Secondary crystallization of poly(tetramethylene oxide)

Abstract

The isothermal crystallization of poly(tetramethylene oxide) has been studied by dilatometry, dielectric measurements, DTA and small-angle X-ray scattering (SAXS). Crystalline regions with very narrow size distributions and amorphous regions with broad distributions are produced, consistent with a morphology of small-angle branched lamellae. During secondary crystallization slight lamellar thickening occurs and there is an increase in the densities of both the crystalline and amorphous phases (both densities being below their ideal values). Secondary crystallization is interpreted in terms of an increasing degree of perfection of the crystalline regions with time and there is evidence for an increased surface free energy.