Microwave Starch Grafting Acrylic Superabsorbent

Super Absorbent Polymer, as a new material, have good water absorption and retention, widely used in people's production and daily life.Microwave radiation is a new heating technology for synthetic SAP. Synthesis of SAP research under the conditions of the microwave has been reported, but the current research is still at an experimental stage. Because of the unique heating style, microwave heating can significantly shorten the process of synthesis time, which is an important means for production industrialization.Starch-acrylic acid graft super absorbent polymer is synthesis in solution polymerization process at traditional condition.The factors influencing the experiment are the types of starch, the amount of water, temperature and time in gelatinizing starch processes, the amount of monomer, degree of neutralization of monomer, initiator, the polymerization temperature, the polymerization reaction time.Using potato starch and potassium persulfate as initiator, the ideal reaction condition is(1) the amount of water, temperature and time in gelatinizing starch processes are 80 mL, 80℃ ,30min; (2) the amount of monomer is 16 mL(3) Degree of neutralization of monomer is 70%; (4) the amount of initiator is 7 mL; (5)the polymerization temperature is 75℃; (6) the polymerization reaction time is 2 hours; (7) the process of the reaction needs nitrogen.Starch-acrylic acid graft super absorbent polymer is synthesis in solution polymerization process at microwave radiation condition. The factors influencing the reaction such as microwave power, the amount of water in gelatinizing starch processes, degree of neutralization of monomer, the amount of monomer, initiator, the polymerization temperature, the polymerization reaction time have investigated. The optimum conditions are determined: the amount of water, in gelatinizing starch processes is 85 mL; microwave radiation power 800W; the amount of initiator is 7 mL; the amount of monomer is 16 mL; the polymerization temperature is 75 ℃; the polymerization reaction time is 25 minutes.L₂₅ (5⁶) orthogonal table is selected to arrange the experiments, the relative importance factors of the reaction is investigated: the amount of water in gelatinizing starch processes> reaction time>the amount of initiator> polymerization temperature> the amount of monomer> microwave radiation power.The synthetic product was observed and characterized. The products synthesizing at traditional condition and microwave condition are observed though Infrared spectroscopy, thermal analysis and Scanning electron microscopy. Infrared spectroscopy confirmed that the monomer can grafted to potato starch chains, the synthetic product is copolymer of starch and acrylic acid. It is also found that synthesizing at microwave condition has certain advantages. By TGA - DTA analysis, the product of weightlessness and thermal decomposition process are investigated, it showed that the product has good thermal stability. SEM pictures clearly shows that the surface of the copolymer morphology and structure characteristics.Comparing the traditional and microwave conditions, they have similar laws of the factors of the amount of water in gelatinizing starch processes, initiator, the amount of monomer, degree of neutralization of monomer, the polymerization temperature, the polymerization reaction time. And at the condition of microwave, energy is lower, reaction time is shortened, synthesis devices is simplified, and without the protection of gas. Product performance is also generally slightly higher than the traditional preparation. It shows that synthesis at microwave radiation condition has good research value and application potential.