Tuning the short chain branch distribution of ethyleneand 1-hexene copolymers by SiO2-supported silylchromate catalyst with different Al-alkyl co-catalysts

SiO pipe materials. The control of the short chain branch (SCB) distribution using this catalyst system is still a great 2-supported silyl chromate catalyst is an important industrial catalyst for production of high grade HDPEchallenge. In this work, ethylene and 1-hexene copolymers were synthesized using SiO2-supported silyl chromatecatalyst combined with triisobutylaluminium (TIBA), triethylaluminium (TEA) and mixed TIBA/TEA at molarratio 1:1 (TIBA/TEA/1:1) as three different Al-alkyl co-catalysts.The temperature rising elution fractionation(TREF) and successive self-nucleation and annealing (SSA, by DSC) methods were combined to analyze the shortchain branch distribution (SCBD) of these ethylene/1-hexene copolymers. The results showed that different typesof co-catalyst had a great influence on SCBD of ethylene/1-hexene copolymers. The copolymer produced withTIBA showed better SCBD than the copolymer produced with TEA, and the copolymer produced with TIBA/TEA/1:1 showed a SCBD in between those with TIBA and TEA. Polyolefns J (2014) 1: 93-105

Keywords:

ethylene/1-hexene copolymerization , Al-alkyl co-catalyst , polymerization kinetics , SiO2-supported silyl chromatecatalyst , short chain branch distribution ,