Fig. 4 demonstrates morphologies of both DP and paraffin/DP composite PCM in both macro- and micro-scales.
As shown in Fig. 4a–c, the yellow1 tinted DP powder in micro-scale is mainly in forms of disc-like and cylindrical shapes, with highly porous microstructure.
Fig. 4d shows that paraffin/DP composite PCM has deeper yellow color in comparison with DP powder, due to the infiltration
of paraffin in liquid state.
Moreover, compared with the numerous pores observed in Fig. 4b and c, there are only few visible pores left after paraffin impregnation (Fig. 4e and f), indicating paraffin is well impregnated into DP pores.