부산대학교 도서관

The thermal stability and recyclability of Polycarbonate resin (PC) composites filled with silica particles which are surface-treated with polyhydric phenol agents has been investigated. The composites were evaluated after molding 4 consecutive times. For the composites containing 1.5wt% silica particles treated with polyhydric phenol, the number-average molecular weight (Mn) of PC in the composites, measured by gel permeation chromatography, decreased from 24300 to 21800 after 4 injection molding cycles, while the unfilled PC resin control decreased to 21000.These results suggest that the PC molecule depolymerized during the injection molding process due to the thermal energy and stress. On the other hand, we found that the surface treatment of silica particles with polyhydric phenol reduced the decrease in PC Izod impact strength to 1/5 that of the neat PC resin. In addition, we studied the effects of multistage surface treatment of silica particles using two phases and three phases with benzophenone, silane-coupling agents. Three phase multistage treated silica particles resulted in higher Mn retention than those containing a single phase with polyhydric phenol.The magnitude of the activation energies (ΔE) related to the thermal degradation of the composites were evaluated by thermo-gravimetry. ΔE increased in the following order: neat PC, composite with the two-phase multistage and that with the three-phase multistage.These findings suggest that the addition of multistage surface-treated particles in PC improved the stability of PC composites. This implies that surface treatment may be an effective method in the recycle of PC resin composites.