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This study presents the fabrication of carbon nanofiber-reinforced epoxy nanocomposites using 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid as filler dispersant. FTIR and XRD measurements were utilized to assess structural attributes and crystallographic change in the composites. In addition, morphological studies were performed by field emission scanning electron microscope while the extent of miscibility between epoxy and IL was computed by Accelrys Materials Studio Software. The conductivity measurement was performed by two point impedance analyzer and result demonstrated increase in the electrical conductivity from ∼10−7to ∼10−5 S cm−1compared to pristine epoxy composite. [ABSTRACT FROM AUTHOR]

Conducting fillers such as graphite, carbon nanotubes, and carbon nanofibers are used as reinforcing agents for enabling the conducting behavior of epoxy resin. The present review focused on the work related to epoxy composite with reinforcement of various nanofillers. Different methods of preparation for epoxy-based conducting nanocomposites are summarized. Various characterization techniques of epoxy composites such as Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy are discussed. Important properties of epoxy-based nanocomposites are explained with different applications of epoxy-based conducting polymers. [ABSTRACT FROM AUTHOR]

Carboxylated multiwalled carbon nanotubes (MWCNTs) were added to polyethersulfone hollow fiber membranes to improve their H2/CH4separation properties. The addition of MWCNTs up to 1 wt% increased macrovoids formation in cross-section, while in 2 wt% loading, decreased due to increase in dope viscosity. The best gas separation performance for the mixed-matrix hollow fiber membranes was achieved at 1 wt% MWCNTs loading with hydrogen permeance of 69 GPU and H2/CH4selectivity of 44.1 at 5 bar(g). Tensile test results showed that incorporation of MWCNTs into the polymeric matrix affected the mechanical properties of the fabricated membranes. [ABSTRACT FROM PUBLISHER]

The present article describes the morphology, mechanical, thermal, electrical, and dielectric properties of polysulfone (PSU) nanocomposites filled with different concentrations of multiwalled carbon nanotubes (MWCNT) and carbon nanofibers (CNF) [Only one carbon material per each]. The tensile strength and tensile modulus of both MWCNT- and CNF-filled nanocomposites increased with the increase in filler loading up to 3 wt.%. The addition of 3 wt.% CNF led to increase in tensile strength and modulus by 22% and 46%, respectively. Similarly at the same loading of MWCNT, the tensile strength and tensile modulus increased by 16% and 44%, respectively. Thermogravimetric analysis indicated continuous upgrade in thermal stability compared to pure PSU matrix up to 3 wt.% nanofiller loading. Electrical conductivity of both nanocomposites obeyed a power law model of the percolation theory having very low percolation threshold of 0.0079 (0.9 wt.%) for PSU/CNF nanocomposite and 0.014 (1.5 wt.%) for PSU/MWCNT nanocomposite. Dielectric properties of nanocomposites were enhanced significantly with increasing MWCNT/CNF concentration, but decreased with increasing frequency. The dielectric constant reached to 8.5 × 109(100 Hz) at 5 wt.% MWCNT and 5.4 × 1010at 5 wt.% CNF, respectively, from the neat PSU matrix (2.1 at 100 MHz). The current (I)–voltage (V) characteristics exhibited ohmic conduction at and above the percolation threshold for both MWCNT- and CNF-filled nanocomposites. [ABSTRACT FROM PUBLISHER]

A kind of new composite material composed of piezoelectric ceramic lead magnesium niobate-lead zirconate-lead titanate (PMN)/carbon nanofibers (CNFs)/epoxy resin (EP) were prepared by a resin casting method. The effects of carbon nanofibers on dielectric properties of PMN/CNFs/EP composites were investigated in this paper. The concetration of CNFs had significant effects on dielectric constant, dielectric loss, dielectric frequency dependence and dielectric temperature dependence of PMN/CNFs/EP composites. When the content of CNFs increased from 0 to 0.8 wt% of the epoxy resin, the dielectric constant at 1 kHz increased sharply from 13.6 to 158, and the dielectric loss increased from 0.0524 to 2.59. In plots of the dielectric constant against frequency and dielectric loss against frequency, the dielectric constant and dielectric loss reduced dramatically at lower frequency ranging from zero to about 105 Hz, then approach to be stable at frequency higher than 105 Hz. Moreover, as to the effects of temperature on dielectric constant and dielectric loss of PMN/CNFs/EP composites, the dielectric constant of composite increased ranging from 25°C to 160°C, and the dielectric loss of composite also showed increase besides that with CNFs content 0.8 wt%. [ABSTRACT FROM AUTHOR]

Rheological properties of carbon nanfiber/polypropylene composites were investigated. CNFs synthesized at 600°C were thermally modified at 2200°C. These CNFs with a curl/twisted morphology were incorporated into polypropylene (PP) by intensive mixing. The untreated CNF composites showed higher dynamic moduli, G' and G'', than the heat-treated CNF composites. Also, stress relaxation results indicated that untreated CNF composites were relaxed in a longer time than heat-treated CNF composites. These results support that the untreated CNF composites needed less CNFs to perform CNF-CNF network than the heat-treated CNF composites did. It is suggested that structural changes can be verified by rheological analyses. [ABSTRACT FROM AUTHOR]