Siloxane core dianhydride modified ether linked cyclohexyl diamine based multi-walled carbon nanotube reinforced polyimide (MWCNT/PI) nanocomposites

A new type of siloxane core based polyimide (PI) was designed and developed by the reaction between siloxane core dianhydride (SDA) and ether linked cyclohexyl diamine (ELCD), using the in-situ polymerization approach via thermal imidization. This PI was further modified with different loading levels of MWCNTs to get MWCNT reinforced PI nanocomposites. The synthesized PIs were then characterized, using analytical methods. From the thermal analysis, it was observed that the values of T-g are increased by about 12 % by incorporating the amine functionalized MWCNTs into the PI matrix than that of neat PI. This is because of the constraint effect of MWCNTs as well as the reduction in the movement of the polymer chains. They also exhibited enhanced values of the dielectric constant, with the successive increase in the incorporation of MWCNTs to the PI matrix. No aggregation and better homogeneity of MWCNTs throughout the PI matrix have been achieved, as evidenced from scanning electron microscopy (SEM). The transmission electron microscopy (TEM) studies indicate that there are no confined domains in and around the region of MWCNTs, after the formation of nanocomposites. It is ascertained that the newly designed MWCNT/PI nanocomposite is responsible for the significant improvement of dispersion, thus possesses attractive flame retardancy and insulation behaviour.