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Mechanical Properties of Polymers and Composites

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 damping ability and mechanical strength are enhanced through the introduction of PU cross-linked epoxy into the PU matrix to form the IPN structure, which shows particle-matrix morphology and exhibits good damping properties.
Abstract: Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU) cross-linked epoxy and polyurethanes based on the mixture of polydiol and polytriol by the one-shot method. The mechanical properties, dynamic mechanical properties, morphology and damping behaviour were investigated. The results show that the damping ability and mechanical strength are enhanced through the introduction of PU cross-linked epoxy into the PU matrix to form the IPN structure. As the epoxy content increases, the tensile strength of the two types of the IPNs decrease in low composition, then increase in high composition. The damping properties of the PU (polyether type) cross-linked epoxy/PU IPNs are much better than those of the PU (polyester type) cross-linked epoxy/PU IPNs, but the mechanical properties reveal an opposite tendency. The sample with 20 wt% epoxy content in the PU cross-linked epoxy/PU IPNs shows particle–matrix morphology and exhibits good damping properties.

29 citations

Journal ArticleDOI
TL;DR: It was found that while older threads demonstrated increased stiffness, age did not necessarily affect their ultimate tensile strength, and dehydration had a more pronounced effect on thread stiffness and also increased the ultimate strength of the material.
Abstract: Dynamic mechanical analysis was used to record the behaviour of hydrated and dehydrated byssal threads under tensile stress and during dynamic thermal cycling. Fresh byssi, and byssi aged two weeks prior to testing, were used to further study the effects of age on the mechanical properties of this material. It was found that while older threads demonstrated increased stiffness, age did not necessarily affect their ultimate tensile strength. Dehydration had a more pronounced effect on thread stiffness and also increased the ultimate strength of the material. In their dry state, byssal threads displayed multiple yield points under tension and these, it is suggested, could equate to different phases within the bulk of the material. Dynamic analysis revealed glass transition (Tg) and ecologically relevant operational temperatures for byssi, where their modulus (E') remained constant. These discoveries are related to the ecological function of byssal threads and to the emerging field of biomimetics.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the principles for materials selection are presented as a model with different steps from definition of functions to the feedback from the delivered product, and examples of methods to fulfil demands for manufacturing, assembly, disassembly, service and recycling, etc, are also presented as well as environmental friendly solutions for product development.

29 citations

Journal ArticleDOI
TL;DR: In this article, a mechanism of radiation-induced degradation of a polymer matrix composite was proposed to explain the dose dependence of the composite strength measured at 77 K and at room temperature.
Abstract: Four kinds of polymer matrix composites (filler, E-glass or carbon fibre cloth; matrix, epoxy or polyimide resin) and pure epoxy and polyimide resins were irradiated with 60Co γ-rays or 2 MeV electrons at room temperature. Mechanical tests were then carried out at 77 K and at room temperature. Following irradiation, the Young's (tensile) modulus of these composites and pure resins remains practically unchanged even at 170 MGy for both test temperatures. The ultimate strength, however, decreases appreciably with increasing dose. The dose dependence of the composite strength depends not only on the combination of fibre and matrix in the composite but also on the test temperature. A relationship is found between the composite ultimate strain and the matrix ultimate strain, thus indicating that the dose dependence of the composite strength is virtually determined by a change in the matrix ultimate strain due to irradiation. Based on this finding, we propose a mechanism of radiation-induced degradation of a polymer matrix composite in order to explain the dose dependence of the composite strength measured at 77 K and at room temperature.

29 citations

Journal ArticleDOI
TL;DR: In this paper, nano-hydroxyapatite nanoparticles were synthesized by sol-gel and the mechanical and biological properties of nanocomposites were studied by tensile test and proliferation and cell adhesion assays using MG-63 osteoblast cells, respectively.
Abstract: Ultrahigh molecular weight polyethylene–based nanocomposites reinforced with nano-sized hydroxyapatite particles were fabricated using internal mixer and compression molding with different weight percent of the nano-hydroxyapatite. In this study, first, hydroxyapatite nanoparticles were synthesized by sol–gel. Then, the mechanical and biological properties of nanocomposites were studied by tensile test and proliferation and cell adhesion assays using MG-63 osteoblast cells, respectively. Results of the tensile test showed that incorporation of 50 wt% nano-hydroxyapatite led to a 345.64% and 57.58% increase in Young's modulus and yield strength (compared to the pure ultrahigh molecular weight polyethylene), respectively. The effect of the nano-hydroxyapatite powders on the MG-63 osteoblast cells behavior was compared to those of a composite (positive control) and a negative control samples. Scanning electron microscopy micrographs revealed that cell–biomaterial interaction was carried out on the surface of...

29 citations


Cites background from "Mechanical Properties of Polymers a..."

  • ...This effect is due to shape, size, and interfacial strength of the HA nanoparticles.(37) Naturally, the particles with the finer size in comparison with the coarser powders will result in more particles at a fixed amount, therefore these particles act as a craze and they lead to decline in elongation....

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