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Poly(phenylene oxide) composites containing crosslinked polystyrene microspheres. II. Dark crosses observed in microscope
Author(s) -
Zhikuan Chai,
Qipeng Guo
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070340614
Subject(s) - polystyrene , materials science , composite material , composite number , polymer , polycarbonate , polymerization , polymer chemistry , methyl methacrylate , phenylene
Extinction phenomena observed between crossed polaroids in microscope were classified into three groups: (1) Poly(2, 6‐dimethyl‐1, 4‐phenylene oxide)/polystyrene composite with crosslinked polystyrene microspheres. Negative dark crosses were observed in the shells of the spheres, the cores of the spheres were completely extinct. The crosses disappeared at 170°C, which is 20°C above T g of the matrix polymer. (2) Polycarbonate composite with glass beads. The dark crosses were positive and outside the glass beads. The crosses disappeared at 130°C, which is 20°C below T g of the matrix polymer. (3) In situ polymerized composites with crosslinked polystyrene microspheres. The dark crosses were the same size of the spheres. They were negative in poly(methyl methacrylate) and poly(vinyl acetate) and positive in polystyrene. The disappearing temperatures of the crosses were 150, 110, and 285°C, respectively. The first two groups of phenomena are explained as the photoelastic effects caused by the thermally induced stresses. The last group is due to the inhomogeneous swelling or contracting of polystyrene networks in the matrices.