دانلود رایگان مقاله دکوراسیون گرافن nanoplatelets با آلومینا برای کامپوزیت اپوکسی

Abstract

Although graphene can significantly improve the thermal conductivity of polymers due to its high aspect ratio and excellent thermal conductance, it causes serious reduction in electrical insulation and thus limits the wide applications of its polymer composites in the thermal management of electronics and systems. To solve this problem, electrically insulating Al2O3 is used to decorate high quality (defect-free) graphene nanoplatelets (GNPs). Aided by supercritical carbon dioxide (scCO2), numerous Al2O3 nanoparticles are formed on the inert GNP surfaces by fast nucleation and hydrolysis of Al(NO3)3 precursor followed by calcination at 600 °C. Alternatively, by controlling nucleation and hydrolysis of Al2(SO4)3 precursor with a buffer solution, Al2(SO4)3 slowly nucleates and hydrolyzes on GNPs to form aluminum hydroxide, which is then converted to Al2O3 nanolayers without phase separation by calcination. Compared to the Al2O3@GNP hybrid with the assistance of scCO2, the hybrid prepared with the help of a buffer solution is highly efficient in conferring epoxy with excellent thermal conductivity while retaining its electrical insulation. Epoxy composite with 12 wt% of Al2O3@GNP hybrid exhibits a high thermal conductivity of 1.49 W/(mK), which is 677% higher than that of neat epoxy, indicating its high potential as thermally conductive and electrically insulating fillers for polymer-based functional composites.

4. Conclusion

We utilize a scCO2-assisted method to decorate the inert defectfree GNP surfaces with numerous Al2O3 nanoparticles by using fast nucleation and hydrolysis of Al(NO3)3 precursor followed by calcination at 600
C. Besides, a buffer solution-assisted deposition approach is applied to deposit the Al2(SO4)3 precursor, which is slowly nucleated and hydrolyzed on GNPs to form aluminum hydroxide; subsequently, this is converted to Al2O3 nanolayers without phase separation after a similar calcination process. The formation of Al2O3 nanoparticles or nanolayers significantly improves the thermal stability of GNPs by 102 and 112
C for Al2O3@GNP-SC and Al2O3@GNP-BS hybrids, respectively. Most importantly, uniquely high thermal conductivity and good electrical insulation could be obtained in epoxy composites filled with these hybrids. Maximum filler loadings for electrical insulation are found to be 10 wt% for Al2O3@GNP-SC and 12 wt% for Al2O3@GNPBS, leading to much higher thermal conductivities of 0.96 and 1.49 W/(mK), respectively. These excellent properties make them strong candidates for thermal management of electronic packaging and electronic devices.