Reaction-induced phase separation in polyoxyethylene/polystyrene blends. I. Ternary phase diagram

摘要

Reaction-induced, phase separation has been studied in polymer blends., A model crystalline-amorphous system consisted of semicrystalline polyoxyethylene (POE) dissolved in the monomer styrene, which was used as a reactive solvent to ease processing. When the styrene was polymerized to polystyrene (PS) in the mold, phase separation and phase inversion are induced, and a polymer blend was formed. Polyoxyethylene was selected with a molar mass, M-n = 8578 g mol(-1) and a polydispersity of 1.19, as determined by using gel permeation chromatography. The polymerization of styrene was initiated by using 1 wt% benzoin methyl ether and 0.2 wt% 2,2'-azobisisobutyronitrile under ultraviolet light. The polymerization kinetics were determined by monitoring the reduction in the intensity of the C=C stretching vibration band at 1631 cm(-1) in the Raman spectrum of styrene. The onset times for the liquid-solid (L-S) phase separation and crystallization of POE from styrene/PS were observed by using simultaneous small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering. Onset times for L-S phase separation determined from the SAXS data were combined with the styrene polymerization kinetics to plot the L-S phase separation data onto a ternary phase diagram for the reactive system POE/styrene/PS at 45degreesC and 50degreesC. [References: 15]