Poly:hydroxy:alkanoate contg. mixt. for heat stable polymer prepn. - additionally comprises cpd. with reactive gps. forming ester bonds with hydroxy or acid gps. of polymer on melting

摘要

A mixt. comprises (a) at least 70 wt.% of polyhydroxyalkanoate, and (b) a cpd., or mixt., with at least 2 reactive gps., e.g. acid and/or alcohol gps., which on melting form ester bonds with free OH and/or acid gps. of the polyhydroxyalkanoate. Mixts. of poly-D(-3)-hydroxybutyric acid with a polyether are excluded. (b) is boric acid, an at least 5C carboxylic acid with at least 2 acid gps., an at least 5C hydroxycarboxylic acid, an at least 5C diol, a polyol and/or a polyether. (c) may contain a plasticiser and/or a nucleating agent and/or other additives. A mixt. of (a), (b) and opt. (c) is melted, when acid and/or OH gps. of the polyhydroxyalkanoate form ester bonds with alcohol and/or acid gps. of (b), giving a polymer contg. at least 70 wt.% of polyhydroxyalkanoate. The polymers are also claimed. USE/ADVANTAGE - Use of the mixts. to prepare polymers with increased heat stability and better mechanical properties is claimed. The mixt. gives a stable melt, with viscosity greater than that of pure polyhydroxyalkanoate me