Study On The Synthesis And Properties Of Superabsorbent Based On KGM

Superabsorbent polymers(SAPs)belong to a kind of hydrophilic polymers with the chain crosslinked lightly.They can absorb and retain a mass of fluids ranging from hundreds to thousands of times of the mass of themselves,and the absorbed water could hardly remove even under a certain pressure.Because of their excellent water absorbency and retention capacity,SAPs have been applied in various fields such as medicine,personal hygiene,and agriculture.Comparing with the synthetic polymers,natural polymers have less toxicity,lower cost and better biodegradability,therefore,extensive attention has been directed toward novel SAPs with many advantages like low toxicity,excellent water absorption and retention,good biodegradatability.Konjac glucomannan(KGM)is a very important natural polymer possessing excellent biocompatibility and biodegradable activities.Moreover,the KGM chain has abundant hydroxyl groups and acetyl groups,which can be benefit to chemical modification.In order to make full use of the rich konjac resources of the western area,broaden the research range for KGM and further improve the extra value of the products,plenty of investigations on the preparation and characteristics of Konjac superabsorbent are listed as follows:(1)The semi-interpenetrating polymer networks of KGM-g-AA-AM/PVP with good water absorbency,salt absorbency,water retention and gel strength were synthesized in an aqueous solution via grafting and crosslinking reactions by using N,N'-methylene-bis-acrylamide(MBA)as crosslinker agent and potassium peroxydisulfate(KPS)as initiator in the presence of polyvinylpyrrolidone(PVP).The structures and surface morphologies of KGM-g-AA-AM/PVP were characterized by infrared spectrum(IR),scanning electron microscope(SEM)and X-ray diffraction(XRD).It is found that the distilled water absorption rate of KGM-g-AA-AM/PVP was up to 1124g/g,and the salt water absorption rate of the polymer was up to 102g/g under the optimized reaction conditions.The superabsorbents showed good water retention property at different temperatures.In addition,the superabsorbents also possess excellent repeated water absorbency,which means it can be recycled for many times,thus it may have a good practical value.(2)The anionic surfactant,sodium dodecyl sulfonate(SDS),is chosen as a foam agent used in preparing porous superabsorbent resins of KGM-g-PAA,which is obtained by free-radical polymerization accompanying with mechanical agitation.This SAP was obtained by adopting solution polymerization,which is very simple and easy to operate.The mechanism for the polymerization was proposed after charactering the cheimical structures of KGM and KGM-g-PAA by IR.Observing the SEM pictures of KGM-g-PAA powder and its freezing dried gel,it is demonstrated that the morphologies of the SDS added sample displays homogeneous and well defined porous structures.With the increase of the amount of SDS,the bulk density of the porous structure formed by the KGM-PAA absorbent gradually decreases from 0.85 g/ml to 0.64 g/ml,the water absorbtion improves from 750 g/g to 985 g/g.The superporous SAP containing suitable loading of SDS not only has higher equilibrium swelling ratio,rapid swelling rate,and also shows stimulus responses to salts and pH,which may allow its applications in several areas such as adsorption,hygiene and biomedical materials.