Crystalline Polymers and Fibers
In this chapter we shall examine the properties of a collection of polymer molecules in the crystalline state. In this state each chain adopts the same ordered conformation. Because of the high degree of molecular order the structure in this state is very similar to that of monomeric solids. It is virtually axiomatic, and has been amply demonstrated, that polymers with a sufficiently regular chain structure will crystallize. The type of chain irregularities that retard or even suppress the crystallization process are chemically different units such as copolymer units, branch points, and chemically identical units that are geometric or stereo-isomers. It should not surprise us that the drastic difference in the chain conformation is reflected in some major differences in properties as compared with the disordered state. For example, the modulus of elasticity increases anywhere from 1,000- to 10,000-fold, reflecting the loss of long-range elasticity in the ordered state. Thus in the crystalline state a polymer chain is not easily deformed.
KeywordsCellulose Sulfide Polyethylene Shrinkage Nylon
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