Additives boosts strength, processability of PLA

As starch-based plastic polylactid acid (PLA) starts to see greater use, a number of additives and modifiers are being developed to help overcome some of the material’s inherent shorfalls. For instance, DuPont Packaging announced the expansion of its Biomax packaging portfolio, including renewably sourced Biomax Thermal 300, at the Sustainable Packaging Coalition’s annual meeting in Denver. Biomax Thermal 300 is a proprietary heat-stabilizing modifier that allows polylactic acid (PLA) thermoformed packaging to withstand elevated temperatures during transport, storage, and use.

The U.S. Food and Drug Administration compliant material, which contains 50% renewably sourced content by weight, is said to increase the dimensional stability of PLA to temperatures up to 95°C at let-down ratios between 2-4% percent by weight. DuPont says adding Biomax Thermal 300 to PLA has a minimal impact on the material’s clarity, while accelerating cycle times during two-stage thermoforming. Untreated, PLA has a tendency to deform at temperatures of 55°C and above, which has limited its adoption to chilled food and beverages.

DuPont already launched another PLA-targeted additive, with Biomax Strong, toughening modifier introduced in 2007 and aiming to improve PLA’s processability, durability, impact strength, and flexibility in rigid structures. Both modifiers can be added directly to the extrusion process versus masterbatching. Market introduction of Biomax Thermal will start in the U.S., with rollout to Europe and Asia early in 2009.

Arkema, too, has announced development of a new additive for processing of PLA. The supplier’s Biostrength 900 metal release lubricant is said by the firm to help processors reap cost savings during extrusion, injection molding, and calendaring of PLA and other biopolymers. Adding Biostrength 900 enables a wider processing window for PLA, helping to limit variations in processing temperatures and shear. More on the material at www.additives-arkema.com. DuPont Engineering Polymers, Wilmington, DE, U.S.A.; +1 800-441-0575; http://plastics.dupont.com.