Radiolytic unsaturation decay in polyethylene. Part III—the effect of certain chain transfer agents |
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Authors: | B J Lyons |
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Institution: | 954 Gold Nugget Circle, Lincoln, CA 95648, USA |
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Abstract: | Small amounts of certain halogenated compounds are found to have, at most, only a slight enhancing effect on the radiolytic decay rates of added poly-unsaturated compounds in polyethylene, but significantly increase the elastic modulus at 433 K (melt modulus) obtained thereby. Experiments with model chlorine-containing additives suggest that this increase is due to a more random distribution of polymer and monomer mediated crosslinks in the polymer, that it does not result from a significant increase in crosslinking and that it is mediated by chlorine atoms, in a similar manner to radiolytic hydrogen atoms, through facilitation of long range free radical migration. Although low molecular weight chloro-paraffins inhibit radiolytically induced growth of melt modulus in monomer containing polyethylenes, even very small additions of chlorinated polyethylenes, which form a separate phase, increase the melt modulus. This again indicates that the active species is the chlorine radical. |
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Keywords: | Polyethylene Allyl unsaturation Methacrylates Acrylates Chain transfer agents Chloro-aromatics Chlorinated polyethylene |
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