Microwave radiations effect on electrical and mechanical properties of poly (vinyl alcohol) and PVA/graphene nanocomposites (original) (raw)
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Influence of microwave irradiation on thermal properties of PVA and PVA/graphene nanocomposites
Journal of Thermal Analysis and Calorimetry, 2019
This article discusses the effect of microwave irradiation on the thermal properties of poly(vinyl alcohol)/graphene nanocomposites, prepared using a solution casting technique. Samples were subjected to microwave radiation for 5, 10 and 15 min at a constant power of 200 watts. The crystallinity and thermal stability of the irradiated samples were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis. Reduction in crystallinity and thermal stability of PVA was observed with incorporation of graphene due to restricted dynamic movement of chains and synergistic instability, respectively. Microwave irradiation for 5 min improved the crystallinity and thermal stability of the nanocomposites. However, further irradiation caused a decrease in the crystallinity as well as in the thermal stability due to degradation. Moreover, the isothermal crystallization kinetics were studied by DSC. An increase in the crystallization rate was observed with graphene incorporation.
Polymers
Polyester nanocomposites reinforced with graphene nanoplatelets (GnPs) with two different lateral sizes are prepared by high shear mixing, followed by compression molding. The effects of the size and concentration of GnP, as well as of the processing method, on the electrical conductivity and electromagnetic interference (EMI) shielding behavior of these nanocomposites are experimentally investigated. The in-plane electrical conductivity of the nanocomposites with larger-size GnPs is approximately one order of magnitude higher than the cross-plane volume conductivity. According to the SEM images, the compression-induced alignments of GnPs is found to be responsible for this anisotropic behavior. The orientation of the small size GnPs in the composite is not influenced by the compression process as strongly, and consequently, the electrical conductivity of these nanocomposites exhibits only a slight anisotropy. The maximum EMI shielding effectiveness (SE) of 27 dB (reduction of 99.8%...
The demand for using textiles in electromagnetic (EM) shielding applications is increasing greatly in recent years. Textiles have many potential applications as EM shielding in the electrical and electronic industries as well as for the production of protective garments. Recently carbon nanotubes (CNTs) have attracted considerable attention for engineering applications due to their physical and chemical properties including electromagnetic radiation absorbing characteristics. Many advantages including exceptional mechanical, electrical and thermal properties, excellent electrical conductivities and high aspect ratio made them very promising for electromagnetic wave absorption.The main aim of this work is to comparison the microwave absorption behaviour of poly (vinyl alcohol) (PVA)/multi walled carbon nanotubes (MWNT) composites in thin film and nanofiber layers. PVA/MWNT composite solution with various MWNT contents (up to 10 wt%) were used to fabricate the nanofiber and thin film ...
Polymer Composites, 2017
To achieve the suitable set of synergistic mechanical, dielectric, and electromagnetic interference shielding properties, polymer blends based on varying the concentration of conductive polymer polyaniline (PANI) in insulative matrix of polyvinyl alcohol (PVA) as well as hybrid composites by adding few layer graphene (FLG) in PVA/PANI polymer blends are prepared using solution casting method. In PVA/PANI blends, by increasing the concentration of PANI, dielectric constant (e 0), dielectric loss (e 00), and total shielding efficiency (SE T) of PVA are enhanced from 4 to 80, 0.72 to 164, and 2.5 to 30 dB at 100 Hz, respectively, at the considerable loss of its mechanical properties particularly the tensile strength from 23.9 to 8.5 MPa. For hybrid composites of PVA/ PANI/FLG, mechanical as well as dielectric and EMI shielding properties are remarkably enhanced at very low loading levels of FLG. The incorporation of small amounts of FLG in PVA/PANI-10 wt%, the e 0 , e 00 , and SE T are increased from 4 to 7,907, 0.5 to 406,947.5 and 2.5 to 99 dB at 100 Hz, respectively, along with the considerable increase in the mechanical properties such as tensile strength from 15.7 to 36.3 MPa and modulus from 0.1 to 0.96 GPa at the loss of strain. In comparison to PVA/ PANI blends, hybrid composites of PVA/PANI/FLG become a promising system for microwave absorption applications.
Influence of graphite nanosheets on the structure and properties of PVC-based nanocomposites
Journal of Applied Polymer Science, 2011
Polyvinyl chloride-(PVC)-based nanocomposites, containing graphite nanosheets (G), which may be used as electromagnetic wave absorbers was developed and investigated. The microstructure of polyvinyl chloride/ graphite nanocomposites (PVC/G) were examined by means of X -ray diffraction, scanning electron microscopy (SEM), and thermal gravimetric analyses (TGA). SEM image reveals that the graphite nanosheets were well dispersed in the PVC matrix without agglomeration. Thermal stability of the PVC/G nanocomposites is improved as a result of inclusion of graphite nanosheets. The PVC/G nanocomposites were characterized to investigate the effect of dispersion of graphite nanosheets in PVC matrix. The dielectric spectroscopy of PVC/G nanocomposites in frequency range from 1 to 12 GHz has been performed. The results show that PVC/ G nanocomposites exhibit high dielectric constant at the measured frequencies. Coefficient of attenuation and coefficient of reflection of PVC/G composites have been also examined in a frequency range from 1 to 12 GHz. The electromagnetic interference shielding effectiveness (EMI) depends on graphite volume fraction in the composite. The results show that the PVC/G represents a new class of conducting lightweight nanomaterial that can absorb electromagnetic waves at microwave frequency and may be promising for future commercial use.
The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene-comethyl meth acrylate) [P(S-co-MMA)] polymer matrix has been studied in this article. Modification of graphene was performed using nitric acid. P(S-co-MMA) polymer was blended via melt blending with pristine and MG. The resultant nanocomposites were irradiated under microwave at three different time intervals (5, 10, and 20 min). Compared to pristine graphene, MG showed improved interaction with P(S-co-MMA) polymer (P) after melt mixing and microwave irradiation. The mechanism of improved dispersion and interaction of modified graphene with P(S-co-MMA) polymer matrix during melt mixing and microwave irradiation is due to the presence of oxygen functionalities on the surface of MG as confirmed from Fourier transform infrared spectroscopy. The formation of defects on modified graphene and free radicals on P(S-co-MMA) polymer chains after irradiation as explained by Raman spectroscopy and X-Ray diffraction studies. The nanocomposites with 0.1 wt% G and MG have shown a 26% and 38% increase in storage modulus. After irradiation (10 min), the storage modulus further improved to 11.9% and 27.6% of nanocomposites. The glass transition temperature of nanocomposites also improved considerably after melt mixing and microwave irradiation (but only for polymer MG nanocomposite). However, at higher irradiation time (20 min), degradation of polymer nanocomposites occurred. State of creation of crosslink network after 10 min of irradiation and degradation after 20 min of irradiation of nanocomposites was confirmed from SEM studies.
Journal of Alloys and Compounds, 2020
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Composites Part B: Engineering, 2016
Multiwall carbon nanotubes (MWCNT) and multilayer graphene (MLG) were studied as microwave susceptor additives for polymers. Different percentages of both nanoparticles were added to polypropylene by melt compounding in order to study the microwave absorption and the polymer heating. Polypropylene was selected as polymer matrix due to its unpolar nature to avoid the influence of polymer polarity and evaluate the influence of the nanoparticles. Electrochemical spectroscopy impedance measurements were carried out to evaluate the conductive and dielectric properties of nanocomposites. Results showed that nanocomposites with higher electrical conductivity have better capacity of absorbing microwave radiation. High values of permittivity and loss tangent also increases the microwave radiation absorption and the ability of the material to convert this electromagnetic radiation into heat. Carbon nanotubes showed better microwave susceptor behavior than graphene multilayer. Nanocomposites with 1% w/w of carbon nanotubes can be compared with the heating efficiency of a polypropylene filled with 10% w/w of multilayer graphene. The higher efficiency of carbon nanotubes it is explained by their higher electrical conductivity and optimal dielectric properties of the nanocomposites compared to multilayer graphene polymer systems.
Advanced Polymer Composite with Graphene Content for Emi Shielding
Deleted Journal, 2024
One of the increasingly common unexpected outcomes of the extensive usage of electronic devices and systems is electromagnetic interference (EMI). The need for efficient fillers and shielding materials to manage electromagnetic interference (EMI) and associated issues is rising. Adding more filler typically means greater production costs, poor dispersion, and unintended agglomeration, which makes polymer composites harder to work with and mechanically weak. Therefore, it is highly desired to design a strong composite with conductive filler content that nonetheless performs well as an EMI shield. Therefore, using a graphene substrate and dispersion of conducting polymers such as polyacetylene and MWCNT fillers, a hybrid polymer composite based on polyetherimide is proposed in this research. Next, the enhancement of EMI shielding efficiency is examined. The design of the graphene substrate was completed with a coating based on nano filler, and the blending methods of the polymer matrix and the reinforcing filler materials are explored. ANSYS-HFSS software is then used to assess the shield's efficacy among others, and the results demonstrated improved performance. Therefore, by putting the suggested design into practice, high-performance EMI shielding materials can be created by combining various shield fillers. As a result, the composites' mechanical, electrical, and EMI shielding qualities will all improve.