Synthesis and characterization of a new super absorbent polymer (SAP) via the use of low-grade kaolin through inverse suspension polymerization

The water absorption of ionic SAP in cement-based materials is small. Therefore, this study synthesized a low-grade kaolin-enhanced SAP through inverse suspension polymerization, and its performances in deionized water, the saturated Ca(OH)2 solution and the supernatant of the cement slurry were investigated. The results indicate that the synthesized SAP revealed a spherical shape with a uniform particle size, showing well dispersion after water saturation. In addition, the use of low-grade kaolin could be beneficial concerning the absorbency of SAP especially using 7.5% low-grade kaolin, as reflected by the consistency results, but its absorbency is sensitive to water temperatures and environmental relative humidity. Besides, compounding inorganic materials into SAP can reduce the cost of SAP synthesis and provide cost efficiency. Finally, the growth of the acrylamide content could deteriorate the absorbency of SAP, but their final equilibrium absorbency could increase, and the absor-bency of the synthesized SAP were similar in the media of the saturated Ca(OH)2 solution and the supernatant of cement slurry.

Automated summary

This study synthesized a low-grade kaolin-enhanced SAP through inverse suspension polymerization and investigated its performances in deionized water, the saturated Ca(OH)2 solution, and the supernatant of the cement slurry. The synthesized SAP showed a spherical shape with uniform particle size and good dispersion after water saturation. The use of low-grade kaolin was found to enhance the absorbency of SAP, especially with 7.5% concentration, but its absorbency was sensitive to water temperatures and relative humidity. Compounding inorganic materials into SAP can reduce synthesis costs and improve cost efficiency. The absorbency of the synthesized SAP was similar in the saturated Ca(OH)2 solution and the supernatant of the cement slurry.