A new model of glass transition phenomenon
- Scientific Technologies, Inc., Glen Allen, VA (United States)
Many polymers and a variety of other materials when cooled from the molten state fail to crystallize and settle in an amorphous phase, commonly referred to as the glassy state. The material in the glassy phase is believed to be in thermodynamic nonequilibrium condition. The laws governing the formation and characteristics of the state are not established yet. However, the optimization of uses and the development of these materials require a quantitative model of the glass transition process. Considering the complexities and importance of the problem, we have taken a pragmatic approach to develop a phenomenological model of glass transition process. The model is based on postulates of generally observed temperature dependent viscoelastic behavior of polymers. We also argue that all isofrequency responses would converge at a temperature, designated as the second-order thermodynamic glass transition temperature. Our model is consistent with the second order transition in the sense of Ehrenfest and statistical mechanics model of Gibbs and DiMargio. Also, it includes generally observed nonlinear and asymmetric kinetics and is consistent with non-equilibrium thermodynamics. The model suggests that it is practically impossible to measure the second transition temperature and that the observed behavior is kinetic. Our model combines the underlying fundamental thermodynamic process with the generally observed kinetic behavior. The formulation of the model is simple. It has potential for many engineering applications. It provides a constitutive equation for thermoviscoelastic materials.
- OSTI ID:
- 175149
- Report Number(s):
- CONF-950686-; TRN: 95:006111-0060
- Resource Relation:
- Conference: Joint applied mechanics and materials summer meeting, Los Angeles, CA (United States), 28-30 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of AMD - MD `95: Summer conference; PB: 520 p.
- Country of Publication:
- United States
- Language:
- English
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