Under the “Mirel” trademark, US bioscience company Metabolix (Cambridge, Massachusetts; www.metabolix.com) has developed new amorphous PHA biopolymers with the physical characteristics of a low Tg rubber. These new rubber modifiers, it says, have been shown to improve the ductility and flexibility of PLA, while also retaining clarity and compostability. Both PHA and PLA biopolymers are compostable. In extrusion applications, the modifiers are claimed to reduce stiffness and brittleness and improve tactile feel, while increasing tear resistance in film.

“Metabolix continues to make great progress in the use of our core PHA technology as a performance-driven modifier in applications where improved performance of both bio-based and conventional polymers such as PLA and PVC is desired,” said Metabolix CEO Joseph Shaulson.

The company is planning to set up a PHA base polymer line with a capacity of up to 3,000 t/y in either the US or Europe, Bob Engle, vice president of biopolymers at Metabolix told Plasteurope.com in an interview at “K 2013” – see Plasteurope.com of 28.10.2013. Within two to three years, he said capacity could be expanded to 10,000 /y. At the recent exhibition “Innovation Takes Root 2014” in Orlando, Florida, Engle presented the extended range as a “unique way to compound PLA.”