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Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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TL;DR: In this article, the influence of adding talc and kaolin fillers on the mechanical properties of nylon 6 was investigated, and the results showed that the tensile strength and modulus of elasticity increased with the increase in filler ratio.
Abstract: Particulate reinforced thermoplastic composites are designed to improve the properties and to lower the overall cost of engineering plastics In this study, the influence of adding talc and kaolin fillers on the mechanical properties of nylon 6 was investigated Fillers, either singly or mixed by various weight ratios between 10 and 30 wt %, were added to nylon 6 Test samples of the composite material were prepared by the injection-molding process Uniaxial tensile and Izod impact tests were carried out Tensile strength, elongation at break, modulus of elasticity, and impact energy were obtained The results showed that the tensile strength and modulus of elasticity of nylon 6 composite increased with the increase in filler ratio, whereas the impact strength and maximum elongation decreased with the increase in filler ratio The optimal nylon composite was determined with the addition of a 10 to 15 wt % filler ratio © 2003 Wiley Periodicals, Inc J Appl Polym Sci 88: 1694–1697, 2003
87 citations
TL;DR: Both methods of glycation enhanced ribose addition and AGE formation in a dose-dependent manner, with glycation in the gel state being more efficient and enhanced mechanical properties similarly, with 250 mM ribose treatment resulting in a 10-fold increase in bulk modulus.
Abstract: This study focuses on the development of a novel method of non-enzymatic glycation of fibrillar collagen gels. In contrast to previous studies in which type I collagen gels were glycated in the solid state, this study presents a method for glycation in solution. Type I collagen in solution or gels was exposed to a range of ribose concentrations from 0–250mM. The binding of ribose to collagen was documented using Fourier Transform Infrared (FTIR) Spectroscopy. Formation of advanced glycation endproducts (AGEs) was quantified by fluorescence measurement. The bulk compressive modulus and viscoelastic time constant of processed gels were determined in stress relaxation studies. Both methods of glycation enhanced ribose addition and AGE formation in a dose dependent manner, with glycation in the gel state being more efficient. Both methods enhanced mechanical properties similarly, with 250mM ribose treatment resulting in a 10-fold increase in bulk modulus.
86 citations
TL;DR: In this paper, the authors combined static and dynamic mechanical analysis on purpose-designed microstructures (microbending of pillar-like structures and picometer-sensitive laser Doppler vibrometry of drumlike structures) to viably and nondestructively estimate Young's modulus, Poisson's ratio, and density of materials for 2P lithography.
Abstract: Two-photon (2P) lithography shows great potential for the fabrication of three-dimensional (3-D) micro- and nanomechanical elements, for applications ranging from microelectromechanical systems to tissue engineering, by virtue of its high resolution (<100 nm) and biocompatibility of the photosensitive resists. However, there is a considerable lack of quantitative data on mechanical properties of materials for 2P lithography and of structures obtained through this technique. In this paper, we combined static and dynamic mechanical analysis on purpose-designed microstructures (microbending of pillar-like structures and picometer-sensitive laser Doppler vibrometry of drum-like structures) to viably and nondestructively estimate Young's modulus, Poisson's ratio, and density of materials for 2P lithography. This allowed us to analyze several polymeric photoresists, including acrylates and epoxy-based materials. The experiments reveal that the 2P exposure power is a key parameter to define the stiffness of the realized structures, with hyperelasticity clearly observable for high-power polymerization. In the linear elastic regime, some of the investigated materials are characterized by a quasi-linear dependence of Young's modulus on the used exposure power, a yet unknown behavior that adds a new degree of freedom to engineer complex 3-D micro- and nanomechanical elements.
86 citations
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...This is probably an effect due to an increased degree of crosslinking, which directly affects the stiffness of the polymerized structure [35]....
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TL;DR: Results from this study indicate that CPU presents a far greater chemical stability than poly(ether)-urethane grafts do, resulting in a stress-free, viable, small-diameter, synthetic vascular graft.
Abstract: Poly(ester) urethane and poly(ether)urethane vascular grafts fail in vivo because of hydrolytic and oxidative degradative mechanisms. Studies have shown that poly(carbonate)urethanes have enhanced resistance. There is still a need for a viable, nonrigid, small-diameter, synthetic vascular graft. In this study, we sought to confirm this by exposing a novel formulation of compliant poly(carbonate)urethane (CPU) manufactured by an innovative process, resulting in a stress-free. Small-diameter prosthesis, and a conventional poly(ether) urethane Pulse-Tec graft known to readily undergo oxidation in a variety of degradative solutions, and we assessed them for the development of oxidative and hydrolytic degradation, changes in elastic properties, and chemical stability. To simulate the in vivo environment, we used buffered solutions of phospholipase A(2) and cholesterol esterase; solutions of H2O2/CoCl2, t-butyl peroxide/CoCl2 (t-but/CoCl2), and glutathione/t-butyl peroxide/CoCl2 (Glut/t-but/CoCl2); and plasma fractions I-IV, which were derived from fresh human plasma centrifuged in poly(ethylene glycol). To act as a negative control, both graft types were incubated in distilled water. Samples of both graft types (100 mm with a 5.0-mm inner diameter) were incubated in these solutions at 37 degreesC for 70 days before environmental scanning electron microscopy, radial tensile strength and quality control, gel permeation chromatography, and in vitro compliance assessments were performed. Oxidative degradation was ascertained from significant changes in molecular weight with respect to a control on all Pulse-Tec grafts treated with t-but/CoCl2, Glut/ t-but/CoCl2, and plasma fractions I-III. Pulse-Tec grafts exposed to the H2O2/CoCl2 mixture had significantly greater compliance than controls incubated in distilled water (p < 0.001 at 50 mmHg). No changes in molecular weight with respect to the control were observed for the CPU samples; only those immersed in t-but/CoCl2 and Glut/t-but,/CoCl2 showed an 11% increase in molecular weight to 108,000. Only CPU grafts treated with the Glut/t-but/CoCl2 mixture exhibited significantly greater compliance (p < 0.05 at 50 mmHg). Overall, results from this study indicate that CPU presents a far greater chemical stability than poly(ether)urethane grafts do. 2001 John Wiley & Sons, Inc.
86 citations
TL;DR: In this paper, the strength of stainless-steel joints with two epoxy adhesives was investigated and finite element analyses showed that failure could be fairly well predicted by a maximum shear strain criterion.
86 citations