Thermal Properties and Crystallization Behaviors of MWCNTs/PTT Composites
碩士 === 萬能科技大學 === 材料科技研究所 === 100 === Multiwalled carbon nanotubes (MWCNTs) was first treated with a mixing acid (H2SO4/HNO3=3/1) to produce carbonyl groups and hydroxyl groups on the surface of the MWCNTs. Then, the acid treated-MWCNTs was blended with poly(trimethylene terephthalate) (PTT) to prep...
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| Format: | Others |
| Language: | zh-TW |
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2011
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| Online Access: | http://ndltd.ncl.edu.tw/handle/37224344913625287893 |
| Summary: | 碩士 === 萬能科技大學 === 材料科技研究所 === 100 === Multiwalled carbon nanotubes (MWCNTs) was first treated with a mixing acid (H2SO4/HNO3=3/1) to produce carbonyl groups and hydroxyl groups on the surface of the MWCNTs. Then, the acid treated-MWCNTs was blended with poly(trimethylene terephthalate) (PTT) to prepare MWCNTs/PTT composites. FTIR results revealed that there are carboxylic groups (–COOH) and –CO stretching absorption in the acid-treated MWCNTs. Thermal stability of the MWCNTs/PTT composites was investigated by TGA. TGA analyses revealed that the 5% thermal decomposition temperature (T5) of the PTT was 409.2oC, and the ash content at 800oC was 4.3%. Both the T5 and ash content of the PTT increased after the MWCNTs addition to the PTT matrix. TMA results showed that the coefficient of thermal expansion (CTE) for the pure PTT was 276.70 ppm/ oC. The CTE value of the composites decreased after the addition of modified-MWCNTs into the PTT matrix. Isothermal and nonisothermal crystallization of PTT was investigated by DSC. From isothermal crystallization analysis, the Avrami index (n) of MWCNTs/PTT composites were between 2~3 and the overall crystallization rate (k) increased with increasing MWCNTs content. This result indicates that MWCNTs act as heterogeneous crystallization. From nonisothermal crystallization analysis, the Avrami exponent (n) of MWCNTs/PTT composites were between 3~4. The nonisothermal crystallization behaviors of the MWCNTs/PTT composites were analyzed with the Avrami-Ozawa equation. The activation energy of MWCNTs/PTT composites were lower than that of pure PTT. This result reveals that the addition of MWCNTs decreases the activation energy of PTT crystallization.
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