The Role of Chain Entanglements and Crystals in the Orientation Process of Polymers
If an amorphous polymer is oriented by drawing, some sort of netpoints must be present in order to prevent the motion of complete chains in different directions. Usually chain entanglements act as such net points. With some polymers, also small crystals formed during drawing may be of influence.In the following we report on investigations performed on polyethylene-terephthalate in order to determine the influence of chain entanglements and small crystals on the orientation. Polyethylene terephthalate has a glass transition temperature of about 70° C. It can be obtained in the amorphous state if quenched from the melt, and it may be oriented without necking by drawing1 in the amorphous state at temperatures between 80 and 110° C.
KeywordsCrystallization Polyethylene Stein Terephthalate
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