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New technology from Teknor Apex Co., Pawtucket, R.I., eliminates a property tradeoff that could allow polylactic acid (PLA) to supplant polystyrene and polypropylene for microwavable frozen-food trays, lids for hot beverage cups, and carry-out containers. Terraloy BP-39070 series enhanced-PLA compounds for extrusion and thermoforming have a bio-based content around 90% and are biodegradable and compostable.

These new compounds are said to overcome the previous tradeoff between PLA’s HDT and Izod impact strength. They exhibit up to twice the HDT and more than four times the impact strength of standard PLA. A typical grade in the series, Terraloy 39070A, exhibits HDT of 100 C and Izod impact strength of 69 J/m. Values for standard extrusion-grade PLA are around 55 C and 16 J/m.

In microwaveable carry-out containers, Terraloy BP-39070 compounds would replace pulped fiber or PP. As a replacement for PS in lids for hot cups, the compounds would be used with cups that typically are themselves compostable. Teknor recently came up with microwaveable Terraloy grades  for injection molding (see Keeping Up section). BP-39070A is optimized for sheet extrusion/thermoforming by building in extra melt strength and faster crystallization than in standard PLA.