Preparation Of Wood Adhesives Based On PVA And A Modified Tapioca Starch

This paper studies the method of PVA and modified tapioca starch and process conditions, with modified PVA and modified tapioca starch-based synthesis high water resistance, good wood adhesive bonding strength, and to explore the synthesis process conditions.1) Studied the oxidative degradation of polyvinyl alcohol and modified polyvinyl alcohol hydrophobized conditions.First, through the single factor experiment to the modified polyvinyl alcohol gel viscosity, degree of cure and plywood open plastic time indicators,screening optimal oxidant, catalyst, hydrophobic agent and the oxidation reaction pH, temperature, time; then by orthogonal experiments were investigated oxidant, catalyst, water repellents impact on the performance of the modified PVA glue. The results show that the reaction time of40min, the reaction temperature is50-55℃,the reaction pH is5, H2O2is0.013mol, FeSO4·7H2O was0.15g, urea1.8g, the best overall performance of modified PVA glue, adhesive bonding strength is dried2.23MPa, wet bonding strength of1.60MPa.2) Esterification modified starch, research the type and amount of esterification agent under alkaline conditions, the reaction temperature, reaction time, plus the impact on the amount of alkali modified starch esterified major performance, to the degree of substitution, settlement plot and relative wetting contact angle as an indicator single factor experiment,Then the temperature, time, esterification agent for orthogonal experiment to further optimize the process conditions.The results show that the reaction time4h, the reaction temperature is110℃, the amount of sodium hydroxide0.4g, quality starch with maleic anhydride ratio50:12, tapioca starch esterified best results, the degree of substitution0.328,wetting contact angle114°3) With modified polyvinyl alcohol gel, modified starch, acrylic emulsion, ammonium persulfate initiators do four orthogonal factors, to determine the optimum conditions based on the preparation of cassava starch and modified PVA wood adhesive,to determine the optimal quality of non-formaldehyde wood adhesives ratio of75:15:11:2, its dry bonding strength reached3.28MPa, wet glue intensity reached1.93MPa, visible, and its performance is better than the modified PVA glue.4) By FTIR and SEM modified PVA gum, modified tapioca starch and modified starch and modified PVA and acrylic emulsion adhesives and other blends were compounded characteristic absorption peaks and morphology analysis.