The influence of molecular weights on the calcium salts absorption of polyacrylic based materials

Abstract

Most of the industries use water as medium for heating, cooling and also washing of the equipment and facing problems caused by hard water which consist of carbonate and sulfate salts which remain on the walls of reactors and pipes. For this reason, different water softeners are used, with ability to absorb metallic ions and prevent agglomeration of salts on surfaces. Polymeric materials, especially polycarboxylates, can be used to prevent this problem. In this work the influence of molecular weight and molecular composition of poly(acrylic acid-co-maleic acid) carboxylate copolymer on the calcium salts absorption was investigated. Copolymers were prepared by radical polymerization in water-borne system using potassium persulfate as initiator and iron ions (Fe2+) as chain length regulator. Molecular structures of obtained polymers were analyzed by FTIR method, and confirmed copolymer structure of resulted polymers. Average molecular weights and degree of polydispersity were determined by GPC. From the results of molecular weights determination it can be concluded that increasing of Fe2+ content leads to decreasing of the molecular weights of copolymers. Presence of ordered structures was confirmed using X-ray diffraction method (XRD). Dispersing capacity results of obtained copolymers have showed that with decreasing of molecular weights of copolymers calcium carbonate dispersing capacity (CCDC) decreased.