Influence of cobalt complex on thermal properties of poly(ethylene terephthalate)/polycarbonate blend

The effects of processing time and concentration of cobalt acetylacetonate III complex in poly(ethylene terephthalate)/polycarbonate reactive blending were investigated. The blend was prepared in an internal mixer at 270 degrees C, 60 rpm, at different processing times (5-20 min) and catalyst concentration (0.00625-0.075 mass%). The reaction product was evaluated by differential scanning calorimetry (DSC), thermogravimetry (TG) and wide angle X-rays scattering (WAXS). In general, the DSC curves showed two glass transition temperatures (T-g's) close to each homopolymer, independent of the processing time and complex's concentration, suggesting the presence of two phases: one rich in PET and other one rich in PC. In all cases, melting temperature (T-m), cold crystallization temperature (T-cc) and crystallinity degree (X-c) were progressively reduced with blending conditions. The TG curves presented two decays. The first one represented the PET rich phase and the other one was related to the PC phase. The WAXS diffractograms showed that the Bragg's angle and interplanar spacing of PET remaining practically unchanged.