| Super absorbent polymers(SAP)are required to have high absorption capability under load(AUL) and the ability to quick absorbing body fluids when it’s used in personal hygiene products. In this paper, two types of super absorbent polymer was synthesized by aqueous solution polymerization. The first one of high absorption capability under load can be used for infant diapers hygiene, which also has very good absorbency and water retention capability. The second one can quickly absorbe body fluids and has excellent absorption capacity, which can be used in feminine hygiene products, adult incontinence products and sanitary napkins surgery. The main results were gained as follows:(1)The super absorbent polymers with interpenetrating network structure, which has high absorption capability under load, was synthesized by solution polymerization of partially neutralized acrylic acid, redox initial system, polyvinyl alcohol and polyethylene glycol using 2,2-Bis(methacryloyloxymethyl)butyl methacrylate as a crosslinking agent. The influences of some reaction conditions on absorption capability under load, absorbency and water retention capability were analysized. For improving the properties of super absorbent polymers, absorption capability under load was pressed as the first indicators, absorbency and water retention capability was pressed as the second index. The optimal conditions were as follows, acrylic acid monomer neutralization degree was 80%, the temperature of polymerization was 70℃,the amount of initiator, crosslinker of trimethylolpropane triacrylate, polyethylene glycol 2000 and polyvinyl alcohol BP-17 were 0.2%, 0.05%, 1% and 0.3%, and the amount of surface cross-linking solution was 7.5%. The absorption capability under load of SAP under optimum conditions was 40.2g/g, atmospheric absorbency and retention of water reached 78.6g/g and 48g/g. And the swelling SAP has good elasticity and dryness. Fourier Transform Infrared analysis(FTIR) showed that the polyvinyl alcohol and polyacrylic acid reacted to form a composite. X- ray diffraction pattern analysis(XRD) indicated polyvinyl alcohol and crosslinked PAA formed SAPwith semi-interpenetrating network structure. Thermal Gravimetry Analysis(TG)found the SAP has better thermal properties and surface crosslinking can increase the thermal stability of SAP. Scanning Electron Microscopy analysis(SEM) showed that the surface of pure polypropylene SAP and the SAP modified by polyvinyl alcohol was very smooth and roughness, and it also demonstrated that PVA and PAA has good compatibility.(2) A fast absorbing super absorbent polymer with porous structure was synthesized by solution polymerization of carboxymethylcellulose, porogen and redox initial system using N, N- methylene bisacrylamide( NMBA) as a crosslinking agent.To improve properties of SAP and find the optimum synthesis conditions, the rate of absorption was pressed as the first indicators, absorption capability under load and atmospheric absorbency were pressed as the second index. Optimal conditions were as follows, the amount of crosslinking agent of N, N’- methylene-bis-acrylamide was 0.03%, the amount of Tween 60, carboxymethyl cellulose(CMC) and porogen were 0.3%, 2% and 3%, and the temperature of polymerization was 40℃,the drying temperature of hydrogel was 110 ℃. The rate of absorption of SAP on optimum conditions was 15.2s, absorption capability under load and atmospheric absorbency reached 33.6g/g and 81.2g /g. FTIR showed that carboxymethylcellulose and polyacrylic acid reacted and produced composite polmer. TG indicated the fast absorbing super absorbent polymer has good thermal stability. SEM demonstrated the surface of this SAP was uneven and has some regular pore structure. |
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