Study On Preparation And Surface Crosslinking Of Super Absorbent Polymer

Super absorbent polymer (SAP) was synthesized by aqueous solution polymerization,with acrylic acid (AA) as main raw material. Some factors influencing the performance ofSAP was investigated. SAP couldn’t be directly used because SAP was so easily agglomeratethat the hydrogel could not absorb more water. So SAP was post-processed and the influenceof some factors was studied. DMP-30was added into the surface crosslinking agents todecrease the surface crosslinking temperature for the purpose of lower residual monomer.Neutralization heat were made full use of and the redox initiator was added under hightemperature to reduce the polymerization time and improve the production efficiency. Theoptimal polymerization conditions were obtained by a large amount of research. Theneutralization degree of AA was80%, the monomer concentration was30%, the crosslinkingagent concentration was0.03%, the initiator concentration was0.2%and the polymerizationtemperature was70℃. The water and saline absorbency first increased then decreased withthe influence of above factors. The largest amount of water and saline absorbency were1053g/g and90.3g/g. SAP was further investigated by Fourier Transform Infrared (FTIR),Thermal Gravimetry Analysis (TG) and Scanning Electron Microscopy (SEM). The resultsshowed sodium polyacrylate SAP was made successfully, which had good thermostability,strong gel strength and high water retention property.The production process were simplified by combining the crushing process andpost-processing technology. The factors influencing the performance of SAP were discussed,such as aluminum sulfate dosage, glycerol dosage, ethylene glycol diglycidyl ether dosage,concentration of crosslinking agents, surface crosslinking temperature and so on. The resultsshowed absorbent under load (AUL) was improved and SAP had better dispersancy. Thehighest AUL was33g/g and the residual monomer was reduced from1889mg/kg to431mg/kgby adding DMP-30. FTIR and TG demonstrated SAP was post-processed sucussfully and hadbetter thermostability while SEM indicated that post-process could increase the surfaceroughness of SAP to solve the problem of congestion.