| 摘要 |
PCT No. PCT/FR86/00438 Sec. 371 Date Oct. 6, 1987 Sec. 102(e) Date Oct. 6, 1987 PCT Filed Dec. 19, 1986 PCT Pub. No. WO87/03888 PCT Pub. Date Jul. 2, 1987.The compositions contain: (a) from 90 to 99.8% by weight of at least one modified polymer of ethylene and, where appropriate, at least one alpha -olefin having from 3 to 12 carbon atoms, the said polymer containing at least 80 mol % of units derived from ethylene, and (b) from 0.2 to 10% by weight of at least one polymer phase (B) comprising at least one polymer containing at least 90 mol % of units derived from at least one alpha -olefin having from 3 to 12 carbon atoms, and at most 10 mol % of units derived from ethylene, the said compositions having a measured limiting viscosity of between 1.5 and 100 times their limiting viscosity calculated from the distribution of the molecular masses. The process for preparing them consists in modifying a polymer (A) containing at least 80 mol % of units derived from ethylene and at most 20 mol % of units derived from at least one alpha -olefin having from 3 to 12 carbon atoms, by means of at least one free-radical initiator brought into contact with the said polymer (A) at a temperature above the melting point of the said polymer (A) for a time longer than or equal to one tenth of the half-life of the said initiator at the temperature in question, and is characterized in that the free-radical initiator, prior to being brought into contact with the polymer (A), is dispersed in at least one polymer phase (B) present in an amount such that its proportion in the resulting composition is between 0.2 and 10% by weight. |
