Thermoforming / Rigid Packaging a-PHA modified PLA for thermoforming Recent reports indicate an emerging market trend toward sustainable packaging options due to environmental awareness among consumers for alternatives with improved biodegradability. For instance, the Foodservice Packaging Institute’s 2015 Trends Report found that there was an increasing focus on compostable packaging and the expectation is that more companies will need to address the demand for sustainable packaging applications in the near future. PLA is one of the more commonly used biopolymers in industrial compostable applications. Because PLA is derived from renewable sources, it is a sought after solution for green packaging material. It is well understood that the physical properties of PLA can present challenges during processing as well as in the performance of finished articles. One problem is the inherent brittleness and relatively low toughness of PLA that can present challenges in adapting the biopolymer to new packaging applications. For example, petroleum-based performance modifiers diminish biobased content and at increased addition rates can compromise compostability. This underscores the need to identify new additives for PLA that improve properties while maintaining biobased content and industrial compostability. Metabolix, a leader in PHA (polyhydroxyalkanoate) technology, launched a new amorphous PHA (a-PHA) biopolymer material in 2015. This a-PHA specialty material is a high molecular weight, low T g rubber that extends the additive space for PHA materials. Metabolix has reported research demonstrating the use of its a-PHA as process aids and performance modifiers for PVC as well as performance modifiers for PLA. It should be noted that the results produced with a-PHA in PVC and PLA are far superior to those using semi-crystalline versions of PHA. Metabolix has shown that a-PHA is an effective modifier for PLA across a range of applications including food and consumer product packaging, film, food service ware, 3D printing filament, fibers and nonwovens. In sheet and thermoforming applications specifically, adding a-PHA at low loading levels (such as less than 5 %) can eliminate the brittle fracture commonly associated with the edge trimming, conveying and cutting of extruded sheets and thermoformed parts. Adding a-PHA also increases the impact strength of the finished part, and at loading levels up to 10 %, an increase in toughness and ductility can be achieved to such an extent that it prevents brittle failure and splintering under impact load. Ultimately, a-PHA modified PLA shows an excellent balance of properties and is not limited to the 1 % loading limit of a noncompostable modifier per ASTM D6400. PLA modified with a-PHA represents an attractive option for producing thermoformed containers for food service ware. These containers have high biocontent and are industrially compostable, per ASTM D6400 and EN13432. Furthermore, the containers are strong, and because PHA and PLA are biopolymers with similar refractive indices, the containers retain a very high level of clarity. Consumers, brand owners and regulators continue to drive incentives to utilize sustainable packaging materials for carry out options as well as divert food waste from landfills. Companies looking to meet growing demands for compostable packaging options should explore a-PHA modified PLA materials as a solution for their food service and consumer packaging applications. www.metabolix.com By: Michael Andrews Director Product and Application Development Metabolix, Inc. Lowell, Massachussetts, USA 14 bioplastics MAGAZINE [02/16] Vol. 11
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