Performance Evaluation of PLA against Existing PET and PS Containers

Poly(lactide) (PLA) polymers are environmentally-friendly biodegradable materials that have garnered growing attention in the past few years as food packaging materials since packages made from PLA have the advantage of being produced from renewable resources, provides significant energy savings, and can be recyclable and compostable. PLA's optical, physical, and mechanical properties have been compared to those of polystyrene (PS) and polyethylene terephthalate (PET) although studies comparing and showing the actual performance of PLA, PS, and PET packages are scarce. The purpose of this study was to investigate and to compare the role of PLA for the food service industry. Two of the commonly used materials to make containers to package fresh food, PET and oriented polystyrene (OPS), were compared with oriented PLA (OPLA). This study involved a number of tests to quantify the physical, mechanical, barrier, and compatibility properties that would affect the selection criteria for containers to be used for food service applications. Based on the results, OPLA, OPS, and PET performances were evaluated. Exposures of the three materials to weak and strong acids for seven days show a minimal reduction in the performance of these polymers. At ambient temperature, PET has the highest impact resistance followed by OPLA and OPS. PET shows the highest oxygen barrier followed by OPLA and OPS. Thus, several of the relevant properties for packaging applications of OPLA are between PET and OPS properties, suggesting that OPLA would also be suitable for some of these applications.