Physical structure and thermal behavior of ethylcellulose
Physical structure and thermal behavior of ethylcellulose
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DOI：
10.1007/s10570-014-0377-1
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发表时间：
2014-10-01
期刊：
影响因子：
5.7
通讯作者：
Marangoni, A. G.
中科院分区：
文献类型：
--
作者：
Davidovich-Pinhas, M.;Barbut, S.;Marangoni, A. G.
研究了不同分子量乙基纤维素（EC）粉体的物理结构和性能。测定了具有大的多分散性的20-144 kDa范围内的分子量。EC热分析揭示了在类似于130摄氏度的玻璃化转变和在类似于180摄氏度的熔融温度。玻璃化转变温度随着聚合物分子量的增加而增加。广角（WAXS）分析检测到在q = 1.5（-1）处的无定形宽峰和在12.6处的明显布拉格峰，这似乎与聚合物的超分子有序结构有关。使用高温粉末X射线衍射分析证实了这些观察结果，其中结晶峰在聚合物的熔融温度以上消失。超小角（USAXS）的结果拟合到Bouacage分形统一模型和分形的平均尺寸为100-600 nm的相对光滑的表面进行了预测。透射电子显微镜（TEM）图像证实了这一预测。根据我们的结果，EC聚合物具有半结晶结构，在无定形背景内具有结晶域。
The physical structure and properties of ethylcellulose (EC) powders of different molecular weights were examined. A molecular weight in the range of 20-144 kDa with a large polydispersity was determined. EC thermal analysis revealed a glass transition at similar to 130 A degrees C and a melting temperature at similar to 180 A degrees C. Glass transition temperatures increased with polymer molecular weight. Wide angle (WAXS) analysis detected an amorphous broad peak at q = 1.5 (-1) and a distinct Bragg's peak at 12.6 , which seems to be related to a supramolecular ordered structure of the polymer. These observations were confirmed using high temperature powder X-ray diffraction analysis where the crystalline peak disappeared above the melting temperature of the polymer. Ultra-small angle (USAXS) results were fitted to the Bouacage fractal unified model and fractals with an average size of 100-600 nm with a relatively smooth surface were predicted. This prediction was confirmed by transmission electron microscopy (TEM) images. According to our results, the EC polymer has a semi-crystalline structure, with crystalline domains within an amorphous background.