Method of improving processability of polymers and resulting polymer compositions

Abstract

A specific class of thermoplastic polymers with improved processability resulting from initial partial degradation of high molecular weight polymers using a chemical prodegradant present in excess of the amount reacted during pelletization. This class of polymers includes polymers and copolymers of polypropylene and butylene. After pelletizing, the polymer including unreacted prodegradant can be safely handled and shipped without difficulty. When remelted by extruding or the like, the prodegradant in the pellets reacts, further reducing the molecular weight as well as narrowing the molecular weight distribution of the polymer to a point where high capacity production of quality fibers and extruded products can be obtained. The prodegradant is preferably of the type that predictably and controllably affects the polymer molecular properties without being significantly affected by minor fluctuations in the polymer producer's or processor's manufacturing steps. Specific preferred embodiments include 2,5-dimethyl - 2,5 bis-(t-butylperoxy) hexyne-3; 3,6,6,9,9-pentamethyl-3-(ethyl acetate)-1,2,4,5-textraoxy cyclononane; .alpha.,.alpha.'-bis (t-butylperoxy) diispropyl benzene and 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane as the prodegradant added in an amount providing an amount of unreacted prodegradant after pelletizing of about 0.01 to 10.0 percent based on the weight of polymer. The present invention reduces the safety hazards present when handling free radical prodegradants by the polymer processor and avoids the need for multiple addition of prodegradants while still producing a material that can be processed easily by the polymer producer and processor.

Dependencies are inferred from the claim text.