In this work, we studied acetone vapor-induced crystallization of BAPC films of various thicknesses by using differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy.
Bisphenol-A polycarbonate (BAPC) pellets (Makrolon 2647) were supplied by Bayer AG, with a number-average molar mass of 1.8 x [10.sup.4] and a polydispersity of 1.13, as estimated by gel permeation chromatography (GPC, 1515, Water Breeze, USA).
Influence of Vapor Exposure Time on the Crystallization Behaviors of BAPC
BAPC samples with a thickness of 10 [micro]m crystallized at 25[degrees]C under acetone vapor of 26.5 KPa for various time periods up to 56 h.
Why is there such a difference between BAPC and PS?
1, a schematic representation is given of a typical birefringence distribution in the cross section of an injection-molded slab of BAPC. (The example is typical for molding conditions, which are used for optical components, i.e.
The relatively large contribution of residual birefringence induced by transient 'volume' stresses (meaning deviatoric stresses coming from density changes as a consequence of pressure and temperature variations) in BAPC is caused by its high rubbery plateau modulus.
BAPC and PS have comparable [C.sub.m], but differ by a factor of more than 10 in [E.sub.r], PS having the smaller value owing to the much larger molecular weight between entanglements (12).