Abstract:Binary and ternary composites were synthesized using a polyester matrix reinforced by two types of carbon inclusions, namely, carbon nanotubes (CNT) and graphite (Gt) (CNT/Gt/Polyester). Thermal analyses were performed, using thermogravimetry and differential scanning calorimetry, which allowed us to observe significant changes in glass transition temperatures and degradation temperatures of the composites. Dielectric measurements were performed in a frequency range from 100 Hz to 1 MHz and temperature from –3… Show more
“…Similar tendency observed on polyester composites reinforced with carbon nanotubes and graphite inclusions has been attributed to the compensating effect of the former to the rigidity effect induced by the latter. 36 Figure 1.Second-heating-scans DSC thermograms of EVA/VeoVa matrix and its composites VR/MCC/MWCNT0.5 and VR/MCC/MWCNT1.…”
Section: Resultsmentioning
confidence: 99%
“…Similar tendency observed on polyester composites reinforced with carbon nanotubes and graphite inclusions has been attributed to the compensating effect of the former to the rigidity effect induced by the latter. 36…”
Dielectric analyses were investigated on vinyl resin emulsion based on ethylene vinyl acetate/vinyl ester of versatic acid terpolymer (EVA/VeoVa) and its composites reinforced with microcrystalline cellulose and multi-wall carbon nanotubes. Dielectric spectra were measured in the frequency range from 10-1 Hz to 107 Hz and the temperature interval from -35°C to 130°C. Three dielectric relaxations were identified for the matrix. The first one, appearing at lower temperatures and higher frequencies, was associated with secondary β relaxation. The second one appearing above the glass transition temperature was attributed to the α relaxation due to the main glass transition of the terpolymer. The third dielectric relaxation appearing at higher temperatures and lower frequencies was attributed to α’ relaxation originating from the motion of more repeat units compared to the α one. The addition of the reinforcements into the matrix gave rise to three additional dielectric phenomena originating either from microcrystalline cellulose or matrix/reinforcement interfaces. Analyses of secondary dielectric relaxations at low temperatures by using the Havriliak-Negami model and those at high temperatures according to an adequate equivalent circuit model allowed probing reinforcement/matrix interactions. This dielectric study was complemented by the thermal, structural and morphological analyses based on differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively
“…Similar tendency observed on polyester composites reinforced with carbon nanotubes and graphite inclusions has been attributed to the compensating effect of the former to the rigidity effect induced by the latter. 36 Figure 1.Second-heating-scans DSC thermograms of EVA/VeoVa matrix and its composites VR/MCC/MWCNT0.5 and VR/MCC/MWCNT1.…”
Section: Resultsmentioning
confidence: 99%
“…Similar tendency observed on polyester composites reinforced with carbon nanotubes and graphite inclusions has been attributed to the compensating effect of the former to the rigidity effect induced by the latter. 36…”
Dielectric analyses were investigated on vinyl resin emulsion based on ethylene vinyl acetate/vinyl ester of versatic acid terpolymer (EVA/VeoVa) and its composites reinforced with microcrystalline cellulose and multi-wall carbon nanotubes. Dielectric spectra were measured in the frequency range from 10-1 Hz to 107 Hz and the temperature interval from -35°C to 130°C. Three dielectric relaxations were identified for the matrix. The first one, appearing at lower temperatures and higher frequencies, was associated with secondary β relaxation. The second one appearing above the glass transition temperature was attributed to the α relaxation due to the main glass transition of the terpolymer. The third dielectric relaxation appearing at higher temperatures and lower frequencies was attributed to α’ relaxation originating from the motion of more repeat units compared to the α one. The addition of the reinforcements into the matrix gave rise to three additional dielectric phenomena originating either from microcrystalline cellulose or matrix/reinforcement interfaces. Analyses of secondary dielectric relaxations at low temperatures by using the Havriliak-Negami model and those at high temperatures according to an adequate equivalent circuit model allowed probing reinforcement/matrix interactions. This dielectric study was complemented by the thermal, structural and morphological analyses based on differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively
“…Since the accumulated charges partly block the external electric field, the dielectric constant increases at these frequency values. The Maxwell -Wagner-Sillars process is an effective mechanism in this frequency regime (Dang et al, 2007;Belhimria et al, 2021). When the frequency of the field is gradually increased, the dipoles can't find enough time to align themselves with the field and the dielectric permittivity is reduced (Mergen et al, 2020).…”
This study presents impedance characteristics of single walled carbon nanotube/vinylester (SWCNT/VE) glass fiber reinforced polymer (GFRP) composites. The impedance measurements were carried out as a function of the frequency over range of 10-2 and 107 Hz at various temperatures between 300 K and 420 K. Bode and Nyquist plots of real and imaginary parts of complex impedance (Z*) were obtained and Cole–Cole approach was used to interpret the impedance characteristics. The results indicated that the bulk resistance of the material decreases significantly as the temperature increases. The frequency-dependent AC conductivities were calculated using the complex impedance data and dimensions of specimen. It has been observed that the alternating current values are compatible with the Jonscher’s power law. The behavior of dielectric constant and loss factor at the various temperatures were analyzed as a function of applied frequency. While the sample exhibited high dielectric permittivity in the low frequency region with the Maxwell-Wagner-Sillars (MWS) effect, it was observed that the permittivity decreased as a result of the dipoles' inability to rotate themselves in the field direction at high frequencies. No dielectric relaxation peak was observed in the loss spectra in our limits. From the results, it can be said that the contribution to the dielectric relaxation is due to the interface polarization and DC conductivity. Electric modulus formalism was also used to describe the conductivity and dielectric relaxation processes of SWCNT/VE binary composite. It was found that the obtained peak maximums shifted to higher frequencies as the temperature increased. It is concluded that the frequency regime below the peak maximum defines the range of mobile charge carriers, and in the regime above the maximum, the charge carriers are limited to short distance potential wells.
“…[1][2][3] Indeed, the nanocomposites made of inorganic nanofillers embedded in a polymeric matrix can combine the unique properties of the constituents giving rise to new and enhanced properties that can differ from those of the single original components. 4 The presence of nanometer sized fillers can change deeply the thermo-mechanical, 5,6 optical, 7 electrical/dielectric, 8,9 and magnetic properties 10 of a polymeric matrix, obviously strongly depending on the nature, 11 shape, 12 size and size distribution 13 of the inorganic nanoparticles (NPs) dispersed within the polymeric matrix. 14 The properties of the nanocomposite materials may be improved by controlling the dispersion of the nanofillers in the polymeric hosts, thus extending the potential exploitation of the resulting composite materials in wide application fields.…”
This work presents an investigation on the optical and structural properties of two series of nanocomposites based on the incorporation of spherical‐ (NDs) or rod‐shaped (NRs) semiconductive crystalline titanium dioxide (TiO2) nanoparticles (NPs) into an insulating amorphous polymethylmethacrylate (PMMA) matrix. The UV–visible absorbance and reflectance measurements reveal that the increase in TiO2 NP concentration within the polymer matrix reduces the forbidden band size for both NDs and NRs, leading to an improvement of the refractive index. SEM and TEM morphological characterizations were performed to investigate the size, size distribution and NPs dispersion within the polymeric matrix. The structural analyses performed by using X‐ray diffraction show peaks ascribed to the TiO2 crystalline structure while infrared (FT‐IR) spectra indicate the occurrence of interactions between nanofillers and the polymer chain of the host matrix.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
