CROSS-LINKING OF POLYMERS AND FOAMS THEREOF

摘要

The invention includes a process comprising (a) forming a polymeric admixture including at least one polyolefin which has been prepared using a single site catalyst and at least a cross-linking amount of at least one poly(sulfonyl azide) cross-linking agent; (b) shaping the resulting admixture; and (c) heating the resulting shaped admixture to a temperature at least the decomposition temperature of the cross-linking agent. The steps take place in any sequence and optionally include substeps. The single site catalyst is preferably a constrained geometry or metallocene catalyst, but optionally another transition metal catalyst which is not a traditional Ziegler Natta Ti/MgC12 catalyst such as a vanadium catalyst. At least one polyolefin is preferably a polyethylene homopolymer; an ethylene copolymer also having at least one alpha olefin comonomer selected from monomers of from 3 to 20 carbon atoms; an elastomeric polymer; an ethylene/alpha olefin/diene terpolymer or interpolymer; a substantially linear ethylene polymer or a combination thereof. At least one polyolefin preferably has a molecular weight distribution less than about 3.5; more preferably all of the polyolefins have that MWD. The polymeric admixture is preferably a blend comprising at least about 5 weight percent of at least one polyolefin made using a single site catalyst and at least one other polymer which differs from the polyolefin by having a different density, a different molecular weight, a different catalyst used in polymerization, a different chemical composition or combination thereof. The invention futher includes all compositions obtainable by the process of the invention as well as all articles formed from these compositions. The articles are preferably thermoformed, compression molded, injection molded, extruded, cast, blow molded, blown, profile extruded, spun, foamed or molded of any composition of the invention. The invention includes a use of any composition of the invention in any process of thermoforming, injection molding, extrusion, casting, blow molding, spinning, blowing, profile extrusion, foaming, compression molding or a combination thereof.