A Physical Chemistry Lab for the Evaluation of Size-Dependent Polymer Properties

In this manuscript we present a Physical Chemistry Laboratory experiment designed to increase undergraduate chemistry majors’ exposure to polymers and the technique of thermal analysis. The lab involves characterizing the phase transitions and associated thermal properties for poly(vinyl alcohol) (PVOH). Students work in pairs to conduct the experiment using a differential scanning calorimeter and analyze the resulting thermogram to determine the melting point, enthalpy of fusion, and glass transition temperature for PVOH samples of varying molecular weight. Aggregate class data from several PVOH samples are used to determine the size dependence of each of these properties. Furthermore, the Flory–Fox equation is evaluated as a model for the size dependence of the glass transition temperature for PVOH. Given appropriate support, most students are successfully able to identify the melting point, enthalpy of fusion, and glass transition temperature of PVOH from the thermograms obtained. Additionally, almost all students are also able to correctly evaluate the size dependence of the thermal properties.