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US 5,397,842 AGranted
Polyolefin/segmented copolymer blend and process
AssigneeRohm and Haas Company
InventorsRaymond G. Hamilton, Mark T. McCarty
Life of this patent
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Abstract
A blend of a polyolefin, such as polypropylene, with a segmented copolymer containing both polyolefin segments and segments derived from greater than 20 to about 100% of a vinyl aromatic monomer is useful in applications where high melt strength is desired.
Claims2
A process for preparing a segmented copolymer of polypropylene or polyethylene with polystyrene which segmented copolymer is essentially free of ungrafted polystyrene and which imparts improved melt strength to polypropylene which comprises:
- (a) mixing the polypropylene or polyethylene with styrene (and optionally up to about 20% by weight, based on total monomer content, of one or more monomers copolymerizable with styrene) in the presence of an initiator having a one-hour half-life at a temperature in the range of from about 110.degree. C. to about 125.degree. C.;
- (b) heating the mixture at a rate of at least 1.degree. C./minute to a temperature of at least 90.degree. C. at which the polypropylene or polyethylene completely swells;
- and
- (c) continuing heating at a rate of at least 1.degree. C./minute to at least 140.degree. C. until grafting occurs.
1 more element
Dependencies are inferred from the claim text.