Effects of supported (nBuCp)2ZrCl2 catalyst active center multiplicity on crystallization kinetics of ethylene homo- and copolymers

摘要: Abstract Two different supported zirconocene, that is, bis( n -butylcyclopentadienyl) zirconium dichloride ( BuCp) 2 ZrCl , catalysts were synthesized. Each catalyst was used to prepare one ethylene homopolymer and ethylene–1-hexene copolymer. Catalyst active center multiplicity polymer crystallization kinetics modeled. Five separate types predicted, which matched the successive self-nucleation annealing (SSA) peak temperatures. The predicted crystallinity well differential scanning calorimetric (DSC) values for a single Avrami–Erofeev index, ranged between 3 polymers experimented. estimated apparent activation energy E did not vary with cooling rates, relative α time or temperature. Therefore, concept of variable/instantaneous found hold. linearly increased weight average lamellar thickness L wav DSC-GT ; each homopolymer, it exceeded corresponding Higher hence slower crystallization, identified as pre-requisite attain higher crystallinity. Crystallization parameters correlated backbone parameters, are influenced by multiplicity.