Abstract
Films and sheets composed by poly (lactic acid) (PLA)/thermoplastic starch (TPS) and TPS/gelatin blends have already been produced and characterized in the literature. However, materials produced with these three biopolymers have not been clearly investigated. In this work, extruded sheets were produced with PLA, TPS (glycerol as plasticizer) and different amounts of gelatin (0, 1, 3 and 5 wt%) in a pilot scale co-rotating twin-screw extruder coupled with a calender. The extruded sheets were characterized in regards to their water solubility, thickness, density, water vapor permeability (WVP), moisture sorption isotherms, mechanical properties and microstructure. The results showed an increase in solubility and WVP besides a decrease of about 30% in tensile strength, Young's modulus and elongation at break. Extruded sheets microstructure revealed smother surfaces and homogeneous morphology with the addition of gelatin. The experiments demonstrated that extrusion and calendering process is a viable way to produce PLA/TPS/gelatin sheets with interesting properties.
Keywords:
biodegradable polymers; extrusion-calendering; hydrophilicity; mechanical characterization; microstructure
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