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The viscoelastic properties of rubber–resin blends. III. The effect of resin concentration
Author(s) -
Class J. B.,
Chu S. G.
Publication year - 1985
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.1985.070300231
Subject(s) - materials science , natural rubber , elastomer , composite material , viscoelasticity , styrene butadiene , polystyrene , rosin , modulus , styrene , polymer chemistry , copolymer , polymer , chemistry , organic chemistry , resin acid
The viscoelastic properties of a rubber–resin blend, which influences performance of the blend as a pressure‐sensitive adhesive, depend upon the structure of the resin as well as its molecular weight. The effect of the concentration of a compatible resin in the blend was examined using a mechanical spectrometer. Four types of resins were used. These are the rosin esters, polyterpenes, pure monomer resins such as polystyrene and poly(vinyl cyclohexane), and petroleum stream resins. Each was examined in blends with both natural rubber and styrene–butadiene rubber over a range of concentrations. It is shown that the temperature of the tan δ peak for compatible systems can be predicted by the Fox equation, T g −1= W 1 T g 1 −1+ W 2 T g 2 −1 , where W 1 and W 2 are the weight fractions of the resin and rubber, respectively, and the T g 's are the tan δ peak temperatures in K. The plateau modulus G N ofor a blend can be identified as the G ′ value in the rubbery plateau at the point where tan δ is at a minimum. The relationship between G N 0and G N 00 , the plateau modulus for the undiluted elastomer, is shown to be proportional to the volume fraction of the elastomer raised to the 2.3–2.4 power for natural rubber with six different compatible resins. The exponent for styrene–butadiene rubber is 2.5–2.6 with four different resins. Using these relationships, both the tan δ peak temperature and plateau modulus can be predicted for a rubber–resin system from data on the unmodified elastomer and on one typical rubber–resin blend.