Investigation of Polymer Filler Interaction In Liquid Silicone Rubber

The physical properties of both natural and synthetic elastomers or rubbers have been extensively analyzed by a variety of methods and techniques. While there has been much study on filler-containing elastomer behavior attributed to the polymer-filler interaction, there is little reported on the role of the mixing or mastication process on physical properties of filled elastomers, both before and after cure.

In this study, the effect of different mixing conditions was investigated using a silica-filled liquid silicone rubber (LSR) composition.  It included three different mixing configurations using both lab and manufacturing scale equipment.    The polymer-filler interactions in the LSR were investigated using established low strain dynamic mechanical experiments in shear as well as high strain cyclical tensile deformation on cured LSR.  While differences in the steady shear viscosity of the uncured silicone polymer-filler mixtures were observed, the cured silicone rubbers showed similar response to low and high strain deformation and hysteresis evaluation.  This confirms the ability to get nearly identical cured performance properties in a controlled LSR formulation using quite different viscous polymer mixing processes