Utilization of lignin extracted from Thai ago-waste as UV-blocking agent for BG-lignin/PLA composites films

Polylactic acid (PLA) is one of the most promising biopolymer materials derived from renewable resources. Due to its mechanical properties, biodegradability, and renewability, PLA is an interesting materials choice for packaging applications. However, PLA has a poor UV absorption that might not be suitable for UV-sensitive products. For improving this property, bio-additives were desired. Lignin is a biodegradable material which is isolated and extracted from plants. Lignin comprises mainly of aromatic monolignol that can provide a good UV absorption and anti-oxidation property. In this current work, organosolv lignin extracted from sugarcane bagasse (BG-lignin) was used as-multifunctional bio-additive for improving the properties of PLA. BG-lignin were determined using several techniques including SEM, DLS, FTIR, quantitative ³¹P NMR, GPC and DSC. BG-lignin/PLA composite films were prepared via melt-extrusion with different addition of BG-lignin contents from 0.1 to 1.0 wt%. Properties of the obtained BG-lignin/PLA composite films including mechanical properties, UV-shielding ability and anti-oxidation property were reported and compared with neat PLA film. An increasing of BG-lignin content resulted in an improvement in UV-shielding ability. The composite film with 0.5 wt% BG-lignin exhibited almost 70% blocking of UVB. At 0.5 wt% loading content of BG-lignin, oxidation-onset temperature of the composite films increased by 33% as compared to neat PLA film.