Bulk reactive extrusion polymerization process producing aliphatic ester polymer compositions

Abstract

A bulk extrusion polymerization process to derive an aliphatic polyester from a suitable ester monomer, preferably .epsilon.-caprolactone. Novel reaction formulations containing less than 100 ppm water and having an acid value less than 0.5 mg KOH/g and preferably less than 0.2 mg KOH/g enable the polymerization of bulk monomer in an extruder in a resident time of less than 2 minutes. Different catalyst and initiator systems, processing protocols, and screw configurations lead to the preferred manufacture of poly(.epsilon.-caprolactone) polymer of number average molecular weight, M.sub.n, greater than 100,000. A novel poly(.epsilon.-caprolactone) intermediate optionally grafted to starch, is described which has significantly different processing and use characteristics as compared to a straight-chain polycaprolactone.

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