Pressure-volume-temperature and glass transition behavior of silica/polystyrene nanocomposite

The pressure-volume-temperature (PVT) behavior and glass transition behavior of a 10 wt % silica nanoparticle-filled polystyrene (PS) nanocomposite sample are measured using a custom-built pressurizable dilatometer. The PVT data are fitted to the Tait equation in both liquid and glassy states; the coefficient of thermal expansion , bulk modulus K, and thermal pressure coefficient are examined as a function of pressure and compared to the values of neat PS. The glass transition temperature (T-g) is reported as a function of pressure, and the limiting fictive temperature (T-f) from calorimetric measurements is reported as a function of cooling rate. Comparison with data for neat PS indicates that the nanocomposite has a slightly higher T-g at elevated pressures, higher bulk moduli at all pressures studied, and its relaxation dynamics are more sensitive to volume. The results for the glassy values suggest that thermal residual stresses would not be reduced for the nanocomposite sample studied. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1131-1138