Water resistant wood adhesive based on starch grafted polyvinyl acetate

Incorporation of bio-based polymers for the synthesis of adhesives has seen a recent surge, it has led to exploration of cellulose, starch, lignin, etc. used as an additive or copolymers to already existing synthetic polymers. In this study, I explore the grafting of starch onto the polyvinyl acetate (PVAc) adhesives. I used raw starch and cold-water soluble starch for the studies and explored its effect on various physical and mechanical properties. An increase in glass transition temperature as well as blue shift in Fourier transform infra-red spectroscopy was observed after grating of starch, confirming the successful grafting of starch onto PVAc. The dry tensile shear strength was measured over the period of 7 days which showed negligible deterioration due to addition of starch in the PVAc homopolymers, interestingly an increase in wet adhesion (similar to 25%) was observed when the samples were kept additionally for 1 day in water. The cold-water soluble starch played an important role of decreasing the hydrophilicity of the adhesives by increasing the contact angle (48.4 degrees) and a quick adhesion to wood substrate was demonstrated with lesser drying time. Long term stability of these adhesives was excellent which was monitored by recording the change in viscosity.