Mold Filling - Gel Time Gel time Gel time is the time at which there is a sharp rise in the viscosity. This graph shows Gel Time for vinyl esters at isothermal condition. Gel time depends on the rate at which chemical reaction proceeds, which in turn depends on the mold wall temperature or the initial temperature of the resin mixture. At much lower conversions, the process can be treated as isothermal and gel times can be estimated for a range of wall temperatures. This graph shows Gel time for polyurethane systems at adiabatic condition.
Heat is generated at much faster rates than it can be conducted out through the mold walls.
Thus, the process can be treated as adiabatic. The adiabatic gel time can be calculated by integrating the kinetic equation up to the gel conversion under adiabatic conditions.