Abstract:

The reaction product between NdCl3·3i-PrOH and Al(i-Bu)3 as catalysts was separated into a soluble and an insoluble part in hexane, and isoprene polymerization behaviors and characteristics of hexane-soluble and insoluble fractions were examined. The results indicated that the hexane-soluble fraction of the catalyst aging with the (Nd+Al) preformation had no activity at room temperature and at 70 ℃, and the catalytic precipitate obtained at 70 ℃ had no active too. The catalysts with the (Nd+IP+Al) preparation pattern showed activity of polymerization at both room temperature and 70 ℃. We speculated that there are two catalyst active centers of (isoprenyl)2NdCl and (isoprenyl)NdCl2 in the polymerization system. The catalytic prepared methods had no effect on the microstructures of polyisoprene(about 96%). The molecular mass of the polyisoprenes obtained by the suspension catalyst and precipitate catalyst was high(Mn＞100×104) and the molecular mass distribution was narrow(Mw/Mn＜2.0), while the polyisoprene obtained by the clear solution catalyst had lower molecular mass(Mn＜30×104) and a very wide molecular mass distribution(Mw/Mn＞5.0).

Key words: Neodymium, Alkyl aluminum, Isoprene, Polyisoprene