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Cavitation of rubber particles in high-impact polystyrene: Effects of crosslinking by γ-irradiation

Authors

  • C.B. Bucknall,

    Corresponding author
    1. Advanced Materials Department, Cranfield University, Cranfield, Bedford MK43 0AL, UK
    • Advanced Materials Department, Cranfield University, Cranfield, Bedford MK43 0AL, UK
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  • V.L.P. Soares

    1. Advanced Materials Department, Cranfield University, Cranfield, Bedford MK43 0AL, UK
    Current affiliation:
    1. Department of Organic Chemistry, Universidade Federal do Rio de Janeiro, Brazil
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Abstract

Tensile tests on high-impact polystyrene (HIPS) show that a 60 Mrad dose of γ-radiation raises the yield stress from 11.5 to 19.8 MPa, and the flow stress from 10.0 to 19.6 MPa, while reducing the elongation at break from 50 to 4%. Similar reductions in fracture resistance are observed in irradiated Charpy impact specimens. The Tg of the rubber phase shifts from −70 to −57 °C, and its estimated shear modulus increases from 0.1 to 0.5 MPa. It is concluded that the observed changes in mechanical properties are due almost entirely to crosslinking of the polybutadiene. This not only inhibits cavitation and fibrillation in the rubbery membranes of the “salami” particles, thereby delaying yield, but also makes the fibrillated membranes more resistant to further dilatation, so that rates of craze thickening in the polystyrene matrix are reduced. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2168–2180, 2004

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