Abstract:
A quantitative study was carried out on the homogeneous zirconocene dichloride / tris(pentafluorophenyl)borane / triethylalum inum (Cp2ZrCl2-B (C6F5)3-TEA) catalyst system in ethylene polymerization. The effect of zirconocene concentration on productivity and polymerization profile was observed. The optimum zirconocene concentration of 5 pmol showed the maximum productivity. The effects of polymerization temperature and the Al/Z r ratio on productivity and polymer properties were studied. The polymerization was carried out at temperature from 20° to 50℃ and the polymer properties determined were molecular weight, molecular w eight distribution, melting point and crystallinity. The catalyst activity increased dramatically between 20° and 30℃ due to the increase of propagation rate. A bove 30℃, rate of deactivation strongly increased and overcame the rate of propagation thus lower activities were observed. The molecular w eight also decreased at higher reaction temperatures causing the melting temperature to decrease. The molecular w eight distribution varied from 4.50- 6.99.
