Investigation of crosslinking ability of sodium metabisulphite with polyvinyl alcohol–corn starch blend and its applicability as wood adhesive

Abstract

ABSTRACT Polyvinyl alcohol (PVA) blended corn starch (S), finds application as a water-based wood adhesive and crosslinking is a tool for enhancing properties. The study investigates the effectiveness of a novel crosslinker, Sodium metabisulphite in PVA/S blend system, and its effect on adhesive properties. The hydroxyl groups of PVA/S react with the crosslinker forming a cross-linked network. The modified blend is formulated with polyvinyl acetate (PVAc) binder, plasticiser and preservatives. Physical properties like viscosity and stability of adhesives have been evaluated in addition to tensile strength on various wooden substrates. Mechanical properties studied using pencil hardness test and ultimate stress of adhesive films showed the enhancements in the mechanical strength of films with the crosslinker. Thermo-mechanical properties studied by dynamic mechanical analysis (DMA) showed enhancement in storage modulus with an increase in glass transition temperature. The modified adhesive showed better cohesion, enhanced tensile strength with excellent stability. In conclusion, the modified adhesive showed better physical, mechanical, thermal and adhesive properties. Hence, this study can be potential in the development of starch incorporated wood adhesives. GRAPHICAL ABSTRACT