Improved thermal conductivity of polydimethylsiloxane/short carbon fiber composites prepared by spatial confining forced network assembly

Traditional compounding method is a common way to construct network to improve thermal conductivity (TC) of polymeric composites. However, the TC of the composites increases slowly when the network has been constructed. There is no percolation threshold in TC, unlike in electrical conductivity. Thus, a method of spatial confining forced network assembly (SCFNA) was used to prepare polydimethylsiloxane (PDMS)/short carbon fiber (SCF) composites to improve the TC. The content of SCF ranging from 2 to 18 wt% was used to illustrate availability of SCFNA method. When the content of SCF was 18 wt%, the TC of PDMS/SCF composites prepared by SCFNA method increased by 7.79 times over the TC of PDMS/SCF composites prepared by traditional compounding method and 10.93 times over the TC of pure PDMS. Comparing the SEM of PDMS/SCF composites prepared by SCFNA method with that prepared by traditional compounding method, the gap between fillers of former was much smaller than that of latter. Moreover, the gap decreased when compression ratio increased. Therefore, the TC of composites prepared by SCFNA method could be improved significantly compared with traditional methods, which provides the possibility to replace thermally conductive materials such as metal with polymeric composites.