| The history of absorbent resin has been stated, and its varieties, developments of techniques have been traced back, and the situation of research in starch absorbent resin has been analyzed in the beginning of this paper. For the situation of our nation and Yunnan Province, the research of absorbent resin through grafting copolymerization of potato starch with acrylic acid for purpose has been put forward. The results of research are expected to heighten producing technology and level of products of potato starch, on the other hand, to perfect related theoretical research.For one thing, the optimum pasting condition of potato starch has been studied and selected for the reaction system. Then the redox initiator has been studied and selected with potentiating agent, which can be initiated reaction preferably in normal temperature. The main components are potassium persulfate and sodium sulfite. The constituent conditions are as follows: mass ratio of potassium persulfate to sodium sulfite to potentiating agent is 10:2:0.01, initiated temperature is 45.0～60.0℃and the grafting time is 3.0～3.5 h.This paper has been studied grafting copolymerization of potato starch with acrylic acid through orthogonal experiment. For the pertinences, the optimum process parameters in the laboratory have been obtained:1) The concrete processing parameters for maximal water-absorption in distilled water are as follows: the amounts of initiator, cross-linking agent are 0.75%, 0.25%, respectively, based on the amount of monomers. The neutralization degree of acrylic acid is 85%. The mass ratio of potato starch to acrylic acid is 1:4.5(g/g). Temperature of grafting and cross-linking are 60.0℃, 120.0℃, respectively. Cross-linking time is 3.0 h.2) The concrete processing parameters for maximal water-absorbing rate in 5.0% NaCl water solution are as follows: the amounts of initiator, cross-linking agent are 0.75%, 0.25%, respectively, based on the amount of monomers. The neutralization degree of acrylic acid is 85%. The mass ratio of potato starch to acrylic acid is l:4.5(g/g). Temperature of grafting and cross-linking are 60.0℃, 120.0℃, respectively. Cross-linking time is 3.0 h. 3) The concrete processing parameters for maximal water-absorbing rate with time in distilled water are as follows: the amounts of initiator, cross-linking agent are 1.25%, 0.40%, respectively, based on the amount of monomers. The neutralization degree of acrylic acid is 70%. The mass ratio of potato starch to acrylic acid is l:4.5(g/g). Temperature of grafting and cross-linking are 55.0℃, 120.0℃, respectively. Cross-linking time is 2.5 h.4) The concrete processing parameters for maximal water-absorbing rate with time in 5.0% NaCl water solution are as follows: the amounts of initiator, cross-linking agent are 0.75%, 0.35%, respectively, based on the amount of monomers. The neutralization degree of acrylic acid is 75%. The mass ratio of potato starch to acrylic acid is 1:3.5(g/g). Temperature of grafting and cross-linking are 50.0℃, 130.0℃, respectively. Cross-linking time is 4.0 h.5) The concrete processing parameters for maximal intensity of absorbent resin are as follows: the amounts of initiator, cross-linking agent are 1.25%, 0.35%, respectively, based on the amount of monomers. The neutralization degree of acrylic acid is 70%. The mass ratio of potato starch to acrylic acid is 1:4.0(g/g). Temperature of grafting and cross-linking are 55.0℃, 120.0℃, respectively. Cross-linking time is 3.0 h.The thermal analysis and SEM have been used to characterize the grafting copolymer in the laboratory. Thermal analysis of samples has indicated that the products have been well thermostable. In addition to the free water and the bound water, there are also part of link water with molecular chain. The morphologies and structures of samples were characterized by SEM. The results have been showed that the grafting product has been prepared preferably by grafting acrylic acid onto potato starch. The framework of main branched chain makes the structure molecular chain have definite rigidity and brittleness. The network structures of the products are also well-proportioned, which are in favor of good absorbability and discharging water characters in different aspects.This paper has been speculated on above grafting copolymerization for possible applications. |
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