| Super absorbent resins (SAR) are lightly crosslinking hydrophilic polymers that can absorb and retain aqueous solutions up to hundreds of times their own weight. In this paper, a graft copolymer was synthesized by copolymerization of acrylic acid (AA) onto cassava starch, with N,N'-methylene diacrylamide as cosslinking agent, potassium persulfate potassium permanganate and hydrogen peroxide-sodium sulfite as an initiator. The effects of the amount of crosslinking agent, monomer, initiator, the reaction temperature, neutralization degree of acrylic acid, the mass ratio of AA/starch and concentration of starch emulsion were studied. The grafting copolymerization was analysed by FT-IR, XRD and TG.-DSC.Three initiation systems, potassium permanganate, potassium persulfate and hydrogen peroxide-sodium sulfite were used to initiate the graft polymerization of acrylic acid (AA) onto cassava starch. The initiating effects were investigated, and the results showed that the potassium permanganate was the best initiator for this reaction. Initiating with potassium permanganate, the influences of the amount of crosslinking agent, monomer, initiator, the reaction temperature, neutralization degree of acrylic acid, the ratio of AA/starch and concentration of starch emulsion were studied. Such a condition was optimized, as concentration of starch emulsion 1.11%, mass ratio of monomer to starch 10:1, 9.0mmol·L-1 crosslinking agent and 6.3mmol·L-1 initiator, 50% neutralization degree of acrylic acid and reaction tmperature 50℃respectively. Under the condition, graft polymerizations of acrylic acid (AA) with cassava starch were done. The absorption rate of the resin was up to 1600 g/g in distilled water, 380 g/g in tap water. The surface sturcture and heat property were analyzed by IR, SEM, TG-DSC, etc. The analysis of IR showed that the synthesized product had carbonyl's character, which proved graft polymerizations of acrylic acid (AA) with cassava starch. TG-DSC analysis indicated that the products had good thermostability. X-RAY showed that the surface structure of starch became amorphous from semi-crystalline. SEM analysis showed that the surface of starch was destroyed by acrylic acid (AA).In the last paper, the evaluations of some influential factors such as retention ability, absorption rate, recovery ability, stability and anti-saltability are researched, and some important conclusions were drawn:(1) The results had shown that the SAR had water retention ability and a satisfied stability.(2) The absorption rate of SAR in distilled water was fast and achieved saturating in the first 150 min respectively.(3) The SAR in electrolyte solution declined with the increase of metal cationic charge and the concentration of solution.(4) The SAR nearly had no absorbency in pure organic solvents, but it had one in the mixture of organic solvents(o) and water(w) with a special volume ratio Vo:Vw and appeared a critical point in specific mixture of organic solvents(o) and water(w) with a special volume ratio Vo:Vw.(5) The results had shown the SAR had outstanding recovery properties.(6) The effect of temperature on the absorbency of SAR was weak, and the SAR was used in a large temperature range.(7) The SAR absorbed more in neutral solutions than in acidic or alkli solutions.
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