118,170 research outputs found
TENSILE PROPERTIES OF FIBERGLASS-REINFORCED POLYESTER FOAMS.
No full textIn the reported test program, high-density structural foams and their fiberglass-reinforced versions have been characterized in tension, and the results were analyzed. The tensile modulus and strength of the nonreinforced foams can be described by the modified Kerner equation and a modified Nicolais-Narkis equation, respectively. The modulus of the reinforced foams can be predicted by using the concepts of the quasi-isotropic laminate theory. The temperature sensitivity of the reinforced foams is markedly reduced and the impact failure in a falling ball test is localized, and energy absorption is accomplished by the formation of numerous small cracks. Fiber reinforcement of foams improves also the heat sag resistance and reduces the coefficient of thermal expansion
The effect of fibre and crystallinity content on the structural relaxation of polyetheretherketone (peek)
No full textEnvironmental Degradation of the Electrical and Thermal Properties of Organic Insulating Materials,
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Environmental aging of epoxy resins: Synergistic effect of sorbed moisture, temperature, and applied stress
No full textConcurrent effect of microporosity and chemical structure on the equilibrium sorption properties of cellulose-based hydrogels
No full textPolyelectrolite hydrogels are crosslinked polymers which display high sorption capacity in water and water solutions. They are widely used in the marked of personal hygiene products, as well as in other biomedical and industrial applications. In the most industrial application they are not biodegradable and prepared starting from acrylamide. In this work, the chemical-physical analysis of a novel class of natural polymers-based microporous superabsorbent hydrogels has been presented. The main focus is the definition of the relationship between material's chemical-physical structure and its equilibrium sorption properties. The effect of the variation of the degree of crosslinking, the polyelectrolyte nature of the backbone and the hydrogel microporosity on its swelling properties has been analysed, and a good agreement with the theoretical statements has been displayed. The effect of the ionic strength and the pH of the external solution in contact with the hydrogel on its equilibrium sorption properties has also been assessed, and an high sensitivity to these variations was detected for all the tested chemical compositions and physical structures. This work have to be considered part of the efforts towards the reduction of the environmental impact of the large scale consumption industrial polymer based products
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