| 摘要 |
<p>The compositions contain a) from 90 to 99.8 % by weight of at least one modified ethylene polymer and, optionally, at least one α-olefin having from 3 to 12 atoms of carbon, said polymer containing at least 8 % in moles 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 % by moles of units derived from at least one α-olefin having from 3 to 12 atoms of carbon and at the most 10 % by moles of units derived from ethylene, said compositions having a measured limit viscosity comprised between 1.5 and a 100 times their limit viscosity calculated from the distribution of molecular masses. Their preparation process comprises the modification of a polymer (A) containing at least 80 % by moles of units derived from ethylene and at the most 20 % by moles of units derived from at least one α-olefin having from 3 to 12 atoms of carbon, by means of at least one initiator of free radicals in presence of said polymer (A) at a temperature higher than the melting temperature of said polymer (A) during a time duration longer or equal to the tenth of the time duration of the half life of said initiator at the temperature in question and is characterised in that the initiator of free radicals is, prior to its being brought in contact with the polymer (A), dispersed into at least one polymer phase (B) present in a quantity such that its proportion in the resulting composition is comprised between 0.2 and 10 % by weight. Application to the production of industrial articles by transformation of said compositions by a technique selected amongst extrusion-blowing, extrusion through flat die, injection and coating.</p> |
