Studies On The Sizing Agent Of Starch Alkenylsuccinate Graft Copolymer

In order to enhance the graft efficiency and obtain high-performance of grafted starch used as warp sizing agents, through esterification of starch with alkenyl succinic anhydride (ASA), an attempt had been made before the graft copolymerization between starch and vinyl monomers. And then preparing starch alkenylsuccinates graft PAA (SAS-g-PAA) by graft copolymerization reactions between starch and acrylic acid which were carried out in aqueous dispersion. Furthermore, the esterification effects of starch with ASA on the graft efficiency of starch graft copolymerization, and behaviors of SAS-g-PAA were also studied. The studied esterifying agents included maleic anhydride, octenylsuccinic anhydride, dodenendylsuccinic anhydride. In addition, the degree of substitution(DS) of starch alkenylsuccinates was adjusted through varying the feeding ratio of esterifying agent to starch. The intrinsic relation between the DS value of starch alkenylsuccinates and the graft efficiency and behaviors of grafted starch sizing agents was researched, and simultaneously investigated influence of ASA carbon chain length on the graft efficiency and behaviors of grafted starch sizing agents.The experimental results indicated that, not only does ASA esterification pretreatment of starch enhance the graft efficiency, but also it improves the serviceability of grafted starch sizing agents. Therefore, ASA esterification pretreatment of starch has a great meaning in the development and research of high-performance grafted starch sizing agent. Trough maleic anhydride pretreatment before the graft copolymerization, the graft efficiency and behaviors of grafted starch sizing agents both could be enhanced, and it is the most favourable way. When the degree of substitution(DS) of starch maleate half ester(SMHE) was in a range of 0.01 to 0.08, this esterification pretreatment can enhance the graft efficiency of starch maleate half ester graft acrylic acid(SMHE-g-PAA) by about 10%～30%. The adhesion to fibers and film behaviors of SMHE-g-PAA were also remarkably improved. The experiments proved that proper DS value of SMHE-g-PAA was in the range of 0.0136 to 0.0206. The influences of the ASA carbon-chain length on graft efficiency and mechanical properties of SAS-g-PAA sizing agents are evident. With the decrease of the carbon-chain length, the graft efficiency between starch and AA increases, and mechanical behaviors of SAS-g-PAA sizing agents enhances.The paper also studied the influence of reaction variables on graft copolymerization between SMHE and acrylamide(AM). The effects of pH value of the polymerization system, molar ratio of H2O2 to Fe2+, concentration of initiator, concentration of AM monomer, polymerization temperature and time on the graft copolymerization between SMHE and AM were examined. The experimental result demonstrated that the variables considered showed above has an evident effect on the graft efficiency and graft ratio, and will little affect the monomer conversion of the graft polymerization. For the polymerization, a condition of pH value3～4, 20:1:1000 for the molar ratio of H2O2/Fe(NH4)2(SO4)2/anhydroglucose, concentration of Fe2+ is 2mmol/L, 1:10 for the mass ratios of AM to SMHE, and at 45℃ under 3h reaction is sufficient to get the graft ratio and graft efficiency of graft copolymerization reach 6.3% and 65.6%, and retain the monomer conversion above 95%.