Isoprene polymerization on titanium-magnesium catalysts

The high activity of a titanium-magnesium catalyst in the polymerization of isoprene with formation of a unique thermoplastic material, synthetic gutta percha, was shown. It is established that a change in polymerization conditions over a wide range has no effect on the content of trans-1,4 units in the polymer. Unlike natural gutta percha with the crystalline phase containing a mixture of alpha-and beta-crystalline modifications, the synthetic trans-1,4-polyisoprene crystallizes only in an alpha-monoclinic form, the melting temperature of which is close to 70 degrees C. The melting followed by crystallization results in formation of a stable beta-crystalline modification with a melting temperature approximating 50 degrees C.