PROPERTIES OF POLY(LACTIC ACID)/NATURAL RUBBER/THERMOPLASTIC STARCH BLOWN FILMS

Abstract

In order to investigate the property enhancement, binary and ternary blend films were conducted in this research by blending poly(lactic acid) (PLA) with natural rubber (NR) and thermoplastic starch (TPS) at different contents. Blend films were produced in a twin screw extruder and formed into blown film. Thermal and mechanical properties, morphology, gas permeability and moisture absorption of all samples were evaluated in detail. From DSC results, NR domains in PLA matrix acting as nucleating agent provided high crystallinity percentage in PLA/NR films. Blinding NR in binary blend films provided the improvement of toughness and gas permeability. The results show that PLA blended with 10 wt% of NR was the optimal composition in PLA/NR films. Additionally, TPS was prepared from mixing cassava starch and glycerol at the weight ratio of 70/30 in a twin screw extruder. The incorporation of hydrophilic TPS into the system importantly affected the enhancement of water vapor permeability and moisture absorption of blend films, especially at high TPS loading. The reasons leading to these outcomes were intensively discussed. Consequently, the ternary blend film with the combination of PLA, NR and TPS is a fascinating approach to develop the properties of film packaging used for extending shelf life of fresh produces. This ternary blend film was practically made from bio-based materials which it can easily degrade in the proper environment as well.