Metabolix's new line of a-PHA grades serve as performance additives for PVC, PLA.

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A new line of amorphous PHA biopolymer grades designed for use as performance additives for PVC and PLA is now readily available from Metabolix, Cambridge, Mass. Production of the new materials is underway at the company’s pilot plant which will be ramped up to 600,000 lbs annual nameplate capacity through this year.

            Amorphous PHA (a-PHA) is a softer and more rubbery (low glass-transition temperature, or Tg) version of PHA which reportedly offers a fundamentally different performance profile from crystalline forms of PHA. The company’s a-PHA is produced by fermentation and extracted using a patented solvent recovery process. Metabilix’s process has been reviewed by EPA and recently cleared the Premanufacture Notice (PMN) requirements for new materials placed into commerce. Metabolix plans to seek FDA clearance for a-PHA in food-contact applications. The company previously received FDA clearance for use of its semi-crystalline PHA grades in food-contact applications.

            At low loading levels, a-PHA can serve as a process aid and performance modifier for PVC. It is said to boost productivity during processing and to enhance mechanical performance, with the potential to deliver cost savings in PVC formulations. In highly-filled composite systems for applications such as flooring systems, wire and cable insulation, roofing membranes, and PVC/wood composites for building and construction, a-PHA’s use enables higher levels of wood pulp, mineral fillers, and PVC recyclate to replace virgin PVC and achieve improved mechanical properties.

            Similarly, a-PHA complementes the bio-content and compostability profile of PLA, while reportedly delivering significant improvements in mechanical properties such as increased toughness, strength, and ductility. Metabolix is working with customers, many of which are focused on developing a-PHA-modified PLA materials for sustainable, bio-based, and compostable packaging applications. In addition to conducting numerous trials for transparent packaging films, the company is working with customers interested in a PHA-modified PLA for thermoformed transparent clamshells used in food service and consumer packaging as well as a-PHA modified PLA for non-wovens used in personal care applications.