Abstract:Polypropylene is a valuable chemical material with a lot of good performance, but it has an inherent lack of tenacity, especially below its glass transition temperature. Its impact-resistance can be modified by adding elastomers.
In this paper, brPE/iPP alloy was obtained under appropriate operating conditions by ethylene polymerization in iPP particles, which was catalyzed by late transition metal catalyst supported in the functionalized iPP particles. First, functionalized polypropylene was prepared with Z-N catalyst in a 2-liters reactor at 70℃ and 2atm. Then the late transition metal catalyst bi-(2,6-dimethylphenyl) pentane diimine nickel dibromide was supported on the fuctionalized iPP particles. When ethylene was input in the reactor, ethylene diffused into iPP particles and polyethylene formed in iPP particles. The obtained product is an alloy of polypropylene and branched polyethylene. By varying the polymerization temperature, the branching degree of polyethylene can be tuned and different brPE/iPP in-reactor alloy could be obtained. Besides the process, we investigated the basic properties of these products.
Experiments showed that the functionalized polypropylene is a good support material for late transition metal catalyst. By adjusting the operating parameters such as temperature, brPE/iPP in-reactor alloy can be prepared When the polymerization temperature increased from 20 ℃ to 50 ℃, the branch of polyethylene varied from 20.0 to 130.4. The branch chain mainly consist of methyl branch, but with the temperature increasing, the long branches, especially amyl , hexyl and longer than hexyl, increase rapidly and the content of long branches are comparable to that of methyl branch.
Keywords: Polypropylene; high-Polyethylene; diimine nickel catalyst; dihydro Myrcene three-silicon ether