Reinforcement Learning, and introducing modified (alterable) QoS variables into the model as elements in the Markov Decision Process tuple. Moreover, we give an example of Reactive-WSC-based mobile banking, to demonstrate the intrinsic capability of the solution in question of obtaining the optimized service composition, characterized by (alterable) target QoS variable sets with optimized values. Consequently, we come to the conclusion that the solution has decent potentials in boosting customer experiences and qualities of services in Web Services, and those in applications in the whole electronic commerce and business sector.

An Automatic Web Service Composition Framework Using QoS-Based Web Service Ranking Algorithm.

Science.gov (United States)

Mallayya, Deivamani; Ramachandran, Baskaran; Viswanathan, Suganya

2015-01-01

Web service has become the technology of choice for service oriented computing to meet the interoperability demands in web applications. In the Internet era, the exponential addition of web services nominates the "quality of service" as essential parameter in discriminating the web services. In this paper, a user preference based web service ranking (UPWSR) algorithm is proposed to rank web services based on user preferences and QoS aspect of the web service. When the user's request cannot be fulfilled by a single atomic service, several existing services should be composed and delivered as a composition. The proposed framework allows the user to specify the local and global constraints for composite web services which improves flexibility. UPWSR algorithm identifies best fit services for each task in the user request and, by choosing the number of candidate services for each task, reduces the time to generate the composition plans. To tackle the problem of web service composition, QoS aware automatic web service composition (QAWSC) algorithm proposed in this paper is based on the QoS aspects of the web services and user preferences. The proposed framework allows user to provide feedback about the composite service which improves the reputation of the services.

Fibre-reinforced composite structures based on thermoplastic matrices with embedded piezoceramic modules

International Nuclear Information System (INIS)

Hufenbach, Werner A; Modler, Niels; Winkler, Anja; Ilg, Juergen; Rupitsch, Stefan J

2014-01-01

The paper presents recent developments for the integration of piezoceramic modules into fibre-reinforced composite structures based on thermoplastic matrices. An adapted hot pressing technology is conceptualized that allows for material homogeneous integration of the active modules. The main focus of this contribution is on the development of a robust and continuous manufacturing process of such novel active composites as well as on the operational testing of the produced samples. Therefore, selected specimens are manufactured as bending beams and investigated by means of electrical impedance measurements, modal analysis and structural excitation tests. In particular, the functionality of representative specimens is characterized based on frequency as well as spatially resolved deflection measurements. Moreover, the mentioned samples are compared to non-integrated piezoceramic modules and to equivalent passive reinforced composite structures. (paper)

Characteristics of Friction Stir Processed UHMW Polyethylene Based Composite

Science.gov (United States)

Hussain, G.; Khan, I.

2018-01-01

Ultra-high molecular weight polyethylene (UHMWPE) based composites are widely used in biomedical and food industries because of their biocompatibility and enhanced properties. The aim of this study was to fabricate UHMWPE / nHA composite through heat assisted Friction Stir Processing. The rotational speed (ω), feed rate (f), volume fraction of nHA (v) and shoulder temperature (T) were selected as the process parameters. Macroscopic and microscopic analysis revealed that these parameters have significant effects on the distribution of reinforcing material, defects formation and material mixing. Defects were observed especially at low levels of (ω, T) and high levels of (f, v). Low level of v with medium levels of other parameters resulted in better mixing and minimum defects. A 10% increase in strength with only 1% reduction in Percent Elongation was observed at the above set of conditions. Moreover, the resulted hardness of the composite was higher than that of the parent material.

Sisal organosolv pulp as reinforcement for cement based composites

OpenAIRE

Joaquim, Ana Paula; Tonoli, Gustavo Henrique Denzin; Santos, Sérgio Francisco Dos; Savastano Junior, Holmer

2009-01-01

The present work describes non-conventional sisal (Agave sisalana) chemical (organosolv) pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP) fibres were produced by the slurry de-watering and pressin...

Comparing and improving reconstruction methods for proxies based on compositional data

Science.gov (United States)

Nolan, C.; Tipton, J.; Booth, R.; Jackson, S. T.; Hooten, M.

2017-12-01

Many types of studies in paleoclimatology and paleoecology involve compositional data. Often, these studies aim to use compositional data to reconstruct an environmental variable of interest; the reconstruction is usually done via the development of a transfer function. Transfer functions have been developed using many different methods. Existing methods tend to relate the compositional data and the reconstruction target in very simple ways. Additionally, the results from different methods are rarely compared. Here we seek to address these two issues. First, we introduce a new hierarchical Bayesian multivariate gaussian process model; this model allows for the relationship between each species in the compositional dataset and the environmental variable to be modeled in a way that captures the underlying complexities. Then, we compare this new method to machine learning techniques and commonly used existing methods. The comparisons are based on reconstructing the water table depth history of Caribou Bog (an ombrotrophic Sphagnum peat bog in Old Town, Maine, USA) from a new 7500 year long record of testate amoebae assemblages. The resulting reconstructions from different methods diverge in both their resulting means and uncertainties. In particular, uncertainty tends to be drastically underestimated by some common methods. These results will help to improve inference of water table depth from testate amoebae. Furthermore, this approach can be applied to test and improve inferences of past environmental conditions from a broad array of paleo-proxies based on compositional data

Kinetics of radiation-induced structural alterations in electron-irradiated polymer-based composites

International Nuclear Information System (INIS)

Zaikin, Yu.A.; Potanin, A.S.; Koztaeva, U.P.

2002-01-01

Complete text of publication follows. In our previous studies measurements of internal friction temperature dependence were used for characterization of thermally activated and radiation-induced structural evolution in different types of polymer-based composites. This paper supplements these measurements with kinetic studies of internal friction (IF) parameters and EPR signals in a glass-cloth epoxy-filled laminate ST-ETF after electron irradiation up to doses of 1-10 MGy. Experiment have shown that the lifetime of free radicals in this composite considerably exceeds the characteristic time of molecular structural rearrangement due to scission and cross-linking after irradiation, as determined from IF measurements. This result is explained by slow proceeding of sterically hindered disproportionation reactions that stabilize the end groups of the macro-chain disrupt during irradiation and finally fix the act of scission. A mathematical model is formulated for description of structural evolution and alterations of IF parameters in polymer-based composites during and after electron irradiation. The description is based on the track model of radiation damage in polymers and phenomenological theory of radiation-induced structural transformations. General description does not give details of radiation-chemical conversion in different structural components of composites but indicates the direction of their structural evolution. In the model considered a composite material was divided into three parts (binder, filler, and a boundary layer). It was supposed that after primary distribution of radiation energy radiation-chemical conversion proceeds independently in each of these regions. It was also suggested that all the radical reactions were of the second order. On the example of glass-cloth laminate ST-ETF it is shown that this model allows to describe alterations in composite structural characteristics during irradiation and in the course of their self-organization after

Preparation of conductive paper composites based on natural cellulosic fibers for packaging applications.

Science.gov (United States)

Youssef, Ahmed M; El-Samahy, Magda Ali; Abdel Rehim, Mona H

2012-08-01

Conducting paper based on natural cellulosic fibers and conductive polymers was prepared using unbleached bagasse and/or rice straw fibers (as cellulosic raw materials) and polyaniline (PANi) as conducting polymer. These composites were synthesized by in situ emulsion polymerization using ammonium persulfate (APS) as oxidant in the presence of dodecylbenzene sulfonic acid (DBSA) as emulsifier. The prepared composites were characterized using Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC), and their morphology was investigated using scanning electron microscope (SEM). Electrical conductivity measurements showed that the conductivity of the paper sheets increases by increasing the ratio of PANi in the composite. Mechanical properties of the paper sheets were also investigated, the results revealed that the values of breaking length, burst factor, and tear factor are decreased with increasing ratio of added PANi, and this effect is more pronounced in bagasse-based composites. The new conductive composites can have potential use as anti-static packaging material or anti-bacterial paper for packaging applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Long-Acting Composite Systems Based on Powdered Medicinal Plants and Nanosilica

Directory of Open Access Journals (Sweden)

Turov, V.V.

2017-03-01

Full Text Available The state of water in the powdered plant materials (calendula, hibiscus and their composite systems with A-300 nanosilicas having different bulk density has been studied by low-temperature 1H NMR spectroscopy method. The change in bulk density has been found to significantly affect the radius of inner cavities in fibrillar space of plant components. The composite systems based on wetting-drying compaction of nanosilica and plant powder have been showed to form a mix with high interaction energy of heterogeneous particles. This results in the effective retention of plant bioactive complex by composite, which enables the development of long-acting herbal drugs.

Micromechanical modeling of tungsten-based bulk metallic glass matrix composites

Energy Technology Data Exchange (ETDEWEB)

Li Hao [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 (United States); Li Ke [Department of Mechanical Engineering, Texas A and M University, TAMU 3123, College Station, TX 77843 (United States)]. E-mail: keli@tamu.edu; Subhash, Ghatu [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 (United States); Kecskes, Laszlo J. [Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Dowding, Robert J. [Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States)

2006-08-15

Micromechanics models are developed for tungsten (W)-based bulk metallic glass (BMG) matrix composites employing the Voronoi tessellation technique and the finite element (FE) method. The simulation results indicate that the computed elastic moduli are close to those measured in the experiments. The predicted stress-strain curves agree well with their experimentally obtained counterparts in the early stage of the plastic deformation. An increase in the W volume fraction leads to a decrease in the yield stress and an increase in the Young's modulus of the composite. In addition, contours of equivalent plastic strain for increasing applied strains provide an explanation why shear bands were observed in the glassy phase, along the W/BMG interface, and in the W phase of failed W/BMG composite specimens.

Performance enhancement of quantum dot-sensitized solar cells based on polymer nano-composite catalyst

International Nuclear Information System (INIS)

Seo, Hyunwoong; Gopi, Chandu V.V.M.; Kim, Hee-Je; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

2017-01-01

Highlights: •We studied polymer nano-composite containing TiO 2 nano-particles as a catalyst. •Polymer nano-composite was applied for quantum dot-sensitized solar cells. •Polymer nano-composite catalyst was considerably improved with TiO 2 nano-particles. •Polymer nano-composite showed higher photovoltaic performance than conventional Au. -- Abstract: Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and TiO 2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V OC , 12.24 mA cm −2 of J SC , 0.57 of FF, and 3.87% of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75%).

Electromagnetic and Dynamic Mechanical Properties of Epoxy and Vinylester-Based Composites Filled with Graphene Nanoplatelets

Directory of Open Access Journals (Sweden)

Fabrizio Marra

2016-07-01

Full Text Available Development of epoxy or epoxy-based vinyl ester composites with improved mechanical and electromagnetic properties, filled with carbon-based nanomaterials, is of crucial interest for use in aerospace applications as radar absorbing materials at radio frequency. Numerous studies have highlighted the fact that the effective functional properties of this class of polymer composites are strongly dependent on the production process, which affects the dispersion of the nanofiller in the polymer matrix and the formation of micro-sized aggregations, degrading the final properties of the composite. The assessment of the presence of nanofiller aggregation in a composite through microscopy investigations is quite inefficient in the case of large scale applications, and in general provides local information about the aggregation state of the nanofiller rather than an effective representation of the degradation of the functional properties of the composite due to the presence of the aggregates. In this paper, we investigate the mechanical, electrical, and electromagnetic properties of thermosetting polymer composites filled with graphene nanoplatelets (GNPs. Moreover, we propose a novel approach based on measurements of the dielectric permittivity of the composite in the 8–12 GHz range in order to assess the presence of nanofiller aggregates and to estimate their average size and dimensions.

Recycling of asbestos tailings used as reinforcing fillers in polypropylene based composites.

Science.gov (United States)

Zhai, Wensi; Wang, Yao; Deng, Yuan; Gao, Hongli; Lin, Zhen; Li, Mao

2014-04-15

In this work, asbestos tailings were recycled and used as reinforcing fillers to enhance the mechanical properties of polypropylene (PP). A silane coupling agent was used to chemically modify the asbestos tailings to increase the compatibility between asbestos tailings and polypropylene matrix. Both raw and chemically treated asbestos tailings with different loading levels (from 3 to 30 wt%) were utilized to fabricate composites. Mechanical properties of these composites have been investigated by dynamic mechanical analysis, tensile test and notched impact test. Results showed that hybridization of asbestos tailings in the composites enhanced the mechanical properties of neat PP evidently, and treated asbestos tailings/PP composites yielded even better mechanical properties compared with those of raw asbestos tailings/PP composites. This recycling method of asbestos tailings not only reduces disposal costs and avoids secondary pollution but also produces a new PP-based composite material with enhanced mechanical properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Organic/inorganic composite membranes based on polybenzimidazole and nano-SiO2

International Nuclear Information System (INIS)

Pu Hongting; Liu Lu; Chang Zhihong; Yuan Junjie

2009-01-01

Organic/inorganic composite membranes based on polybenzimidazole (PBI) and nano-SiO 2 were prepared in this work. However, the preparation of PBI/SiO 2 composite membrane is not easy since PBI is insoluble in water, while nano-SiO 2 is hydrophilic due to the hydrophilicity of nano-SiO 2 and water-insolubility of PBI. Thus, a solvent-exchange method was employed to prepare the composite membrane. The morphology of the composite membranes was studied by scanning electron microscopy (SEM). It was revealed that inorganic particles were dispersed homogenously in the PBI matrix. The thermal stability of the composite membrane is higher than that of pure PBI, both for doped and undoped membranes. PBI/SiO 2 composite membranes with up to 15 wt% SiO 2 exhibited improved mechanical properties compared with PBI membranes. The proton conductivity of the composite membranes containing phosphoric acid was studied. The nano-SiO 2 in the composite membranes enhanced the ability to trap phosphoric acid, which improved the proton conductivity of the composite membranes. The membrane with 15 wt% of inorganic material is oxidatively stable and has a proton conductivity of 3.9 x 10 -3 S/cm at 180 deg. C.

MAPLE deposition of polypyrrole-based composite layers for bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Paun, Irina Alexandra, E-mail: irina.paun@physics.pub.ro [Faculty of Applied Sciences, University Politehnica of Bucharest, RO-060042 (Romania); National Institute for Laser, Plasma and Radiation Physics, Magurele, Bucharest RO-077125 (Romania); Acasandrei, Adriana Maria [Horia Hulubei National Institute for Physics and Nuclear Engineering IFIN-HH, Magurele, Bucharest RO-077125 (Romania); Luculescu, Catalin Romeo, E-mail: catalin.luculescu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, Magurele, Bucharest RO-077125 (Romania); Mustaciosu, Cosmin Catalin [Horia Hulubei National Institute for Physics and Nuclear Engineering IFIN-HH, Magurele, Bucharest RO-077125 (Romania); Ion, Valentin [National Institute for Laser, Plasma and Radiation Physics, Magurele, Bucharest RO-077125 (Romania); Mihailescu, Mona; Vasile, Eugenia [Faculty of Applied Sciences, University Politehnica of Bucharest, RO-060042 (Romania); Dinescu, Maria, E-mail: dinescum@nipne.ro [National Institute for Laser, Plasma and Radiation Physics, Magurele, Bucharest RO-077125 (Romania)

2015-12-01

Highlights: • PPy-based composite layers for bone regeneration were produced by MAPLE. • Conductive PPy nanograins were embedded in insulating PLGA and PU matrices. • PLGA was chosen for providing biodegradability and PU for toughness and elasticity. • The layers conductivities reached 10{sup −2} S/cm for PPy loadings of 1:10 weight ratios. • The layers promoted osteoblast viability, proliferation and mineralization. - Abstract: We report on biocompatible, electrically conductive layers of polypyrrole (PPy)-based composites obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) for envisioned bone regeneration. In order to preserve the conductivity of the PPy while overcoming its lack of biodegradability and low mechanical resilience, conductive PPy nanograins were embedded in two biocompatible, insulating polymeric matrices, i.e. poly(lactic-co-glycolic)acid (PLGA) and polyurethane (PU). PLGA offers the advantage of full biodegradability into non-toxic products, while PU provides toughness and elasticity. The PPy nanograins formed micro-domains and networks within the PLGA and PU matrices, in a compact spatial arrangement favorable for electrical percolation. The proposed approach allowed us to obtain PPy-based composite layers with biologically meaningful conductivities up to 10{sup −2} S/cm for PPy loadings as low as 1:10 weight ratios. Fluorescent staining and viability assays showed that the MG63 osteoblast-like cells cultured on the PPy-based layers deposited by MAPLE were viable and retained their capacity to proliferate. The performance of the proposed method was demonstrated by quantitative evaluation of the calcium phosphate deposits from the cultured cells, as indicative for cell mineralization. Electrical stimulation using 200 μA currents passing through the PPy-based layers, during a time interval of 4 h, enhanced the osteogenesis in the cultured cells. Despite their lowest conductivity, the PPy/PU layers showed the best

Magnetoelectric(ME) Composites and Functional Devices Based on ME Effect

Science.gov (United States)

Gao, Junqi

Magnetoelectric (ME) effect, a cross-coupling effect between magnetic and electric orders, has stimulated lots of investigations due to the potential for applications as multifunctional devices. In this thesis, I have investigated and optimized the ME effect in Metglas/piezo-fibers ME composites with a multi-push pull configuration. Moreover, I have also proposed several devices based on such composites. In this thesis, several methods for ME composites optimization have been investigated. (i) the ME coefficients can be enhanced greatly by using single crystal fibers with high piezoelectric properties; (ii) the influence of volume ratio between Metglas and piezo-fibers on ME coefficients has been studied both experimentally and theoretically. Modulating the volume ratio can increase the ME coefficient greatly; and (iii) the annealing process can change the properties of Metglas, which can enhance the ME response as well. Moreover, one differential structure for ME composites has been proposed, which can reject the external vibration noise by a factor of 10 to 20 dB. This differential structure may allow for practical applications of such sensors in real-world environments. Based on optimized ME composites, two types of AC magnetic sensor have been developed. The objective is to develop one alternative type of magnetic sensor with low noise, low cost and room-temperature operation; that makes the sensor competitive with the commercially available magnetic sensor, such as Fluxgate, GMR, SQUID, etc. Conventional passive sensors have been fully investigated, including the design of sensor working at specific frequency range, sensitivity, noise density characterization, etc. Furthermore, the extremely low frequency (man-portable multi-axial geomagnetic sensor has been developed which has the highest resolution of 10 nT for DC magnetic field. Based on the geomagnetic sensor, some demonstrations have been finished, such as orientation monitor, magnetic field mapping, and

Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Hiroyuki, E-mail: fukkun-fukuda@jwri.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kondoh, Katsuyoshi; Umeda, Junko [Joining and Welding Research Institution, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Fugetsu, Bunshi [Hokkaido University, Niow5, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

2011-06-15

Research highlights: {yields} Using the IPA based solution, the oxide-free pure Mg/CNTs composite powders could be prepared. {yields} The mechanical strength of the pure Mg composite reinforced with CNTs was not improved though the elongation was enhanced due to the elimination of MgO and less residual strain in the composite. {yields} The mechanical strength of the AZ61Mg alloy composite reinforced with CNTs was improved with maintaining adequate ductility due to the interfacial strengthening of Al{sub 2}MgC{sub 2} ternary carbide. {yields} The CNT addition was not influenced on the microstructure and grain orientations of the AZ61 Mg alloy matrix. - Abstract: Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al{sub 2}MgC{sub 2} compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.

Mechanical and physical properties of wood fiber-reinforced, sulfur-based wood composites

Science.gov (United States)

Chung-Yun Hse; Ben S. Bryant

1993-01-01

Sulfur-based composite was made from sulfur impregnated, oven dried, wet-formed fiber mats. The fiber mats consisted of a 50/50 mixture of recycled newsprint pulp and mechanical hardwood pulp from several species made from chips in a laboratory refiner. The thickness of the composites was 0.125 inch and the specific gravity of the unimpregnated fiber mat was 0.2. The...

Low Working-Temperature Acetone Vapor Sensor Based on Zinc Nitride and Oxide Hybrid Composites.

Science.gov (United States)

Qu, Fengdong; Yuan, Yao; Guarecuco, Rohiverth; Yang, Minghui

2016-06-01

Transition-metal nitride and oxide composites are a significant class of emerging materials that have attracted great interest for their potential in combining the advantages of nitrides and oxides. Here, a novel class of gas sensing materials based on hybrid Zn3 N2 and ZnO composites is presented. The Zn3 N2 /ZnO (ZnNO) composites-based sensor exhibits selectivity and high sensitivity toward acetone vapor, and the sensitivity is dependent on the nitrogen content of the composites. The ZnNO-11.7 described herein possesses a low working temperature of 200 °C. The detection limit (0.07 ppm) is below the diabetes diagnosis threshold (1.8 ppm). In addition, the sensor shows high reproducibility and long-term stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite Materials Based on Hemp and Flax for Low-Energy Buildings

Science.gov (United States)

Brzyski, Przemysław; Barnat-Hunek, Danuta; Suchorab, Zbigniew; Łagód, Grzegorz

2017-01-01

The article presents the results obtained in the course of a study on prospective application of flax/hemp wastes as a filling material of lime-based composites in the construction of low-energy buildings. The utilized filler comprised the hydrated lime with clay and Portland cement used as additives. The analysis involved evaluation of such properties as porosity, density, thermal conductivity, absorptivity, permeability, as well as compressive and flexural strength. Depending on the quantity of the filler, the properties of the composite changed. This, in turn, enabled to evaluate whether the utilized composite met the thermal requirements established for low-energy buildings. Afterwards, the obtained data were cross-referenced with the results gathered in the case of a room built of autoclaved aerated concrete. In order to prevent reaching the critical surface humidity, the internal surface temperature had to be calculated. Moreover, the chances of interstitial condensation occurring in the wall made of the analyzed lime–flax–hemp composite were determined as well. The study showed that the composite exhibits low strength, low density, low thermal conductivity, and high absorptivity. The external walls made of the lime–flax–hemp composite receive a limited exposure to condensation, but not significant enough to constitute any threat. The requirements established for low-energy buildings can be met by using the analyzed composite. PMID:28772871

Power loss separation in Fe-based composite materials

Energy Technology Data Exchange (ETDEWEB)

Kollar, Peter, E-mail: peter.kollar@upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Safarik University, Park Angelinum 9, 04154 Kosice (Slovakia); Bircakova, Zuzana; Fuezer, Jan [Institute of Physics, Faculty of Science, Pavol Jozef Safarik University, Park Angelinum 9, 04154 Kosice (Slovakia); Bures, Radovan; Faberova, Maria [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Kosice (Slovakia)

2013-02-15

The frequency dependence of total losses measured in the frequency range from dc to 1 kHz of two Fe-based soft magnetic composites (prepared by compaction of an ASC 100.29 iron powder mixture with 10 vol% of commercial thermoset resin and of a Somaloy{sup Registered-Sign} 700 powder) was analyzed. We found out that hysteresis losses (per volume unit) are higher for the composite with lower volume concentration of iron particles (i.e. mixture of iron with resin) and consequently weaker magnetic interaction between particles. On the other hand, higher specific resistivity of the sample with lower magnetic fraction causes lower contribution of eddy current losses to the total losses. A linear dependence of the total energy losses on frequency was observed and from them the contribution of excess losses was obtained. The detailed study of the excess losses resulted in an explanation of the frequency dependence of these losses in composite materials. - Highlights: Black-Right-Pointing-Pointer It was observed that excess losses in SMC depend on the frequency linearly. Black-Right-Pointing-Pointer Two components of eddy current losses (inter- and intra-particle) were analyzed. Black-Right-Pointing-Pointer Larger amount of insulator causes the eddy current inside ferromagnetic particles.

A model-based approach to studying changes in compositional heterogeneity

NARCIS (Netherlands)

Baeten, L.; Warton, D.; Calster, van H.; Frenne, De P.; Verstraeten, G.; Bonte, D.; Bernhardt-Romermann, M.; Cornelis, R.; Decocq, G.; Eriksson, O.; Hommel, P.W.F.M.

2014-01-01

1. Non-random species loss and gain in local communities change the compositional heterogeneity between communities over time, which is traditionally quantified with dissimilarity-based approaches. Yet, dissimilarities summarize the multivariate species data into a univariate index and obscure the

Preparation and analysis of multilayer composites based on polyelectrolyte complexes

Energy Technology Data Exchange (ETDEWEB)

Petrova, V. A. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Orekhov, A. S. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Chernyakov, D. D. [St. Petersburg State Chemical Pharmaceutical Academy (Russian Federation); Baklagina, Yu. G. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Romanov, D. P. [Russian Academy of Sciences, Grebenshchikov Institute of Silicate Chemistry (Russian Federation); Kononova, S. V. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Volod’ko, A. V.; Ermak, I. M. [Russian Academy of Sciences, Elyakov Pacific Institute of Bioorganic Chemistry, Far-Eastern Branch (Russian Federation); Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Skorik, Yu. A., E-mail: yury-skorik@mail.ru [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation)

2016-11-15

A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan–hyaluronic acid, chitosan–alginic acid, and chitosan–carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs.

Cotton-based Cellulose Nanomaterials for Applications in Composites and Electronics

Science.gov (United States)

Farahbakhsh, Nasim

A modern society demands development of highly valued and sustainable products via innovative process technologies and utilizing bio-based alternatives for petroleum based materials. Systematic comparative study of nanocellulose particles as a biodegradable and renewable reinforcing agent can help to develop criteria for selecting an appropriate candidate to be incorporated in polymer nanocomposites. Of particular interest has been nanocellulosic materials including cellulose nanocrystal (CNC) and micro/nanofibrilated cellulose (MFC/NFC) which possess a hierarchical structure that permits an ordered structure with unique properties that has served as building blocks for the design of green and novel materials composites for applications in flexible electronics, medicine and composites. Key differences exist in nanocellulosic materials as a result the process by which the material is produced. This research demonstrates the applicability for the use of recycled cotton as promising sustainable material to be utilized as a substrate for electronic application and a reinforcing agent choice that can be produced without any intensive purification process and be applied to synthetic-based polymer nanocomposites in melt-processing. (Abstract shortened by ProQuest.).

Hierarchical polypyrrole based composites for high performance asymmetric supercapacitors

Science.gov (United States)

Chen, Gao-Feng; Liu, Zhao-Qing; Lin, Jia-Ming; Li, Nan; Su, Yu-Zhi

2015-06-01

An advanced asymmetric supercapacitor with high energy density, exploiting hierarchical polypyrrole (PPy) based composites as both the anode [three dimensional (3D) chuzzle-like Ni@PPy@MnO2] and (3D cochleate-like Ni@MnO2@PPy) cathode, has been developed. The ultrathin PPy and flower-like MnO2 orderly coating on the high-conductivity 3D-Ni enhance charge storage while the unique 3D chuzzle-like and 3D cochleate-like structures provide storage chambers and fast ion transport pathways for benefiting the transport of electrolyte ions. The 3D cochleate-like Ni@MnO2@PPy possesses excellent pseudocapacitance with a relatively negative voltage window while preserved EDLC and free transmission channels conducive to hold the high power, providing an ideal cathode for the asymmetric supercapacitor. It is the first report of assembling hierarchical PPy based composites as both the anode and cathode for asymmetric supercapacitor, which exhibits wide operation voltage of 1.3-1.5 V with maximum energy and power densities of 59.8 Wh kg-1 and 7500 W kg-1.

Carbon cluster formation during thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and 1,3,5-triamino-2,4,6-trinitrobenzene high explosives from ReaxFF reactive molecular dynamics simulations.

Science.gov (United States)

Zhang, Luzheng; Zybin, Sergey V; van Duin, Adri C T; Dasgupta, Siddharth; Goddard, William A; Kober, Edward M

2009-10-08

We report molecular dynamics (MD) simulations using the first-principles-based ReaxFF reactive force field to study the thermal decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) at various densities and temperatures. TATB is known to produce a large amount (15-30%) of high-molecular-weight carbon clusters, whereas detonation of nitramines such as HMX and RDX (1,3,5-trinitroperhydro-1,3,5-triazine) generate predominantly low-molecular-weight products. In agreement with experimental observation, these simulations predict that TATB decomposition quickly (by 30 ps) initiates the formation of large carbonaceous clusters (more than 4000 amu, or approximately 15-30% of the total system mass), and HMX decomposition leads almost exclusively to small-molecule products. We find that HMX decomposes readily on this time scale at lower temperatures, for which the decomposition rate of TATB is about an order of magnitude slower. Analyzing the ReaxFF MD results leads to the detailed atomistic structure of this carbon-rich phase of TATB and allows characterization of the kinetics and chemistry related to this phase and their dependence on system density and temperature. The carbon-rich phase formed from TATB contains mainly polyaromatic rings with large oxygen content, leading to graphitic regions. We use these results to describe the initial reaction steps of thermal decomposition of HMX and TATB in terms of the rates for forming primary and secondary products, allowing comparison to experimentally derived models. These studies show that MD using the ReaxFF reactive force field provides detailed atomistic information that explains such macroscopic observations as the dramatic difference in carbon cluster formation between TATB and HMX. This shows that ReaxFF MD captures the fundamental differences in the mechanisms of such systems and illustrates how the ReaxFF may be applied to model complex chemical phenomena

1983 AFOSR/AFRPL Chemical Rocket Research Meeting, Abstracts and Agenda. Includes: Abstracts on Advanced Diagnostics of Reacting Flow, 28 February - 3 March 1983, Lancaster, California.

Science.gov (United States)

1983-02-01

0w 5680 RDX as they do in HMX . 5600 - 98 198 298 398 Temp. (K) A SECOND POLYMORPH OF RDX • I’ s . II !Th,"’rieI Spectral evidence of the second...Bernecker, R. R., and D. Price, Combustion and Flame, 22:111 (1974). 3. Campbell, A. W., "Deflagration-to-Detonation Transition in Granular HMX ," 1980...thermophysical properties of HMX , RDX , and AP are being made. Shown in Figure I is the general approach for making the thermophysical property determinations

Molecular Dynamics in Nitramines and Modified Nitramines

Science.gov (United States)

1983-11-01

34melts"? Uhat is the structure of RDX and HMX molecules in the "melt", solution, and ,gas phases? What is the structure of the O- RDX polymorph ? These... RDX molecule has 4sentially 3v oeulrsrutr L~j -in all environments except the stable solid"V- RDX ph&*e. The RDX and HMX --~J meslts were found to be...otion and phase transition characteristics of HMX . These studies involve approaches not previously used in this field such as 14 N nuclear quadrupole

Comparison Effectiveness of Pixel Based Classification and Object Based Classification Using High Resolution Image In Floristic Composition Mapping (Study Case: Gunung Tidar Magelang City)

Science.gov (United States)

Ardha Aryaguna, Prama; Danoedoro, Projo

2016-11-01

Developments of analysis remote sensing have same way with development of technology especially in sensor and plane. Now, a lot of image have high spatial and radiometric resolution, that's why a lot information. Vegetation object analysis such floristic composition got a lot advantage of that development. Floristic composition can be interpreted using a lot of method such pixel based classification and object based classification. The problems for pixel based method on high spatial resolution image are salt and paper who appear in result of classification. The purpose of this research are compare effectiveness between pixel based classification and object based classification for composition vegetation mapping on high resolution image Worldview-2. The results show that pixel based classification using majority 5×5 kernel windows give the highest accuracy between another classifications. The highest accuracy is 73.32% from image Worldview-2 are being radiometric corrected level surface reflectance, but for overall accuracy in every class, object based are the best between another methods. Reviewed from effectiveness aspect, pixel based are more effective then object based for vegetation composition mapping in Tidar forest.

Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

Directory of Open Access Journals (Sweden)

S. Mitrović

2014-06-01

Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

Effects of void anisotropy on the ignition and growth rates of energetic materials

Science.gov (United States)

Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

2017-06-01

Initiation of heterogeneous energetic materials is thought to occur at hot spots; reaction fronts propagate from sites of such hot spots into the surrounding material resulting in complete consumption of the material. Heterogeneous materials, such as plastic bonded explosives (PBXs) and pressed materials contain numerous voids, defects and interfaces at which hot spots can occur. Amongst the various mechanisms of hot spot formation, void collapse is considered to be the predominant one in the high strain rate loading conditions. It is established in the past the shape of the voids has a significant effect on the initiation behavior of energetic materials. In particular, void aspect ratio and orientations play an important role in this regard. This work aims to quantify the effects of void aspect ratio and orientation on the ignition and growth rates of chemical reaction from the hot spot. A wide range of aspect ratio and orientations is considered to establish a correlation between the ignition and growth rates and the void morphology. The ignition and growth rates are obtained from high fidelity reactive meso-scale simulations. The energetic material considered in this work is HMX and Tarver McGuire HMX decomposition model is considered to capture the reaction mechanism of HMX. The meso-scale simulations are performed using a Cartesian grid based Eulerian solver SCIMITAR3D. The void morphology is shown to have a significant effect on the ignition and growth rates of HMX.

Polyurea-Based Aerogel Monoliths and Composites

Science.gov (United States)

Lee, Je Kyun

2012-01-01

aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

Leaching of the potentially toxic pollutants from composites based on waste raw material

Directory of Open Access Journals (Sweden)

Terzić Anja

2012-01-01

Full Text Available The disposal of the fly ash generated in coal based power-plants may pose a significant risk to the environment due to the possible leaching of hazardous pollutants, such as toxic metals. Also, there is a risk of leaching even when fly ash is built-in the construction composites. Fly ashes from various landfills were applied in several composite samples (mortar, concrete and brick without any physical or thermal pre-treatment. The leachability of the potentially toxic pollutants from the fly ash based products was investigated. The leaching behavior and potential environmental impact of the 11 potentially hazardous elements was tracked: Pb, Cd, Zn, Cu, Ni, Cr, Hg, As, Ba, Sb and Se. A detailed study of physico-chemical characteristics of the fly ash, with accent on trace elements and the chemical composition investigation is included. Physico/chemical properties of fly ash were investigated by means of X-ray fluorescence, differential thermal analysis and X-ray diffraction methods. Scanning electron microscope was used in microstructural analysis. The results show that most of the elements are more easily leachable from the fly ash in comparison with the fly ash based composites. The leaching of investigated pollutants is within allowed range thus investigated fly ashes can be reused in construction materials production.

Porous silicon-cyclodextrin based polymer composites for drug delivery applications.

Science.gov (United States)

Hernandez-Montelongo, J; Naveas, N; Degoutin, S; Tabary, N; Chai, F; Spampinato, V; Ceccone, G; Rossi, F; Torres-Costa, V; Manso-Silvan, M; Martel, B

2014-09-22

One of the main applications of porous silicon (PSi) in biomedicine is drug release, either as a single material or as a part of a composite. PSi composites are attractive candidates for drug delivery systems because they can display new chemical and physical characteristics, which are not exhibited by the individual constituents alone. Since cyclodextrin-based polymers have been proven efficient materials for drug delivery, in this work β-cyclodextrin-citric acid in-situ polymerization was used to functionalize two kinds of PSi (nanoporous and macroporous). The synthesized composites were characterized by microscopy techniques (SEM and AFM), physicochemical methods (ATR-FTIR, XPS, water contact angle, TGA and TBO titration) and a preliminary biological assay was performed. Both systems were tested as drug delivery platforms with two different model drugs, namely, ciprofloxacin (an antibiotic) and prednisolone (an anti-inflammatory), in two different media: pure water and PBS solution. Results show that both kinds of PSi/β-cyclodextrin-citric acid polymer composites, nano- and macro-, provide enhanced release control for drug delivery applications than non-functionalized PSi samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of Energy Drinks on Discoloration of Silorane and Dimethacrylate-Based Composite Resins.

Science.gov (United States)

Ahmadizenouz, Ghazaleh; Esmaeili, Behnaz; Ahangari, Zohreh; Khafri, Soraya; Rahmani, Aghil

2016-08-01

This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month. Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull) and artificial saliva (control) for one week and one month. Color was re-assessed after each storage period and ΔE values were calculated. The data were analyzed using the Kruskal Wallis and Mann-Whitney U tests. Filtek Z250 composite showed the highest ΔE irrespective of the solutions at both time points. After seven days and one month, the lowest ΔE values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ΔE values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points. Prolonged immersion time in all three solutions increased ΔE values of all composites. However, the ΔE values were within the clinically acceptable range (<3.3) at both time points.

Bio-based composite pedestrian bridge. Part 2: materials and production process

NARCIS (Netherlands)

Lepelaar, Mark; Hoogendoorn, Alwin; Blok, Rijk; Teuffel, Patrick; Kawaguchi, K.; Ohsaki, M.; Takeuchi, T.

2016-01-01

The Bio-based composite bridge is a 3TU project which aims to design and realize a 14m span pedestrian bridge made from fibre-reinforced polymers (FRP) and which is introduced in part 1 of this paper. Part 2 will focus on various studies about bio-based materials, which are suitable for structural

Topological and thermal properties of polypropylene composites based on oil palm biomass

Energy Technology Data Exchange (ETDEWEB)

Bhat, A. H., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com; Dasan, Y. K., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com [Department of Fundamental and Applied Sciences, Universiti Teknologi Petronas, 31750 Perak (Malaysia)

2014-10-24

Roughness on pristine and polymer composite surfaces is of enormous practical importance for polymer applications. This study deals with the use of varying quantity of oil palm ash as a nanofiller in a polypropylene based matrix. The oil palm ash sample was preprocessed to break the particles into small diameter by using ultra sonication before using microfluidizer for further deduction in size and homogenization. The oil palm ash was made to undergo many passes through the microfluidizer for fine distribution of particles. Polypropylene based composites containing different loading percentage oil palm ash was granulated by twin screw extruder and then injection molded. The surface morphology of the OPA passed through microfluidizer was analyzed by Tapping Mode - Atomic Force Microscopy (TMAFM). Thermal analysis results showed an increase in the activation energy values. The thermal stability of the composite samples showed improvement as compared to the virgin polymer as corroborated by the on-set degradation temperatures and the temperatures at which 50% degradation occurred.

Topological and thermal properties of polypropylene composites based on oil palm biomass

International Nuclear Information System (INIS)

Bhat, A. H.; Dasan, Y. K.

2014-01-01

Roughness on pristine and polymer composite surfaces is of enormous practical importance for polymer applications. This study deals with the use of varying quantity of oil palm ash as a nanofiller in a polypropylene based matrix. The oil palm ash sample was preprocessed to break the particles into small diameter by using ultra sonication before using microfluidizer for further deduction in size and homogenization. The oil palm ash was made to undergo many passes through the microfluidizer for fine distribution of particles. Polypropylene based composites containing different loading percentage oil palm ash was granulated by twin screw extruder and then injection molded. The surface morphology of the OPA passed through microfluidizer was analyzed by Tapping Mode - Atomic Force Microscopy (TMAFM). Thermal analysis results showed an increase in the activation energy values. The thermal stability of the composite samples showed improvement as compared to the virgin polymer as corroborated by the on-set degradation temperatures and the temperatures at which 50% degradation occurred

Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

International Nuclear Information System (INIS)

Khoerunnisa, Fitri; Hendrawan,; Sonjaya, Yaya; Putri, Oceu Dwi

2016-01-01

Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp"3, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.

Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

Energy Technology Data Exchange (ETDEWEB)

Khoerunnisa, Fitri, E-mail: fitri.khoerunnisa@gmail.com; Hendrawan,; Sonjaya, Yaya; Putri, Oceu Dwi [Department of Chemistry, Indonesia University of Education, Setiabudi 229 Bandung, West Java, Indonesia 40154 (Indonesia)

2016-04-19

Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp{sup 3}, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.

Eco-Friendly (Water Melon Peels: Alternatives to Wood-based Particleboard Composites

Directory of Open Access Journals (Sweden)

U. D. Idris

2011-12-01

Full Text Available The aim of this study was to investigate the suitability of using water melon peels as alternatives to wood-based particleboard composites. The water melon peels composite boards were produced by compressive moulding using recycled low density polyethylene (RLDPE as a binder. The RLDPE was varies from 30 to 70wt% with interval of 10wt%. The microstructure, water absorption(WA, thickness swelling index(TS, modulus of rupture (MOR, modulus of elasticity (MOE, internal bonding strength(IB, impact strength and wear properties of the boards were determined. The results showed that high modulus of rupture of 11.45N/mm2, MOE of 1678N/mm2, IB of 0.58N/mm2, wear rate of 0.31g were obtained from particleboard produced at 60wt%RLDPE. The uniform distribution of the water melon particles and the RLDPE in the microstructure of the composites board is the major factor responsible for the improvement in the mechanical properties. The results showed that the MOE, MOR and IB meet the minimum requirements of the European standards, for general purpose like panelling, ceiling, partitioning. Hence, water melon particles can be used as a substitute to wood-based particleboard for general purpose applications also besides being environmental friendly of using watermelon and RLDPE in production of particleboard, this alternative to wood-based particleboard is very cost-effective.

Spent fuel isotopic composition data base system on WWW. SFCOMPO on W3

International Nuclear Information System (INIS)

Suyama, Kenya

1997-11-01

Spent Fuel Composition Data Base System 'SFCOMPO' has been developed on IBM compatible PC. This data base system is not widely used, since users must purchase the data base software by themselves. 'SFCOMPO on W3' is a system to overcome this problem. User can search and visualize the data in the data base by accessing WWW server through the Internet from local machine. Only a browsing software to access WWW should be prepared. It enables us to easily search data of spent fuel composition if we can access the Internet. This system can be operated on WWW server machine which supports use of Common Gateway Interface (CGI). This report describes the background of the development of SFCOMPO on W3 and is it's user's manual. (author)

Renewable and superior thermal-resistant cellulose-based composite nonwoven as lithium-ion battery separator.

Science.gov (United States)

Zhang, Jianjun; Liu, Zhihong; Kong, Qingshan; Zhang, Chuanjian; Pang, Shuping; Yue, Liping; Wang, Xuejiang; Yao, Jianhua; Cui, Guanglei

2013-01-01

A renewable and superior thermal-resistant cellulose-based composite nonwoven was explored as lithium-ion battery separator via an electrospinning technique followed by a dip-coating process. It was demonstrated that such nanofibrous composite nonwoven possessed good electrolyte wettability, excellent heat tolerance, and high ionic conductivity. The cells using the composite separator displayed better rate capability and enhanced capacity retention, when compared to those of commercialized polypropylene separator under the same conditions. These fascinating characteristics would endow this renewable composite nonwoven a promising separator for high-power lithium-ion battery.

Sensor-based vibration signal feature extraction using an improved composite dictionary matching pursuit algorithm.

Science.gov (United States)

Cui, Lingli; Wu, Na; Wang, Wenjing; Kang, Chenhui

2014-09-09

This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP) algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP) is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and reconstruction algorithm

Sensor-Based Vibration Signal Feature Extraction Using an Improved Composite Dictionary Matching Pursuit Algorithm

Directory of Open Access Journals (Sweden)

Lingli Cui

2014-09-01

Full Text Available This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and

Preparation and characterization of poly(vinylidene fluoride) based composite electrolytes for electrochemical devices

International Nuclear Information System (INIS)

Karabelli, D.; Leprêtre, J.-C.; Cointeaux, L.; Sanchez, J.-Y.

2013-01-01

Highlights: • Macroporous PVdF based membranes for electrochemical applications were prepared with support materials. • Woven PET and PA fabrics and non-woven cellulose paper are used as support materials. • Porous structure of PVdF was obtained on the support material. • Interaction between the electrolyte solvent and the composite material played an important role on the mechanical properties. • Compared to the pure PVdF separators, enhanced mechanical strength was obtained for composite separators, without decreasing the ionic conductivity. -- Abstract: PVdF-based separators are very promising materials in electrochemical energy storage systems but they suffer from fairly poor mechanical properties. To overcome this drawback, composite PVdF separators were fabricated and characterized in electrolytes of Li-ion batteries and supercapacitors. Macroporous PVdF composite separators were prepared by phase inversion method using PA and PET, and non-woven cellulose as support layers. Ionic conductivity and thermomechanical analyses were performed using electrolytes of Li-ion batteries and supercapacitors. The composite approach allowed a tremendous increase of the mechanical performances of the separator (between 340 and 750 MPa) compared to the unreinforced PVdF separator (56 MPa), without compromising the ionic conductivities (up to 15.6 mS cm −1 )

Study of carbon nanotubes based Polydimethylsiloxane composite films

International Nuclear Information System (INIS)

Shahzad, M I; Giorcelli, M; Shahzad, N; Guastella, S; Castellino, M; Jagdale, P; Tagliaferro, A

2013-01-01

Thanks to their remarkable characteristics, carbon nanotubes (CNTs) have fields of applications which are growing every day. Among them, the use of CNTs as filler for polymers is one of the most promising. In this work we report on Polydimethylsiloxane (PDMS) composites with different weight percentages (0.0% to 3.0%) of multiwall carbon nanotubes (MWCNTs) having diameter 10–30 nm and length 20–30 μm. To achieve optimum dispersion of CNTs in PDMS matrix, high speed mechanical stirring and ultrasonication were performed. By using the doctor blade technique, 70 μm thick uniform films were produced on glass. They were subsequently thermally cured and detached from the glass to get flexible and self standing films. The surface morphological study done by FESEM, shows that CNTs are well dispersed in the PDMS. Raman spectroscopy and FTIR were used to investigate the possible structural changes in the polymer composite. To examine the optical behavior UV-VIS spectroscopy was employed in both specular and diffused modes. A linear increase in absorption coefficient is found with the increasing percentage of CNTs while the transmittance decreases exponentially. The results confirm the dependence of optical limiting effect on the quantity of MWCNTs. Based on optical study, MWCNTs/PDMS composite films can be a promising material to extend performances of optical limiters against laser pulses, which is often required in lasing systems.

A systematic composite service design modeling method using graph-based theory.

Science.gov (United States)

Elhag, Arafat Abdulgader Mohammed; Mohamad, Radziah; Aziz, Muhammad Waqar; Zeshan, Furkh

2015-01-01

The composite service design modeling is an essential process of the service-oriented software development life cycle, where the candidate services, composite services, operations and their dependencies are required to be identified and specified before their design. However, a systematic service-oriented design modeling method for composite services is still in its infancy as most of the existing approaches provide the modeling of atomic services only. For these reasons, a new method (ComSDM) is proposed in this work for modeling the concept of service-oriented design to increase the reusability and decrease the complexity of system while keeping the service composition considerations in mind. Furthermore, the ComSDM method provides the mathematical representation of the components of service-oriented design using the graph-based theoryto facilitate the design quality measurement. To demonstrate that the ComSDM method is also suitable for composite service design modeling of distributed embedded real-time systems along with enterprise software development, it is implemented in the case study of a smart home. The results of the case study not only check the applicability of ComSDM, but can also be used to validate the complexity and reusability of ComSDM. This also guides the future research towards the design quality measurement such as using the ComSDM method to measure the quality of composite service design in service-oriented software system.

Epoxy composites based on inexpensive tire waste filler

Science.gov (United States)

Ahmetli, Gulnare; Gungor, Ahmet; Kocaman, Suheyla

2014-05-01

Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young's modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites.

Epoxy composites based on inexpensive tire waste filler

International Nuclear Information System (INIS)

Ahmetli, Gulnare; Gungor, Ahmet; Kocaman, Suheyla

2014-01-01

Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young’s modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites

Microwave sintering of hydroxyapatite-based composites

International Nuclear Information System (INIS)

Fang, Y.; Roy, D.M.; Cheng, J.; Roy, R.; Agrawal, D.K.

1993-01-01

Composites of hydroxyapatite/partially stabilized zirconia (HAp/PSZ) and hydroxyapatite/silicon carbide whiskers (HAp/SiC) were sintered at 1100-1200 degrees C by microwave at 2.45 GHz. Characterization of the sintered composites was carried out by density, microstructure, phase composition, and fracture toughness measurements. The results show that although not yet fully densified, a much higher sintered density in the HAp/PSZ composite was achieved by microwave sintering than by conventional sintering at the same temperature. A relative density of 93% was achieved by 20 min. microwave processing at 1200 degrees C. Comparatively, 2 h conventional sintering of the same material at 1200 degrees C led to only 75.5% relative density. K IC of this microwave sintered HAp/PSZ of 93% density was found to be 3.88 MPa√m, which is 250% of the value for pure HAp of the same density. A further increase in K IC could be expected if full or nearly full densification was achieved. Sintering of PSZ particles in the HAp/PSZ composite was also observed in the microwave processed sample. Microwave sintering of HAp/SiC was not successful in the current study due to the oxidation of SiC in air at high temperature. 8 refs., 4 figs., 1 tab

A base composition analysis of natural patterns for the preprocessing of metagenome sequences.

Science.gov (United States)

Bonham-Carter, Oliver; Ali, Hesham; Bastola, Dhundy

2013-01-01

On the pretext that sequence reads and contigs often exhibit the same kinds of base usage that is also observed in the sequences from which they are derived, we offer a base composition analysis tool. Our tool uses these natural patterns to determine relatedness across sequence data. We introduce spectrum sets (sets of motifs) which are permutations of bacterial restriction sites and the base composition analysis framework to measure their proportional content in sequence data. We suggest that this framework will increase the efficiency during the pre-processing stages of metagenome sequencing and assembly projects. Our method is able to differentiate organisms and their reads or contigs. The framework shows how to successfully determine the relatedness between these reads or contigs by comparison of base composition. In particular, we show that two types of organismal-sequence data are fundamentally different by analyzing their spectrum set motif proportions (coverage). By the application of one of the four possible spectrum sets, encompassing all known restriction sites, we provide the evidence to claim that each set has a different ability to differentiate sequence data. Furthermore, we show that the spectrum set selection having relevance to one organism, but not to the others of the data set, will greatly improve performance of sequence differentiation even if the fragment size of the read, contig or sequence is not lengthy. We show the proof of concept of our method by its application to ten trials of two or three freshly selected sequence fragments (reads and contigs) for each experiment across the six organisms of our set. Here we describe a novel and computationally effective pre-processing step for metagenome sequencing and assembly tasks. Furthermore, our base composition method has applications in phylogeny where it can be used to infer evolutionary distances between organisms based on the notion that related organisms often have much conserved code.

Morphological structure of Gluconacetobacter xylinus cellulose and cellulose-based organic-inorganic composite materials

Science.gov (United States)

Smyslov, R. Yu; Ezdakova, K. V.; Kopitsa, G. P.; Khripunov, A. K.; Bugrov, A. N.; Tkachenko, A. A.; Angelov, B.; Pipich, V.; Szekely, N. K.; Baranchikov, A. E.; Latysheva, E.; Chetverikov, Yu O.; Haramus, V.

2017-05-01

Scanning electron microscopy, ultra-small-angle neutron scattering (USANS), small-angle neutron and X-ray scattering (SANS and SAXS), as well as low-temperature nitrogen adsorption, were used in the studies of micro- and mesostructure of polymer matrix prepared from air-dry preliminarily disintegrated cellulose nano-gel film (synthesized by Gluconacetobacter xylinus) and the composites based on this bacterial cellulose. The composites included ZrO2 nanoparticles, Tb3+ in the form of low molecular weight salt and of metal-polymer complex with poly(vinylpyrrolydone)-poly(methacryloyl-o-aminobenzoic acid) copolymer. The combined analysis of the data obtained allowed revealing three levels of fractal organization in mesostructure of G. xylinus cellulose and its composites. It was shown that both the composition and an aggregation state of dopants have a significant impact on the structural characteristics of the organic-inorganic composites. The composites containing Tb3+ ions demonstrate efficient luminescence; its intensity is an order of magnitude higher in the case of the composites with the metal-polymer complex. It was found that there is the optimal content of ZrO2 nanoparticles in composites resulting in increased Tb3+ luminescence.

Interfacial damage identification of steel and concrete composite beams based on piezoceramic wave method.

Science.gov (United States)

Yan, Shi; Dai, Yong; Zhao, Putian; Liu, Weiling

2018-01-01

Steel-concrete composite structures are playing an increasingly important role in economic construction because of a series of advantages of great stiffness, good seismic performance, steel material saving, cost efficiency, convenient construction, etc. However, in service process, due to the long-term effects of environmental impacts and dynamic loading, interfaces of a composite structure might generate debonding cracks, relative slips or separations, and so on, lowering the composite effect of the composite structure. In this paper, the piezoceramics (PZT) are used as transducers to perform experiments on interface debonding slips and separations of composite beams, respectively, aimed at proposing an interface damage identification model and a relevant damage detection innovation method based on PZT wave technology. One part of various PZT patches was embedded in concrete as "smart aggregates," and another part of the PZT patches was pasted on the surface of the steel beam flange, forming a sensor array. A push-out test for four specimens was carried out and experimental results showed that, under the action of the external loading, the received signal amplitudes will increasingly decrease with increase of debonding slips along the interface. The proposed signal energy-based interface damage detection algorithm is highly efficient in surface state evaluations of composite beams.

Influence of a peracetic acid-based immersion on indirect composite resin.

Science.gov (United States)

Samuel, Susana Maria Werner; Fracaro, Gisele Baggio; Collares, Fabrício Mezzomo; Leitune, Vicente Castelo Branco; Campregher, Ulisses Bastos

2011-06-01

The aim of this study was to evaluate the influence of immersion in a 0.2% peracetic acid-based disinfectant on the three-point flexural strength, water sorption and water solubility of an indirect composite resin. Specimens were produced according to ISO 4049:2000 specifications and were divided in two groups: Control group, with no disinfection and Disinfected group, with three 10 min immersions in the peracetic acid intercalated with 10 min immersions in sterile distilled water. All evaluations were conducted in compliance with ISO specifications. Three-point flexural strength, water sorption and solubility of indirect composite resin before and after immersion showed no statistical significant differences (p > 0.05) and met ISO standard requirements. Immersion in peracetic acid solution showed no influence in indirect composite resin tested properties.

Fatty acid esters-based composite phase change materials for thermal energy storage in buildings

International Nuclear Information System (INIS)

Sarı, Ahmet; Karaipekli, Ali

2012-01-01

In this study, fatty acid esters-based composite phase change materials (PCMs) for thermal energy storage were prepared by blending erythritol tetrapalmitate (ETP) and erythritol tetrastearate (ETS) with diatomite and expanded perlite (EP). The maximum incorporation percentage for ETP and ETS into diatomite and EP was found to be 57 wt% and 62 wt%, respectively without melted PCM seepage from the composites. The morphologies and compatibilities of the composite PCMs were structurally characterized using scanning electron microscope (SEM) and Fourier transformation infrared (FT–IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by differential scanning calorimetry (DSC) analysis. The DSC analyses results indicated that the composite PCMs were good candidates for building applications in terms of their large latent heat values and suitable phase change temperatures. The thermal cycling test including 1000 melting and freezing cycling showed that composite PCMs had good thermal reliability and chemical stability. TG analysis revealed that the composite PCMs had good thermal durability above their working temperature ranges. Moreover, in order to improve the thermal conductivity of the composite PCMs, the expanded graphite (EG) was added to them at different mass fractions (2%, 5%, and 10%). The best results were obtained for the composite PCMs including 5wt% EG content in terms of the increase in thermal conductivity values and the decrease amount in latent heat capacity. The improvement in thermal conductivity values of ETP/Diatomite, ETS/Diatomite, ETP/EP and ETS/EP were found to be about 68%, 57%, 73% and 75%, respectively. Highlights: ► Fatty acid esters-based composite PCMs were prepared by blending ETP and ETS with diatomite and expanded perlite. ► The composite PCMs were characterized by using SEM, FT–IR, DSC and TG analysis methods. ► The DSC results indicated that the composites PCMs had good thermal

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

Science.gov (United States)

Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

2017-02-07

The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

Antibacterial properties of nanocomposite materials and compositions on there bases

International Nuclear Information System (INIS)

Podol'skaya, V.I.; Vojtenko, O.Yu.; Grishenko, N.I.; Ul'berg, Z.P.; Yakubenko, L.N.

2012-01-01

The structured nanobiocomposite materials based on microbial cells and colloidal silver can serve as the new adjuvant systems. These composite materials being filled with active components, in particular the medications allow to prepare the long release preparations with synergetic effect or can just contribute to prolonged drug action

Microshear bond strength of preheated silorane- and methacrylate-based composite resins to dentin.

Science.gov (United States)

Demirbuga, Sezer; Ucar, Faruk Izzet; Cayabatmaz, Muhammed; Zorba, Yahya Orcun; Cantekin, Kenan; Topçuoğlu, Hüseyin Sinan; Kilinc, Halil Ibrahim

2016-01-01

The aim of this study was to investigate the effect of preheating on microshear bond strength (MSBS) of silorane and methacrylate-based composite resins to human dentin. The teeth were randomly divided into three main groups: (1) composite resins were heated upto 68 °C; (2) cooled to 4 °C; and (3) control [room temperature (RT)]. Each group was then randomly subdivided into four subgroups according to adhesive system used [Solobond M (Voco), All Bond SE (Bisco), Clearfil SE Bond (CSE) (Kuraray), Silorane adhesive system (SAS) (3M ESPE)]. Resin composite cylinders were formed (0.9 mm diameter × 0.7 mm length) and MSBS of each specimen was tested. The preheated groups exhibited the highest MSBS (p composite resins may be an alternative way to increase the MSBS of composites on dentin. © Wiley Periodicals, Inc.

Effect of electron beam irradiation on thermal and mechanical properties of aluminum based epoxy composites

Science.gov (United States)

Visakh, P. M.; Nazarenko, O. B.; Sarath Chandran, C.; Melnikova, T. V.; Nazarenko, S. Yu.; Kim, J.-C.

2017-07-01

The epoxy resins are widely used in nuclear and aerospace industries. The certain properties of epoxy resins as well as the resistance to radiation can be improved by the incorporation of different fillers. This study examines the effect of electron beam irradiation on the thermal and mechanical properties of the epoxy composites filled with aluminum nanoparticles at percentage of 0.35 wt%. The epoxy composites were exposed to the irradiation doses of 30, 100 and 300 kGy using electron beam generated by the linear electron accelerator ELU-4. The effects of the doses on thermal and mechanical properties of the aluminum based epoxy composites were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The results revealed that the studied epoxy composites showed good radiation resistance. The thermal and mechanical properties of the aluminum based epoxy composites increased with increasing the irradiation dose up to 100 kGy and decreased with further increasing the dose.

Spent fuel isotopic composition data base system on WWW. SFCOMPO on W3

Energy Technology Data Exchange (ETDEWEB)

Suyama, Kenya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-11-01

Spent Fuel Composition Data Base System `SFCOMPO` has been developed on IBM compatible PC. This data base system is not widely used, since users must purchase the data base software by themselves. `SFCOMPO on W3` is a system to overcome this problem. User can search and visualize the data in the data base by accessing WWW server through the Internet from local machine. Only a browsing software to access WWW should be prepared. It enables us to easily search data of spent fuel composition if we can access the Internet. This system can be operated on WWW server machine which supports use of Common Gateway Interface (CGI). This report describes the background of the development of SFCOMPO on W3 and is it`s user`s manual. (author)

A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/Nylon-6 blends.

Science.gov (United States)

Liu, Hongzhi; Yao, Fei; Xu, Yanjun; Wu, Qinglin

2010-05-01

A novel wood flour (WF)-filled composite based on the microfibrillar high-density polyethylene (HDPE) and Nylon-6 co-blend, in which both in situ formed Nylon-6 microfibrils and WF acted as reinforcing elements, was successfully developed using a two-step extrusion method. At the 30wt.% WF loading level, WF-filled composite based on the microfibrillized HDPE/Nylon-6 blend exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of WF reduced short-term creep response of HDPE matrix and the presence of Nylon-6 microfibrils further contributed to the creep reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

Pyrolysis behaviour of silicone-based ceramifying composites

International Nuclear Information System (INIS)

Mansouri, J.; Burford, R.P.; Cheng, Y.B.

2006-01-01

In this work the effect of firing temperature on microstructure and chemical composition of silicone-mica composites was studied. Field emission electron microscopy (FESEM) and electron probe microanalysis (EPMA) were used to explore the changes in microstructure and local microchemical composition when samples were heated at 600 and 1000 deg. C. EPMA showed the presence of skin formation and preferential migration of silica to the surface. These effects were more pronounced at higher temperatures. XRD analysis of mica and composites at different temperatures also showed the formation of new phases as a result of reaction between the decomposition products of mica and silica

Design Intend Solving: Dynamic Composition Method for Innovative Design Based on Virtual Cloud Manufacturing Resource Generators

Directory of Open Access Journals (Sweden)

Yi-Cong Gao

2013-01-01

Full Text Available Recently, there has been growing interest in composition of cloud manufacturing resources (CMRs. Composition of CMRs is a feasible innovation to fulfill the user request while single cloud manufacturing resource cannot satisfy the functionality required by the user. In this paper, we propose a new case-based approach for the composition of CMRs. The basic idea of the present approach is to provide a computational framework for the composition of CMRs by imitating the common design method of reviewing past designs to obtain solution concepts for a new composite cloud manufacturing resource (CCMR. A notion of virtual cloud manufacturing resource generators (VCMRGs is introduced to conceptualize and represent underlying CCMRs contained in existing CCMRs. VCMRGs are derived from previous CCMRs and serve as new conceptual building blocks for the composition of CMRs. Feasible composite CMRs are generated by combining VCMRGs using some adaptation rules. The reuse of prior CCMRs is accomplished via VCMRGs within the framework of case-based reasoning. We demonstrate that the proposed approach yields lower execution time for fulfilling user request and shows good scalability.

A review on mechanical properties of magnesium based nano composites

Science.gov (United States)

Tarafder, Nilanjan; Prasad, M. Lakshmi Vara

2018-04-01

A review was done on Magnesium (Mg) based composite materials reinforced with different nano particles such as TiO2, Cu, Y2O3, SiC, ZrO2 and Al2O3. TiO2 and Al2O3 nanoparticles were synthesised by melt deposition process. Cu, Y2O3, SiC and ZrO2 nanoparticles were synthesised by powder metallurgy process. Composite microstructural characteristics shows that the nano-size reinforcements are uniformly distributed in the composite matrix and also minimum porosity with solid interfacial integrity. The mechanical properties showed yield strength improvement by 0.2 percentage and Ultimate tensile strength (UTS) was also improved for all the nano-particles. But UTS was adversely affected with TiO2 reinforcement while ductility was increased. With Cu reinforcement elastic modulus, hardness and fracture resistance increased and improved the co-efficient of thermal expansion (CTE) of Mg based matrix. By Y2O3 reinforcement hardness, fracture resistance was improved and ductility reached maximum by 0.22 volume percentage of Y2O3 and decreased with succeeding increase in Y2O3 reinforcement. The readings exposed that mechanical properties were gathered from the composite comprising 2.0 weight percentage of Y2O3. Ductility and fracture resistance increased with ZrO2 reinforcement in Mg matrix. Using Al2O3 as reinforcement in Mg composite matrix hardness, elastic modulus and ductility was increased but porosity reduced with well interfacial integrity. Dissipation of energy in the form of damping capacity was resolved by classical vibration theory. The result showed that an increasing up to 0.4 volume percentage alumina content increases the damping capacity up to 34 percent. In another sample, addition of 2 weight percentage nano-Al2O3 particles showed big possibility in reducing CTE from 27.9-25.9×10-6 K-1 in Magnesium, tensile and yield strength amplified by 40MPa. In another test, Mg/1.1Al2O3 nanocomposite was manufactured by solidification process followed by hot extrusion

Comparison of the mechanical properties between carbon nanotube and nanocrystalline cellulose polypropylene based nano-composites

International Nuclear Information System (INIS)

Huang, Jun; Rodrigue, Denis

2015-01-01

Highlights: • SWCNT and NCC can effectively improve the mechanical properties of nano-composites. • SWCNT is more effective than NCC to increase modulus and strength. • Longer NCC is more effective to improve the mechanical properties of nano-composites. • It is more economic to use NCC than SWCNT to improve mechanical properties. - Abstract: Using beam and tetrahedron elements to simulate nanocrystalline cellulose (NCC), single wall carbon nanotube (SWCNT) and polypropylene (PP), finite element method (FEM) is used to predict the mechanical properties of nano-composites. The bending, shear and torsion behaviors of nano-composites are especially investigated due to the limited amount of information in the present literature. First, mixed method (MM) and FEM are used to compare the bending stiffness of NCC/PP and SWCNT/PP composites. Second, based on mechanics of materials, the shear moduli of both types of nano-composites are obtained. Finally, fixing the number of fibers and for different volume contents, four NCC lengths are used to determine the mechanical properties of the composites. The bending and shearing performances are also compared between NCC and SWCNT based composites. In all cases, the elastic–plastic analyses are carried out and the stress or strain distributions for specific regions are also investigated. From all the results obtained, an economic analysis shows that NCC is more interesting than SWCNT to reinforce PP

Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

Directory of Open Access Journals (Sweden)

Cesar Augusto Galvão Arrais

2013-04-01

Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

Directory of Open Access Journals (Sweden)

Laura AlveBastos

2015-02-01

Full Text Available Objectives The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE, the specific self-etching adhesive system (Adhesive System P90, 3M ESPE was used with and without pre-etching (Pre-etching/Silorane and Silorane groups. Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray, with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups, or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE (Three-step/Methacrylate group (n = 6. The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm, and coupled to a universal test machine (0.5 mm/min to perform microtensile testing. Results Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05. However, it was not significantly different from Preetching/Silorane and Methacrylate groups. Conclusions Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

Survival of Direct Posterior Composites With and Without a Bulk Fill Base.

Science.gov (United States)

McGuirk, C; Hussain, F; Millar, B J

2017-09-01

Direct composite restorations are increasingly popular and a flowable bulk-fill base material (SDR, Dentsply) claims to minimise stress through a more flexible polymerisation process. This retrospective audit of restorations placed in general practice compares SDR based restorations with conventional composite restorations. Restorations were all placed by one operator using a similar clinical technique and were audited as Group G, placed with a conventional layering composite (G-aenial, GC) and Group S which had a bulk-fill base of SDR (Dentsply) and then were covered with G-aenial (GC). Data regarding survival, post-operative sensitivity and mode of failure were recorded and analysed. In total 54 Group S restorations and 71 Group G restorations were followed for a minimum of 24 months. Group S had a 92.6% survival and Group G 93%. Group S was more prone to failure by tooth fracture (p=0.033). In both groups failure was more likely in larger cavities, in both those with an increased number of surfaces (p⟨0.001) and cuspal coverage (p=0.004). There appears to be similar survival of the two techniques in the short-term although there were significantly more tooth fractures in teeth restored with SDR. Copyright© 2017 Dennis Barber Ltd.

Single step synthesis of chitin/chitosan-based graphene oxide–ZnO hybrid composites for better electrical conductivity and optical properties

International Nuclear Information System (INIS)

Anandhavelu, S.; Thambidurai, S.

2013-01-01

Highlights: ► UV absorption at 260–360 nm confirmed strong binding of ZnO with chitosan–GO sheets. ► Chitin-based GO–ZnO shows higher electrical conductivity than chitosan-based GO–ZnO. ► Chitin-based GO–ZnO will useful in sensing, catalysis and energy storage applications. -- Abstract: We synthesized two composites/hybrid composites with a graphene oxide (GO)/mixed GO–ZnO filler using either a chitin or a chitosan matrix. Fourier transform infrared spectroscopy analysis confirmed that chitin had been converted to chitosan during matrix fabrication because only chitosan, ZnO and GO were shown to be present in the composites/hybrid composites. Raman spectroscopy indicated the display of D and G bands at 1345 cm −1 and 1584 cm −1 , respectively. UV absorption peaks appeared at 260–360 nm and 201 nm in both hybrid composites, which indicate a strong binding of ZnO within the chitosan–GO sheets. High resolution scanning electron microscopy and atomic force microscopy studies demonstrated that on a molecular scale ZnO was well dispersed in the hybrid composites. Impedance spectroscopy and a four-probe resistivity method were used for room temperature electrical conductivity measurements. The electrical conductivity of the chitin-based GO–ZnO hybrid composites was estimated to be ∼5.94 × 10 6 S/cm and was greater than that of the chitosan-based GO–ZnO hybrid composite (∼4.13 × 10 6 S/cm). The chitin-based GO–ZnO hybrid composite had a higher optical band gap (3.4 eV) than the chitosan-based GO–ZnO hybrid composite (3.0 eV). The current–voltage measurement showed that electrical sheets resistance of the chitosan-based composites decreased with formation of ZnO

Analysis of composition and microstructural uniformity of hybrid glass/carbon fibre composites

DEFF Research Database (Denmark)

Beauson, Justine; Markussen, Christen Malte; Madsen, Bo

2013-01-01

level are investigated. The different levels of compositions in the composites are defined and experimentally determined. The composite volume fractions are determined using an image analysis based procedure. The global fibre volume fractions are determined using a gravimetrical based method. The local...... methods, a standard deviation based method and a fast Fourier transform method, are used to quantify the difference in microstructural uniformity between composites, and to detect and quantify any repeating pattern in the composite microstructure....

Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

DEFF Research Database (Denmark)

Sørensen, Rene; Lund, Erik

2012-01-01

This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either...

Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

OpenAIRE

Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho; Garcia, Lucas da Fonseca Roberti

2014-01-01

Objectives The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/S...

Supercapacitors Based on Nickel Oxide/Carbon Materials Composites

OpenAIRE

Lota, Katarzyna; Sierczynska, Agnieszka; Lota, Grzegorz

2011-01-01

In the thesis, the properties of nickel oxide/active carbon composites as the electrode materials for supercapacitors are discussed. Composites with a different proportion of nickel oxide/carbon materials were prepared. A nickel oxide/carbon composite was prepared by chemically precipitating nickel hydroxide on an active carbon and heating the hydroxide at 300 ∘C in the air. Phase compositions of the products were characterized using X-ray diffractometry (XRD). The morphology of the composite...

Flammability and thermal properties studies of nonwoven flax reinforced acrylic based polyester composites

Science.gov (United States)

Rasyid, M. F. Ahmad; Salim, M. S.; Akil, H. M.; Ishak, Z. A. Mohd.

2017-12-01

In the pursuit of green and more sustainable product, natural fibre reinforced composites originating from renewable resources has gained interest in recent years. These natural fibres exhibit good mechanical properties, low production costs, and good environmental properties. However, one of the disadvantages of natural fibre reinforced composites is their high flammability that limits their application in many fields. Within this research, the effect of sodium silicate on the flammability and thermal properties of flax reinforced acrylic based polyester composites has been investigated. Sodium silicate is applied as binder and flame retardant system in impregnation process of the natural flax fiber mats. The addition of sodium silicate significantly improved the flame retardant efficiency but reduced the degree of crosslinking of the composites.

Graphite nanoplatelets and carbon nanotubes based polyethylene composites: Electrical conductivity and morphology

International Nuclear Information System (INIS)

Haznedar, Galip; Cravanzola, Sara; Zanetti, Marco; Scarano, Domenica; Zecchina, Adriano; Cesano, Federico

2013-01-01

Graphite nanoplatelets (GNPs) and/or multiwalled-carbon nanotubes (MWCNTs)/low density polyethylene (LDPE) composites have been obtained either via melt-mixing or solvent assisted methods. Electrical properties of samples obtained through the above mentioned methods are compared and the conductance values as function of filler fraction are discussed. The corresponding percolation thresholds are evaluated. Conductivity maps images are acquired under low-potentials scanning electron microscopy (0.3 KV) and the relationship between the obtained conductivity images and electric properties is highlighted. The synergistic role of CNTs (1D) and GNPs (2D) in improving the conductive properties of the polymer composites has been shown. - Highlights: • Graphite nanoplatelets (GNPs) and GNPs/MWCNT LDPE composites. • Low potential SEM conductivity maps. • Conducting paths between 1D and 2D C-structures (synergistic effect) are obtained. • Composites based on hybrid 1D/2D combinations show lower percolation thresholds

Mathematical Model For Autoclave Curing Of Unsaturated Polyester Based Composite Materials

Directory of Open Access Journals (Sweden)

Adnan A. Abdul Razak

2013-05-01

Full Text Available Heat transfer process involved in the autoclave curing of fiber-reinforced thermosetting composites is investigated numerically. A model for the prediction of the temperature and the extent of the reaction across the laminate thickness during curing process in the autoclave of unsaturated polyester based composite has been developed. The governing equation for one dimensional heat transfer, and accounting for the heat generation due to the exothermic cure reaction in the composites had been used.  It was found that the temperature at the central of the laminate increases up to the external imposed temperature, because of the thermal conductivity of the resin and fiber. The heat generated by the exothermic reaction of the resin is not adequately removed; the increase in the temperature at the center increases the resins rate reaction, which in turn generates more heat.

Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

Science.gov (United States)

Joslin, Steven M.

1995-01-01

A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

Agricultural residues based composites part II: Hydration characteristics of cement- cellulosic fibers composites

International Nuclear Information System (INIS)

Hekal, E.E.; Kishar, E.A.; Abd-El-Khader, A.H.; Ibrahim, A.A.; Mobarak, F.M.

2005-01-01

The aim of this study is the utilization of the local agricultural wastes, such as ice straw bagasse, cotton stalks and linen fibers, which cause a big environmental problem. Different cement-fiber composites were prepared using 1.5, 3, 4.5 and 6% fibers by weight of cement. The lengths of the fibers used were 0.5, 0.8, and 1.25 mm. Hydration of the different, composites was carried out at room temperature for various lime intervals namely, 1.3,7 .28 and 90 days. Combined water contents, compressive strength and phase composition of the different prepared composites were examined

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

Science.gov (United States)

Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi Chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

2017-01-01

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P composite resin type, preheating and interactive effect of these variables on gap formation were significant (Pcomposite resins (Pcomposite resins at room temperature compared to composite resins after 40 preheating cycles (Pcomposite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

Hot-Spots and Holiness: Faith-Based Topics in Freshman Composition.

Science.gov (United States)

Worth, Jan

For an instructor of freshman composition at the University of Michigan at Flint, faith-based writing topics offer particular challenges and sometimes intersect in troubling ways with her own prejudices and personal history as a teacher and as a person. But if handled correctly, she believes that a teacher's interaction with students about…

Magnetoimpedance of cobalt-based amorphous ribbons/polymer composites

Energy Technology Data Exchange (ETDEWEB)

Semirov, A.V., E-mail: semirov@mail.ru [Irkutsk State University, Irkutsk (Russian Federation); Derevyanko, M.S.; Bukreev, D.A.; Moiseev, A.A.; Kudryavtsev, V.O. [Irkutsk State University, Irkutsk (Russian Federation); Safronov, A.P. [Ural Federal University, Yekaterinburg (Russian Federation)

2016-10-01

The combined influence of the temperature, the elastic tensile stress and the external magnetic field on the total impedance and impedance components were studied for rapidly quenched amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons. Both as-cast amorphous ribbons and Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16}/polymer amorphous ribbon based composites were considered. Following polymer coverings were studied: modified rubber solution in o-xylene, solution of butyl methacrylate and methacrylic acid copolymer in isopropanol and solution of polymethylphenylsiloxane resin in toluene. All selected composites showed very good adhesion of the coverings and allowed to provide temperature measurements from 163 K up to 383 K under the applied deforming tensile force up to 30 N. The dependence of the modulus of the impedance and its components on the external magnetic field was influenced by the elastic tensile stresses and was affected by the temperature of the samples. It was shown that maximal sensitivity of the impedance and its components to the external magnetic field was observed at minimal temperature and maximal deforming force depended on the frequency of an alternating current. - Highlights: • Impedance and its components of amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons were studied. • MI sensitivity to the magnetic field depends on a temperature and a deforming force. • Polymer covering can affect the functional properties of the composite.

Analysis of composition and microstructural uniformity of hybrid glass/carbon fibre composites

Energy Technology Data Exchange (ETDEWEB)

Beauson, J.; Markussen, C.M.; Madsen, Bo

2013-09-01

In hybrid fibre composites, the intermixing of the two types of fibres imposes challenges to obtain materials with a well-defined and uniform microstructure. In the present paper, the composition and the microstructural uniformity of hybrid glass/carbon fibre composites mixed at the fibre bundle level are investigated. The different levels of compositions in the composites are defined and experimentally determined. The composite volume fractions are determined using an image analysis based procedure. The global fibre volume fractions are determined using a gravimetrical based method. The local fibre volume fractions are determined using volumetric calculations. A model is presented to predict the interrelation of volume fractions in hybrid fibre composites. The microstructural uniformity of the composites is analysed by the determined variation in composite volume fractions. Two analytical methods, a standard deviation based method and a fast Fourier transform method, are used to quantify the difference in microstructural uniformity between composites, and to detect and quantify any repeating pattern in the composite microstructure. (Author)

Preparation and characterization of composites based on the blends of collagen, chitosan and hyaluronic acid with nano-hydroxyapatite.

Science.gov (United States)

Sionkowska, Alina; Kaczmarek, Beata

2017-09-01

3D porous composites based on the blend of chitosan, collagen and hyaluronic acid with the addition of nano-hydroxyapatite were prepared. SEM images for the composites were made and the structure was assessed. Mechanical properties were studied using a Zwick&Roell Testing Mashine. In addition, the porosity and density of composites were measured. The concentration of calcium ions released from the material was detected by the complexometric titration method. The results showed that in 3D porous sponge based on the blend of chitosan, collagen and hyaluronic acid, inorganic particles of nanohydroxyapatite can be incorporated, as well as that the properties of 3D composites depend on the material composition. Mechanical parameters and thermal stability of ternary biopolymeric blends were improved by the addition of hydroxyapatite. Moreover, the porosity of ternary materials was higher than in materials based on pure chitosan or collagen. All composites were characterized by a porous structure with interconnected pores. Calcium ions can be released from the composite during its degradation in water. Copyright © 2017 Elsevier B.V. All rights reserved.

Solar-thermal conversion and thermal energy storage of graphene foam-based composite

KAUST Repository

Zhang, Lianbin

2016-07-11

Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

Science.gov (United States)

Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

2016-08-14

Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

Synthesis and densification of Cu-coated Ni-based amorphous composite powders

International Nuclear Information System (INIS)

Kim, Yong-Jin; Kim, Byoung-Kee; Kim, Jin-Chun

2007-01-01

Spherical Ni 57 Zr 20 Ti 16 Si 2 Sn 3 (numbers indicate at.%) amorphous powders were produced by the gas atomization process, and ductile Cu phase was coated on the Ni-based amorphous powders by the spray drying process in order to increase the ductility of the consolidated amorphous alloy. The characteristics of the as-prepared powders and the consolidation behaviors of Cu-coated Ni-based amorphous composite powders were investigated. The atomization was conducted at 1450 deg. C under the vacuum of 10 -2 mbar. The Ni-based amorphous powders and Cu nitrate solution were mixed and sprayed at temperature of 130 deg. C. After spray drying and reduction treatment, the sub-micron size Cu powders were coated successfully on the surface of the atomized Ni amorphous powders. The spark plasma sintering process was applied to study the densification behavior of the Cu-coated composite powders. Thickness of the Cu layer was less than 1 μm. The compacts obtained by SPS showed high relative density of over 98% and its hardness was over 800 Hv

Towards More Sustainable Material Formulations: A Comparative Assessment of PA11-SGW Flexural Performance versus Oil-Based Composites

Directory of Open Access Journals (Sweden)

Helena Oliver-Ortega

2018-04-01

Full Text Available The replacement of commodity polyolefin, reinforced with glass fiber (GF, by greener alternatives has been a topic of research in recent years. Cellulose fibers have shown, under certain conditions, enough tensile capacities to replace GF, achieving competitive mechanical properties. However, if the objective is the production of environmentally friendlier composites, it is necessary to replace oil-derived polymer matrices by bio-based or biodegradable ones, depending on the application. Polyamide 11 (PA11 is a totally bio-based polyamide that can be reinforced with cellulosic fibers. Composites based on this polymer have demonstrated enough tensile strength, as well as stiffness, to replace GF-reinforced polypropylene (PP. However, flexural properties are of high interest for engineering applications. Due to the specific character of short-fiber-reinforced composites, significant differences are expected between the tensile and flexural properties. These differences encourage the study of the flexural properties of a material prior to the design or development of a new product. Despite the importance of the flexural strength, there are few works devoted to its study in the case of PA11-based composites. In this work, an in-depth study of the flexural strength of PA11 composites, reinforced with Stoneground wood (SGW from softwood, is presented. Additionally, the results are compared with those of PP-based composites. The results showed that the SGW fibers had lower strengthening capacity reinforcing PA11 than PP. Moreover, the flexural strength of PA11-SGW composites was similar to that of PP-GF composites.

Stochastic-Strength-Based Damage Simulation of Ceramic Matrix Composite Laminates

Science.gov (United States)

Nemeth, Noel N.; Mital, Subodh K.; Murthy, Pappu L. N.; Bednarcyk, Brett A.; Pineda, Evan J.; Bhatt, Ramakrishna T.; Arnold, Steven M.

2016-01-01

The Finite Element Analysis-Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program was used to characterize and predict the progressive damage response of silicon-carbide-fiber-reinforced reaction-bonded silicon nitride matrix (SiC/RBSN) composite laminate tensile specimens. Studied were unidirectional laminates [0] (sub 8), [10] (sub 8), [45] (sub 8), and [90] (sub 8); cross-ply laminates [0 (sub 2) divided by 90 (sub 2),]s; angled-ply laminates [plus 45 (sub 2) divided by -45 (sub 2), ]s; doubled-edge-notched [0] (sub 8), laminates; and central-hole laminates. Results correlated well with the experimental data. This work was performed as a validation and benchmarking exercise of the FEAMAC/CARES program. FEAMAC/CARES simulates stochastic-based discrete-event progressive damage of ceramic matrix composite and polymer matrix composite material structures. It couples three software programs: (1) the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC), (2) the Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Program (CARES/Life), and (3) the Abaqus finite element analysis program. MAC/GMC contributes multiscale modeling capabilities and micromechanics relations to determine stresses and deformations at the microscale of the composite material repeating-unit-cell (RUC). CARES/Life contributes statistical multiaxial failure criteria that can be applied to the individual brittle-material constituents of the RUC, and Abaqus is used to model the overall composite structure. For each FEAMAC/CARES simulation trial, the stochastic nature of brittle material strength results in random, discrete damage events that incrementally progress until ultimate structural failure.

DETERMINATION OF PHASE COMPOSITION OF SEALING COATING BASED ON APC (ALUMINOPHOSPHATE COMPOUNDS

Directory of Open Access Journals (Sweden)

BOLSHAKOV V. I.

2017-02-01

Full Text Available Summary. Goal. To investigate the phase composition of the obtained sealing coatings based on aluminophosphate compound (APC and the impact of temperature rise on it. Methods. Qualitative X-ray phase analysis (XRPA and differential thermal analysis (DTA are used as the methods of research. Roentgenograms for structural analysis were obtained on a DRON-4-07 using filtered copper radiation in the secondary beam. Registration and initial processing of diffraction patterns was performed using the software package PDOS with the output of the diffraction patterns on the screen. Using the "loupe" option allowed to identify weak interference lines, which increased the accuracy of the method of qualitative XRPA. The thermograms for DTA received on the device type Termoskan-2. The results. It is revealed that base of coating is X-ray amorphous phase. There are following crystalline phases: Al, AlPO4, Al (PO3 3, BN found in the coating. It is revealed that annealing doesn’t make a significant influence on the phase composition of the crystalline phases and the coating doesn’t lose properties after annealing during repeated thermal stress. Scientific novelty. The phase composition of the proposed sealing coatings based on APC and produced by plasma spraying, and the effect of annealing on the phase composition of the coating are investigated. The reaction of synthesis of primary material forming on the basis of APC for coating is offered. Practical significance. The results can be used in aviation technology in the development of gas turbine engines (GTE and the design of the compressors. The sealing coating may be used to improve the reliability of the compressor and to increase the efficiency ratio of turbine engine. During the operation the compressor’s blades touch the sealing coating of compressor’s stator and grooves it without causing locking and destruction of the rotor. Therefore, the development of new sealing coating compositions that

Carbon nanotube—cuprous oxide composite based pressure sensors

International Nuclear Information System (INIS)

Karimov, Kh. S.; Chani, Muhammad Tariq Saeed; Khalid, Fazal Ahmad; Khan, Adam; Khan, Rahim

2012-01-01

In this paper, we present the design, the fabrication, and the experimental results of carbon nanotube (CNT) and Cu 2 O composite based pressure sensors. The pressed tablets of the CNT—Cu 2 O composite are fabricated at a pressure of 353 MPa. The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm. The sizes of the Cu 2 O micro particles are in the range of 3–4 μm. The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm, respectively. In order to make low resistance electric contacts, the two sides of the pressed tablet are covered by silver pastes. The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m 2 . The simulation result of the resistance—pressure relationship is in good agreement with the experimental result within a variation of ±2%. (condensed matter: structural, mechanical, and thermal properties)

Characterization of water sorption, solubility, and roughness of silorane- and methacrylate-based composite resins.

Science.gov (United States)

Giannini, M; Di Francescantonio, M; Pacheco, R R; Cidreira Boaro, L C; Braga, R R

2014-01-01

The objective of this study was to evaluate the surface roughness (SR), water sorption (WS), and solubility (SO) of four composite resins after finishing/polishing and after one year of water storage. Two low-shrinkage composites (Filtek Silorane [3M ESPE] and Aelite LS [Bisco Inc]) and two composites of conventional formulations (Heliomolar and Tetric N-Ceram [Ivoclar Vivadent]) were tested. Their respective finishing and polishing systems (Sof-Lex Discs, 3M ESPE; Finishing Discs Kit, Bisco Inc; and Astropol F, P, HP, Ivoclar Vivadent) were used according to the manufacturers' instructions. Ten disc-shaped specimens of each composite resin were made for each evaluation. Polished surfaces were analyzed using a profilometer after 24 hours and one year. For the WS and SO, the discs were stored in desiccators until constant mass was achieved. Specimens were then stored in water for seven days or one year, at which time the mass of each specimen was measured. The specimens were dried again and dried specimen mass determined. The WS and SO were calculated from these measurements. Data were analyzed by two-way analysis of variance and Tukey post hoc test (α=0.05). Filtek Silorane showed the lowest SR, WS, and SO means. Water storage for one year increased the WS means for all composite resins tested. The silorane-based composite resin results were better than those obtained for methacrylate-based resins. One-year water storage did not change the SR and SO properties in any of the composite resins.

Processing of high performance composites based on peek by aqueous suspension prepregging

Directory of Open Access Journals (Sweden)

Liliana Burakowski Nohara

2010-06-01

Full Text Available The use of polyamic acid (PAA precursor as interphase in polymer composites is one of the many applications of polyimides (PIs. In this work, composites based on poly(ether-ether-ketone (PEEK and carbon fibers were prepared using two manufacturing techniques for thermoplastic composites: hot compression molding, and aqueous polymeric suspension prepregging using PIs as interphase. Two PAAs were synthesized and used as interphases: 3,3'-4,4'-benzophenonetetracarboxylic dianhydride/oxydianiline (BTDA/ODA and pyromellitic dianhydride/oxydianiline (PMDA/ODA. The PAA/PI systems were analyzed by differential scanning calorimetry (DSC, thermogravimetry (TGA, Fourier transform infrared spectroscopy (FTIR and nuclear magnetic resonance (NMR. Results from these analyses confirmed the synthesis of these compounds. Aqueous polymeric suspension prepregging was more efficient than hot compression molding when the PMDA/ODA PAA/PI interphase was used; also, the interlaminar shear strength of composites produced using this technique was 14.5% higher than the one produced using hot compression molding.

Petri Net-Based R&D Process Modeling and Optimization for Composite Materials

Directory of Open Access Journals (Sweden)

Xiaomei Hu

2013-01-01

Full Text Available Considering the current R&D process for new composite materials involves some complex details, such as formula design, specimen/sample production, materials/sample test, assessment, materials/sample feedback from customers, and mass production, the workflow model of Petri net-based R&D process for new composite materials’ is proposed. By analyzing the time property of the whole Petri net, the optimized model for new composite materials R&D workflow is further proposed. By analyzing the experiment data and application in some materials R&D enterprise, it is demonstrated that the workflow optimization model shortens the period of R&D on new materials for 15%, definitely improving the R&D efficiency. This indicates the feasibility and availability of the model.

Preparation and Characterization of Carbon Nanotubes-Based Composite Electrodes for Electric Double Layer Capacitors

International Nuclear Information System (INIS)

Seo, Min Kang; Park, Soo Jin

2012-01-01

In this work, we prepared activated multi-walled carbon nanotubes/polyacrylonitrile (A-MWCNTs/C) composites by film casting and activation method. Electrochemical properties of the composites were investigated in terms of serving as MWCNTs-based electrode materials for electric double layer capacitors (EDLCs). As a result, the A-MWCNTs/C composites had much higher BET specific surface area, and pore volume, and lower volume ratio of micropores than those of pristine MWCNTs/PAN ones. Furthermore, some functional groups were added on the surface of the A-MWCNTs/C composites. The specific capacitance of the A-MWCNTs/C composites was more than 4.5 times that of the pristine ones at 0.1 V discharging voltage owing to the changes of the structure and surface characteristics of the MWCNTs by activation process

The Vibration Based Fatigue Damage Assessment of Steel and Steel Fiber Reinforced Concrete (SFRC Composite Girder

Directory of Open Access Journals (Sweden)

Xu Chen

2015-01-01

Full Text Available The steel-concrete composite girder has been usually applied in the bridge and building structures, mostly consisting of concrete slab, steel girder, and shear connector. The current fatigue damage assessment for the composite girder is largely based on the strain values and concrete crack features, which is time consuming and not stable. Hence the vibration-based fatigue damage assessment has been considered in this study. In detail, a steel-steel fiber reinforced concrete (SFRC composite girder was tested. The steel fiber reinforced concrete is usually considered for dealing with the concrete cracks in engineering practice. The composite girder was 3.3m long and 0.45m high. The fatigue load and impact excitation were applied on the specimen sequentially. According to the test results, the concrete crack development and global stiffness degradation during the fatigue test were relatively slow due to the favourable performance of SFRC in tension. But on the other hand, the vibration features varied significantly during the fatigue damage development. Generally, it confirmed the feasibility of executing fatigue damage assessment of composite bridge based on vibration method.

Pressure Sensitive Sensors Based on Carbon Nanotubes, Graphene, and Its Composites

Directory of Open Access Journals (Sweden)

Asar Ali

2018-01-01

Full Text Available Carbon nanotubes (CNTs and graphene have attracted a great deal of interest due to their outstanding mechanical, optical, electrical, and structural properties. Most of the scientists and researchers have investigated the optical and electrical properties of these materials. However, due to unique electromechanical properties of these materials, it is required to explore the piezoresistive properties of bulk nanostructured CNTs, graphene, and CNT-graphene composites. We investigated and compared the sensitivities and piezoresistive properties of sandwich-type pure CNT, pure graphene, and CNT-graphene composite pressure sensors. For all the samples, increase in pressure from 0 to 0.183 kNm−2 results in a decrease in the impedance and direct current (DC resistance. Sensitivity and percentage decrease in resistance and impedance of CNT-graphene composite were lower than pure CNT while being higher than pure graphene based sample. Moreover, under the same external applied pressure, the sensitivity and percentage decrease in impedance for pure CNT, pure graphene, and CNT-graphene composite were smaller than the corresponding sensitivity and percentage decrease in resistance. The achieved experimental results of the composite sample were compared with simulated results which exhibit reasonable agreement with each other. The deviations of simulated resistance-pressure and impedance-pressure curves from experimental graphs were 0.029% and 0.105%, respectively.

A novel and efficient water-based composite binder for LiCoO{sub 2} cathodes in lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Chu, Yung-Ju [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei (China); Peng, Xing-Wei [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei (China); Wang, Fu-Ming; Yang, Chang-Rung [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung, Hsinchu (China); Li, Chia-Chen [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei (China); Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei (China); Lee, Jyh-Tsung

2007-11-15

The dispersion, adhesion strength, electrical, and electrochemical properties of LiCoO{sub 2} cathodes in lithium-ion batteries with the addition of a new composite binder composed of two acrylic emulsions, poly(butyl acrylate)-based (PBA) and polyacrylonitrile-based (PA) latex in a ratio of 3:7, were evaluated. PBA binder has a low-glass transition temperature of 10 C, which can improve the flexibility of the electrode. This new composite binder has a very good binding ability as same as the typical organic solvent-based binder, poly(vinylidene fluoride). The dispersions of the water-based cathode slurries with the composite binder were measured by analyzing the viscosity and sedimentation behaviors. The results show that the new composite binder can well disperse the LiCoO{sub 2}. Moreover, using the new composite binder could greatly improve the rate capabilities and the cycle stability of water-based LiCoO{sub 2} cathodes. (author)

Influence of Graphene Nanosheets on Rheology, Microstructure, Strength Development and Self-Sensing Properties of Cement Based Composites

Directory of Open Access Journals (Sweden)

Sardar Kashif Ur Rehman

2018-03-01

Full Text Available In this research, Graphene oxide (GO, prepared by modified hammer method, is characterized using X-ray Diffraction (XRD, Fourier Transform Infrared (FT-IR Spectrometry and Raman spectra. The dispersion efficiency of GO in aqueous solution is examined by Ultraviolet–visible spectroscopy and it is found that GO sheets are well dispersed. Thereafter, rheological properties, flow diameter, hardened density, compressive strength and electrical properties of GO based cement composite are investigated by incorporating 0.03% GO in cement matrix. The reasons for improvement in strength are also discussed. Rheological results confirm that GO influenced the flow behavior and enhanced the viscosity of the cement based system. From XRD and Thermogravimetric Analysis (TGA results, it is found that more hydration occurred when GO was incorporated in cement based composite. The GO based cement composite improves the compressive strength and density of mortar by 27% and 1.43%, respectively. Electrical properties results showed that GO–cement based composite possesses self-sensing characteristics. Hence, GO is a potential nano-reinforcement candidate and can be used as self-sensing sustainable construction material.

Halide salts accelerate degradation of high explosives by zerovalent iron

International Nuclear Information System (INIS)

Kim, Jong Sung; Shea, Patrick J.; Yang, Jae E.; Kim, Jang-Eok

2007-01-01

Zerovalent iron (Fe 0 , ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe 0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl - and Br - was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br - was present in solution. - The addition of halide ions promotes the degradation of high explosives by zerovalent iron

Segmentation of 9Cr Steel Samples based on Composition and Mechanical Property

Science.gov (United States)

Krishnamurthy, Narayanan; Maddali, Siddharth; Vyacheslav, Romanov; Hawk, Jeffrey

Data mining approaches were used to look at composition-process-property linkage in 9Cr steel. We present results of cluster identification using 7 principal composition elements and analyze its significance with respect to mechanical tensile properties. Data set comprises 82 compositional variants of 9Cr steel whose Cr weight fraction ranges 8-13%. The alloys underwent heat treatments (homogenization, normalization, and 1 to 3 tempering cycles) and were tested for tensile and creep properties at room temperature and elevated temperatures (427/800 oC median/max). In this study, alloys were partitioned into groups, and their mechanical properties were analyzed for significant differences across groups. Normalized weight fractions were used to delineate groups of alloys. Partitioning Around Medoids (PAM) clustering was used, with dissimilarities instead of distance metrics. Dataset of 21 chemical components, with Fe being the majority component, followed by Cr and C. Major contributors of composition to PAM clustering were obtained from PCA scores. Mean ultimate tensile strength of segmented groups of alloys was analyzed with ANOVA & Tukey HSD tests to identify the final 3 groups based on composition and mechanical property.

High Performance Graphene Oxide Based Rubber Composites

Science.gov (United States)

Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

2013-01-01

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

Composite Scaffolds Based on Silver Nanoparticles for Biomedical Applications

Directory of Open Access Journals (Sweden)

Jenel Marian Patrascu

2015-01-01

Full Text Available This paper presents the synthesis, characterisation, and in vitro testing of homogenous and heterogeneous materials containing silver nanoparticles (nanoAg. Three types of antiseptic materials based on collagen (COLL, hydroxyapatite (HA, and collagen/hydroxyapatite (COLL/HA composite materials were obtained. The synthesis of silver nanoparticles was realized by chemical reaction as well as plasma sputtering deposition. The use of chemical reduction allows the synthesis of homogenous materials while the plasma sputtering deposition can be easily used for the synthesis of homogeneous and heterogeneous support. Based on the in vitro assays clear antiseptic activity against Escherichia coli was relieved even at low content of nanoAg (10 ppm.

Ceramic compositions based on nano forsterite/nano magnesium aluminate spinel powders

International Nuclear Information System (INIS)

Khattab, R.M.; Wahsh, M.M.S.; Khalil, N.M.

2015-01-01

According to the wide applications in the field of chemical and engineering industries, forsterite (Mg_2SiO_4)/spinel (MgAl_2O_4) ceramic compositions were the matter of interest of several research works during the last three decades. This work aims at preparation and characterization of improved ceramic bodies based on forsterite and spinel nano powders through controlling the forsterite and spinel contents in the prepared mixes. These prepared ceramic compositions have been investigated through measuring the densification parameters, cold crushing strength as well as volume resistively. Nano spinel was added from 0 to 30 mass% on expense of nano forsterite matrix and fired at 1550 °C for 2 h. The phase composition of the fired samples was examined using x-ray diffraction (XRD) technique. The microstructure of some selected samples was shown using scanning electron microscope (SEM). A pronounced improvement in the sintering, mechanical properties and volume resistively were achieved with increasing of nano spinel addition up to 15 mass%. This is due to the improvement in the matrix of the prepared forsterite/spinel bodies as a result of well distribution of spinel in the forsterite matrix as depicted by SEM analysis. - Highlights: • Ceramic compositions based on nano forsterite/nano-MgAl_2O_4 spinel were synthesized. • CCS was improved (333.78 MPa) through 15 mass% of nano-MgAl_2O_4 spinel addition. • Volume resistivity was enhanced to 203*10"1"3 Ohm cm with 15 mass% of spinel addition. • Beyond 15 mass% spinel, CCS and volume resistivity were decreased.

Supercapacitors Based on Nickel Oxide/Carbon Materials Composites

Directory of Open Access Journals (Sweden)

Katarzyna Lota

2011-01-01

Full Text Available In the thesis, the properties of nickel oxide/active carbon composites as the electrode materials for supercapacitors are discussed. Composites with a different proportion of nickel oxide/carbon materials were prepared. A nickel oxide/carbon composite was prepared by chemically precipitating nickel hydroxide on an active carbon and heating the hydroxide at 300 ∘C in the air. Phase compositions of the products were characterized using X-ray diffractometry (XRD. The morphology of the composites was observed by SEM. The electrochemical performances of composite electrodes used in electrochemical capacitors were studied in addition to the properties of electrode consisting of separate active carbon and nickel oxide only. The electrochemical measurements were carried out using cyclic voltammetry, galvanostatic charge/discharge, and impedance spectroscopy. The composites were tested in 6 M KOH aqueous electrolyte using two- and three-electrode Swagelok systems. The results showed that adding only a few percent of nickel oxide to active carbon provided the highest value of capacity. It is the confirmation of the fact that such an amount of nickel oxide is optimal to take advantage of both components of the composite, which additionally can be a good solution as a negative electrode in asymmetric configuration of electrode materials in an electrochemical capacitor.

Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

Energy Technology Data Exchange (ETDEWEB)

Jawaid, M. [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abdul Khalil, H.P.S., E-mail: akhalilhps@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

2011-06-15

Highlights: {yields} Woven hybrid composites show good tensile and flexural properties. {yields} Hybridization with 20% woven jute gives rise to sufficient modulus to composites. {yields} Layering pattern affect mechanical properties of hybrid composites. {yields} Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

International Nuclear Information System (INIS)

Jawaid, M.; Abdul Khalil, H.P.S.; Abu Bakar, A.

2011-01-01

Highlights: → Woven hybrid composites show good tensile and flexural properties. → Hybridization with 20% woven jute gives rise to sufficient modulus to composites. → Layering pattern affect mechanical properties of hybrid composites. → Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

Supercapacitor electrodes based on polyaniline-silicon nanoparticle composite

Energy Technology Data Exchange (ETDEWEB)

Liu, Qiang; Yau, Siu-Tung [Department of Electrical and Computer Engineering, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115 (United States); Nayfeh, Munir H. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2010-06-15

A composite material formed by dispersing ultrasmall silicon nanoparticles in polyaniline has been used as the electrode material for supercapacitors. Electrochemical characterization of the composite indicates that the nanoparticles give rise to double-layer capacitance while polyaniline produces pseudocapacitance. The composite shows significantly improved capacitance compared to that of polyaniline. The enhanced capacitance results in high power (220 kW kg{sup -1}) and energy-storage (30 Wh kg{sup -1}) capabilities of the composite material. A prototype supercapacitor using the composite as the charge storage material has been constructed. The capacitor showed the enhanced capacitance and good device stability during 1000 charging/discharging cycles. (author)

Non-destructive evaluation of teeth restored with different composite resins using synchrotron based micro-imaging.

Science.gov (United States)

Fatima, A; Kulkarni, V K; Banda, N R; Agrawal, A K; Singh, B; Sarkar, P S; Tripathi, S; Shripathi, T; Kashyap, Y; Sinha, A

2016-01-01

Application of high resolution synchrotron micro-imaging in microdefects studies of restored dental samples. The purpose of this study was to identify and compare the defects in restorations done by two different resin systems on teeth samples using synchrotron based micro-imaging techniques namely Phase Contrast Imaging (PCI) and micro-computed tomography (MCT). With this aim acquired image quality was also compared with routinely used RVG (Radiovisiograph). Crowns of human teeth samples were fractured mechanically involving only enamel and dentin, without exposure of pulp chamber and were divided into two groups depending on the restorative composite materials used. Group A samples were restored using a submicron Hybrid composite material and Group B samples were restored using a Nano-Hybrid restorative composite material. Synchrotron based PCI and MCT was performed with the aim of visualization of tooth structure, composite resin and their interface. The quantitative and qualitative comparison of phase contrast and absorption contrast images along with MCT on the restored teeth samples shows comparatively large number of voids in Group A samples. Quality assessment of dental restorations using synchrotron based micro-imaging suggests Nano-Hybrid resin restorations (Group B) are better than Group A.

Image segmentation with a novel regularized composite shape prior based on surrogate study

Energy Technology Data Exchange (ETDEWEB)

Zhao, Tingting, E-mail: tingtingzhao@mednet.ucla.edu; Ruan, Dan, E-mail: druan@mednet.ucla.edu [The Department of Radiation Oncology, University of California, Los Angeles, California 90095 (United States)

2016-05-15

Purpose: Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. Methods: In the variational image segmentation framework, a regularization for the composite shape prior is designed to incorporate the geometric relevance of individual training data to the target, which is inferred by an image-based surrogate relevance metric. Specifically, this regularization is imposed on the linear weights of composite shapes and serves as a hyperprior. The overall problem is formulated in a unified optimization setting and a variational block-descent algorithm is derived. Results: The performance of the proposed scheme is assessed in both corpus callosum segmentation from an MR image set and clavicle segmentation based on CT images. The resulted shape composition provides a proper preference for the geometrically relevant training data. A paired Wilcoxon signed rank test demonstrates statistically significant improvement of image segmentation accuracy, when compared to multiatlas label fusion method and three other benchmark active contour schemes. Conclusions: This work has developed a novel composite shape prior regularization, which achieves superior segmentation performance than typical benchmark schemes.

Image segmentation with a novel regularized composite shape prior based on surrogate study

International Nuclear Information System (INIS)

Zhao, Tingting; Ruan, Dan

2016-01-01

Purpose: Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. Methods: In the variational image segmentation framework, a regularization for the composite shape prior is designed to incorporate the geometric relevance of individual training data to the target, which is inferred by an image-based surrogate relevance metric. Specifically, this regularization is imposed on the linear weights of composite shapes and serves as a hyperprior. The overall problem is formulated in a unified optimization setting and a variational block-descent algorithm is derived. Results: The performance of the proposed scheme is assessed in both corpus callosum segmentation from an MR image set and clavicle segmentation based on CT images. The resulted shape composition provides a proper preference for the geometrically relevant training data. A paired Wilcoxon signed rank test demonstrates statistically significant improvement of image segmentation accuracy, when compared to multiatlas label fusion method and three other benchmark active contour schemes. Conclusions: This work has developed a novel composite shape prior regularization, which achieves superior segmentation performance than typical benchmark schemes.

On the formation of silicide precipitates in niobium-silicide based composites

International Nuclear Information System (INIS)

Bewlay, B.P.; Grylls, R.J.; Fraser, H.L.

1999-01-01

Composites based on Nb-Si are attractive candidates for use as structural materials at the very high temperatures required for future aircraft engines. The composites described were produced by directional solidification, which gives a microstructure consisting of Nb dendrites with an Nb 3 Si-Nb eutectic. The aim of this paper is to provide a detailed characterization of precipitates observed in the Nb dendrites in both binary and higher-order alloys. The precipitates possess the Nb 3 Si stoichiometry, but not the stable Nb 3 Si structure. The precipitates form a metastable orthorhombic crystal structure which is related to the Nb matrix via a simple orientation relationship

Qualitative Beam Profiling of Light Curing Units for Resin Based Composites.

Science.gov (United States)

Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Moeginger, Ing Bernhard

2016-12-01

This study investigates two technically simple methods to determine the irradiance distribution of light curing units that governs the performance of a visible-light curing resin-based composites. Insufficient light irradiation leads to under-cured composites with poor mechanical properties and elution of residual monomers. The unknown irradiance distribution and its effect on the final restoration are the main critical issues requiring highly sophisticated experimental equipment. The study shows that irradiance distributions of LCUs can easily be determined qualitatively with generally available equipment. This significantly helps dentists in practices to be informed about the homogeneity of the curing lights. Copyright© 2016 Dennis Barber Ltd.

Tribological behaviour and statistical experimental design of sintered iron-copper based composites

Science.gov (United States)

Popescu, Ileana Nicoleta; Ghiţă, Constantin; Bratu, Vasile; Palacios Navarro, Guillermo

2013-11-01

The sintered iron-copper based composites for automotive brake pads have a complex composite composition and should have good physical, mechanical and tribological characteristics. In this paper, we obtained frictional composites by Powder Metallurgy (P/M) technique and we have characterized them by microstructural and tribological point of view. The morphology of raw powders was determined by SEM and the surfaces of obtained sintered friction materials were analyzed by ESEM, EDS elemental and compo-images analyses. One lot of samples were tested on a "pin-on-disc" type wear machine under dry sliding conditions, at applied load between 3.5 and 11.5 × 10-1 MPa and 12.5 and 16.9 m/s relative speed in braking point at constant temperature. The other lot of samples were tested on an inertial test stand according to a methodology simulating the real conditions of dry friction, at a contact pressure of 2.5-3 MPa, at 300-1200 rpm. The most important characteristics required for sintered friction materials are high and stable friction coefficient during breaking and also, for high durability in service, must have: low wear, high corrosion resistance, high thermal conductivity, mechanical resistance and thermal stability at elevated temperature. Because of the tribological characteristics importance (wear rate and friction coefficient) of sintered iron-copper based composites, we predicted the tribological behaviour through statistical analysis. For the first lot of samples, the response variables Yi (represented by the wear rate and friction coefficient) have been correlated with x1 and x2 (the code value of applied load and relative speed in braking points, respectively) using a linear factorial design approach. We obtained brake friction materials with improved wear resistance characteristics and high and stable friction coefficients. It has been shown, through experimental data and obtained linear regression equations, that the sintered composites wear rate increases

Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

Energy Technology Data Exchange (ETDEWEB)

Mo, Yao; Liu, Qi; Fan, Jinchen, E-mail: Jinchen.fan@shiep.edu.cn; Shi, Penghui; Min, Yulin, E-mail: ahaqmylin@126.com; Xu, Qunjie [Shanghai University of Electric Power, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering (China)

2015-07-15

Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 10{sup 4} S/m.

Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

International Nuclear Information System (INIS)

Mo, Yao; Liu, Qi; Fan, Jinchen; Shi, Penghui; Min, Yulin; Xu, Qunjie

2015-01-01

Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 10 4  S/m.

Plasticized Biodegradable Poly(lactic acid) Based Composites Containing Cellulose in Micro- and Nanosize

OpenAIRE

Halász, Katalin; Csóka, Levente

2013-01-01

The aim of this work was to study the characteristics of thermal processed poly(lactic acid) composites. Poly(ethylene glycol) (PEG400), microcrystalline cellulose (MCC), and ultrasound-treated microcrystalline cellulose (USMCC) were used in 1, 3, and 5 weight percents to modify the attributes of PLA matrix. The composite films were produced by twin screw extrusion followed by film extrusion. The manufactured PLA-based films were characterized by tensile testing, differential scanning calorim...

Magnetostrictive and mechanical properties of Terfenol-D composites based on polymer

Science.gov (United States)

Rodríguez, C.; Cuevas, J. M.; Orue, I.; Vilas, J. L.; Barandiarán, J. M.; Fernandez-Gubieda, M. L.; Leon, L. M.

2007-07-01

Several composites, with outstanding magnetostrictive properties, have been synthesized combining a polyurethane base elastomer, with polycrystalline powders of Terfenol-D with a preferential orientation obtained by curing the material in a magnetic field. The morphology of the polymer matrix can be modified by changing the ratio of the hard /soft segment (F) of the polyurethane from 0.6 to 1.5. The influence of the morphology in the magnetostrictive response, for different composites, has been studied by following the storage modulus, E', in DMTA analysis. The magnetostrictive response has been studied as a function of Terfenol-D particle size and distribution (0-300, 212-300, 106-212, 0-38 μm), as well as a function of the content of the magnetostrictive particles in the composite. The highest response (about 1390 ppm) was obtained for a F=1.5 polyurethane and 50% wt of Terfenol-D of 212-300 μm particle size, oriented with a magnetic field of 0.5 T.

Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

Science.gov (United States)

Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

2017-12-01

Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

Modeling and Simulation of Voids in Composite Tape Winding Process Based on Domain Superposition Technique

Science.gov (United States)

Deng, Bo; Shi, Yaoyao

2017-11-01

The tape winding technology is an effective way to fabricate rotationally composite materials. Nevertheless, some inevitable defects will seriously influence the performance of winding products. One of the crucial ways to identify the quality of fiber-reinforced composite material products is examining its void content. Significant improvement in products' mechanical properties can be achieved by minimizing the void defect. Two methods were applied in this study, finite element analysis and experimental testing, respectively, to investigate the mechanism of how void forming in composite tape winding processing. Based on the theories of interlayer intimate contact and Domain Superposition Technique (DST), a three-dimensional model of prepreg tape void with SolidWorks has been modeled in this paper. Whereafter, ABAQUS simulation software was used to simulate the void content change with pressure and temperature. Finally, a series of experiments were performed to determine the accuracy of the model-based predictions. The results showed that the model is effective for predicting the void content in the composite tape winding process.

Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends.

Science.gov (United States)

Liu, H; Wu, Q; Zhang, Q

2009-12-01

Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones-Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.

Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

KAUST Repository

Almuhammadi, Khaled Hamdan

2016-12-29

Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

An Electrochemical pH Sensor Based on the Amino-Functionalized Graphene and Polyaniline Composite Film.

Science.gov (United States)

Su, W; Xu, J; Ding, Xianting

2016-12-01

Conventional glass-based pH sensors are usually fragile and space consuming. Herein, a miniature electrochemical pH sensor based on amino-functionalized graphene fragments and polyaniline (NH 2 -G/PANI) composite film is developed via simply one-pot electrochemical polymerization on the ITO-coated glass substrates. Cyclic Voltammetry (CV), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Raman Spectra are involved to confirm the successful synthesis and to characterize the properties of the NH 2 -G/PANI composite film. The developed electrochemical pH sensor presents fast response, high sensitivity (51.1 mV/pH) and wide detection range when applied to PBS solutions of pH values from 1 to 11. The robust reproducibility and good stability of the developed pH sensors are investigated as well. Compared to the conventional glass-based pH meters, the NH 2 -G/PANI composite film-based pH sensor could be a promising contender for the flexible and miniaturized pH-sensing devices.

Deflection hardening behaviour of short fibre reinforced fly ash based geopolymer composites

International Nuclear Information System (INIS)

Shaikh, F.U.A.

2013-01-01

Highlights: • Deflection hardening behaviour is achieved in the DFRGC similar to that observed in DFRCC. • The first crack load or in other word the limit of proportionality (LOP) of DFRGC is similar to that of DFRCC. • The DFRGC also exhibited higher deflection at peak load than DFRCC. • The toughness at peak load of DFRGC is also high than that of DFRCC. • The ductility of DFRGC is also higher than that of DFRCC. - Abstract: This paper reports the newly developed ductile fibre reinforced geopolymer composite (DFRGC) exhibiting deflection hardening and multiple cracking behaviour. The binder of the above composite is different from that used in conventional cement based system. The class F fly ash is used instead of Portland cement in DFRGC and is activated by alkaline liquids (sodium hydroxide and sodium silicate). In this study, two types of fibres namely steel (ST) and polyvinyl alcohol (PVA) fibres are used in mono as well as in ST–PVA hybrid form, with a total volume fraction of 2%. The deflection hardening behaviour of newly developed DFRGC is also compared with that of conventional ductile fibre reinforced cementitious composites (DFRCC). The effects of two different sizes of sand (1.18 mm, and 0.6 mm) and sand/binder ratios of 0.5 and 0.75 on the deflection hardening and multiple cracking behaviour of both DFRGC and DFRCC are also evaluated. Results revel that the deflection hardening and multiple cracking behaviour is achieved in geopolymer based DFRGC similar to that of cement based system. For a given sand size and sand content, comparable deflection hardening behaviour, ultimate flexural strength and the deflection at peak load are observed in both cement and geopolymer based composites irrespective of fibre types and combination. The deflection hardening behaviour of DFRGC is also confirmed by the calculated toughness index values of I 20 > 20. The scanning electron microscope (SEM) study shows no degradation of PVA and steel fibres in the

Multi-scale cellulose based new bio-aerogel composites with thermal super-insulating and tunable mechanical properties.

Science.gov (United States)

Seantier, Bastien; Bendahou, Dounia; Bendahou, Abdelkader; Grohens, Yves; Kaddami, Hamid

2016-03-15

Bio-composite aerogels based on bleached cellulose fibers (BCF) and cellulose nanoparticles having various morphological and physico-chemical characteristics are prepared by a freeze-drying technique and characterized. The various composite aerogels obtained were compared to a BCF aerogel used as the reference. Severe changes in the material morphology were observed by SEM and AFM due to a variation of the cellulose nanoparticle properties such as the aspect ratio, the crystalline index and the surface charge density. BCF fibers form a 3D network and they are surrounded by the cellulose nanoparticle thin films inducing a significant reduction of the size of the pores in comparison with a neat BCF based aerogel. BET analyses confirm the appearance of a new organization structure with pores of nanometric sizes. As a consequence, a decrease of the thermal conductivities is observed from 28mWm(-1)K(-1) (BCF aerogel) to 23mWm(-1)K(-1) (bio-composite aerogel), which is below the air conductivity (25mWm(-1)K(-1)). This improvement of the insulation properties for composite materials is more pronounced for aerogels based on cellulose nanoparticles having a low crystalline index and high surface charge (NFC-2h). The significant improvement of their insulation properties allows the bio-composite aerogels to enter the super-insulating materials family. The characteristics of cellulose nanoparticles also influence the mechanical properties of the bio-composite aerogels. A significant improvement of the mechanical properties under compression is obtained by self-organization, yielding a multi-scale architecture of the cellulose nanoparticles in the bio-composite aerogels. In this case, the mechanical property is more dependent on the morphology of the composite aerogel rather than the intrinsic characteristics of the cellulose nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hybrid Composites Based on Carbon Fiber/Carbon Nanofilament Reinforcement

Directory of Open Access Journals (Sweden)

Mehran Tehrani

2014-05-01

Full Text Available Carbon nanofilament and nanotubes (CNTs have shown promise for enhancing the mechanical properties of fiber-reinforced composites (FRPs and imparting multi-functionalities to them. While direct mixing of carbon nanofilaments with the polymer matrix in FRPs has several drawbacks, a high volume of uniform nanofilaments can be directly grown on fiber surfaces prior to composite fabrication. This study demonstrates the ability to create carbon nanofilaments on the surface of carbon fibers employing a synthesis method, graphitic structures by design (GSD, in which carbon structures are grown from fuel mixtures using nickel particles as the catalyst. The synthesis technique is proven feasible to grow nanofilament structures—from ethylene mixtures at 550 °C—on commercial polyacrylonitrile (PAN-based carbon fibers. Raman spectroscopy and electron microscopy were employed to characterize the surface-grown carbon species. For comparison purposes, a catalytic chemical vapor deposition (CCVD technique was also utilized to grow multiwall CNTs (MWCNTs on carbon fiber yarns. The mechanical characterization showed that composites using the GSD-grown carbon nanofilaments outperform those using the CCVD-grown CNTs in terms of stiffness and tensile strength. The results suggest that further optimization of the GSD growth time, patterning and thermal shield coating of the carbon fibers is required to fully materialize the potential benefits of the GSD technique.

Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

KAUST Repository

Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

2016-01-01

Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

School-Based BMI and Body Composition Screening and Parent Notification in California: Methods and Messages

Science.gov (United States)

Madsen, Kristine A.; Linchey, Jennifer

2012-01-01

Background: School-based body mass index (BMI) or body composition screening is increasing, but little is known about the process of parent notification. Since 2001, California has required annual screening of body composition via the FITNESSGRAM, with optional notification. This study sought to identify the prevalence of parental notification…

Investigating a Drop-on-Demand Microdispenser for Standardized Sample Preparation

Science.gov (United States)

2012-09-01

potassium chlorate were obtained from Sigma-Aldrich. 1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7- tetranitro-tetrazocine (HMX), 2,4,6... potassium chlorate , HMX, TNT, RDX, PETN, urea, and sugar. The analyte of interest was dissolved in the appropriate solvent and then diluted to various

Effect of different bleaching strategies on microhardness of a silorane-based composite resin.

Science.gov (United States)

Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

2016-01-01

Background. Dentists' awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P bleaching agents significantly decreased microhardness compared to the control group (P 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used.

A single frequency component-based re-estimated MUSIC algorithm for impact localization on complex composite structures

International Nuclear Information System (INIS)

Yuan, Shenfang; Bao, Qiao; Qiu, Lei; Zhong, Yongteng

2015-01-01

The growing use of composite materials on aircraft structures has attracted much attention for impact monitoring as a kind of structural health monitoring (SHM) method. Multiple signal classification (MUSIC)-based monitoring technology is a promising method because of its directional scanning ability and easy arrangement of the sensor array. However, for applications on real complex structures, some challenges still exist. The impact-induced elastic waves usually exhibit a wide-band performance, giving rise to the difficulty in obtaining the phase velocity directly. In addition, composite structures usually have obvious anisotropy, and the complex structural style of real aircrafts further enhances this performance, which greatly reduces the localization precision of the MUSIC-based method. To improve the MUSIC-based impact monitoring method, this paper first analyzes and demonstrates the influence of measurement precision of the phase velocity on the localization results of the MUSIC impact localization method. In order to improve the accuracy of the phase velocity measurement, a single frequency component extraction method is presented. Additionally, a single frequency component-based re-estimated MUSIC (SFCBR-MUSIC) algorithm is proposed to reduce the localization error caused by the anisotropy of the complex composite structure. The proposed method is verified on a real composite aircraft wing box, which has T-stiffeners and screw holes. Three typical categories of 41 impacts are monitored. Experimental results show that the SFCBR-MUSIC algorithm can localize impact on complex composite structures with an obviously improved accuracy. (paper)

Spheroidization behavior of dendritic b.c.c. phase in Zr-based モ-phase composite

Directory of Open Access Journals (Sweden)

Sun Guoyuan

2013-03-01

Full Text Available The spheroidization behavior of the dendritic b.c.c. phase dispersed in a bulk metallic glass (BMG matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-based モ-phase composite. The Zr-based composite with the composition of Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.5 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction (XRD and scanning electron microscope (SEM. The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of the モ-Zr solid solution with the body-centered-cubic (b.c.c. structure. Based on the differential scanning calorimeter (DSC examination results, and in view of the b.c.c. モ-Zr to h.c.p. メ-Zr phase transition temperature, a semi-solid holding temperature of 900 ìC was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c. モ-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture.

Facile Fabrication of 100% Bio-based and Degradable Ternary Cellulose/PHBV/PLA Composites

Directory of Open Access Journals (Sweden)

Tao Qiang

2018-02-01

Full Text Available Modifying bio-based degradable polymers such as polylactide (PLA and poly(hydroxybutyrate-co-hydroxyvalerate (PHBV with non-degradable agents will compromise the 100% degradability of their resultant composites. This work developed a facile and solvent-free route in order to fabricate 100% bio-based and degradable ternary cellulose/PHBV/PLA composite materials. The effects of ball milling on the physicochemical properties of pulp cellulose fibers, and the ball-milled cellulose particles on the morphology and mechanical properties of PHBV/PLA blends, were investigated experimentally and statistically. The results showed that more ball-milling time resulted in a smaller particle size and lower crystallinity by way of mechanical disintegration. Filling PHBV/PLA blends with the ball-milled celluloses dramatically increased the stiffness at all of the levels of particle size and filling content, and improved their elongation at the break and fracture work at certain levels of particle size and filling content. It was also found that the high filling content of the ball-milled cellulose particles was detrimental to the mechanical properties for the resultant composite materials. The ternary cellulose/PHBV/PLA composite materials have some potential applications, such as in packaging materials and automobile inner decoration parts. Furthermore, filling content contributes more to the variations of their mechanical properties than particle size does. Statistical analysis combined with experimental tests provide a new pathway to quantitatively evaluate the effects of multiple variables on a specific property, and figure out the dominant one for the resultant composite materials.

Radiation curable adhesive compositions and composite structures

International Nuclear Information System (INIS)

Brenner, W.

1984-01-01

This disclosure relates to novel adhesive compositions and composite structures utilizing the same, wherein said adhesive compositions contain an elastomer, a chemically compatible ethylenically unsaturated monomer, a tackifier, an adhesion promoter, and optionally, pigments, fillers, thickeners and flow control agents which are converted from the liquid to the solid state by exposure to high energy ionizing radiation such as electron beam. A particularly useful application for such adhesive compositions comprises the assembly of certain composite structures or laminates consisting of, for example, a fiber flocked rubber sheet and a metal base with the adhesive fulfilling the multiple functions of adhering the flocked fiber to the rubber sheet as well as adhering the rubber sheet to the metal base. Optionally, the rubber sheet itself may also be cured at the same time as the adhesive composition with all operations being carried out at ambient temperatures and in the presence of air, with exposure of said assembly to selected dosages of high energy ionizing radiation. These adhesive compositions contain no solvents thereby almost eliminating air pollution or solvent toxicity problems, and offer substantial savings in energy and labor as they are capable of curing in very short time periods without the use of external heat which might damage the substrate

State of the art of durability-performance evaluation of hardened cement based on phase compositions

International Nuclear Information System (INIS)

Kurashige, Isao; Imoto, Harutake; Yamamoto, Takeshi; Hironaga, Michihiko

2006-01-01

Upgrading durability-performance evaluation technique for concrete is urgently demanded in connection to its application to radio-active waste repository which needs ultra long-term durability. Common concrete structures also require an advanced method for minimizing the life-cycle cost. The purpose of this research is to investigate current problems and future tasks on durability-performance evaluation of hardened cement from the view point of phase composition. Although the phase composition of hardened cement has not fully been reflected to durability-performance evaluation, it influences concrete durability as well as its pore structure. This report reviews state of the art of the factors affecting phase composition, analytical and experimental evaluation techniques for phase composition, and durability-performance evaluation methods of hardened cement based on phase composition. (author)

High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites.

Science.gov (United States)

Erden, Fuat; Li, Hui; Wang, Xizu; Wang, FuKe; He, Chaobin

2018-04-04

In the present work, we report the fabrication of high-performance thermoelectric materials using TiO2/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm-1 can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO2 nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO2/a-CNT and TiO2/PANI. The resulting TiO2/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK-2 was obtained for the ternary composite of 30% TiO2/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO2 suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.

Production and Characterization of WC-Reinforced Co-Based Superalloy Matrix Composites

Science.gov (United States)

Özgün, Özgür; Dinler, İlyas

2018-05-01

Cobalt-based superalloy matrix composite materials were produced through the powder metallurgy technique using element powders at high purity and nano-sized wolfram carbide (WC) reinforcement in this study. An alloy that had the same chemical composition as the Stellite 6 alloy but not containing carbon was selected as the matrix alloy. The powder mixtures obtained as a result of mixing WC reinforcing member and element powders at the determined ratio were shaped by applying 300 MPa of pressure. The green components were sintered under argon atmosphere at 1240 °C for 120 minutes. The densities of the sintered components were determined by the Archimedes' principle. Microstructural characterization was performed via X-ray diffraction analysis, scanning electron microscope examinations, and energy-dispersive spectrometry. Hardness measurements and tensile tests were performed for determining mechanical characteristics. The relative density values of the sintered components increased by increasing the WC reinforcement ratio and they could almost reach the theoretical density. It was determined from the microstructural examinations that the composite materials consisted of fine and equiaxed grains and coarse carbides demonstrating a homogeneous dispersion along the microstructure at the grain boundaries. As it was the case in the density values, the hardness and strength values of the composites increased by increasing the WC ratio.

Si-doping bone composite based on protein template-mediated assembly for enhancing bone regeneration

Science.gov (United States)

Yang, Qin; Du, Yingying; Wang, Yifan; Wang, Zhiying; Ma, Jun; Wang, Jianglin; Zhang, Shengmin

2017-06-01

Bio-inspired hybrid materials that contain organic and inorganic networks interpenetration at the molecular level have been a particular focus of interest on designing novel nanoscale composites. Here we firstly synthesized a series of hybrid bone composites, silicon-hydroxyapatites/silk fibroin/collagen, based on a specific molecular assembled strategy. Results of material characterization confirmed that silicate had been successfully doped into nano-hydroxyapatite lattice. In vitro evaluation at the cellular level clearly showed that these Si-doped composites were capable of promoting the adhesion and proliferation of rat mesenchymal stem cells (rMSCs), extremely enhancing osteoblastic differentiation of rMSCs compared with silicon-free composite. More interestingly, we found there was a critical point of silicon content in the composition on regulating multiple cell behaviors. In vivo animal evaluation further demonstrated that Si-doped composites enabled to significantly improve the repair of cranial bone defect. Consequently, our current work not only suggests fabricating a potential bone repair materials by integrating element-doping and molecular assembled strategy in one system, but also paves a new way for constructing multi-functional composite materials in the future.

Si-doping bone composite based on protein template-mediated assembly for enhancing bone regeneration

Institute of Scientific and Technical Information of China (English)

Qin YANG; Yingying DU; Yifan WANG; Zhiying WANG; Jun MA; Jianglin WANG; Shengmin ZHANG

2017-01-01

Bio-inspired hybrid materials that contain organic and inorganic networks interpenetration at the molecular level have been a particular focus of interest on designing novel nanoscale composites.Here we firstly synthesized a series of hybrid bone composites,silicon-hydroxyapatites/silk fibroin/collagen,based on a specific molecular assembled strategy.Results of material characterization confirmed that silicate had been successfully doped into nano-hydroxyapatite lattice.In vitro evaluation at the cellular level clearly showed that these Si-doped composites were capable of promoting the adhesion and proliferation of rat mesenchymal stem cells (rMSCs),extremely enhancing osteoblastic differentiation of rMSCs compared with silicon-free composite.More interestingly,we found there was a critical point of silicon content in the composition on regulating multiple cell behaviors.In vivo animal evaluation further demonstrated that Si-doped composites enabled to significantly improve the repair of cranial bone defect.Consequently,our current work not only suggests fabricating a potential bone repair materials by integrating element-doping and molecular assembled strategy in one system,but also paves a new way for constructing multi-functional composite materials in the future.

Composite Based EHV AC Overhead Transmission Lines

DEFF Research Database (Denmark)

Sørensen, Thomas Kjærsgaard

and analysed with regard to the possibilities, limitations and risks widespread application of composite materials on EHV AC overhead transmission lines may present. To form the basis for evaluation of the useability of composite materials, dierent overhead line projects aimed at reducing the environmental...

On the low pressure shock initiation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine based plastic bonded explosives

Science.gov (United States)

Vandersall, Kevin S.; Tarver, Craig M.; Garcia, Frank; Chidester, Steven K.

2010-05-01

In large explosive and propellant charges, relatively low shock pressures on the order of 1-2 GPa impacting large volumes and lasting tens of microseconds can cause shock initiation of detonation. The pressure buildup process requires several centimeters of shock propagation before shock to detonation transition occurs. In this paper, experimentally measured run distances to detonation for lower input shock pressures are shown to be much longer than predicted by extrapolation of high shock pressure data. Run distance to detonation and embedded manganin gauge pressure histories are measured using large diameter charges of six octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) based plastic bonded explosives (PBX's): PBX 9404; LX-04; LX-07; LX-10; PBX 9501; and EDC37. The embedded gauge records show that the lower shock pressures create fewer and less energetic "hot spot" reaction sites, which consume the surrounding explosive particles at reduced reaction rates and cause longer distances to detonation. The experimental data is analyzed using the ignition and growth reactive flow model of shock initiation in solid explosives. Using minimum values of the degrees of compression required to ignite hot spot reactions, the previously determined high shock pressure ignition and growth model parameters for the six explosives accurately simulate the much longer run distances to detonation and much slower growths of pressure behind the shock fronts measured during the shock initiation of HMX PBX's at several low shock pressures.

Bioinspired twisted composites based on Bouligand structures

Science.gov (United States)

Pinto, F.; Iervolino, O.; Scarselli, G.; Ginzburg, D.; Meo, M.

2016-04-01

The coupling between structural support and protection makes biological systems an important source of inspiration for the development of advanced smart composite structures. In particular, some particular material configurations can be implemented into traditional composites in order to improve their impact resistance and the out-of-plane properties, which represents one of the major weakness of commercial carbon fibres reinforced polymers (CFRP) structures. Based on this premise, a three-dimensional twisted arrangement shown in a vast multitude of biological systems (such as the armoured cuticles of Scarabei, the scales of Arapaima Gigas and the smashing club of Odontodactylus Scyllarus) has been replicated to develop an improved structural material characterised by a high level of in-plane isotropy and a higher interfacial strength generated by the smooth stiffness transition between each layer of fibrils. Indeed, due to their intrinsic layered nature, interlaminar stresses are one of the major causes of failure of traditional CFRP and are generated by the mismatch of the elastic properties between plies in a traditional laminate. Since the energy required to open a crack or a delamination between two adjacent plies is due to the difference between their orientations, the gradual angle variation obtained by mimicking the Bouligand Structures could improve energy absorption and the residual properties of carbon laminates when they are subjected to low velocity impact event. Two different bioinspired laminates were manufactured following a double helicoidal approach and a rotational one and were subjected to a complete test campaign including low velocity impact loading and compared to a traditional quasi-isotropic panel. Fractography analysis via X-Ray tomography was used to understand the mechanical behaviour of the different laminates and the residual properties were evaluated via Compression After Impact (CAI) tests. Results confirmed that the biological

Boron-nitrogen based hydrides and reactive composites for hydrogen storage

DEFF Research Database (Denmark)

Jepsen, Lars H.; Ley, Morten B.; Lee, Young-Su

2014-01-01

Hydrogen forms chemical compounds with most other elements and forms a variety of different chemical bonds. This fascinating chemistry of hydrogen has continuously provided new materials and composites with new prospects for rational design and the tailoring of properties. This review highlights...... a range of new boron and nitrogen based hydrides and illustrates how hydrogen release and uptake properties can be improved. © 2014 Elsevier Ltd....

Geometric optimization of a neutron detector based on a lithium glass–polymer composite

Energy Technology Data Exchange (ETDEWEB)

Mayer, M., E-mail: mike.f.mayer@gmail.com [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Nattress, J. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Trivelpiece, C. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Jovanovic, I. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

2015-06-01

We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from {sup 252}Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10{sup −7} for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection.

Process conditions and volumetric composition in composites

DEFF Research Database (Denmark)

Madsen, Bo

2013-01-01

The obtainable volumetric composition in composites is linked to the gravimetric composition, and it is influenced by the conditions of the manufacturing process. A model for the volumetric composition is presented, where the volume fractions of fibers, matrix and porosity are calculated...... as a function of the fiber weight fraction, and where parameters are included for the composite microstructure, and the fiber assembly compaction behavior. Based on experimental data of composites manufactured with different process conditions, together with model predictions, different types of process related...... effects are analyzed. The applied consolidation pressure is found to have a marked effect on the volumetric composition. A power-law relationship is found to well describe the found relations between the maximum obtainable fiber volume fraction and the consolidation pressure. The degree of fiber...

A Knowledge-Based Tutor for Music Composition. CITE Report No. 16.

Science.gov (United States)

Holland, Simon

The work described here forms part of a project using models of musical ideas within an artificial intelligence and education framework whose goal is to encourage and facilitate music composition by novices. Formal knowledge of the domain (popular music) is too incomplete and fragmented to support a traditional expert-based tutor for precisely…

Microhardness of resin composite materials light-cured through fiber reinforced composite.

NARCIS (Netherlands)

Fennis, W.M.M.; Ray, N.J.; Creugers, N.H.J.; Kreulen, C.M.

2009-01-01

OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC

Silk Composite with a Fluoropolymer as a Water-Resistant Protein-Based Material

Directory of Open Access Journals (Sweden)

Keiji Numata

2018-04-01

Full Text Available Silk-based materials are water-sensitive and show different physical properties at different humidities and under wet/dry conditions. To overcome the water sensitivity of silk-based materials, we developed a silk composite material with a fluoropolymer. Blending and coating the silk protein-based materials, such as films and textiles, with the fluoropolymer enhanced the surface hydrophobicity, water vapor barrier properties, and size stability during shrinkage tests. This material design with a protein biopolymer and a fluoropolymer is expected to broaden the applicability of protein-based materials.

Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies.

Science.gov (United States)

Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho; Garcia, Lucas da Fonseca Roberti

2015-02-01

The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p adhesive system to dentin.

Rubber Composites Based on Polar Elastomers with Incorporated Modified and Unmodified Magnetic Filler

Directory of Open Access Journals (Sweden)

Ján Kruželák

2016-01-01

Full Text Available Rubber magnetic composites were prepared by incorporation of unmodified and surface modified strontium ferrite into rubber matrices based on NBR and NBR/PVC. Strontium ferrite was dosed to the rubber matrices in concentration scale ranging from 0 to 100 phr. The main goal was to investigate the influence of the type of ferrite on the curing process, physical-mechanical and magnetic properties of composites. The mutual interactions between the filler and rubber matrices were investigated by determination of cross-link density and SEM analysis. The incorporation of magnetic fillers leads to the increase of cross-link density and remanent magnetic induction of composites. Moreover, the improvement of physical-mechanical properties was achieved in dependence on the content of magnetic fillers. Surface modification of ferrite contributed to the enhancement of adhesion on the interphase filler-rubber. It can be stated that ferrite exhibits reinforcing effect in the composite materials and this reinforcing behavior was emphasized with the increase in polarity of the rubber matrix.

Preparation and properties of carbohydrate-based composite films incorporated with CuO nanoparticles.

Science.gov (United States)

Shankar, Shiv; Wang, Long-Feng; Rhim, Jong-Whan

2017-08-01

The present study aimed to develop the carbohydrate biopolymer based antimicrobial films for food packaging application. The nanocomposite films of various biopolymers and copper oxide nanoparticles (CuONPs) were prepared by solvent casting method. The nanocomposite films were characterized using SEM, FTIR, XRD, and UV-vis spectroscopy. The thermal stability, UV barrier, water vapor permeability, and antibacterial activity of the composite films were also evaluated. The surface morphology of the films was dependent on the types of polymers used. The XRD revealed the crystallinity of CuONPs in the composite films. The addition of CuONPs increased the thickness, tensile strength, UV barrier property, relative humidity, and water vapor barrier property. The CuONPs incorporated composite films exhibited strong antibacterial activity against Escherichia coli and Listeria monocytogenes. The developed composite films could be used as a UV-light barrier antibacterial films for active food packaging. Copyright © 2017 Elsevier Ltd. All rights reserved.

Current-Voltage Characteristics of the Composites Based on Epoxy Resin and Carbon Nanotubes

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Iwona Pełech

2015-01-01

Full Text Available Polymer composites based on epoxy resin were prepared. Multiwalled carbon nanotubes synthesized on iron-cobalt catalyst were applied as a filler in a polymer matrix. Chlorine or hydroxyl groups were incorporated on the carbon nanotubes surface via chlorination or chlorination followed by hydroxylation. The effect of functionalized carbon nanotubes on the epoxy resin matrix is discussed in terms of the state of CNTs dispersion in composites as well as electrical properties. For the obtained materials current-voltage characteristics were determined. They had a nonlinear character and were well described by an exponential-type equation. For all the obtained materials the percolation threshold occurred at a concentration of about 1 wt%. At a higher filler concentration >2 wt%, better conductivity was demonstrated by polymer composites with raw carbon nanotubes. At a lower filler concentration <2 wt%, higher values of electrical conductivity were obtained for polymer composites with modified carbon nanotubes.

A paper-based electrode using a graphene dot/PEDOT:PSS composite for flexible solar cells

KAUST Repository

Lee, Chuan-Pei

2017-04-22

We have synthesized a metal-free composite ink that contains graphene dots (GDs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) that can be used on paper to serve as the counter electrode in a flexible dye-sensitized solar cell (DSSC). This paper-based GD/PEDOT:PSS electrode is low-cost, light-weight, flexible, environmentally friendly, and easy to cut and process for device fabrication. We determined the GD/PEDOT:PSS composite effectively fills the dense micro-pores in the paper substrate, which leads to improved carrier transport in the electrode and a 3-fold enhanced cell efficiency as compared to the paper electrode made with sputtered Pt. Moreover, the DSSC with the paper electrode featuring the GD/PEDOT:PSS composite did not fail in photovoltaic tests even after bending the electrode 150 times, whereas the device made with the Pt-based paper electrode decreased in efficiency by 45% after such manipulation. These exceptional properties make the metal-free GD/PEDOT:PSS composite ink a promising electrode material for a wide variety of flexible electronic applications.

Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

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Yongsheng Wang

2014-04-01

Full Text Available The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass–matrix composite (MGMC were investigated by using an in-situ tensile test under transmission electron microscopy (TEM. It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.

Mechanically Activated Combustion Synthesis of MoSi₂-Based Composites

Energy Technology Data Exchange (ETDEWEB)

Shafirovich, Evgeny [Univ. of Texas, El Paso, TX (United States)

2015-09-30

The thermal efficiency of gas-turbine power plants could be dramatically increased by the development of new structural materials based on molybdenum silicides and borosilicides, which can operate at temperatures higher than 1300 °C with no need for cooling. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. One approach is based on the fabrication of MoSi2-Mo5Si3 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of Mo5Si3. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, materials based on Mo5SiB2 phase are promising materials that offer favorable combinations of high temperature mechanical properties and oxidation resistance. However, the synthesis of Mo-Si-B multi-phase alloys is difficult because of their extremely high melting temperatures. Mechanical alloying has been considered as a promising method, but it requires long milling times, leading to large energy consumption and contamination of the product by grinding media. In the reported work, MoSi2-Mo5Si3 composites and several materials based on Mo5SiB2 phase have been obtained by mechanically activated self-propagating high-temperature synthesis (MASHS). Short-term milling of Mo/Si mixture in a planetary mill has enabled a self-sustained propagation of the combustion front over the mixture pellet, leading to the formation of MoSi2-T1 composites. Combustion of Mo/Si/B mixtures for the formation of T2 phase becomes possible if the composition is designed for the addition of more exothermic reactions leading to the formation of MoB, TiC, or TiB2. Upon ignition, Mo/Si/B and Mo/Si/B/Ti mixtures exhibited spin combustion, but the products were porous, contained undesired secondary phases, and had low oxidation resistance. It has been shown that use of

A usability evaluation of a SNOMED CT based compositional interface terminology for intensive care

NARCIS (Netherlands)

Bakhshi-Raiez, F.; de Keizer, N. F.; Cornet, R.; Dorrepaal, M.; Dongelmans, D.; Jaspers, M. W. M.

2012-01-01

Objective: To evaluate the usability of a large compositional interface terminology based on SNOMED CT and the terminology application for registration of the reasons for intensive care admission in a Patient Data Management System. Design: Observational study with user-based usability evaluations

Composite adhesive bonds reinforced with microparticle filler based on egg shell waste

Science.gov (United States)

Müller, Miroslav; Valášek, Petr

2018-05-01

A research on composite adhesive bonds reinforced with waste from hen eggs processing, i.e. egg shell waste (ESW) is based on an assumption of the utilization of agricultural/food production waste. The aim of the research is to gain new pieces of knowledge about the material utilization of ESW, i.e. to evaluate possibilities of the use of various concentrations of ESW microparticles smaller than 100 µm based on hen egg shells as the filler in a structural resin used for a creation of adhesive bonds from bearing metal elements. An adhesive bond strength, an elongation at break and a fracture surface were evaluated within the research on adhesive bonds. The experiment results proved the efficiency of ESW filler in the area of composite adhesive bonds. The adhesive bond strength was increased up of more than 17 % by adding 40 wt.% of ESW microparticles.

Thickness effect on electric resistivity on polystyrene and carbon black- based composites

Energy Technology Data Exchange (ETDEWEB)

Hernandez-Lopez, S; Vigueras-Santiago, E [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA) Facultad de Quimica, Paseo Colon Esquina con Paseo Tollocan, s/n, CP 50000, Toluca (Mexico); Mayorga-Rojas, M; Reyes-Contreras, D, E-mail: eviguerass@uaemex.m [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. Av. Instituto Literario 100 Ote. C. P. 50000, Toluca (Mexico)

2009-05-01

Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30{mu}m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100 deg. C, slightly up to T{sub g} of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at T{sub g}, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 mu m thickness sample the hysteresis loop was lost after four cycles.

Hierarchical Assembly of Multifunctional Oxide-based Composite Nanostructures for Energy and Environmental Applications

Directory of Open Access Journals (Sweden)

Hui-Jan Lin

2012-06-01

Full Text Available Composite nanoarchitectures represent a class of nanostructured entities that integrates various dissimilar nanoscale building blocks including nanoparticles, nanowires, and nanofilms toward realizing multifunctional characteristics. A broad array of composite nanoarchitectures can be designed and fabricated, involving generic materials such as metal, ceramics, and polymers in nanoscale form. In this review, we will highlight the latest progress on composite nanostructures in our research group, particularly on various metal oxides including binary semiconductors, ABO₃-type perovskites, A₂BO₄ spinels and quaternary dielectric hydroxyl metal oxides (AB(OH₆ with diverse application potential. Through a generic template strategy in conjunction with various synthetic approaches—such as hydrothermal decomposition, colloidal deposition, physical sputtering, thermal decomposition and thermal oxidation, semiconductor oxide alloy nanowires, metal oxide/perovskite (spinel composite nanowires, stannate based nanocompostes, as well as semiconductor heterojunction—arrays and networks have been self-assembled in large scale and are being developed as promising classes of composite nanoarchitectures, which may open a new array of advanced nanotechnologies in solid state lighting, solar absorption, photocatalysis and battery, auto-emission control, and chemical sensing.

Colorimetric test-systems for creatinine detection based on composite molecularly imprinted polymer membranes.

Science.gov (United States)

Sergeyeva, T A; Gorbach, L A; Piletska, E V; Piletsky, S A; Brovko, O O; Honcharova, L A; Lutsyk, O D; Sergeeva, L M; Zinchenko, O A; El'skaya, A V

2013-04-03

An easy-to-use colorimetric test-system for the efficient detection of creatinine in aqueous samples was developed. The test-system is based on composite molecularly imprinted polymer (MIP) membranes with artificial receptor sites capable of creatinine recognition. A thin MIP layer was created on the surface of microfiltration polyvinylidene fluoride (PVDF) membranes using method of photo-initiated grafting polymerization. The MIP layer was obtained by co-polymerization of a functional monomer (e.g. 2-acrylamido-2-methyl-1-propanesulfonic acid, itaconic acid or methacrylic acid) with N, N'-methylenebisacrylamide as a cross-linker. The choice of the functional monomer was based on the results of computational modeling. The creatinine-selective composite MIP membranes were used for measuring creatinine in aqueous samples. Creatinine molecules were selectively adsorbed by the MIP membranes and quantified using color reaction with picrates. The intensity of MIP membranes staining was proportional to creatinine concentration in an analyzed sample. The colorimetric test-system based on the composite MIP membranes was characterized with 0.25 mM detection limit and 0.25-2.5mM linear dynamic range. Storage stability of the MIP membranes was estimated as at least 1 year at room temperature. As compared to the traditional methods of creatinine detection the developed test-system is characterized by simplicity of operation, small size and low cost. Copyright © 2013 Elsevier B.V. All rights reserved.

Tracing explosive in solvent using quantum cascade laser with pulsed electric discharge system

Energy Technology Data Exchange (ETDEWEB)

Park, Seong-Wook; Tian, Chao; Martini, Rainer, E-mail: rmartini@stevens.edu [Department of Physics and Engineering Physics, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, New Jersey 07030 (United States); Chen, Gang [School of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China); Chen, I-chun Anderson [Newport Corporation/Oriel Instruments, 150 Long Beach Boulevard, Stratford, Connecticut 06615 (United States)

2014-11-03

We demonstrated highly sensitive detection of explosive dissolved in solvent with a portable spectroscopy system (Q-MACS) by tracing the explosive byproduct, N{sub 2}O, in combination with a pulsed electric discharge system for safe explosive decomposition. Using Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), the gas was monitored and analyzed by Q-MACS and the presence of the dissolved explosive clearly detected. While HMX presence could be identified directly in the air above the solutions even without plasma, much better results were achieved under the decomposition. The experiment results give an estimated detection limit of 10 ppb, which corresponds to a 15 pg of HMX.