Graphene: Prepared by High Speed Shearing-assisted Exfoliation and Application in Thermal Conductive Silicon

doi:10.15541/jim20160659

Abstract

Abstract:

Graphene dispersion was produced by centrifugation after exfoliating the graphite in aqueous solutions containing sodium cholate as a surfactant with high speed shearing machine. The exfoliated graphene (thickness≤4 layers) showing large lateral size of around 2-3 μm and high quality (I_D/I_G≈0.15) was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and Raman spectroscopy. After freeze drying, Graphene was added in the silver-silicone rubber to produce a hybrid graphene-metal thermal conductive silicone rubber, and steady-state heat flow method was applied to study the thermal conductivity of the composite. It was found that as filler loading fraction of graphene increased from 0 to 3vol%, thermal conductivity of siliver-silicone rubber dramatically improved from 4.9 W/(m·K)to 12.367 W/(m·K). This result suggests that little-defect graphene with few layers prepared by exfoliating can significantly enhance the thermal conductivity of silicone rubber by synergy effect when combined with silver powder.

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Key words: liquid exfoliation, graphene, thermal conductivity

CLC Number:

TQ174

SHI Zhi-Hui, LI Ying, YAN Lu, CAO Yun-Zhen. Graphene: Prepared by High Speed Shearing-assisted Exfoliation and Application in Thermal Conductive Silicon[J]. Journal of Inorganic Materials, 2017, 32(9): 955-960.

Figures/Tables 4

Fig. 1 (a-c) A Silverson model L5M high-shear mixer with mixing head in 2l beaker of graphene dispersion; (d) Graphene dispersion produced by shear exfoliation; (e-f) TEM image of individual nanosheets and its electron diffraction pattern; (g-h) AFM height profiles of graphene dispersion(10 μm×10 μm); (i-j) Histogram of number of layers and lateral size of graphene flakes

Fig. 2 Raman spectrum of graphene after freeze drying

Fig. 3 SEM images of the silver microflake samples before (a-b) and after (c-d) iodine modification

Fig. 4 Thermal conductivity of the samples vs various silver filler loadings (a) and the samples vs various graphene filler loadings (b)

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