THERMAL-STRESSES, RELAXATION, AND HYSTERESIS IN GLASS

The theory of A. R. Cooper, Jr., and other viscoelastic theories of th ermal stresses in glass are reviewed. The role of structural relaxatio n in the evolution of the free strain and stress relaxation times is e xamined. An explanation of the hysteresis loop observed on thermal con traction/expansion curves in the glass transition region is offered. S ingle-exponential models are reviewed on the merit of the insight they provide into the physics of stress development. Their numerical perfo rmance is compared with that of the more comprehensive theories.