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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 (Tm) 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 [ABSTRACT FROM AUTHOR]

Abstract Nanocomposites of Polyvinylidene Flouride (PVDF) with Multi-walled Carbon Nanotubes (MWCNTs) possess excellent thermal, piezoelectric and conductive behaviors. However, the potential of MWCNTs as filler in polymer composites is hampered by their poor dispersion into the matrix, corresponding to the strong inter-tubular and weak inter tubular-polymer chain interactions. This issue is successfully overcome by utilizing di-glycidyl ether of bisphenol-A (DGEBA) grafted MWCNTs (DG-MWCNTs) as reinforcement in PVDF matrix. To synthesize the desired nanocomposites, the easier to manipulate, solution casting technique was employed. The resulting PVDF/DG-MWCNTs nanocomposites have different loadings of filler ranging from 1.0 wt% to 10 wt% , and have shown variation in the phase transformation from α-phase to β-phase along with improvements in thermal and dielectrical behaviors. It was revealed by the impedance spectroscopy (IS) that the reinforcement of PVDF with DG-MWCNTs leads to an increase in the dielectric permittivity. This increase was found higher enough to reach up to ∼5288 (at ∼100 Hz) and 214 (at ∼102 Hz) for filler loading of 10 wt %. The increase is several hundreds of magnitude i.e. , ∼204 at ∼102 Hz higher than the PVDF matrix, while retaining a low level conductivity (4.18 × 10−6 S/cm). This enhancement in the dielectric permittivity is attributed to the strong interfacial interaction between PVDF and DG-MWCNTs, and was explained by the Maxwell-Wagner-Sillar (MWS) effect. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is a semicrystalline thermoplastic and electroactive polymer with piezoelectric and pyroelectric properties, thermal stability, elasticity, and chemical resistance. PVDF exits in five different phases (α, β, δ, γ, and ε-phase). Unique properties of this polymer enhances its use in chemical, biomedical, and electronic industries such as supercapacitors, transducers, actuators, and batteries. Carbon nanotube (CNT) is used as reinforcement to exploit full potential of PVDF in energy, electronics, and membrane technology. The nanofiller affects morphology, piezoelectric, pyroelectric, electrical, dielectric, thermal, and mechanical properties of PVDF-based nanocomposite. CNT content and chemical modification influence properties as well as application of PVDF. [ABSTRACT FROM AUTHOR]

In order to improve the dispersion state of multi-walled carbon nanotubes (MWCNTs) and to get a synergistic effect when incorporated in polyvinylidene flouride (PVDF) matrix, multi-walled carbon nanotubes (MWCNTs) were oxidized and then grafted with di-glycidyl ether of bisphenol-A (DGEBA) by a linker moiety, hexamethylene diamine (HMD). Modified MWCNTs (HD-MWCNTs) with various concentrations of 1.0 wt% to 10 wt% were incorporated in polyvinylidene fluoride (PVDF) matrix for the fabrication of polymeric nanocomposites (PVDF/HD-MWCNTs). Compared to pristine MWCNTs (P-MWCNTs), the structural and thermal analysis of both modified MWCNTs showed a well crystalline structure with a uniform tubular morphology as well as uniform and improved dispersion was achieved in their nanocomposites with PVDF. Enhanced dispersion is attributed to a strong interfacial interaction of the modified MWCNTs with polymer chains of PVDF. Therefore, by thermal analysis of PVDF/HD-MWCNTs nanocomposites both melting temperature (T m) and temperature of crystallization (T c) have revealed the uniform distribution of nanotubes and enhancement of heterogeneous nucleating effect leading to formation of β-phase which is in complete agreement with SEM, FTIR, XRD, TGA and d 33 value. Piezoelectric and electrical conductivity values measured for PVDF/HD-MWCNTs nanocomposites were observed to rise with increase in concentration of HD-MWCNTs up to 5 wt% where the percolation threshold (f c) is attained. PVDF/HD-MWCNTs nanocomposite with highest electrical conductivity of 1.13 x 10−3 Scm−1 at filler loading of 5 wt% was successfully achieved. These simultaneous improvement in properties anticipate that PVDF/HD-MWCNTs nanocomposites can be useful for variety of energy applications. [Display omitted] [ABSTRACT FROM AUTHOR]