Abstract:In this work, we undertook a comparative study of the dynamic dielectric analysis of two unidirectional epoxy composites: flax-fiber-reinforced epoxy and flax/carbon-fiber-reinforced epoxy (FCFRE). In both composites, three relaxation processes were identified. The first one is the water dipoles polarization imputed to the presence of polar water molecules in flax fiber. The second relaxation process associated with conductivity occurs as a result of the carriers charges diffusion noted for high temperature ab… Show more
“…This phenomenon appears in the systems dominated by the carriers according to the cluster model. 42 Accordingly, the existence of cluster in heterogeneous structure may give rise to a site containing charge carriers. The motion of these latter inside the cluster under applied electric field effect contribute to the quasi-continuous conductivity illustrated by quasi-dc plateau on ac conductivity (normalσ′) curves in the intermediate temperature range for the terpolymer matrix and its both composites VR/MCC/MWCNT0.5 and VR/MCC/MWCNT1 as depicted in Figures 5(a)-(c).…”
Section: Resultsmentioning
confidence: 99%
“…Similar behavior has been obtained for unidirectional flax-fibers reinforced epoxy hybrid composites. 42 Figure 6.3D representation of imaginary part of the electric modulus for the matrix (a) The composite VR/MCC/MWCNT0.5 (b) and the composite VR/MCC/MWCNT1 (c) versus frequency and temperature.…”
Section: Resultsmentioning
confidence: 99%
“…Similar behavior has been obtained for unidirectional flax-fibers reinforced epoxy hybrid composites. 42…”
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
“…This phenomenon appears in the systems dominated by the carriers according to the cluster model. 42 Accordingly, the existence of cluster in heterogeneous structure may give rise to a site containing charge carriers. The motion of these latter inside the cluster under applied electric field effect contribute to the quasi-continuous conductivity illustrated by quasi-dc plateau on ac conductivity (normalσ′) curves in the intermediate temperature range for the terpolymer matrix and its both composites VR/MCC/MWCNT0.5 and VR/MCC/MWCNT1 as depicted in Figures 5(a)-(c).…”
Section: Resultsmentioning
confidence: 99%
“…Similar behavior has been obtained for unidirectional flax-fibers reinforced epoxy hybrid composites. 42 Figure 6.3D representation of imaginary part of the electric modulus for the matrix (a) The composite VR/MCC/MWCNT0.5 (b) and the composite VR/MCC/MWCNT1 (c) versus frequency and temperature.…”
Section: Resultsmentioning
confidence: 99%
“…Similar behavior has been obtained for unidirectional flax-fibers reinforced epoxy hybrid composites. 42…”
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
“…The results show that the presence of two carbon fiber plies in the hybrid composite leads to two interfacial polarization effects and locally decreases the adhesion of flax fibers in the epoxy matrix. [16] This study investigates the effect of carbon/flax hybridisation with varying flax volume fractions on the tensile, flexural, impact, and vibration properties including comparison of modelling and experimental data. The work shows that compared with aluminium, the hybrid composites offer beneficial mechanical and damping properties.…”
Numerous research studies are carried out in order to investigate various properties and implement the potential of hybrid carbon/flax composites for technical applications. This review aims to present a summary of materials and manufacturing techniques, which are currently used for the fabrication of the carbon/flax composites, and describe the reported tensile, bending, impact, and damping properties of the resulting hybrid materials as well as the attempts to model some of these properties.
“…12 Therefore, improving its compatibility with the matrix through grafting and other methods is basic. 13 Balachandrakurup 14 addressed the incompatibility between butadiene rubber and cellulose using epoxidized NR. Compared to vulcanized rubber, the use of cellulose epoxidized NR significantly improved the tensile strength, tear strength, modulus, and wear index by 150%, 93%, 47%, and 19%, respectively.…”
With the increasing environmental requirements for improving products and materials using renewable and sustainable resources, cellulose has been seen as one of the most attractive and promising alternatives to traditional inorganic fillers. We developed a new modification method to improve the interface compatibility between natural rubber and sisal cellulose, to improve the mechanical and thermal conductivity properties of rubber composite. Microcrystalline cellulose (MCC) was extracted from sisal cellulose and then the hydrophobic cellulose (SA‐MCC) was prepared by grafting stearic acid on the surface of MCC. MCC and SA‐MCC were added to the thermal conductivity composite material composed of natural rubber and boron nitride. The results showed that the thermal conductivity and tensile properties of the natural rubber composites increased by 17.3% and 20%, respectively, under the addition of 1.8 wt% SA‐MCC. Furthermore, the interfacial interaction between the components in the composite was studied by molecular dynamics simulation. The solubility parameters, free volume fraction, and molecular binding energy were calculated to verify the effectiveness of the modification. This work is expected to provide a theoretical basis for the design and preparation of high‐performance natural rubber composite materials.Highlights
Cellulose microcrystals were successfully extracted from sisal fiber and modified.
Through the combination of boron nitride and the modified cellulose microcrystals, the thermal conductivity and tensile properties of thermal rubber were successfully improved synchronously.
A reasonable molecular simulation model was established to analysis the strengthening mechanism from the microscopic point of view.
The molecular simulation conclusions on interface enhancement are in good agreement with the experimental properties.
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