A study on melt processing and thermal properties of fluoroelastomer nanocomposites

Fluoroelastomer (FKM)/layered clay nanocomposites were prepared by melt mixing and their clay dispersion, morphological, rheological and thermal properties were characterized. Wide angle X-ray diffraction (XRD) and transmission electron microscopic (TEM) studies revealed the presence of intercalated/exfoliated clay layers with good dispersion at lower levels of filler loading. Both the pure FKM and FKM/clay nanocomposites showed shear thinning behavior and temperature dependency on shear stress. The apparent shear viscosity of the FKM/organo clay (O-MMT) nanocomposites was lower than that of the pure polymer at all shear rates and temperatures. The activation energy of the melt flow process decreased with increasing shear rate for all of the systems studied. However, the FKM/O-MMT hybrids exhibited higher activation energy compared to other filled systems. The nanocomposites exhibited reduced equilibrium die-swell with a smooth extrudate appearance. A comparison of the flow properties of the nanocomposites with the conventional composites revealed that the nanocomposites exhibited improved processability. The addition of layered clay increased the glass transition temperature of FKM. Although, the addition of untreated clay improved the thermal stability of FKM, organo clay reduced degradation initiation temperature due to the decomposition of organic component of modified clay.