Characterization For The Effect Of Plasma-Induced Graft Polymerization On Starch Grafted With Polyacrylic Acid

As the sizing for yarn, the starch graft polyacrylic acid holds the capabilities of abundance, low production costs and good biodegradability without the starch slurry viscosity instability, poor film quality and poor adhesion to hydrophobic fibers.The starch pretreated under cold plasma is subjected to graft acrylic acid (AAc) on the surface because of creating peroxy radical after plasma treatment. Then the starch-g-PAAc can be prepared by the solution of polymerization at high monomer concentration after the glow discharge plasma treatment. The influence of four technologic conditions of the plasma to the graft effect has been investigated as following: the discharge time, the discharge power, the gas pressure and the time of exposed in the air. These graft effect indicators were lower than them calculated in other graft copolymerization experiments. In orthogonal experiment, the decisive indicator was calculated by graft effect indicators weight added with the weight: graft ration 0.6, monomer conversion 0.3 and grafting efficiency 0.1. By range analysis, these significances of conditions from strong to weak were the time of exposed in the air, the discharge time, the discharge power and the gas pressure. Through direct analysis, results showed that the conditions of plasma was the best when the discharge time was 3min, the discharge power was 180w, the gas pressure was 50Pa, the time of exposed in the air was 10min. Under these conditions, the decisive indicator was 9.63% with 7.06% grafting ratio, 5.36% monomer conversion and 37.85% grafting efficiency.The factors have been discussed which impact the measurement and calculation of the graft ratio, because it is an essential indicator which describes the structure of graft copolymers of starch and influences the sizing effect. On the starch surface, adhesion homopolymers were distinctly showed through the analysis of IR and microscopic observation and influenced the calculated grafting ratio higher than the actual graft ratio. In addition, the adding NaOH solution for neutralization of the starch graft copolymer need overleap in the graft polymerization process.In the graft copolymerization experiment, the starch film as the specimen can calculate a more accurate weight of grafting copolymer because of the homopolymers on film surfaces easy to remove and accurately study the relationship between the plasma's technologic conditions and the graft mass unit area (g/m~2) because of the clear surface area of starch films.The starch films pretreated with cold plasma were used as the specimen in graft copolymerization experiment. The influence of four technologic conditions of the plasma mentioned above on the graft mass unit area (g/m~2) was investigated. With the increase in discharge power, the graft mass unit area (g/m~2 ) increased when the discharge time short and reduced after increase when the discharge time long. With the increased in gas pressure and discharge time, the graft mass unit area (g/m~2) changed from rise to drop. When discharge time and discharge power were high, the graft mass unit area (g/m~2) was high but the grafting ratio was low in the starch graft copolymer. The evidence of graft copolymer has been researched by means of IR. The graft was occurred on the surface of starch film through the testing result of SEM photograph. But, IR spectroscopy quantitative analysis has not been applied in the characterization for graft effect.Finally, in the experiment process, the specimen need be choice form and area and the calculation of the graft mass unit area (g/m~2) need choice the surface area base on the IR spectroscopy.By comparing the graft ratio of the grafted starch and the graft mass unit area (g/m~2) of the starch films, the results of graft effect were inconsistent when discharge time and discharge power were high. However, they were consistent in addition to the conditions mentioned above. So the relationship between the plasma's technologic conditions and the graft mass unit area (g/m~2) can be used for characterizing the influence of the plasma's technologic conditions to the graft ratio of the grafted starch.