Epoxy functionalized multi‐walled carbon nanotubes/polyvinylidene fluoride nanocomposites: Microstructure, morphology, thermal, piezoelectricity and conductivity investigations

Multi‐walled carbon nanotubes (MWCNTs) were modified by grafting to di‐glycidyl ether of bisphenol‐A (DGEBA) through 4,4′‐diaminodiphenylsulfone functionality, and subsequently were used as reinforcement in polyvinylidene fluoride (PVDF) to fabricate ef‐MWCNTs/PVDF nanocomposites for the very first time. Comparing to the nonfunctionalized pristine MWCNTs (p‐MWCNTS) and acyl chloride‐modified MWCNTs (ac‐MWCNTs), the ef‐MWCNTs have shown better and enhanced dispersion into the PVDF matrix, owing to the better interface formation due to the improved interaction between the tubes and the polymer chains. Consequently, the ef‐MWCNTs/PVDF nanocomposites have shown higher melting temperature (T_m) corresponding to the increased β‐phase fraction formation. This was also reflected in the piezoelectric analyses in which the ef‐MWCNTs/PVDF nanocomposites have shown increased β‐phase dependent piezoelectric constant, d₃₃, reaching above 8.0 PC/N comparing to 5.0 PC/N in case of ac‐MWCNTs/PVDF. Similarly, a reverse trend has been observed after the percolation threshold in the conductivity of ac‐MWCNTs/PVDF nanocomposites. Contrarily, the conductivity of ef‐MWCNTs/PVDF nanocomposites have shown a regular increase after the percolation threshold with increasing ef‐MWCNTs wt% loading. In a nutshell, we have achieved better dispersion even at highest applied wt% loadings of MWCNTs into PVDF matrix upon functionalizing with epoxy, corresponding to strong interfacial interactions between the tubes and polymer chains. POLYM. COMPOS., 40:E776–E794, 2019. © 2018 Society of Plastics Engineers