Factors That Influence the Mechanical Properties of Semicrystalline Polymers

Inasmuch as semicrystalline polymers are composed of both crystalline and amorphous regions, they may, in a sense, be considered composite materials. Therefore, the elastic modulus may be taken as some combination of the moduli of crystalline and amorphous phases. 

8 FACTORS THAT INFLUENCE THE MECHANICAL PROPERTIES OF SEMICRYSTALUNE POLYMERS 

The magnitude of the tensile modulus does not seem to be direetly influenced by molecular weight. On the other hand, for many polymers it has been observed that tensile strength increases with increasing molecular weight. TS is a function of the number-average molecular weight. 

For some polymers, dependence of tensile strength on number-average molecular weight 

Furthermore, increasing the crystallinity of a polymer generally enhances its strength in addition, the material tends to become more brittle. The influence of chain chemistry and structure (branching, stereoisomerism, etc.) on degree of crystallinity was discussed in Chapter 14. 

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Factors that Influence the Mechanical Properties of Semicrystalline Polymers 593... 

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