Preparation of long-branched polyethylene by in situ poly-merization using late transition metal and metallocene catalysts

An in situ polymerization method was investigated to prepare long-branched polyethylene (LBPE) with ethylene alone and a single cocatalyst, methylalumoxane (MAO), by using a dual functional catalytic system containing late transition metal oligomerization catalyst and metal-locene copolymerization catalyst. The obtained long-branched polyethylene has the characteristics of low melting point, high activity and well-dispersed sequence distribution.

Preparation of PE/MMT nanocomposite by monomer intercalation and in situ copolymerization

The catalyst {[(2-ArN=C(Me))2C5H3N]FeCl3} (Ar = 2-C6H4(i-Pr)) with methylaluminoxane (MAO) as co-catalyst was intercalated between layers of montmorillonite (MMT) for ethylene oligomerization. Metallocene catalyst Me2Si(Ind)2ZrCl2 and MAO was then added to form a dual functional catalytic system. A PE/MMT nanocomposite was prepared by copolymerization of ethylene with α-olefins produced in situ from ethylene over the dual functional catalytic system. The catalytic system was of high polymeric activity. The resultant PE/MMT nanocomposites were stable and got increases in tensile strength and temperature of maximum weight loss (Tonset).

The effect of co-catalysts on the morphology of isotactic polypropene prepared using metallocene catalyst

SiO2/rac-Me2Si[2-Me-4-Naph-Ind]2ZrCl2 was prepared and different co-catalysts were used in bulk polymerization of propene. The morphology of polypropene could be controlled by altering the co-catalysts. The isotactic polypropene with good morphology and high bulk density were prepared. The formation mechanism of active centers was proposed, by which the effect of co-catalysts on the morphology of polypeopene was analyzed.