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Structure and properties of injection moldings of polypropylene/polystyrene blends
Author(s) -
Fujiyama Mitsuyoshi
Publication year - 1997
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/(sici)1097-4628(19970222)63:8<1015::aid-app8>3.0.co;2-l
Subject(s) - materials science , polypropylene , composite material , molding (decorative) , polystyrene , crystallinity , melt flow index , izod impact strength test , polymer , copolymer , ultimate tensile strength
A homoisotactic polypropylene (PP) was melt blended with 0–30 wt % of three kinds of polystyrene (PS) with melt flow indexes lower than, similar to, and higher than that of PP. The blends were injection molded at cylinder temperatures of 200–280°C, and the structure and properties of the injection moldings were studied. With PS blending, although the PP molding whitened, no surface defect such as layer peeling and pearl‐like appearance occurred. The rigidity and dimensional accuracy of the molding improved without much deterioration in impact strength and heat resistance. At the same time the fluidity also improved. The injection moldings of PP/PS blends did not show clear skin/core structure under a polarizing microscope. The degrees of crystallinity and crystalline c ‐axis orientation decreased with PS blending. PS particles were the smallest when the ratio of the viscosity of the PS to that of PP at molding shear rate was slightly lower than unity. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1015–1027, 1997