‘Green’ composites based on liquid crystalline cellulose fibers and avocado seed starch

Abstract

Fully biodegradable unidirectional green composites with excellent tensile properties were fabricated by combining one of the highest specific strength liquid crystalline cellulose (LCC) fibers as the reinforcement and microfibrillated cellulose (MFC) strengthened nonedible avocado seed starch (AVS)-based resin. MFC/AVS resin was crosslinked using 1,2,3,4-butane tetracarboxylic acid as well as plasticized using sorbitol or glycerol. Combination of alkali, mechanical and thermal treatments improved LCC fiber fracture stress from 1.5 GPa to over 1.9 GPa and Young’s modulus from 49 to 64 GPa. While the type and amount of plasticizer used changed the fracture strain of MFC/AVS resin, they also showed significant influence on the mechanical properties of the unidirectional composites. These composites prepared by hand lay-up, based on modified LCC fibers resulted in fracture stress of over 380 MPa and Young’s modulus of 19.5 GPa with less than 40% fiber content. Results suggest that there is scope to improve the properties further by using higher fiber content and automated manufacturing. These ‘green’ composites with excellent strength and stiffness may be used in many applications such as construction, automobile and others.