Transformation of Liquid to Amorphous Solid: The Time to Vitrify for Styrene Polymerization

摘要

A model is presented for the calculation of the time to vitrify versus 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 versus time the vitrification curve is S-shaped; the time passes through a maximum just above the the glass transition temperature of the unreacted monomer and passes through a minimum just below the maximum 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 reaction. In this communication the model is applied to the bulk polymerization of styrene by the free radical mechanism. (Author)