Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PM...Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PMMA obtained has higher number average molecular weight and wider molecular weight distribution compared with those obtained by solution polymerization with homogeneous catalyst system, although the polymerization activity is lower.展开更多
Calix[4]titanium in combination with Al(iBu) 3 formed a homogeneous catalyst system.This homogeneous catalyst system was found to be an active catalyst system for the polymerization of ethylene.The effects of Al/Ti mo...Calix[4]titanium in combination with Al(iBu) 3 formed a homogeneous catalyst system.This homogeneous catalyst system was found to be an active catalyst system for the polymerization of ethylene.The effects of Al/Ti molar ratio,solvent,concentration of catalyst and polymerization temperature on the polymerization were studied in detail.Polyethylene having M W of 9.4×10 5 is obtained under following conditions:[Ti]=5×10 -4 mol/L,Al/Ti=20,T=35℃,t=1h,ethylene pressure=1 0MPa.The catalytic activity is 60 7kg PE/mol Ti·h.Other alkyl aluminums as cocatalysts were also investigated.For various alkyl aluminums the catalytic activity decreased in the following order:AlEt 3>Al(iBu) 3>AlEt 2Cl>Al(iBu) 2Cl.展开更多
Calix[8]arene neodymium was prepared by reacting calix[8]arene with metallic sodium in a mixture of benzene and isopropanol, then with anhydrous neodymium chloride. Calix[8]arene neodymium in combination with Al( i Bu...Calix[8]arene neodymium was prepared by reacting calix[8]arene with metallic sodium in a mixture of benzene and isopropanol, then with anhydrous neodymium chloride. Calix[8]arene neodymium in combination with Al( i Bu) 3 as a cocatalyst was active in the polymerization of ethylene. Effects of Al/Nd molar ratio, concentration of catalyst and temperature on the ethylene polymerization were studied in detail. Polyethylene having M v of 97×10 4 was obtained under the following conditions: [Nd]=8×10 -4 mol/L, the molar ratio of Al to Nd=15, 80 ℃, 0.5 h; ethylene pressure=1.2 MPa, and the catalytic activity is 24 kg PE/(mol Nd·h) .展开更多
文摘Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PMMA obtained has higher number average molecular weight and wider molecular weight distribution compared with those obtained by solution polymerization with homogeneous catalyst system, although the polymerization activity is lower.
文摘Calix[4]titanium in combination with Al(iBu) 3 formed a homogeneous catalyst system.This homogeneous catalyst system was found to be an active catalyst system for the polymerization of ethylene.The effects of Al/Ti molar ratio,solvent,concentration of catalyst and polymerization temperature on the polymerization were studied in detail.Polyethylene having M W of 9.4×10 5 is obtained under following conditions:[Ti]=5×10 -4 mol/L,Al/Ti=20,T=35℃,t=1h,ethylene pressure=1 0MPa.The catalytic activity is 60 7kg PE/mol Ti·h.Other alkyl aluminums as cocatalysts were also investigated.For various alkyl aluminums the catalytic activity decreased in the following order:AlEt 3>Al(iBu) 3>AlEt 2Cl>Al(iBu) 2Cl.
文摘Calix[8]arene neodymium was prepared by reacting calix[8]arene with metallic sodium in a mixture of benzene and isopropanol, then with anhydrous neodymium chloride. Calix[8]arene neodymium in combination with Al( i Bu) 3 as a cocatalyst was active in the polymerization of ethylene. Effects of Al/Nd molar ratio, concentration of catalyst and temperature on the ethylene polymerization were studied in detail. Polyethylene having M v of 97×10 4 was obtained under the following conditions: [Nd]=8×10 -4 mol/L, the molar ratio of Al to Nd=15, 80 ℃, 0.5 h; ethylene pressure=1.2 MPa, and the catalytic activity is 24 kg PE/(mol Nd·h) .