Effects of supercritical carbon dioxide on crystallisation behaviour of polycarbonate/poly(methyl methacrylate) blends

Abstract

SnCl₂·2H₂O-modified polycarbonate (PC)/poly(methyl methacrylate) (PMMA) (80/20 w/w) blends were prepared by melt blending using a torque rheometer. Supercritical carbon dioxide (scCO₂) has been used to induce the crystallisation of PC/PMMA blends while the crystallisation behaviour and morphology of these blend systems under different saturation temperatures, saturation pressures, saturation times and co-solvent contents were characterised by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The gravimetric experiment shows that the solubility of scCO₂ in PC/PMMA blends increases with the increase of saturation temperature, pressure and time. The DSC curves demonstrate that in these blend systems, the induced crystallisation of PC has been found and two kinds of crystals with different thicknesses exist in it. From the SEM images, it can be found that the structure of PC crystal becomes more perfect and its crystallinity also increases with the increase of saturation temperature, pressure, time and co-solvent content.