Gelation of methylcellulose hydrogels under isothermal conditions

The current work deals with the gelation of methylcellulose (MC) in aqueous solutions under isothermal conditions. The isothermal gelation was monitored during two consecutive heating and cooling cycles. The gelation was observed to occur early during the second cycle and progress at a higher rate. Micelle-like structures were found to form in MC solutions during the first gelation cycle. These were largely responsible for the accelerated gelation during the second heating cycle. The influence from the state of water was examined by studying the gelation phenomenon for MC using either cold or hot DI water as solvent. The possible mechanism involved is discussed. A gel indexing method was established to provide a quantitative measure for the state of gelation achievable using different MC concentrations with either cold or hot water solvent. Stabilization kinetics for the gel under isothermal conditions was described using the Malkin and Kulichikhin model. The kinetics parameters were determined. (c) 2007 Wiley Periodicals, Inc.