Heterogeneous bubble nucleation in PCL/clay nanocomposite foams

Nanocomposites based on biodegradable polycaprolactone (PCL) and organically modified layered silicates (organoclay) have been prepared by melt mixing. The isothermal crystallization of polycaprolactone/clay nanocomposites showed that the well dispersed organoclay platelets acted as nucleating agents in PCL matrix, as confirmed by a remarkable reduction of the crystallization half-time t1/2. The nanocomposites showed much higher complex viscosity than that of the neat PCL and pseudo-solid like behavior in the low frequency range. The foaming process of PCL/clay nanocomposites containing 2 and 5%wt of clay were investigated by using a batch process. The results showed that the presence of clay resulted in the increase of cell density and a reduction of cell size compared to pure PCL and higher densities due to the higher viscosity of the melt.