Effects of Hydrophobic Nanosilica on Phase Diagram of Poly(ɛ-caprolactone)/Poly(styrene-co-acrylonitrile) Blends

Abstract

Nanoparticles, in addition to reinforcing polymer blends, also strongly influence their phase behavior and their presence reduces molecular movements, phase separation kinetics and phase dissolution. In this research, the effect of hydrophobic silica nanoparticles on the phase behavior of polycaprolactone (PCL)/poly(styrene-co-acrylonitrile) (SAN) blends was investigated. Since the phase diagram in the molten state is usually obtained through temperature dynamic techniques, nanoparticles in the blends cause unrealistic phase separation temperatures. In this research, an attempt has been made to obtain the phase separation temperatures of PCL/SAN blends in the presence of hydrophobic silica nanoparticles under conditions close to thermodynamic equilibrium conditions using a rheological approach. The rheological phase transition temperature and the spinodal temperature of the lower-critical solution temperature (LCST) diagram, obtained through the temperature sweep tests, were transferred to higher temperatures by reducing the cooling rate of the test. Contrary to the initial expectation, in PCL/SAN blends with the addition of hydrophobic nanosilica, it was observed that these temperatures were transferred to higher temperatures in most concentrations.