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Polystyrene/bisphenol a polycarbonate (PS/PC) molecular composite by in situ polymerization. II. Effect of different molecular size of PC on the blending behavior and properties
Author(s) -
Jang Lee Wook,
Lee Dong Choo
Publication year - 2002
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.11518
Subject(s) - miscibility , polycarbonate , polystyrene , materials science , polymer chemistry , polymer , glass transition , composite number , polymerization , molar mass , chemical engineering , monomer , composite material , engineering
The influences of different molecular sizes and contents of bisphenol A polycarbonate (PC) on the miscibility, morphology, and physical properties of a polystyrene/PC (PS/PC) molecular composite are examined. The polymerization of the matrix monomer, styrene, which is completely miscible with PC, affords an apparently homogeneous mixture that remains stable on heating to above the glass transition temperature ( T g ) of the pure matrix and solubilizes in common organic solvents. Both the molecular and material characterizations for the purified products are examined in full detail by various instrumental analyses and microscopy. An enhanced miscibility with higher molar mass of PC was confirmed by both the unambiguous scanning electron microscopy (SEM) images, showing subinclusions of PS/PC microdomains in the matrix, and the characteristic size exclusion chromatograms (SEC) of the fractionated sample, exhibiting homogeneous molecular mixing. With increased molecular size of PC and its content, the T g increases proportionally and shows a shift to higher temperatures than that of pure PC, indicating the reduced segmental motion of PC chains due to the intimate chain entanglement with PS chains. Except for the case of the lowest molar mass of PC, both the thermal and tensile properties of the composite are also elevated. The conformational similarity between the two long flexible‐chain polymers has clearly accentuated the tendency for miscibility. This effect is due mainly to the increase in entropy gained by mixing, which in turn leads to reinforcement of n –π complex formation between the carbonate and benzene mixtures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1610–1618, 2003