Temperature dependence of the dynamic mechanical properties of filled polymers

TLDR: In this paper, a theory was developed to explain the jump in the relative modulus of filled polymers near the glass transition temperature Tg and the subsequent decrease in relative modulation at temperatures above Tg, based on the concept that there are some particle-particle contacts in doublets and in agglomerates containing a larger number of particles.

Abstract: A theory has been developed to explain the jump in the relative modulus of filled polymers near the glass transition temperature Tg and the subsequent decrease in relative modulus at temperatures above the glass transition temperature. The theory is based upon the concept that there are some particle–particle contacts in doublets and in agglomerates containing a larger number of particles. Below Tg motion of particles at the contact points is possible because of the high modulus of the polymer. At Tg particle–particle motion mostly ceases because of the low modulus of the polymer. At higher temperatures, the mismatch in the coefficients of expansion allows some motion to occur at points of contact and slippage may occur at the polymer–particle interfaces, so the modulus decreases. It is shown theoretically and experimentally that both the elastic modulus and the mechanical damping depend upon the nature of the surface of the particles.