THE RELATIONSHIPS BETWEEN POLYMERS AND GLASS TRANSITION TEMPERATURES
Abstract
The glass transition is an experimental manifestation of the extremely large activation energies for molecular motion encountered as the temperature of a liquid is lowered. As an approach to the effect of molecular structure on this phenomenon, low-shear melt viscosities were obtained as a function of temperature for three homologous series of polymers: polypropylene, poly(chlorotrifluorethylene) and poly(propylene oxide). A kinetic model of the glass transition was devised for computer simulation of dilatometric behavior in the region of a transition. The assumption that the dielectric and volume relaxation times are equal was shown to be satisfactory for prediction of dilatometric results on polymers. The effects of rate of heating, activation energy and coefficients of expansion on the measurement of transitions were demonstrated. The Gibbs-DiMarzio theory of the glass transition was cast in a form suitable for very short chains and shown to agree quantitatively with To values for the lower n-alkanes. The Eyring transition state theory of relaxation processes was shown to be applicable to dielectric relaxation in polymers with modification to allow for a temperature-dependent activation free energy.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1966
- Accession Number
- AD0649869
Entities
People
- L. V. Gallacher
- O. G. Lewis