1. Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi 030024, PR China 2. Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan, Shanxi 030024, PR China 3. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, PR China
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DOI:
10.7502/j.issn.1674-3962.2015.05.05
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Abstract:
Since carbon nanotubes (CNTs) were first discovered in 1990, due to its excellent physical properties, it has become a potential material in many fields, especially in the field of polymers filled with CNTs, which have been received increasing attentions. Although significant progress in mechanical, thermal, electrical and rheological properties has been made in developing nanocomposites with different polymer matrices, a general understanding for the mechanism has not yet emerged. In other words, how the addition of nanofillers can affect the microstructure of polymer? And how the microstructures can affect the macropropeties? A major direction in the further development of nanocomposites is finding out the simple structure-property relationship. In this report, polycarbonate (PC)/multi-walled carbon nanotube (MWCNT) composites have been prepared by solution mixing. The influences of temperature on the free volume of MWCNT/PC composites were investigated by positron annihilation lifetime spectroscopy (PALS). Three methods, including PALS, dynamic mechanical analysis and differential scanning calorimetry were used to determine the glass transition temperature (Tg) of PC/MWCNT composites. The experimental results indicated that the higher the MWCNT contents, the lower the Tg, which attributes to the large free volume hole and the enhanced polymer mobility in PC/MWCNT composites with higher MWCNT contents.