Lignin-ester derivatives as novel thermoplastic materials

Abstract

Spruce and eucalyptus lignins isolated by an organosolv process and lauroyl chloride were used as raw material for the synthesis of lignin-ester derivatives. The obtained products presented new and interesting properties suitable for use as thermoplastic materials. Esterification of the lignins was confirmed by FTIR, GPC, DSC and contact angle measurements. The modification of lignin –OH groups increased the molecular weight properties, changed its thermal behavior (reducing greatly T_g), and improved the hydrophobicity of the material. For composite elaboration, commercial cellulose acetate was used as reinforcement in different percentages (5%, 10%, 25% and 50%) to manufacture composites by press moulding. Thermal and mechanical tests as well as wetting behavior of the composites surface against water analysis were carried out. Surface morphology was analyzed by SEM. The mechanical test revealed tensile strength and Young modulus values of 130–900 kPa and 2–50 MPa respectively, with high elongation at break (5–130%) for eucalyptus lignin composites, while spruce lignin composites showed more a rigid (40–60 MPa) and tough (300–1400 kPa) behavior, but with the ability to deform only up to 6%.