Influence of aging and crystallinity on the molecular motions in bisphenol-A polycarbonate (original) (raw)

1996, Journal of Polymer Science Part B: Polymer Physics

Thermally Stimulated Depolarization Current technique, Differential Scanning Calorimetry, and Dynamic Mechanical Analysis have been applied to amorphous and semicrystalline bisphenol-A polycarbonate with crystallinity degrees up to 21.8%, in a temperature interval covering the a and ( 3 relaxations. The secondary p transition is found to be the sum of three components whose variations in aged and annealed specimens have shown the cooperative character of the p, and pz modes, contrary to the localized nature of the p3 component. A T, decrease was observed by both TSDC and DSC as a function of X , and has been related to the possible confinement of the mobile amorphous phase in regions whose sizes are smaller than the correlation lengths of the cooperative movements that characterize the motions occurring a t TC The a relaxation intensity variations with crystallinity show the existence of an abundant rigid amorphous phase in the semicrystalline material. The relaxation parameters deduced from the Direct Signal Analysis of the a relaxation for the mobile amorphous phase do not show significant deviations from those found for the amorphous material. The existence of the rigid amorphous phase has been associated to the ductile-to-brittle transition experienced by the material at low crystallinity levels. 0 1996

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