WHAT LARGE AMPLITUDE OSCILLATING SHEAR CHARACTERIZATION AND MODELING REVEAL ABOUT CARBON-BLACK/RUBBER INTERACTIONS

Abstract

ABSTRACT The concept of topological constraints refers to the strong interactions that spontaneously develop when a rigid material with an appropriate surface geometry (or topology) comes into contact with a soft polymer-type material that has the capability to conform its components (i.e., chain segments) to that surface. Applied to carbon black (CB)–filled rubber compounds, this concept means that a number of measurable bulk properties, such as viscosity and/or modulus, readily reflect an adsorption–desorption balance of chain segments on appropriate sites on CB aggregates. With respect to either strain magnitude or temperature or both, that balance may be affected in a reversible manner, and relatively simple mathematical models can be developed to treat measured rheological quantities that are directly related to CB–rubber interactions. Because of their experimental simplicity, strain sweep (SS) test protocols with suitable dynamic rheometers are particularly attractive, in this respect, as demonstrated through experiments on a series of CB-filled compounds and the adequate mathematical modeling of results gathered when playing with the strain amplitude and the temperature, at constant frequency.