Effect of poly(lactic acid) coating on mechanical and physical properties of thermoplastic starch foams from potato starch

摘要

Single-use packaging is widely used in the food industry, and is mainly made of expanded polystyrene (EPS). These packages are discarded immediately after use and generate large amounts of waste. Thermoplastic starch (TPS) foams can be used in these situations due to the fact that starch is from renewable sources and biodegradable. Despite of these advantages, TPS has great affinity with water, which makes difficult its application as packaging. Such problem can be solved by coating the TPS foam with a hydrophobic material which prevents contact of water with the starch. In this work, poly(lactic acid) (PLA) was used as a coating due to its hydrophobicity and also for being a biodegradable material. Three coating concentrations were evaluated: 2%, 4% and 6% w/v PLA. The foams were made from potato starch, water and glycerol (62/5/33% m/m). PLA coatings increased the density, tensile strength and impact strength of the foams. TPS foams with 6% w/v PLA coating exhibited an excellent reduction of 225% in water absorption when compared to TPS foam.