| 摘要 |
Linear polypentadienes having a cis-1, 4 unit content higher than 65%, an isotactic configuration of the asymmetric carbon atoms and a crystalline structure in the solid state with an identity period along the chain axis of about 8.1</>rA, are made by polymerizing 1, 3-pentadiene in the presence of a catalyst obtained from a soluble titanium compound of the formula Ti(OR)4 in which R is an organic radical, and an organic aluminium compound of the formula, <FORM:0961269/C3/1> different hydrocarbon radicals, and R1 is a hydrogen atom or a hydrocarbon radical. The polymerization may be effected in bulk or in the presence of a hydrocarbon solvent. The titanium compound may be titanium tetra-n-butoxide, tetraisopropoxide, tetraphenolate, or tetraethoxide. Specified aluminium compounds are dimethyl to dioctyl aluminium monohydride, ethyl isobutyl, ethyl propyl, or ethyl hexyl aluminium monohydride, aluminium triethyl, aluminium trihexyl, aluminium triisobutyl, aluminium tridodecyl, aluminium tricyclohexyl, or aluminium diethyl monobenzyl. The catalyst is generally preformed in a hydrocarbon solvent. The cis-content of the polymer resulting from the polymerization can be increased by dissolving the polymer in benzene and precipitating it with methyl ethyl ketone. The polymerization reaction is terminated with methanol and the polymer purified by conventional techniques. The polymer may be vulcanized. Specification 931,900 is referred to. |
