Prediction of the glass transition temperature of polymers: A model based on the principle of corresponding states

Abstract

SynopsisThe application of corresponding state principles to describe the properties of polymers is implicit in many of the fundamental studies of polymeric behavior. The seminal works of Prigogine, Hildebrand, Eyring, Flory, Gibhs, and DiMarzio in which multidimensional lattice representations and refined statistical mechanical approaches have been used are the basis for much of today's understanding of the thermodynamic behavior of polymers and their solutions. In this work the lattice energy of a polymer is defined in terms of reduced molecular parameters, and it is assumed that all polymers with the same functional form for their lattice energies will be in corresponding states. A reduced second order transition temperature is defined relative to a characteristic temperature T' = s~*/Zko*c, where the molecular parameters refer to the properties of the repeating segments of the polymer chain. Equations are derived that express the effects of molecular weight, plasticization, degree of crosslinking, and copolymerimtion on the second order (i.e., glass) transition temperature. In their limits, the equations are shown to reduce in form to equations derivable from free volume theory. They are also used to analyze succttssfully a variety of glass transition temperature data available in the Literature on homogeneous uncrosslinked and crosslinked polymers, plasticized polymers, and random copolymers.

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

“…The infinit T g (i.e., the T g for α = 1) is about 115 • C for DGEBA/EDA, 63 • C for DGEBA/MEDA, and 0 • C for DGEBA/n-BuA. Good fi to the classical DiBenedetto equation [11] were achieved for the firs one. T g on DGEBA/n-BuA is almost invariable because there is no cross-linking on the system.…”

Vitrification during the Isothermal Cure of Thermosets: Comparison of Theoretical Simulations with Temperature‐Modulated DSC and Dielectric Analysis

“…As the reaction proceeds, the glass transition temperature increases from its initial value, T g0 , being that of the mixture of monomers of resin and cross-linking agent, and, in the absence of vitrification, will reach a limiting value, T g∞ , corresponding to the fully cured system (α=1). The relationship between the degree of cure and the glass transition temperature of the curing system can be described by the DiBenedetto equation: [16,20] T T (6) where λ is a fit parameter related to the ratio of heat capacities of the fully cured and uncured system. The effect of λ is also investigated in these simulations.…”

The Use of Matlab in the Study of the Glass Transition and Vitrification in Polymers

“…In the simulation of cure with vitrification, therefore, there are two important aspects to consider: first, the dependence of the glass transition temperature of the curing system on the degree of cure, and second, the expression for the diffusion rate constant, and its dependence on temperature. The relationship between the degree of cure, α, and the glass transition temperature, T g , of the curing system can be described by the DiBenedetto equation (DiBenedetto, 1987;Pascault & Williams, 1990):…”