Synergistic reinforcement of nanoclay and mesoporous silicate fillers in polycaprolactone: The effect of nanoclay on the compatibility of the components

Biodegradable nanocomposites based on poly(ε-caprolactone) (PCL) reinforced by mesoporous silicate (MCM) were prepared by a melt-extrusion process using a second nanoclay, i.e. modified organophilic silicate layers as compatibilizer. The compatibilizing role of the nanoclay was studied with respect to the morphological, melt-rheological and dynamic mechanical properties of these nanocomposites. Transmission electron microscopy showed that a homogeneous dispersion of MCM had been achieved with addition of the nanoclay (0.5 wt.%) to the PCL/MCM composite. Oscillatory frequency sweep measurements showed that addition of about 3.0 wt.% MCM, in the presence of silicate layers (0.5 wt.%), led to a solid-like response where a percolated network structure is formed. As a result, the Elastic modulus (E), in the rubbery plateau, increased significantly with the filler contents at all temperatures studied, having, at a loading level of only 4 wt.%, values approximately 50% higher than the neat PCL. This reinforcement is probably due to a synergistic effect that arises from the combination of the modified layered clays and the mesoporous silicate particles. In comparison, in the absence of silicate layers, the mesoporous silicate aggregates inside the PCL matrix, and the reinforcement was negligible.