| 摘要 |
<p>A polyolefin blend comprising, in physical admixture, a major p6rtion of particles of a polyethylene and a minor portion of particles of a composition of a thermoplastic second polyrher, is disclosed. The polyethylene is selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and at least one C<Sub>4</Sub>- C,<Sub>o</Sub> higher alpha-olefin, and the second polymer is a normally solid thermoplastic polymer having a melting point of less than 185°C and a shear viscosity that is not more than that of the polyethylene when measured at 200°C and a shear rate of 400 sec ' with the proviso that the second polymer is not a homopolymer or copolymer derived solely from hydrocarbon alpha-olefins having 2-10 carbon atoms. Examples of second polymers are (a) homopolymers and copolymers of unsaturated hydrocarbons in which at least one monomer is other than a C<Sub>2</Sub>- C<Sub>10</Sub> alpha-olefin, e.g. ethylene/propylene elastomers, polystyrene and styrene/butadiene/styrene copolymers, (b) copolymers of ethylene with ethylenically unsaturated carboxylic acids and anhydrides, and esters thereof, and (c) modified polymers e.g. chlorinated polyethylene, grafted and ionomeric polymers. The composition of the second polymer contains a reactive agent that is capable of reacting with polyolefins that are in a molten state, such agents being cross-linking agents and/or modifying agents. In an alternative embodiment, the polyethylene may be more broadly defined as being a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms. The blends may be used in a wide variety of processes, including blow-moulding processes, film and pipe extrusion processes, sheet thermo-forming processes and rotational moulding processes.</p> |
