Synthesis and Characterization of Diolefin/Propylene Copolymers by Ziegler‐Natta Polymerization

Abstract

Summary: Diolefins can be used as comonomers in propylene copolymerizations in order to modify some of the final properties of the obtained poly(propylene) (PP) resins. Although reduction of catalyst activity can be expected when such copolymerizations are performed with standard heterogeneous Ziegler-Natta catalysts, copolymers containing 1,5-hexadiene (HD) and 1,7-octadiene (OD) can be produced at high rates when the comonomer content is sufficiently low (below 2 mol%); however, the presence of very small amounts of 5-ethylidene-2-norbornene (ENB) leads to complete catalyst inhibition. It is shown that incorporation of dienes lead to decrease of the melting point of the final product, especially in presence of ENB. When compared to HD, addition of OD causes more pronounced modification of the melt flow index and weight-average molecular weight, although the xylene solubles is less sensitive to the comonomer feed when the comonomer composition is low. Obtained results indicate that small amounts of dienes can be used at plant site to modify the final properties of PP resins produced with standard heterogeneous Ziegler-Natta polymerizations.

Preparation of functionalizable poly(propylene–styrene)/polyacrylonitrile millimeter‐scale particles with core‐shell morphology

“…Then the precipitate is separated through vacuum filtration, constituting the insoluble fraction. The contents of the filter paper (which contains the insoluble fraction) are then placed in an oven at 60°C for 2 h. A 50 mL aliquot was collected from the filtrate to remove the solvent by evaporation under heating at 80°C, thus providing the soluble fraction 36 . SX was performed in triplicate and the fractions were calculated with Equations and : where is the mass of soluble polymer fraction and crucible after solvent evaporation, is the mass of crucible, is the initial xylene volume used for fractionation, is the filtrate volume aliquot, and is the initial mass of PP.…”

“…The contents of the filter paper (which contains the insoluble fraction) are then placed in an oven at 60 C for 2 h. A 50 mL aliquot was collected from the filtrate to remove the solvent by evaporation under heating at 80 C, thus providing the soluble fraction. 36 SX was performed in triplicate and the fractions were calculated with Equations 1 and 2:…”

“…After fractionation, the sample was vacuum filtered to separate the soluble and insoluble fractions. The insoluble polymer fraction retained in the paper filter was dried in a circulation oven at 60 C for 12 h. 36 Next, the dried insoluble polymer fraction was weighted and the experimental insoluble fraction (IF exp ) was calculated with the following equation:…”

Propylene Polymerization over MgCl2‐Supported Ziegler–Natta Catalysts Containing Tri‐Ether as the Internal Donor

“…The bulk polymerization of propylene was carried out according to the procedure reported in the literature [36][37][38][39] with the following modifications.…”

“…25 The xylene solubility (XS) can be used to characterize the crystalline and amorphous fractions of the final polymer. 36 Polypropylene isotacticity was determined using a procedure based on dissolving a shot of polypropylene in O-xylene at 135˚C, cooling the solution to 25˚C under controlled conditions, filtering the solid phase, distilling the O-xylene from the solution, and measuring the mass of the dissolved substances. The xylene solubility results of the obtained polypropylenes are presented in Table II.…”