Polymerised Lignin as a Reinforcing Agent in Microfibrillated Cellulose/Wood Composites

Abstract

Lignin is an abundant structural material found in lignocellulosic biomass in various configurations. It is a complex natural polymer, and being an environmentally friendly material, it has much potential for improving the mechanical properties of various products. Lignin can be extracted using different pulping methods, and each method produces lignin with a different structure. The lignin used for various applications must, therefore, be studied to find the optimal lignin fraction for each end-use. In composite materials, lignin can be useful for its many properties, which include antibacterial, retention ability, and mechanical property enhancement. In this thesis, two types of lignin were polymerised with several types of cellulosic materials to see how lignin would affect the properties of natural composites and how efficient polymerisation on the materials can be. Microfibrillated cellulose (MFC) and sawdust were used as cellulosic materials to create lignin-polymerised particleboards, in which MFC would function as a binder between the wood particles. Lignin was polymerised to the fibres with laccase treatment to enhance certain composite properties, such as mechanical strength and water resistance. The results reveal that using unbleached MFC with additional lignin added, enhances the mechanical properties ofparticleboards when compared to those produced with MFC alone.