Preparation And Properties Of Starch-based Wood Adhesive

Through oxidation, gelatinization and graft copolymerization modified starch was gained by using soluble starch as raw material. Then a novel low-cost, high performance, low-pollution, modified starch-based wood adhesive was synthesized. The preparation process and conditions were investigated.Preparation of modified starch and its properties were studied. The optimal conditions of starch oxidation were as follows: the ratio of starch to water was 1:5, the reaction time was 60min, the reaction temperature was 60℃, the dosage of H₂O₂ was 7ml.Using ammonium persulfate as initiator, polyvinyl acetate, vinyl Acetate, and butyl acrylate mixture grafted oxidized starch was synthesized and characterized. The optimal conditions were as follows: monomer mass was 150g, monomer weight ratio was 1:10:4 (PVA:butyl acrylate:vinyl acetate), monomer dropwise time was 2h, pH value was 5, graft reaction temperature was 65℃, grafting reaction time was 4h. Infrared spectrum analysis proved that the graft copolymerization reaction proceeded effectively under these optimal conditions. Starch-based wood adhesive was prepared using modified starch and other additives such as cross-linking agent partial sodium borate, diluent urea, plasticizers glycerol auxiliaries, and preservative sodium benzoate.The optimal conditions for preparation of starch-based wood adhesive were determined by orthogonal test: the amount of partial sodium borate was 2%; the amount of urea was 16%; the amount of glycerol was 1.5%; added additives temperature at 55℃, reaction time was 30min; And additives added sequence was: cross-linker partial sodium borate, diluent urea, plasticizer glycerin, preservatives sodium benzoate. For the adhesive prepared under the best conditions, the non-volatile matter content, viscosity and tensile shear strength were 37.3%, 2.05Pa.s, and 18.43MPa, respectively.The performance of the starch-based wood adhesive prepared under the optimum conditions was analyzed. Comparing those parameters with the properties of the commercial adhesives and the Technical standards for polyvinyl acetate emulsion wood adhesive shows that the performances of starch-based wood adhesive are fully met the national standards for polyvinyl acetate emulsion wood adhesive. And its viscosity and bond strength are better than those of the commercial commodities. Lower cost and less pollution make it a broad market prospects in the wood processing market.