Liquefaction Of Rice Husk And Preparation Of Polyurethane Adhesive From Liquefaction Products

The liquefaction of rice husk fiber in the mixture of polyhydric and sulfuric acid as the catalyst under atmospheric pressure and low temperature was studied to produce liquefied rice husk polyols.We can synthesize polyurethane adhesive(PU)from liquefied rice husk polyols by partly replacing polyols and mechanical properties and viscosity of polyurethane adhesive was analyzed.The rice husk fiber was liquefied in the mixture of polyethylene glycol(PEG400)and glycol.The impacts of the reaction time,the reaction temperature,the type and content of catalyst,the liquid-solid ratio and the composition of liquefy reagents on the liquefaction behavior were studied.The results showed when liquid to solid mass ratio was 7:1,the amount of n-octanol was 20% and sulfonic acid was 6%,liquefaction yield was 80% at 150? after 120 min.Infrared spectrum was used to investigate the residues under different reaction time.In the incipient reaction stage,lignin in rice husk was liquefied wholly;with the prolongation of liquefaction,the amount of cellulose decreased gradually,but cellulose was not completely liquefied;XRD analysis of the crystallinity of liquefaction residue found that lignin and hemicelluloses degraded faster than cellulose and cellulose in amorphous region degraded faster than that in crystalline region did.we can synthesize polyurethane adhesive(PU)from liquefied rice husk polyols by reacting it with oligomer polyols,4,4-Diphenyl methane diisocyanate(MDI)and in the synthesis of the polyurethane adhesive,the pre-polymerization temperature,the amount of liquefied rice husk polyols,the species of oligomer polyols,R value(molar ratio of-NCO and-OH)and the type of small molecule cross-linking agent were investigated.The results showed that the optimum synthetic latex as follows: the pre-polymerization temperature was 70?,polybutylene adipate 1000(PBA1000)was the raw materials,the amount of liquefied rice husk polyols was 10%,R value was 1.2 and the cross-linking agent was trimethylolpropane(TMP).In this case,the viscosity of the polyurethane adhesive was 5290mPa/s,the tensile strength was 6.4MPa,and elongation at break was 890%.Moreover,with the increasing of R-value,the viscosity of polyurethane adhesive decreases firstly and then increases,the tensile strength rises,the elongation at break decreases.But there are some bubbles in the polyurethane film when the R value is too high,and the mechanical properties deteriorates.