| 摘要 |
<p>The hydrosilylation of terminal double bonds in polypropylene (PP) or other polymers is effected in the melt phase. The double bonds were created by peroxide initiated degradation of PP in an extruder or a batch mixer. A hydride terminated polydimethylsiloxane is employed as a model substance to investigate the feasibility of hydrosilylating the terminal double bonds of the degraded polypropylene. The reaction may be carried out in three different reactors, namely a hot press, a batch mixer and a screw extruder. Two different reaction mechanisms may be used to effect the hydrosilylation reaction, namely a radical chain addition mechanism and a platinum catalysed mechanism with a colloid forming catalyst, platinum divinyltetramethyldisiloxane (Karstedt's catalyst). Catalytic amounts of a peroxide initiator are able to initiate the addition of silanes to the double bonds of the degraded polypropylene. Both reactions, namely degradation and hydrosilylation, may be performed simultanously. A platinum colloid formed in the initial stage of the platinum catalysed hydrosilylation may be stabilized by adding t-butylhydroperoxide as cocatalyst, which results in the hydrosilylation at high yields.</p> |
