Toughness and Compatibility Improvement of Thermoplastic Starch/Poly(lactic acid) Blends

Poly(lactic acid) (PLA), produced from renewable resources, is one of the most widely used biodegradable polymers. PLA has high strength and high modulus. However, its brittleness and high cost limit its application. Starch has been used as filler for environmental friendly polymers due to its low cost, biodegradable, and availability as a renewable source. Thermoplastic starch (TPS) is a biodegradable material based on starch. Incorporation of TPS into PLA matrix can reduce material cost and increases its biodegradation rate. However, PLA and TPS form immiscible blend leading to poor mechanical properties of the blend. The compatibility of the blend can be improved by adding compatibilizers. Moreover, in order to improve toughness of the TPS/PLA blend, poly(butylenes adipate-co-terephthalate) (PBAT), is introduced into the blend. In this study, PLA/TPS blends are prepared using an internal mixer and test specimens are molded using a compression molding. TPS is obtained from cassava starch and glycerol at ratio of 70/30 wt%. The ratio of TPS/PLA blend is 10/90 wt%. Poly(lactic acid) grafted maleic anhydride (PLA-g-MA) is used as a compatibilizer at contents of 3, 5, and 7 phr. PBAT content is 10 wt%. Mechanical, morphological, and thermal properties of the blends are investigated.