Study On Corn Starch Adhesive Using For Plywood

Starch is a high polymer which is composed of a great deal of glucose unit. It has thousands of hydroxy which combine with water to form strong hydrogen bond and make it have too weak water-resistant to reach class II adhesive level and satisfy the requirements of wood-based panel production. This thesis tried to improve water endurance performance to meet the application demand of class II plywood by a series of chemical modification means which include oxidation treatment, grafting alkene high polymer and adding cross-linking agent to reduce the number of hydroxyl and introduce other active bases.This thesis firstly studied the oxidization of corn starch . By adopting to relatively mature oxidation ways of four oxidants -- Sodium hypochlorite(NaClO), hydrogen peroxide (H2O2), potassium permanganate (KMnO4), Sodium periodate (NaIO4) ,the oxidation experiment was studied and the best oxidant was selected by means of chemical analysis and infrared absorption spectroscopy ( IR ) analysis. The optimal oxidation process of two-step potassium permanganate oxidation was determined using the orthogonal design program means by inspecting the four influence factors of potassium permanganate, sodium hydroxide, sulfuric acid and the concentration of starch emulsion which using carbonyl and carboxyl base content for evaluating indicators.On the base of establish oxidation process of corn starch, the preparation of corn starch adhesive was studied. The orthogonal design program was used as main experiment means. According to the class II water endurance bonding strength index of the plywood which was adhered by the very corn starch adhesive, the best preparation process of starch adhesive was obtained through observing the influence factors of oxidant, acrylamide and cross-linking agent. By Compared the solidified time of organic acid ,phosphoric acid, ammonium chloride and mixed catalyzer (H3PO4:NH4Cl=7:3), the optimal catalyzer and the amount of which was chosen. The best hot-pressing technical parameter was confirmed through observing influence factors of hot-pressing temperature ,hot-pressing pressure and hot-pressing time. In addition, this thesis also analyzed the chemical mechanism of corn starch adhesive by IR spectrum.The results are shown that:(1) The best oxidant is sodium periodate, potassium permanganate is suitable for corn starch oxidation as the cost and properties are concerned;(2)The optimal two-step potassium permanganate oxidation oxidization process is : sodium hydroxide 0.6g,...