Research Of Synthesis And Characteristics Of Polyacrylonitrile/Montmorillonite Superabsorbent Composite Polymer

In order to improve the disadvantage of superabsorbent polymer, for example, high costand low salt resistance, the aim of this paper is to synthesize a kind of superabsorbentcomposite polymer based on waste polyacrylonitrile. The influence of addition ofmontmorillonite on characteristics of superabsorbent composite polymer has been discussed.Through the analysis of XRD, the synthesis mechanism of polyacrylonitrile/montmorillonitesuperabsorbent composite polymer has been investigated.In the experiment, alkaline hydrolysis of waste polyacrylonitrile is used. The factors, suchas reaction time, ratio of the reactants, are investigated to make sure the effect on thehydrolysis of each factor. The experimental results show that the longer the time the better thehydrolysis reaction within the bounds. The degree of hydrolysis of waste polyacrylonitrile canbe controlled by changing the dosage ratio of waste polyacrylonitrile, alkali and water.Three kinds of cross-link agents, potassium chloride, aluminium chloride, and N,N-methylene-bis-acrylamide have been chosen. The polymer after synthesis is of no absorbencyusing N,N-methylene-bis-acrylamide as cross-link agent. With aluminium chloride being thecross-link agent, the superabsorbent polymer has better salt resistance and gel strengthcompared with the other cross-link agents.Using aluminium chloride as the cross-link agent, it has planned to test four kinds ofmontmorillonite which are purified montmorillonite, Na-modified montmorillonite, organicmodified montmorillonite, and pillared montmorllonite. In the same conditions of theexperiment, the effects of montmorillonite addition on characteristics of superabsorbentcomposite polymer have been discussed. The results show that addition of pillaredmontmorillonite has made the superabsorbent composite polymer more resistant to saltcompared with the other kinds of montmorillonite.Subsequently, it is ascertained that the synthesis of superabsorbent composite polymer issynthesized in the condition in which the polymer has the best absorbent characteristics aftersynthesis. The conditions are that dosage of pillared montmorillonite is 6ï¼…, cross-link agent isaluminium chloride whose concentration is 10ï¼…and dosage is 2.5mL, and the synthesis can be accomplished in room temperature. It has concluded that polyhydroxy-Al cations in themontmorillonite layers which is the pillaring agent of montmorillonite have functioned as thecross-link agent in the composite polymer, and the composite polymer has had better saltresistance but worse absorbent rate because of the addition of pillared montmorillonite.Lastly, on the grounds of XRD analysis, the synthesis mechanism of superabsorbentcomposite polymer has been investigated: polyhydroxy-Al cations in the montmorillonitelayers not only have pillared montmorillonite but also have functioned as the cross-link agentin the composite polymer; with the aluminium chloride slowly added in the reaction system,Al ions have cross-linked with hydrolyzed polyacrylonitrile and the huge three-dimensionalnet structure after cross-linking has caused the montmorillonite layers extended to a little largeextent, after which the montmorillonite layers just mix in the composite polymer.