(315a) Flexible Packaging Applications of Polylactide, Triethyl Citrate, and Cellulose Acetate Blends

Polylactide (PLA) is a bio-based, biodegradable polymer that is inexpensive and readily available. It is derived from lactic acid, which can be produced via the fermentation of any sugar-containing crop.  Under suitable conditions, PLA will compost into the natural end products of carbon dioxide, water, and humus.  Already used in a variety of compostable service ware (cups, bowls, utensils, etc.) and other disposable products, PLA has gained popularity over the past few years as industry and the public have become aware of the impact of waste materials (especially non-degradable plastics) on the earth’s ecosystems as well as the need for sustainable materials from renewable starting products. PLA’s high modulus and low elongation at break, however, make the unmodified polymer unsuitable for uses in flexible packaging applications, an area where the need for biodegradable polymers is evident.  In this study, PLA is blended with Triethyl Citrate (TEC), an ester of citric acid, and Cellulose Acetate (CA), an organic acid ester of cellulose, to produce an all-renewable, eco-friendly polymer blend.  TEC serves as a plasticizer that increases the flexibility of the brittle PLA, and CA acts to retain the solid-like properties of the material.  Thermal, mechanical, and rheological properties of the blends at varying percentages of TEC and CA are studied.  A decrease in glass transition temperature (Tg) and increase in elongation at break indicate that plasticization of PLA has occurred at all TEC concentrations studied. Water vapor and oxygen permeability studies are also carried out to quantify the blend’s viability as a food packaging material.  In addition, the biodegradation behavior of the blends is examined in an enzyme solution.