WEB EXCLUSIVE: Metabolix, Inc., Cambridge, Mass., has developed a series of biobased PHA (polyhydroxyalkanoate) copolymers that act as plasticizers, impact modifiers, and processing aids for rigid and flexible PVC.

WEB EXCLUSIVE: Metabolix, Inc., Cambridge, Mass., has developed a series of biobased PHA (polyhydroxyalkanoate) copolymers that act as impact modifiers, flexibilizers,and processing aids for rigid and flexible PVC. PHA is a bioresin produced by microbial fermentation of plant starches. Data on effectiveness of new PHA copolymers was presented late last month at the SPE Vinyltec conference in Chicago by Dr. Yelena Kann, senior polymer scientist at Metabolix.

She said the new PHA copolymers are readily miscible with PVC and can perform as high-molecular-weight, readily dispersible flexibilizers that show low migration, low extractables, and little volatile loss or staining characteristics.

In impact modification, PHA-rubber copolymers reportedly outperformed the best commercial MBS core/shell impact modifiers and did not compromise PVC transparency or UV stability.

As a processing aid, the metal-adhering properties of PHA copolymers promoted hogeneous shear melting of PVC and prevented overheating and degradation.

Metabolix worked closely with AlphaGary Corp., Leominster, Mass., a custom compounder of PVC, TPO, and TPE, to validate the new PHA copolymers. Metabolix plans to produce them at a 20-million-lb/yr plant being built in Spain. Samples should be available early next year.