Mechanical, thermal and decomposition behavior of poly(ε-caprolactone) nanocomposites with clay-supported carbon nanotube hybrids

Poly(ε-caprolactone) (PCL) nanocomposites with hybrid clay-supported carbon nanotubes (Clay-CNT) in concentrations 0.5, 1.0 and 2.5 wt% were prepared by melt mixing. Mechanical, structural and thermal properties of the nanocomposites were studied. All nanocomposites exhibited similar stress-strain patterns to those of neat PCL but, with increasing nanofiller content yield point and Young's Modulus values increased, despite the absence of chemical interactions between PCL and Clay-CNT. It was also found that the crystallinity of the nanocomposites is the same as for neat PCL, but the nanofiller acts as nucleating agent which promotes the crystallization and also allows it to occur at higher temperatures. Thermal stability is instead negatively influenced by the nanofiller, since Clay-CNT catalyzes the decomposition of PCL at lower temperature. The monomer ε-caprolactone is the main decomposition product resulting from intramolecular esterification while cis-elimination at ester bonds (β-hydrogen bond scission) is favored at higher temperatures.