Effects of Solvent-induced Crystallization on the Amorphous Phase of Polycarbonate of bisphenol A)
Titel:
Effects of Solvent-induced Crystallization on the Amorphous Phase of Polycarbonate of bisphenol A)
Auteur:
Aharoni, Shaul M. Murthy, N. Sanjeeva
Verschenen in:
International journal of polymeric materials
Paginering:
Jaargang 42 (1998) nr. 3-4 pagina's 275-283
Jaar:
1998-12-01
Inhoud:
By the combined use of DSC, WAXD and pycnometry techniques, it was demonstrated that the increase in free volume and reduction in Tg observed in semi-crystalline poly(carbonate of bisphenol A) (PC), whose crystallization was solvent-induced, are due to the creation of many microvoids, microcavities and crazes in the amorphous fraction of the polymer during the crystallization. Accordingly, the polymer chains and chain-segments present right at the polymer-air interfaces, forming the walls of these micro-cavities, are more mobile than the chains and segments in the bulk amorphous phase, resulting in a commensurate reduction in Tg. Upon annealing at elevated temperatures the microvoids, etc., heal, the polymer-air interfacial specific surface area decreases, and Tg increases toward the Tg of the bulk amorphous PC containing no microvoids, crazes and internal polymer-air interfaces.
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