Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene-co-methyl methacrylate)/graphene nanocomposites (original) (raw)
Related papers
Poly (styrene-co-methyl methacrylate) [P(st-mma)] composite containing 0.1 wt% modified graphene (MG) was prepared via melt blending. MG was prepared by oxidation method using nitric acid. The P(st-mma) and P(st-mma)MG composite were irradiated using microwave radiation. The degradation mechanism and thermal stability of the irradiated and un-irradiated samples was analyzed by TGA. P(st-mma)MG showed high thermal stability. The average activation energy of thermal degradation was found to be 200 kJ/mol for P(st-mma), 214 kJ/mol for P(st-mma)MG. The activation energy was highest for 10 min irradiated nanocomposites indicating an improvement in stability. The degradation mechanism was investigated by comparing the master plots constructed using the experimental data with theoretical master plots of various kinetic models. The thermal degradation of P(st-mma) and P(st-mma)MG composite before and after irradiation governs the random scission mechanism. SEM and TEM micro-graphs showed improved interactions and degradation of composites after 10 min and 20 min irradiation respectively.
Poly(styrene-co-methyl meth acrylate)/graphene and poly(styrene-co-methyl meth acrylate)/modified graphene nano composites were prepared via melt blending. The effects of pristine (G) and modified graphene (MG) and microwave irradiation on the properties of styrene-co-methyl meth acrylate (P(S-co-MMA) polymer matrix were studied. Modification of graphene was done by chemical oxidation method using nitric acid. The nanocomposites were irradiated under microwave at different time intervals (5, 10 and 20 minutes) with fixed power of 1000Watt. Compared to pristine graphene, modified graphene showed improved interaction with P(S-co-MMA) polymer after melt mixing and microwave irradiation. The mechanism of formation of covalent bonds and improved interfacial interaction of pristine and modified graphene with P(S-co-MMA) polymer matrix induced by microwave irradiation was attributed to the formation of defects on graphene and free radicals on P(S-co-MMA) polymer chains explained by FT-IR, ...
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.
Surfaces and Interfaces, 2018
Solution casting technique was used to prepare electrically conductive nanocomposites. Graphene was used as conductive inclusive in the Poly (vinyl alcohol) matrix. Nanocomposites further irradiated using microwave radiation for different interval of time (5, 10 and 15 min). Different characterization techniques were utilized including SEM, XRD and Raman Spectra to completely understand the properties change in non-irradiated and irradiated sample. Increase in electrical conductivity was observed with the increase in graphene percentage. Sample with 10% graphene inclusion exhibited 3.55 S/cm electrical conductivity with comparison to 0.021 S/cm for 1% graphene composite. Percolation threshold was observed for the sample holding 5% graphene with the electrical conductivity value of 2.17 S/cm. Different empirical models were also used to produce the trends for conductivity of composite at different graphene percentages. It was observed that the Scarisbrick model with the 0.1 geometrical factor (C) affirmed the harmonization in theoretical and experimental values of electrical conductivity. Electromagnetic inference shielding effectiveness was perceived for different composite samples using vector network analyzer (VNA). Observations show the increase in EMI shielding with the increase in graphene percentage. Moreover, both electrical conductivity and Electromagnetic inference shielding effectiveness improved after radiation. Due to agglomeration and bi-layered structure domination, tensile properties of composite films were found to be decreased especially at high graphene.
Molecules, 2013
Polymethylmethacrylate-graphene (PMMA/RGO) nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH), the product was reduced via microwave irradiation (MWI) to obtain R-(GO-PMMA) composites. In the second approach, a mixture of graphite sheets (RGO) and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA) composites. The composites were characterized by FTIR, 1 H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI.
Composites Part A-applied Science and Manufacturing, 2011
Poly(methyl methacrylate) (PMMA)/graphene nanocomposites were prepared by in situ emulsion polymerization. Raman and Fourier transform infrared spectra showed that PMMA polymer contained partially reduced graphite oxide. Dynamic mechanical analysis and differential scanning calorimetry analysis showed that graphene in the PMMA matrix acted as reinforcing filler; it enhanced the storage moduli and glass transition temperatures of the nanocomposites. Thermogravimetric analysis showed that the thermal stability of the nanocomposites increased by ca. 35°C. The electrical conductivity of nanocomposite with 3 wt.% graphite oxide was 1.5 S m À1 at room temperature.
Journal of Thermoplastic Composite Materials, 2018
Poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) (90/10) nanocomposites containing various amounts of graphene nanoplatelets were fabricated by solution method and then the effects of graphene concentration on morphology, thermal, mechanical, and electrical properties of the nanocomposites were investigated. Characterization by electron microscopy and X-ray diffraction of the nanocomposites showed a relatively good dispersion of graphene sheets in the polymer matrix. The results indicated that thermal stability, glass transition temperature, and mechanical properties of PMME/PEO blend improved by increasing graphene concentration. The electrical properties of polymer nanocomposites revealed a significant improvement with increasing the amount of graphene and the percolation threshold was about 3.33 wt% of graphene.
Open Journal of Synthesis Theory and Applications, 2016
Serials of polystyrene/SiO 2 Nano composites (PS/SiO 2) with different content of inorganic fillers were successfully prepared by the in situ bulk radical polymerization of styrene under microwave irradiation. The effect of the amount of Nano SiO 2 on the properties of the PS/SiO 2 Nanocomposites along with the average relative molecular masses (Mn, Mz and Mw) was investigated by thermal analysis and X-Ray Diffraction (XRD). Their structural model was proposed on the basis of the Optical Microscopy, FTIR (Fourier Transform Infrared) analysis, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and X-Ray Diffraction (XRD). The dispersion of nanoparticles in Polystyrene is observed in the magnified image. The effect of microwave irradiation power on molecular weight of polystyrene was also studied. It was found that, the microwave assisted reaction needs less time as compare to conventional polymerization and found to be in between 10 to 15 min.
Efficiency of Microwave Heating of Weakly Loaded Polymeric Nanocomposites
Journal of Engineered Fibers and Fabrics
Electrical and thermal conductivity of materials are typically correlated, while some applications, including thermoelectrics, require these parameters to be controlled independently. Such independent control of thermal and electromagnetic properties can be achieved by using nanocomposites. In this study, nanocomposites were produced by mixing a small amount of carbon nanofibers (CNF), carbon coated cobalt (Co), and nickel nanowires (NiNW) with paraffin, which has low thermal and almost zero electrical conductivity. The fraction of nanoinclusions in the paraffin matrix was very low (below 1%). We showed that the thermal properties of nanocomposites are essentially the same as those of pure paraffin, while electromagnetic properties are significantly different. To determine the dependence of the heating rate on filler concentration, paraffin-based samples were heated in a microwave oven. We found that the heating rate of nanocomposites made of carbon nanofibers is much greater than t...