Reactivity Ratios Of AA/MA And The Research Of Grafted Starch With AA/MA Monomers Catalyzed By HRP

As a natural renewable macromolecular resource,starch with the advantages of abundant sources,low price and biodegradability has become one of the three main sizing materials and is widely used in the sizing of natural cellulose fiber and its blended warp yarn with chemical fiber.However,the defects in the molecular structure of starch material lead to its film-forming property,poor toughness and corruption,which affect its application in warp sizing.In order to overcome the property defect of starch,it is necessary to modify the structure of starch.At present,horseradish peroxidase(HRP),as a kind of high active enzyme,has attracted the attention of researchers at home and abroad for its high catalytic efficiency,low pollution and ecological friendliness.Moreover,it is often used in the graft polymerization of vinyl monomers and starch.However,the grafting type is mostly monomeric graft copolymerization.Limited by the type of grafting monomers,the grafting product performance is single.In this study,the feasibility and type of copolymerization of acrylic acid and methyl acrylate with similar structure and complementary performance under HRP enzyme catalysis was investigated,and two monomers were grafted onto the starch main chain to prepare multigraft starch with good flexibility,good film-formation and easy to adjust.This paper is mainly divided into three parts:(1)The copolymerization of acrylic acid and methyl acrylate was performed under HRP enzyme catalysis.The feasibility and copolymerization law of acrylic acid and methyl acrylate under HRP enzyme catalysis system were discussed.The copolymer was characterized by FTIR and ~1H NMR,and the composition of the copolymer was obtained.The thermal properties and microstructure of the product were characterized by DTG and Py-GC/MS and the type of polymerization was verified.The results show that HRP can catalyze the copolymerization of acrylic acid with methyl acrylate.The calculated results of fineman-ross and kelen-tudos show that the competitive polymerization rates of acrylic and methyl acrylate are 0.485 and 0.215 respectively.It is shown that the monomer AA is more prone to self-polymerization than MA and the copolymerization mode of AA and MA tends to alternate copolymerization.Therefore,when AA feeding is relatively small,AA feeding example is always less than the proportion of AA in the product,and vice versa.(2)Based on the above research,HRP enzyme catalyzed starch grafting acrylic acid/methyl acrylate was studied.Molecular structure and thermal properties of starch grafted acrylic acid/methyl acrylate were characterized by FTIR,~1H NMR,GPC,TG,DSC and Py-GC/MS.The results showed that both monomers were grafted onto starch molecules in the form of small molecules,and the structure of the branched chain was similar to that of the copolymerization between two monomers.After grafting,binary grafted starch still has good thermal stability,and the introduction of acrylic acid and methyl acrylate destroys the compact structure between starch molecules,resulting in loose structure of starch molecules,reducing the tendency of starch crystallization.(3)In order to explore the binary graft starch slurry performance,process optimization concludes:HRP enzyme concentration=12 U/mL,T=40?,pH=7.0,t=4h,monomer ratio=4:6,the weight ratio of AA/MA=3:7,grafting rate was 39.16%,the grafting efficiency was30.26%.When the total grafting rate is too high,low to the dosing raio of acrylic products will hard to paste.Therefore,the effects of different acrylic acid feeding ratios on the properties of starch slurry were studied by controlling the preparation process parameters and when the total grafting rate was 10%.The results showed that with the increase of acrylic acid feed ratio,the viscosity and viscoelasticity of the slurry improved,and the hydrophilicity also improved.The adhesion of grafted starch slurry to pure cotton and poly-cotton roving was improved.In this paper,the polymerization reaction of two vinyl monomers AA/MA under the condition of environmentally friendly HRP enzyme as initiator was studied for the first time and the competitive rate of the two monomers was analyzed.The rule of two monomers polymerization was analyzed.It provides a new idea for HRP enzymatic polymerization of vinyl monomers.It is of great significance to improve the structure and properties of the enzymatic vinyl polymerization molecules and to improve the environmental synthesis of vinyl polymers.On this basis,two monomers were synthesized by HRP enzyme.The graft starch was prepared by polymerization,precipitation and extraction.It provides a new idea for multicomponent grafting of starch,which is of certain significance in improving the properties of starch and improving the application of starch in textile industry.