| Summary: | 碩士 === 長庚大學 === 化工與材料工程研究所 === 91 === Abstract
Poly(trimethylene terephthalate) (PTT) and polycarbonate (PC) blends were prepared in the Laboratory Mixing Molder (LMM) at 280℃. The samples with different compositions were blended for 5, 10, 15 and 20 minutes, respectively, with a rotor rotation rate of 180 rpm. According to the blending condition, the effects of sample composition and blending time on the miscibility and thermal properties of the blends were investigated. The differential scanning calorimeter (DSC) results showed that the original two glass transition temperatures (Tg，s) of the blends transformed to one single Tg with extending the blending time. This phenomenon indicated that the miscibility of the blends was enhanced with the occurrence of transesterification between PTT and PC. In addition, the transesterification led to the decrease of crystallinity in the blends. It was also found that the sample composition played a major role in the occurrence of transesterification. Particularly, the transesterification occurred seriously for composition with 50 wt％ of PTT. The thermogravimetric analyzer (TGA) results showed that the blend with a higher PC content exhibited a better thermal stability. Nevertheless, the blending time affected slightly the thermal stability of the samples. The direct evidence of the transesterification between PTT and PC was obtained by the Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H NMR) experiments. These two experimental results confirmed that the transesterification underwent seriously while the blends prepared at 280℃ for 20 minutes. The wide angle X-ray diffractometer (WAXD) results indicated that the transesterification in the blends did not change the crystal structure of PTT. The polarized optical microscope (POM) and scanning electron microscope (SEM) photographs showed that the blends prepared with a shorter blending time exhibited two distinct morphological features, which depended on the blend composition. As the blending time was extended, the occurrence of transesterification resulted in a homogeneous feature of the blends.
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