Thermal Conductivity of GSA-SDS Composites

The term Tf is introduced here to account for the influence of SDS added into the composite and is the ratio of the thermal conductivities of the composite with SDS and without SDS. The analogy is similar to the relative density and has been used in numerous literatures (Woignier and Phalippou 1988). In Fig. 6.8b, the addition of SDS, however, initially increases the thermal conductivity factor, Tf, by 1.066 0.036 and exhibits a gradual downward slope even with increasing amount of SDS. It follows a linear function with tit 7 = 0.618. 

In the previous chapter, the optimized mechanical properties are achieved when 0.56 %wt. SDS was added to the GSA composites. The GSA-SDS composites of various aerogel granule sizes are fabricated with 0.56 %wt. SDS for gelatin to silica aerogel granules mass fraction ratios of 0.2 0.8 and 0.4 0.6 respectively. The effects of the granule size on the thermal conductivity are investigated for the temperature profile described in Sect. 6.1 is shown in Fig. 6.9. 

1 Influence of Silica Aerogel Granules on the Thermal Conductivity of GSA-SDS (FD) Composites 

From the experimental results and observations, it can be deduced that the thermal conductivity of the GSA-SDS composite blocks is a function of 7f, weight fractions and thermal conductivities of constituent materials and as well as mean temperature, Hence, it can be expressed as Agsasds =f(Tf, aba k(d, Tm), Agei)- 

13 for which the equations of thermal conductivity of the silica aerogel granules and porous gelatin were derived earlier and plotted against the experimental data as shown in Fig. 6.10. 

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