Liquid Pool Copolymerization of Propylene/1‐Butene with a MgCl₂‐Supported Ziegler‐Natta Catalyst

Abstract

Summary: Liquid pool propylene/1‐butene copolymerizations were carried out in a batch reactor with a high activity Ziegler‐Natta catalyst system. Experimental runs were performed to evaluate the effect of the 1‐butene content on the crystallinity and melt temperature of the polymer resins. According to the results, 1‐butene can be significantly incorporated into the polymer chain at high polymerization rates over the whole range of copolymer compositions, leading to a decrease in the melting temperature (Tm) of the polymer, when compared to the poly(propylene) homopolymer, allowing for reduction of the sealing initiation temperature. It was observed by GPC and MFI measurements that the average molecular weights and the polydispersity index of the copolymer significantly decreased when compared to the ones obtained from poly(propylene). Despite high polymerization rates, polymer particles with good morphological features were produced in all cases. It was also observed that the absence of an external electron donor led to low crystallinity values for both the poly(propylene) homopolymer and for copolymers with different fractions of 1‐butene, when compared to literature values frequently reported for polymer resins based on 1‐butene and propylene. The obtained results indicate that a family of bulk propylene/1‐butene copolymer grades can be successfully developed for packaging and film applications.Surface morphology and molecular weight distribution (deconvoluted into Schulz‐Flory distributions) of the propylene/1‐butene copolymer.imageSurface morphology and molecular weight distribution (deconvoluted into Schulz‐Flory distributions) of the propylene/1‐butene copolymer.

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

“…This approach has been used to understand the distribution of active site types in Ziegler-Natta catalysts for propylene polymerization as a function of polymerization temperature and time, type of cocatalyst and electron donor, copolymerizations with other α-olefins, and catalyst synthesis conditions. [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] Similar deconvolution studies were used to understand the effect of polymerization conditions and catalyst formulations for the polymerization of ethylene and α-olefins with Ziegler-Natta [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] and Phillips/chromium catalysts. [82][83][84] Other studies used MWD deconvolution to identify active site populations for the polymerization of 1-octene, [85] 1-hexene, [86][87][88][89] and 1-butene [90,91] with Ziegler-Natta catalysts.…”

In situ synthesis of novel trans‐1, 4‐polyisoprene/isotactic polybutene reactor blends with multi‐component structure

“…24 Isotactic polybutene (iPB), first synthesized by Natta, 25 is a semi-crystalline polymer with outstanding properties including excellent resistance to creep and environmental stress cracking, and so on. 26 In order to enrich the structure and expand the application, many researchers reported the copolymerization [27][28][29][30][31][32] and in-reactor alloys [33][34][35][36] of butene and α-olefin, such as ethylene, propylene, or styrene, to extend the properties and applications of iPB.…”