Transformation of liquid to amorphous solid: The time to vitrify for styrene polymerization
Abstract
A model is presented for the calculation of the time to vitrify vs. temperature for isothermal polymerization by the chain growth mechanism. The model is based on the glass transition temperature (Tg) rising from its initial value to the reaction temperature. The relationships between Tg and the volume fraction of polymer and monomer, the volume fraction of polymer and the extent of reaction, and the extent of reaction and time are also required. In a plot of temperature vs. time the vitrification curve is generally S-shaped; the time passes through a maximum just above the glass transition temperature. The model applies to linear polymerization in which monomer and high molecular weight polymer are the dominant species, i.e., to chain reactions. In this communication the model is applied to the bulk polymerization of styrene by the free radical mechanism.
