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Temperature dependence of dynamic mechanical properties of mixed polymer systems. II
Author(s) -
McIntyre A. D.
Publication year - 1963
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.1963.070070410
Subject(s) - copolymer , materials science , glass transition , diluent , polymer , melting point , polymer chemistry , monomer , dispersion (optics) , dynamic modulus , dynamic mechanical analysis , styrene , thermodynamics , composite material , chemistry , organic chemistry , physics , optics
The temperature dependence at constant frequency of the viscous component E 2 (1/ T ) of the dynamic modulus has been determined for a homologous series of butadiene–acrylonitrile copolymers supported in a matrix of styrene homopolymer. The results, which agree with those reported earlier for a homologous series of butadiene–styrene copolymers, indicate that the transition temperature of a given plastic homopolymer, as measured from dynamic mechanical properties at essentially constant frequency in the range 200–300 cycles/sec., is depressed by the presence of a copolymerized rubbery diluent as the melting point of crystalline polymers is depressed by the presence of noncrystallizing comonomers. In addition, it has been found that the transition temperature is depressed by the presence of monomeric diluents much as the melting point of crystalline polymers is depressed by the presence of monomeric diluents. Two earlier assumptions, that the dynamic properties in the frequency range of interest should be independent of both the molecular weight of the rubbery copolymer and the degree of dispersion of the copolymer in the thermoplastic matrix, have been subjected to experimental scrutiny. The assumption regarding the dependence on molecular weight has been substantiated, at least for DP's in excess of 100. The assumption regarding the dependence on the degree of dispersion has been negated; the area under the E 2 (1/ T ) peak was found to be considerably greater for a coarse dispersion than for a fine one.