Gelation and fusion of vinyl plastisols

The gelation of vinyl plastisols at constant temperature has been found to follow the equation ln [(C − C_e)/(U − C_e)] = (− π²/a²)D_τ + ln (8/π²), where C is the resin phase concentration, C_e the equilibrium resin phase concentration, U the critical resin phase concentration, a the average particle size, D the diffusion constant, and τ the time required for the onsent of gelation. A light reflectance apparatus capable of measuring the gelation process is described. The effect that various resin–plasticizer parameters have on the gelation and fusion process is discussed. The light-reflectance apparatus is also useful for estimating various resin and formulating parameters.