Study On The Effect Of Inorganic Materials On The Absorbability Of Polyacrylic Acid Sodium

Polyacrylic acid sodium?PAA-Na?as a superabsorbent polymer shows special water absorption function,which has a three-dimensional network structure with a suitable degree of crosslinking.It can be widely applied in different fields,such as agriculture,health care,health products.Inorganic-organic composite superabsorbent polymers display excellent properties,such as higher absorbency,absorption rate,salt tolerance,thermal stability and so on.Carbon nanotubes?CNTs?and SiO₂ as inorganic materials are always used to synthesize inorganic-organic composites because of large surface areas and functional groups at the surfaces.In the present study,CNTs and SiO₂/PAA-Na composites were synthesized.Effects of experimental conditions on absorbency of the composites were investigated.The contents of the present study are listed as the following:1.CNTs/PAA-Na superabsorbent composites were synthesized by free-radical polymerization in aqueous solution in the absence of nitrogen protection condition by using AA and CNTs as raw materials,where ammonium persulfate?APS?was used as an initiator,N,N'-methylene-bis-acrylamide?MBA?as a crosslinker.Effects of the amount of CNTs,initiator,crosslinker and the reaction temperature on water absorbency were studied.The results show that the synthetic resin display the best water absorbency when the mass ratio of the crosslinker to AA is 0.04 wt%,the initiator to AA is 0.3 wt%,the CNTs to AA is 0.3 wt%,and the reaction temperature is 75?.The water absorbency of the CNTs/PAA-Na reached the highest as 1423 g/g and 104g/g in distilled water and in saline water,respectively,which were 1.5-fold compared with PAA-Na resin.2.SiO₂/PAA-Na superabsorbent composites were synthesized,where vinyl triethoxysilane was used for the surface modification of silica in order to improve the interface compatibility between silica and sodium polyacrylic acid.The SiO₂/PAA-Na were synthesized by the method as described before.Effects of factors on the absorbing abilities of the absorbent resins were investigated.After the addition of SiO₂,the SiO₂/PAA-Na shows rough surface and porous structure,which may enhance water absorbency.The water absorption rate is superior to CNTs/PAA-Na.The water absorbency of the SiO₂/PAA-Na reached the highest as 1224g/g and 83g/g in distilled water and in saline water,respectivel.3.A highly water-absorptive resin was prepared by a sol-gel aqueous method,SS/PAA-Na superabsorbent was prepared by sol-gel method using acrylic acid as monomer and tetraethyl orthosilicate?TEOS?as precursor.Effects of the ratio of raw materials on the water absorption and saline absorption were studied.The results show that the water absorption is higher than that of the SiO₂/PAA-Na and the water absorbency of the SS/PAA-Na reached the highest as 1389 g/g and 95 g/g in distilled water and in saline water,respectively.