TGA analysis (Fig. 11) also suggests that the existence of C15A clay mineral particle within PSF matrix imparts better thermal stability. Although both samples seem to exhibit a similar major decomposition range (425.8–480C), the onset decomposition temperature for neat membrane was 364.5C while the MMM does not start to decompose until it reached 412.2C. Inorganic fillers generally possess inherently good thermal properties compared to polymeric materials. Upon heating,the heat was absorbed by the fillers thus decomposition rate was suppressed which resulted in relatively higher decomposition temperature [35]. Therefore the improvement of thermal stability of the MMM can be attributed to the shielding effect of clay particle [36].