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Mechanical behavior of injection‐molded polystyrene/polyethylene blends: Fracture toughness vs. fatigue crack propagation
Author(s) -
Bureau M. N.,
Di Francesco E.,
Dickson J. I.,
Denault J.
Publication year - 1999
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.11499
Subject(s) - materials science , composite material , polystyrene , polyethylene , fracture toughness , fracture mechanics , toughness , polymer blend , molding (decorative) , extrusion , rheology , phase (matter) , polymer , copolymer , chemistry , organic chemistry
Blends of polystyrene and polyethylene (PS/PE), including belnds in which a styrene/ethylene‐butylene/styrene (SEBS) terpolymer was employed as a compatibilizer, were studied. Their rheology showed that the effect of the addition of SEBS to PS/PE blends was strongly affected by the blend composition and the shear rates involved in the blending and post‐forming processes. The addition of PE to PS led to a reduction of fracture toughness compared with that of PS. This effect was attributed to the fine minor phase morphology of the blends obtained after extrusion blending and injection molding. The fatigue crack propagation (FCP) results showed that the fatigue crack growth rates were significantly reduced at low and moderate range of stress intensity factor (Δ K ) by the presence of PE. Performance was enhanced when SEBS was present. The results also showed that both the fracture toughness and the FCP behavior of the blends were strongly dependent on the loading direction, the minor phase morphology, the composition of the blend, and, to a lesser degree, the presence of a compatibilizer. This study demonstrates that the fracture toughness and the FCP performance of such polymer blends can vary inversely.