FIGURE 6 (a) Water contact angle, (b) Water absorption of PP and SCG/PP composites
3.3.3 Thermal stability
To study the influence of SCG under different heat treatment conditions on the thermal stability of PP composite, the thermal decomposition curve of the composite was tested, as shown in Figure 7. The initial thermal decomposition temperature of PP is 385 °C. After adding filler, the thermal stability of PP decreases, which is manifested as the advance of the initial thermal decomposition temperature. The thermal decomposition trend was similar after the addition of fillers, and the first stage of thermal decomposition was attributed to the partial decomposition of SCG. Compared with the SCG/PP composite, the thermal stability of the NSCG/PP and ASCG/PP composite are slightly improved, and the initial thermal decomposition temperature is increased from 265 ℃ to 280 ℃. After heat treatment, the O/C ratio of SCG decreases and has stronger thermal stability (Leow et al., 2021). However, the thermal stability of SCG/PP composites treated in different atmospheres is similar, indicating that SCG fillers treated in different atmospheres have little effect on the thermal stability of PP. The results of the specific thermogravimetric values are summarized in Table 1.