The crystallization of high molecular weight poly‐(tetramethylene oxide) and related polymers

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Abstract
Using dilatometric techniques, detailed investigations have been made of the crystallization and melting behavior of high molecular weight poly(tetramethylene oxide), low molecular weight poly(tetramethylene oxide) glycol, and a high molecular weight copolymer prepared by the chain extension of the glycol. The degree of crys‐tallinity is expressed as a function of time and temperature. Using fast melting rates, the apparent melting point of the bulk polymers has been found to depend on both the temperature of crystallization and the level of crystallization allowed to develop before melting. Extrapolation gave an estimated equilibrium melting point for high molecular weight homopolymer of about 51°C. The highest experimentally observed melting point was 43°C. Visual observations have been made on crystallization of these materials from dilute solution (⪕3%) in toluene. Under some experimental conditions crystallization was accompanied by gel formation while under other conditions two distinct and separable phases were formed. Measurements were made on the dissolution temperatures of solutions crystallized under different experimental conditions.

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