The effect of concentration and temperature on gelation time

Abstract

An empirical equation of the form t=ac^{- Q/RT} has been presented which represents the variation of the setting time (t) of a gel with both concentration (c) and temperature (T). This functions as a modified type of Arrhenius' equation at constant concentration, and expresses the kinetics of gelation at constant temperature. Plots of log t vs. (log c)/T yield a straight line, suggesting that reaction order varies with temperature, and activation energy with concentration. The condition of equal setting time, achieved with increasing concentrations at elevated temperatures, is possibly the point of balance between (a) the concentration of primary colloidal particles, and (b) the extent of secondary aggregation, the latter factor being dominant at low concentrations and temperatures, and the former at higher ones.