Preparation and performance of a lignosulfonate-AMPS-itaconic acid graft copolymer as retarder for modified phosphoaluminate cement

In this article, a new type of graft copolymer retarder as modified phosphoaluminate cement (MPC) has been discussed. Graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and itaconic acid (IA) onto sodium lignosulfonate (LS) was performed using potassium persulfate as an initiator by free radical aqueous solution copolymerization. The optimal LS/AMPS/IA copolymer (OLSAI) was obtained under the optimum reaction conditions: mass ratio of LS/(AMPS + IA) = 1:1, temperature = 60 °C, mole ratio of AMPS/IA = 9:1, initiator concentration = 1%, pH value = 5. The synthesized copolymer OLSAI was characterized by FTIR analysis. The experimental results demonstrate that the OLSAI has excellent retarding ability, dispersing power, thermal-resistant and pressure-tolerant properties, and little negative impact on the compressive strength of MPC. The graft copolymer OLSAI is expected to be an excellent retarder for MPC.