(590h) Improvement of Thermal and Mechanical Properties of Lignin Copolymers and Synthetic Polymer/Lignin Copolymer Blends

Lignin is arguably one of the most abundant bio-based polymers found in nature, and it can be extracted from the lignocellulosic part of the plant. Lignin is made up of 15% to 35% of the biomass, depending on the type of plant. It has a cell wall structure that is responsible for the rigidity and strength of the plant. With its abundance, inexpensiveness, and biodegradability, it has been used in blending with synthetic polymers to obtain new potential polymeric materials that have comparable chemical and mechanical properties to synthetic homopolymers. However, lignin and synthetic polymer blending display a non-uniform distribution, low miscibility, and poor properties in blends. Therefore, lignin must be chemically modified or used in conjunction with a compatibilizer when blending with synthetic polymers. The objective of this research is to synthesize copolymers from lignin and synthetic polymer – resulting in a potentially biodegradable polymer containing improved chemical and mechanical properties that can also be used in blending with synthetic homopolymers. Activators Generated by Electron Transfer Atomic Radical Polymerization (AGET ATRP) is the method used in this work due to its high molecular weight control, better oxygen insensitivity, less toxicity, and high industrial applicability. The three chosen monomers in this work are methyl methacrylate (MMA), methacrylic acid (MAA), and styrene (S) because of the hydrophobicity and similarity in their structures. The lignin copolymers synthesized from this work are tested to determine the chemical and thermal properties through FTIR, NMR, DSC, and TGA analysis. Their mechanical and surface morphology properties are investigated through tensile testing, optical microscopy, and SEM analysis. Lignin copolymers show an enhancement in thermal properties, such as increased thermal stability and higher glass transition temperature compared to native lignin. Moreover, due to the lignin backbone, lignin copolymers also show biodegradability. When used in a blend with synthetic homopolymers, they display an improvement in miscibility and mechanical properties compared to based lignin and synthetic polymer blending. This work will promote more use of lignin in the renewable plastic industry, and it will also benefit the agricultural economy.