Glass Transition
Paul C. Hiemenz, Timothy P. Lodge · Polymer Chemistry · 2007
Here we resume a sequence of three chapters that treat polymers in the solid state. In Chapter 10 we examined the formation of polymer networks and rubber elasticity. In Chapter 13 we will consider crystallinity in polymers and the associated crystallization transition from the high temperature, liquid state. In this chapter we take up the subject of the glass transition, whereby a polymer liquid is cooled in such a way as to solidify without adopting a crystalline packing. Among the three classes of polymer solid-network, crystal, and glass-the glassy state is the most universal; relatively few polymers are used to form networks; a significant fraction can never crystallize, but all can form glasses. Furthermore, all three topics are central to understanding the utility of polymer materials. In Chapter 9 and Chapter 11 we covered some properties of polymer liquids, especially those pertaining to flow. In almost all cases, polymers are synthesized, charac- terized, and processed in the liquid state, and consequently the material in Chapter 9 and Chapter 11 represents a foundation for many diverse areas of polymer science. However, most polymer applications rely on the properties in the solid state; consequently, Chapter 10, Chapter 12, and Chapter 13 provide the background for understanding how polymers are chosen or developed for one application or another.