3 января, 2016 
Pokraskin The properties of elastomers make them very different from other materials, in particular with regards to entropy elasticity, viscoelasticity and chemical structure, which is a macro network.
Due to a three-dimensional network, elastomers do not flow and are insoluble, but swellable. When the temperature increases, they will not melt until degradation occurs.
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Table 8.7 Fiber types and characteristic applications.
PES = polyethylene-styrene; PVA = polyvinyl acetate. |
When conceiving a rubber formulation, its components can carefully be selected to obtain a wide variety of properties. The Tg determines their viscoelastic properties, and active fillers induce typical nonlinearities (dependence of deformation). Owing to a chemical network, elastomers have high failure tolerance with regard to solvents and peak temperatures.
Low strength, however, is a disadvantage of elastomers, as is sometimes their low modulus, but reinforcing elastomers with steel, textile or glass fibers can solve this problem. During the forming process, chemical crosslinking takes place that allows chemical bonding to take place between the elastomer and different substrates (fibers, wires, metal parts). When rigid materials are used as reinforcements, anisotropic components can be produced — that is, components that show high strength and elastic behavior in one or several directions, and high deform — ability and viscoelastic behavior in other directions. This unique combination of properties is taken advantage of in the manufacture of a wide variety of products that contribute 90% of the total amount of textile-reinforced products manufactured. Composites are mainly subject to dynamic stress and corrosive conditions, requiring strong and durable adhesion between the elastomer and the reinforcement to withstand the mechanical and chemical conditions, which can only be achieved by chemical bonds.
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