Synthesis and characterization of starch stabilized polyvinyl acetate- Vinyl neodecanoate- Methyl methacrylate copolymer-based wood adhesive

Abstract

Abstract Commercially available polyvinyl alcohol (PVA) stabilized polyvinyl acetate (PVAc) based emulsion adhesives are economical, non-hazardous, form colourless glueline with very strong bonds to different types of woods and bond sets at normal room temperature by water loss. On the other hand, they are neither moisture nor heat resistant, and show poor strength at high relative humidity and high temperature. The purpose of this research paper is to enhance the water resistance of PVAc emulsion-based adhesive, by providing the adhesive with controllable cross-linking ability. To reduce the dependency on hydrocarbon sources, Starch was used as a stabilizing media during synthesis of PVAc emulsion. Here, emulsion polymerisation was used to synthesise starch stabilized polyvinyl acetate- Vinyl neodecanoate- Methyl methacrylate (PVAc-VeoVa10-MMA) copolymers. Further, the samples are formulated with PVA solution, Aluminium nitrate, plasticizer, and preservatives, and compared against copolymer sample with PVA stabilizing media. Fourier transform infrared (FTIR) spectroscopy was used to characterise the copolymerisation and crosslinking reaction. Glass transition temperatures (Tg) of the polymer films were measured using Differential Scanning Calorimetry (DSC). The performance of the crosslinked emulsions-based adhesive was evaluated in accordance with the EN 204–205 standard by measuring the tensile shear strength of wood joints in dry and wet conditions. The experimental results showed substantial increases in Tg and viscosity in starch stabilized (PVAc-VeoVa10-MMA) copolymers- based adhesive. The crosslinked starch stabilized (PVAc-VeoVa10-MMA) copolymers adhesives showed slight inferior wood adhesive performance in wet condition as compare to crosslinked PVA stabilized (PVAc-VeoVa10-MMA) copolymers adhesives which was also validated from contact angle test. The method developed provides a simple and practical route to emulsions with improved water resistance and bonding strength with the addition of starch as stabilizing media. The method for enhanced moisture resistance of PVAc wood adhesive was ecological, sustainable, and cost effective.