| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 가을 (10/13 ~ 10/14, 제주 ICC) |
| 권호 | 30권 2호 |
| 발표분야 | 복합재료 |
| 제목 | Isothermal Crystallization Kinetics and Morphological changes of Poly (ethylene terephthalate) (PET)/A-Zeolite Nanocomposites Revealed by DSC, Time-Resolved SAXS Analysis |
| 초록 | The crystallization kinetics and morphological changes of poly(ethylene terephthalate)(PET)/A-zeolite nanocomposites were investigated by using differential scanning calorimetry (DSC) and time-resolved small-angle X-ray scattering (TR-SAXS). The Avrami equation was found to successfully describe the isothermal crystallization process. With Avrami analysis using DSC, the Avrami exponent and rate constant were calculated from fitting by using the double logarithmic form of the Avrami equation. The Avrami exponent increased from 3 to about 5 with increasing A-zeolite contents, indicating a change in crystal growth form. The k, rate constant, showed a increasing trend as increase of A-zeolite contents. The synchrotron small-angle X-ray scattering data revealed morphological changes during crystallization, and these parameters of each sample were obtained by correlation function. The long period and the size of the amorphous region decreased with crystallization time in the initial crystallization portion during crystallization of nanocomposites at 180 oC and 230 oC. This observation could be caused by the insertion of subsidiary lamellae between two existing dominant lamellae. In the results of heating at a rate of 5℃/min after isothermal crystallization at 180℃ for 20 min, invariants and the lamellar thickness for all samples are increased with increasing temperature due to crystal thickening. Amorphous region and long period was also increased with temperature owing to the thermal expansion resulting from the increased molecular mobility. As the zeolite content increased, long period and amorphous region size increased. It is suggested that since PET molecules piercing into zeolite pore cannot make perfect crystal folding, imperfect crystal start to melt at earlier temperature, as reveled by SAXS profiles during heating. And some PET molecules piercing into zeolite pore are rejected into amorphous region, resulting in increased amorphous region size and increased long period, respectively. However, spherulite size are decreased with increasing nanofiller content owing to the increased nucleating site. Guinier plot gives the particle size and volume. As the zeolite content increases, particle size and volume increased. Especially, those values for 2 wt% nanocomposite were abruptly increased owing to the aggregation of zeolite particles. 참고문헌 1. J. W. Park, S. S. Im, Journal of Polymer Science: Part B: Polymer Physics, 40, 1931 (2002). 2. W. D. Lee, S. S. Im, Journal of Polymer Science: Part B: Polymer Physics, 43, 805 (2005). |
| 저자 | 신영학, 이완덕, 임승순 |
| 소속 | 한양대 |
| 키워드 | PET; zeolite; nanocomposite; crystallization kinetics; SAXS; DSC |
