Synthesis of reticular long-carbon-chain polysiloxane and its hydrophobic modification of phosphogypsum-based materials

Abstract

Phosphogypsum is a solid waste that is discharged in large quantities during the production of phosphoric acid. The hemihydrate phosphogypsum produced after dewatering has great potential for application in the field of construction materials; however, its poor water resistance and creep melting in a humid environment for a long period of time lead to a reduction in its mechanical properties, which greatly limits its large-scale industrial application in the field of functional building materials. In this study, long-carbon-chain/alkoxy polysiloxanes (PVD-L) were synthesized using a silica–hydrogen addition reaction, and reticulated long-carbon-chain polysiloxanes (PVD-C) were prepared via the catalytic reaction of organotin. The effects of the synthesis of the intermediate product PVD-L and the internal mixing of PVD-C on the physical properties, surface wettability, pore structure, and microstructure of the phosphogypsum-based materials were investigated. The results showed that the hydrophobically modified phosphogypsum-based material had a water absorption of 6.6%, a softening coefficient of 0.82, a contact angle of 112.9°, and a porosity of 37.86% when the PVD-C internal mixing was 1.5%.