Preparation and properties of jute / poly ( lactic acid ) / acetylated kraft lignin based thermoplastic polyurethane biocomposites

Poly(lactic acid) (PLA) is a popular one and used for bioplastics and biomedical applications. However, its brittleness and low thermal resistance restrict its application as bioplastics in spite of its comparable strength to general purpose plastics. Lignin, complex aromatic heteropolymer from woody plants, was studied in many ways for high-value utilization. Jute, a kind of lignocellulosic fibers with low density and high specific modulus, is applied as reinforcement of biocomposites in many studies. In this study, alkali-treated jute (AJ) / poly(lactic acid) (PLA) / acetylated softwood kraft lignin based thermoplastic polyurethane (ASKLTPU) biocomposites were prepared as bioplastics with high content of natural resources and biodegradability. ASKLTPU was prepared by solution casting method as thermoplastic polyurethanes (TPU) with relatively high lignin content (up to 60 weight % of ASKL), and applied for improving brittleness of PLA. AJ was used for further reinforcement PLA/ASKLTPU blends and alkali-treated jute (AJ) / poly(lactic acid) (PLA) / acetylated softwood kraft lignin based thermoplastic polyurethane (ASKLTPU) biocomposites were prepared by melt blending and hot press method. Mechanical properties, thermal properties, and water absorbancy of ASKLTPU, PLA / ASKLTPU, and AJ / PLA / ASKLTPU biocomposites are investigated. Especially, TPU60 (ASKLTPU with 60 wt. % content of ASKL) shows significant increase of Young's modulus. After introduction of 15 wt.% of AJ to PLA/ASKLTPU blend(80/20, w/w), tensile strength and Young's modulus increases significantly. Thermal properties of PLA / ASKLTPU blends and AJ / PLA / ASKLTPU biocomposites are investigated by differential scanning calorimetry (DSC). The blends are partially miscible, and shows clearer thermal transition as PLA content increases. Consequently, prepared novel biocomposites has a potential of alternative to commercial plastics