Free volume and crystallinity of poly(ethylene naphthalate) treated in pressurized carbon dioxide
作者：Anna Andersson, Wentao Zhai, Jian Yu, Jiasong He and Frans H.J. Maurer
關鍵字：Positron annihilation，Supercritical fluids，Temperature modulated DSC
論文來源：期刊
具體來源：Polymer, 2010, 51(1): 146-152
發表時間：2009年
The free volume and crystallization behaviour of poly(ethylene naphthalate) (PEN) treated in pressurized carbon dioxide was studied, using Positron Annihilation Lifetime Spectroscopy (PALS) and Differential Scanning Calorimetry (DSC). PALS probes the values of free volume cavity sizes in materials, thus making it possible to investigate the effect of pressurized carbon dioxide treatment on free volume hole sizes in PEN. The crystallinity and melting behaviour of PEN was analyzed with temperature modulated DSC. We found that the carbon dioxide pressure during treatment of PEN was the prime parameter affecting the value of free volume after the treatment. The free volume sizes were observed to be insensitive to the other two parameters, temperature and time. Increasing the time of the treatment however, increased the crystallinity of PEN. Interestingly, this was not coupled to a decrease in ortho-Positronium intensity as was expected, indicating that positronium may form in the crystalline fraction of the polymer as well as in the amorphous fraction.