Opitimization Of Production And Study Of Properties Of Starch-based Wood Adhesive

The research of developing environmental high-performance wood adhesive by utilizing low-cost starch resources is one of the hot research fields.Since the poor shear strength and storage stability of traditional starch adhesive didn't meet requirments of the starch adhesive market, we should choose the optimum process conditions and suitable copolymerization monomers to prepare a new kind of starch-based wood adhesive with high-shear strength and good-storage stability.Firstly,we chose the optimum process conditions to prepare the starch-based wood adhesive by the index of grafting parameters. After the optimization, the best grafting copolymerization conditions were: an APS quantity of 1.16% of dry starch weight,a reacting temperature of 70℃,an reacting pH of 5,an reacting time of 3h,a monomer's adding rate of 380.88 mL (/kg?h),a mass radio between monomer with starch of 6:5 and the heat treat conditions of 85℃30min,the graft radio of the starch-based wood adhesive prepared under the conditions is largest up to 50.83%.After analysing the relatioanship between grafting parameters with shear strength,we found the percent grafting and the average molecular weight of branched chain both had an good effect on the bonding strength,besides the percent grafting had a greater effect on the bonding strength than the average molecular weight of branched chain's.Secondly,the effect of grafting coplymerization on the properties of the prepared adhesive was studied.The experimental results showed when the comonomer was BA, the shear strength of the adhesive was improved,and separate dropping had a better effect than blending droping.When the comonomer was Veova10,the storage stability of the adhesive was improved ,and blending dropping had a better effect than separate dropping.Finally,BA and Veova10 were both used to modify the adhesive ,and the modified adhesive's properties were best when the BA monomer's additive amount was 7.5% of total monomers'amount and the Veova10 monomer's additive amount was 12.5% of total monomers'amount.Thirdly,the assistants of the adhesive were chose and optimized.The emulsifer of SDS,the diluent of urea,the oxidant of APS all had some effect on the storage stability of adhesive.The orthogonal experimental results showed three assistants all had a good effect on the storage stability of adhesive,and the sequence was SDS>urea>APS;among the three assistants ,only urea had a good influent on the shear strength.Finally,according to the situations of adhesive, three assiatants'adding amounts were as follows:SDS was 2.28% (w/w, base on the dry starch weight),urea was 22.86%(w/w, base on the dry starch weight),APS was 2.86‰(w/w, base on the dry starch weight).Finally, the instability mechanism of adhesive is discussed.Hydrogen bonding force is the main factor of adhesives'instability.At last,the properties of starch-based wood adhesive prepared at optimal conditions we analyzed.Properties of starch-based wood adhesive were compared with industry standard of polyvinyl acetate wood adhesives.