Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT

Abstract

A high-activity Ziegler-Natta catalyst of TiCl 4 -supported MgCl 2 (ethoxide type) was prepared. Ethyl benzoate (EB) and polydimethylsiloxane (PDMS) were used as internal donors, while p-methyl toluate (MPT) and triethylaluminum (TEA) were used as the external donor and cocatalyst, respectively. Suspension copolymerization of ethylenepropylene (EPM) was carried out in n-heptane using the catalyst system. The relative pressures of 1.5 : 1 and 2 : 1 atmosphere of propylene-to-ethylene (P P /P E ) gave a polymer with elastomeric properties. The relative pressure of propylene-to-ethylene higher and lower than the above values, however, gave a homopolymer or copolymer without elastomeric properties. The effect of the TEA concentration, H 2 concentration, temperature, and pressure of P P /P E on the yield of the polymer obtained was investigated. The effects of these factors on the glass transition temperature (T g ) and ethylene content of the polymer were studied. The content of ethylene in EPM was determined using the FTIR technique. The molar ratio of Al : MPT : Ti ϭ 355 : 107 : 1 gave a polymer with an ethylene content of about 32%. However, a ratio lower than AL : MPT : Ti ϭ 355 : 107 : 1 did not give a good elastomeric polymer. The highest productivity of the catalyst was obtained at a molar ratio of AL : MPT : Ti ϭ 355 : 107 : 1. Increasing the temperature from 45 to 70°C caused a slight increase of Et % content and a decrease of the T g of the copolymer obtained, while the highest productivity of the catalyst was obtained at 55°C with good elastomeric properties using an AL : MPT : Ti ϭ 497 : 107 : 1 molar ratio. Increasing the pressure of propylene from 1.5 to 2.5 atm caused a sharp decrease in the T g and ethylene content of the polymer. When the ethylene content in the copolymer was increased, the T g value had a tendency to be closer to the polyethylene T g .

Copolymerization of Nonpolar Olefins and Allyl Acetate Using Nickel Catalysts Bearing a Methylene-Bridged Bisphosphine Monoxide Ligand

“…Both catalyst 2a and 2b showed comparable activity for PP than PE at 50 °C (entries 4 and 6). Although this tendency is rather rare, similar examples were reported in the literature for Ziegler–Natta catalysts. − The high activity for PP may be related to the lower steric hindrance around the Ni center in the 5-membered metallacycle, that is advantageous for the facile coordination of sterically demanding propylene. Electronically, the higher electron density of the CC double bond of propylene is favorable both for coordination of the monomer to the metal center and for stabilization of a cationic transition state of olefin insertion.…”

Dependence of comonomer effect and hydrogen effect on internal donor in ethylene/1-hexene copolymerizations with MgCl2-supported catalysts

“…In recent years, many publications reported the copolymerization of ethylene with α-olefin [6][7][8][9][10]. However, there are very few references dealing with the roles of electron donors in the catalysts and the mechanism.…”

Comparative study of copolymerization and terpolymerization of ethylene/propylene/diene monomers using metallocene catalyst

“…In most technical processes for production of EPDM rubbers, soluble or highly dispersed vanadium compounds such as VCl 4 , V(acac) 3 , VOCl 3 , VO(OR) 3 , cocatalyzed by alkylaluminum chloride in presence of an organic halogen promoter or in some cases titanium catalysts, are used. It is inconvenient to use vanadium, because the residual vanadium content in the polymer of above 10 ppm causes discoloration, aging, and toxicity 1–6. In addition, these vanadium‐based catalysts drastically lose productivity in presence of dienes.…”