N. Yavari; M. Poorabdollah; L. Rajabi
Abstract
In this study, unmodified graphite and graphite modified with a silane agent were used to ameliorate the thermal conductivity coefficient and dynamical properties of unsaturated polyester resin. The effect of unmodified graphite and modified graphite addition on thermal conductivity coefficient and dynamical ...
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In this study, unmodified graphite and graphite modified with a silane agent were used to ameliorate the thermal conductivity coefficient and dynamical properties of unsaturated polyester resin. The effect of unmodified graphite and modified graphite addition on thermal conductivity coefficient and dynamical properties of unsaturated polyester resin in the graphite amounts of 0.02% and 0.3% by weight were studied using solid thermal conductivity measuring device and DMA test. The results showed that the silane modifier can help to create strong covalent bonds between graphite particles and unsaturated polyester resin network and cause changes in thermal and dynamic properties compared to unmodified graphite particles. Adding 0.3% of the weight of the unmodified graphite to the unsaturated polyester resin resulted in a 7% raise in the storage modulus in the glassy region. However, adding the same amount of graphite modified using the silane agent increased the storage module by 33% in the glassy region. Silane modifier caused better dispersion of graphite particles in the resin structure. Superior dispersion of graphite particles caused more interaction between graphite particles and resin network, which significantly increased the modulus of unsaturated polyester resin. In contrast, better dispersion of graphite particles because of the presence of silane agent increased the thermal resistance at the surface of graphite particles, which reduced the thermal conductivity coefficient compared to unmodified graphite.
Materials synthesize and production
A. Hadi; J. Karimi-Sabet; S. M. A. Moosavian; S. Ghorbanian
Volume 12, Issue 4 , October 2015, , Pages 52-68
Abstract
After fullerene and nanotubes, graphene is a new allotrope of carbon. This attractive nanomaterial can be produced by different methods. In this work, we have used the less common approach for preparation of graphene. This technique is based on the utilization of supercritical fluid. Ethanol was used ...
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After fullerene and nanotubes, graphene is a new allotrope of carbon. This attractive nanomaterial can be produced by different methods. In this work, we have used the less common approach for preparation of graphene. This technique is based on the utilization of supercritical fluid. Ethanol was used as the solvent for exfoliation of pristine graphite, at the temperature of 400 oC and pressure of 40 MPa. In addition, supercritical ethanol was used to reduce and exfoliate graphite oxide. FT-IR spectra indicate that reduction and exfoliation of graphite oxide can be done in supercritical ethanol, simultaneously. Effect of graphite oxidation on the yield and quality of graphene was investigated and results showed that oxidation of graphite can improve the yield of supercritical process from 12.5% to 26.8%, but Raman spectra revealed that quality of graphene samples produced by graphite oxide is lower than neat graphite. Moreover, the impacts of initial graphite concentration and sonication power on the exfoliation yield were studied. Finally, hybrid structure of graphene and titanium dioxide nanoparticles were prepared by ultrasonic method and used for photocatalytic degradation of methylene blue dye pollutant. Results revealed that titanium dioxide nanoparticles show better photocatalytic performance in presence of graphene sheets.