Study On Water Absorbent Resin Prepared By Sisal Fiber Grafting With Acrylate And Acrylamide

Cellulose-based water absorbent resin was prepared by grafting acrylate and acrylamide on sisal fiber, which was initiated by Na2S2O3 and persulfates. The effect of pretreatment of sisal fiber, adding order and quantity of persulfates, concentration of Na2S2O3 , monomers and reaction temperature on water absorbent resin was studied. The effect of initiator, ratio of monomers and concentration of cross-linking agent on quantity and rate of water adsorption, water-keeping property and repeat water adsorption property of the product was also studied. The structure of product was characterized by FTIR, TG and DSC.High graft ratio is due to pretreatment of sisal fiber by NaOH solution and steam explosion and low graft ratio is due to pretreatment of sisal fiber by suds and ammonia solution compared with pretreatment of sisal fiber by mixed acids. Cooperation function is appeared when (NH4)2S2O8 and K2S2O8 solution in turn are used for initiator graftiung on cellulose which had been dunked in Na2S2O3 solution. The function is best at condition that two persulfates volume ratio is 1/1. The optimum condition of preparation of water absorbent resin is listed as follow: reaction temperature is 45 °C; the weight of sisal fiber is 0.5g; the concentration of Na2S2O3 solution is 0.5mol/L; the volumes of (NH4)2S2O8 and K2S2O8 solution are 2.5mL³.5mL; monomer concentration is 2mol/L².5mol/L and the quantity of cross-linking agent is 1.25-2.5 X 10^-4mol. The water or salt solution absorption is connected with quantity of cross-linking agent, acrylamide and the quantity and degree of neutralization of crylic acid, except for quantity of initiators. The ability of pure water or salt solution adsorption is effected by quantity of cross-linking agent, acrylamide and crylic acid, degree of neutralization of crylic acid on; but the effect of the quantity of initiator is weak. The max water adsorption ratio is 530g/g and the max salt-solution absorption ratio is 58g/g; the rate of water absorption is 8g/min. The keeping-water property and thermal stability of resin are favorable. FTIR shows the water absorbent resin is graft copolymer of cellulose and polyacrylate. TG and DSC show the resin's stability is better than cellulose's and the hydrogel has good keeping-water property, in which the most water was nature water.