ABSTRACT
Diverse, nonlinear thermo-mechanical behavior has been observed experimentally for polymeric glasses (see Chapter 4), where a number of constitutive models have been proposed to describe various aspects of these experiments. Although there have been numerous papers comparing the predictions of a specific constitutive model with experimental data, these studies have primarily focused on the prediction of just that constitutive model for a relatively limited set of data. Moreover, there has not been a definitive review where the predictions from different constitutive models have been critically compared to the same data set in order to determine which components of a constitutive model are needed to predict a given class of experiments. To the extent that a constitutive model is a precise statement of a hypothesis concerning the physical processes that give rise to the behavior, the paucity of comprehensive analyses of the predictions of various constitutive models is an indicator of the lack of a generally agreed-upon understanding of the processes that control the deformation of glasses. The objective of this chapter is to begin a critical and comprehensive analysis of the collection of constitutive models that have been proposed to describe aspects of the thermomechanical behavior of polymeric glasses. We anticipate that this type of analysis will provide a more solid foundation for future analyses, creating a better point of departure for an improved understanding of the glassy state.
