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The effects of blending small amounts of homopolystyrene on the mechanical properties of a low styrene content styrene‐butadiene‐styrene block copolymer
Author(s) -
Flosenzier Linda S.,
Rohlfing John H.,
Schwark Alodia M.,
Torkelson John M.
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760300108
Subject(s) - polystyrene , materials science , copolymer , styrene , polybutadiene , styrene butadiene , composite material , ultimate tensile strength , dispersity , morphology (biology) , lamellar structure , polymer chemistry , polymer , biology , genetics
Tensile, cyclic, and tear properties were compared for several styrene‐butadiene‐styrene (SBS) triblock copolymers, KRATON D2104, D1101 and D1102, and blends of D2104 with monodisperse polystyrene of various molecular weights. D2104 is expected to have a morphology of polystyrene spheres in a polybutadiene continuous matrix. The mechanical properties of D2104 were compared to the properties of SBS materials which have higher styrene contents and exhibit cylindrical or lamellar morphologies. Blending the D2104 with polystyrene (molecular weights ranging from 2000 to 51,000) to 24 and 28 wt % total styrene content showed that the tensile strength obtained for a blend was dependent on the molecular weight of the polystyrene added. Cycle testing of the D2104‐polystyrene blends showed that with increasing polystyrene content the softening effect increases with increasing strain. This indicates that the degree of phase continuity of the polystyrene domains may be changing from a spherical morphology to a cylindrical morphology similar to that of pure SBS with 28 wt % styrene content. Tear test results for the blends were also observed to be similar to the results for pure SBS of the same total polystyrene content.