期刊
EUROPEAN POLYMER JOURNAL
卷 49, 期 4, 页码 865-872出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.eurpolymj.2012.12.015
关键词
Poly(L-lactic acid); Biodegradable polymers; Crystallization; Nucleating agents; Bisurea compounds
资金
- National Basic Research Program of China (973 Program) [2011CB606004]
- National Nature Science Foundation of China [21074109]
- National Key Technology R&D Program of China [2012BAD11B03]
- PCSIRT
A series of novel organic bisurea (BUr) compounds were facilely synthesized from phenyl isocyanate and a variety of diamines, and their roles as crystallization nucleating agents of commercial poly(L-lactic acid) (PLLA) were investigated through differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). Their crystallization accelerating efficiency depends on the methylene numbers in molecular structure: the less the CH2 number, the faster the crystallization rate. Among them, 1,1'-(ethane-1,2-diyl)bis(3-phenylurea) (BUr1) acts as the most effective crystallization accelerating agent. In the presence of ca. 2 wt% BUr1, the melt crystallization enthalpy of PLLA increases from almost 0 to 31.2 J/g under cooling rate of 10 degrees C/min, and the isothermal melt crystallization rate (t(1/2)(-1)) increased by 10.5 times at 140 degrees C. Much higher nucleation density and smaller spherulite size of PLLA were observed by POM, indicating obvious heterogeneous nucleation effect. And the crystal structure of PLLA remains unchanged after incorporation of the nucleator. (C) 2012 Elsevier Ltd. All rights reserved.
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