Studies on Effects of Different Cross-Linkers on the Properties of Starch-Based Wood Composites

Abstract

A green route is demonstrated to prepare biobased composites from renewable resources like starch and soft wood with engineering aspects. In this process, three different cross-linkers such as glutaraldehyde (GA), dimethyloldihydroxyethyleneurea (DMDHEU), and N-methylol acrylamide (NMA) have been used to cross-link methyl methacrylate-grafted starch with wood flour. Water is used as a solvent and glycerol as a plasticizer in the preparation of wood starch composites. Effects of these cross-linkers on different properties of the composites have been investigated through a limiting oxygen index test and mechanical, dynamic mechanical, and thermogravimetric analysis. DMDHEU cross-linked composites show the least water uptake capacity compared to NMA- and GA-based cross-linked composites due to their better cross-linked structure as DMDHEU contains a higher number of functional groups. The interaction among polymer, cross-linker, and wood has been found to be the maximum in DMDHEU cross-linked composites as revealed by FTIR and SEM studies. DMDHEU cross-linked composites also exhibit higher mechanical and thermal properties.