INFLUENCE OF BUTADIENE/STYRENE COPOLYMERS ON THE MODIFICATION OF POLYPROPYLENE IN ELECTRON BEAM IRRADIATION

ISSN： 0091-4037

Source： International Journal of Polymeric Materials, Vol.52, Iss.4, 2003-04, pp. : 335-344

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Abstract

Radiation chemistry of the system: styrene/butadiene/styrene (SBS) copolymer with polypropylene, has been investigated in the full range of proportions from 0% SBS-100% PP to 100% SBS-0% PP. Ionizing energy deposition is distributed to absorbing moieties according to their contribution to the electron pool in the material. The participation of primary ionization acts in constituents of low concentration is negligible, but these compounds take part in secondary reactions. These are detected by specific techniques for determination of transients, e.g., byelectron paramagnetic resonance (EPR). Radiation generates alkyl radicals inthe pure PP, which change subsequently into peroxide radicals in the presence ofoxygen. At high concentration of SBS the transfer of paramagnetic centers SBS^•→PP^• is observed. Important product analysis methods, i.e., UV-Visabsorption spectrophotometry, can be applied in polymer chemistry only as diffuse reflected light spectrophotometry (DRS), described in the preceding paper, as a new approach to the radiolysis recognition. The presence of stable unsaturations formed by radiation are observed by DRS. These effects are drastically reduced already by the presence of 10% of SBS, what indicates intensive protection action and the transfer of single ionization spur sites.