Thermal, mechanical, and rheological properties of poly(ε-caprolactone)/halloysite nanotube nanocomposites

Naturally available halloysite nanotubes (HNTs) with hollow nanotubular structures were used as reinforcement in poly(epsilon-caprolactone) (PCL). The PCL/HNT nanocomposites were prepared by melt mixing the polymer with as-received HNTs up to 10 wt % in an internal batch mixer. Transmission electron microscopy analysis indicated that the HNTs were dispersed uniformly on the nanoscale throughout the PCL matrix. Differential scanning calorimeter studies revealed that the PCL crystallinity was decreased in the nanocomposites, and the HNTs dispersed in the PCL matrix led to an increase in the non-isothermal crystallization temperature of the PCL. Tensile and dynamic mechanical tests showed great enhancement in strength and stiffness at low HNT content, while still maintaining the ductility of the PCL. The glass transition temperature (Tg) of the pristine PCL was substantially increased with increase in filler loading, which indicates good reinforcing effect imparted by the addition of HNT. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior, and a percolated network of HNT particles was formed. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013