Significantly Accelerated Spherulitic Growth Rates for Semicrystalline Polymers through the Layer-by-Layer Film Method

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• 作者：Yaqiong Zhang ; Hongjun Xu ; Jingjing Yang ; Shouyu Chen ; Yunsheng Ding ; Zhigang Wang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：March 21, 2013
• 年：2013
• 卷：117
• 期：11
• 页码：5882-5893
• 全文大小：692K
• 年卷期：v.117,no.11(March 21, 2013)
• ISSN：1932-7455

文摘

The influence of a molten liquid polymer layer on the crystallization of the beneath semicrystalline polymer has been seldom considered. In the study, the nucleation and growth of spherulites for the beneath polylactide (PLA) layer in poly(ethylene oxide)/polylactide (PEO/PLA) double-layer films during isothermal crystallization at various temperatures above the melting point of PEO have been investigated by using polarized optical microscopy, with the particular results compared with that for neat PLA and PLA/PEO blend films. It is interesting to find that the top covering molten PEO layer can greatly accelerate the spherulitic growth rate (G) of the beneath PLA layer. Another significant result is that the temperature for the measurable nucleation and spherulitic growth of PLA in the double-layer films can be eventually pushed down close to the glass transition temperature of neat PLA. The changes of glass transition temperature, T_g, for PEO/PLA multilayer films have been measured by using modulated differential scanning calorimetry and dynamic mechanical analysis, which reveal slight decreases of T_g for PLA layer due to the influence of PEO layer. The layer structures of fractured surface of the double-layer films are analyzed on the basis of the observation from scanning electron microscopy, and the existence of interdiffusion areas with irregular boundary between PEO and PLA layers is the key clue to understanding the significant acceleration of G for PLA. The layer-by-layer film method infers promising applications, which might be considered to well replace the blending method.