Morphologies and properties of epoxy/multi-walled carbon nanotube nanocomposite foams prepared through the free-foaming and limited-foaming process

摘要

Microcellular epoxy/multi-walled carbon nanotube (EP/MWCNT) composite foams loaded with 2 wt% (mass fraction) of MWCNT were prepared through the free-foaming process (Fre-foam) and limited-foaming process (Lim-foam) using chemical foaming agent (CFA), respectively. The morphologies of EP/MWCNT composite foams with different densities were analyzed by scanning electron microscopy (SEM). It was found that the cell size of both Fre-foam and Lim-foam decreased with increasing the density, while Lim-foam exhibited a smaller cell size and a higher cell density in contrast to those of Fre-foam at similar density. In addition, the dynamic mechanical properties, thermal stability, and electrically and thermal conductive properties of the EP/MWCNT foams in the density range of 0.278 g/cm(3)-1.108 g/cm(3) were investigated and the difference in performances between Fre-foam and Lim-foam was analyzed. Lim-foam had an obviously lower crosslink density than that of Fre-foam due to the effect of compressed gas, which was clearly reflected in the results of gel fraction, glass transition temperature (T-g), molecular weight between crosslinks (M-c), and initial thermal decomposition temperature. Compared with Fre-foam, Lim-foam had superior thermal conductive property and exhibited weak electrically conductive property, indicating the conductive pathway was affected by the foaming process.