Characteristics of Bioplastics Based on Chitosan and Kraft Lignin Derived from <i>Acacia mangium</i>

Biodegradable plastics are types of plastics that can decompose into water and carbon dioxide the actions of living organisms, mostly by bacteria. Generally, biodegradable plastics are obtained from renewable raw materials, microorganisms, petrochemicals, or a combination of all three. This study aims to develop an innovative bioplastic by combining chitosan and lignin. Bioplastic was prepared by casting method and characterized by measuring the mechanical properties like tensile strength, Young’s modulus, and elongation at break. The chemical structure, together with the interactions among chitosan and lignin and the presence of new chemical bonds, were evaluated by FTIR, while the thermal properties were assessed by thermogravimetric analysis. The water vapor permeability, tests and transparency as well as biodegradability, were also carried out. The results show a tensile strength value of 34.82 MPa, Young’s modulus of 18.54 MPa, and elongation at a break of 2.74%. Moreover, the interaction between chitosan and lignin affects the intensity of the absorption peak, leading to reduced transparency and increased thermal stability. The chitosan/lignin interactions also influence the crystalline size, making it easier to degrade and more flexible rather than rigid. The contact angle shows the bioplastic’s ability to resist water absorption for 4 minutes. In the biodegradation test, the sample began to degrade after 30 days of soil burial test observation.