PC / PMMA Reactive Blending Its Foaming In Supercritical CO ₂

In this paper, in order to investigate the compatibilizing effect of the transesterification catalyst SnCl2·2H2O for PC/PMMA and the influence of process conditions on the morphology of PC/PMMA blend, the PC/PMMA blend was prepared by melt blending using torque rheometer in the presence of SnCl2·2H2O. And then the behavior of dissolution and diffusion of supercritical CO2into PC/PMMA blend was studied. Meanwhile, the influence on the behavior of crystallization of blend in the supercritical CO2was investigated by the DSC. In addition, the effects of process conditions on the microcellular morphology of PC/PMMA blend under constrained condition.The results showed that SnCl2·2H2O initiated the transesterification between PC and PMMA which was found to form the graft copolymer PC-g-PMMA, leading to enhancing the miscibility of the blend. The PC/PMMA blend had only one Tg and the transparency was65%. It also proved SnCl2·2H2O was extremely effective to catalyze the reaction of PC and PMMA and the optimal content of SnCl2·2H2O was about0.015%-0.02%. The size of PMMA phase diminished with the increase of the content of SnCl2·2H2O, the blending time and the blending temperature, but the phase separation appeared under higher blending temperature. The size of PMMA phase increased slightly because of the cohesion with the increase of screw speed. However, the size of PMMA phase diminished obviously when the screw speed was80rpm. Moreover, the PC in the blend showed two different crystal forms, and the degree of completeness of the crystal structure and the solubility of CO2both increased with the increase of saturation temperature, saturation time, saturation pressure and the addition of acetone. In addition, the cell diameter increased with increasing foaming time and foaming temperature or the decrease of saturation pressure. The cell density diminished with the decrease in saturation pressure or the increase of foaming time, and it first increased and then decreased with the increasing foaming temperature.