Oxidative polymerisation of calcium ligninsulphonate
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
The study of the formation of ligninsulphonate gels of low concentrations and catalysed by ferric chloride was made with particular reference to their use as groutings for ground electrodes for the New Zealand Electricity Department. The physical, electrical and chemical properties of these gels were investigated and "optimal" gels of least cost mixtures, of satisfactory performance were formulated. Among other additives tested, copper chloride was selected as the best substitute for ferric chloride as a promoter to give better gels. A dimerisation-condensation mechanism as the primary mechanism for gelation of calcium ligninsulphonate is not supported by evidence collected here and an alternative, oxidative reaction for the polymerisation is established. Transition metal chlorides with favourable electron-transfer properties strongly catalyse the redox process and hydrogen ions released from hydrolysis of these salts contribute to the promotion of the gelation as an essential reagent. Attempts were made to utilise the understanding of the chemical properties process of gelation to help improve on the "optimal" gels.