| Chitosan is a natural stable alkaline polysaccharide;it has extremely wide application value and regarded as the key material in science field.Chitosan has good biocompatibility,film forming properties,hygroscopicity and moisturizing properties,so that it can be used to prepare super absorbent polymers.While it is extracted and transformed from shrimp and crab shells by acid and alkali,this production process has serious pollution and high cost,which restricts its application.Therefore,it is meaningful to synthesize chitosan at a low cost through a semi-synthetic process using the cellulose as a raw material.Synthesis chitosan analogues derivatization and evaluate its water retention and adhesive properties can prove the application value of the product.In this paper our group has adopted a new process which uses the water-soluble biobased sulfate as intermediate and the carboxylates as catalyst to synthesize 6-aminocellulose by the ammonia substitution reaction.The optimum conditions for the synthesis of chitosan analogues were determined:the reaction temperature is 180℃,the reaction time is 16 h,the reaction pressure is 1.2 MPa,the catalyst is acetic acid,benzoic acid or salt,the molar ratio of sulfate group ammonia:carboxylate salt is equal to 1:2:0.1.The addition of the catalyst can increase the degree of substitution from 0.24 to 0.70,the reaction yield can be increased from 73%to 81%and the reaction time can be shortened by 8 h.It has been found that high degree of substitution of chitosan analogues can be precipitated easily.The water-soluble ammonia-substituted derivatives 6-N-carboxymethyl chitosan can be successfully synthesized in alcohol-water solvents,with the chitosan analogue as raw material,while the natural carboxymethyl chitosan is oxygen substituted.The products were characterized and analyzed by 13C-NMR,1H-NMR,IR,elemental analysis,SEM,thermogravimetry,XRD and so on.It was found that 6-aminocellulose and its derivatives have good adhesive properties,can greatly increase the bonding strength and water resistance of styrene-acrylic emulsion adhesives.When the addition of 6-aminocellulose is 20%,the bonding strength of the styrene-acrylic emulsion adhesive can be increased by 15%;while when the addition of carboxymethyl chitosan is 20%,the bonding strength can be increased by 30%,and successfully pass the water resistance test for 8 hours,which in line with national standards.In this paper,6-aminocellulose super absorbent polymer was prepared by solution polymerization method,of which the absorption capacity is 25 times.While,the water absorption rate of chitosan super absorbent polymer is 30 to 40 times and of the raw materials CS is 10 times.Meanwhile,compounding method was adopted to neutralize 6-aminocellulose and cellulose sulfate to prepare a new type of super absorbent polymer of which the absorption capacity was up to 31 times.The absorption capacity is similar to the product synthesised by chitosan,and even similar to that of polyacrylamide,though the cost is much lower than both.Chitosan analogues and derivatives have a wide range of raw materials,low prices,green products,and obvious advantages in cost-effectiveness,and they have good prospects for popularization and application.In this paper,a new process was developed to get high degree of substitution and yield of chitosan analogues and derivatives.It can realize large-scale,low-cost production,which has excellent water retention and adhesion properties.This product has macromolecular structure,significant cost-effective and great application value. |
