Thermogravimetric properties

The thermal stability of the pure Phe and Phe nanocomposite membranes with different filler content was investigated by thermogravimetric analysis. The TGA thermograms corresponding to the thermal decomposition of pure Phenoxy and Phe – nanocomposite films are shown in fig. 27 and fig. 28.

Thermogravimetric properties

Fig. 27. Thermograms of (a) Phe (b) PRC3 (c) PNC3

 

Thermogravimetric properties

Fig. 28. Shows typical THA thermograms of (a) PRC1 (b) PRC2 (c) PNC2

 

As can be observed, both pure polymer and nanocomposite materials decompose in a single stage. If we compare the thermal stability of the polymer and the critical loading percentage nanocomposite membranes of PNC3 and PRC3, it is clear that PNC3 is more stable than pure Phenoxy and PRC3. The pristine Phe is thermally stable up to 275 oC. Since, the Phe nanocomposite membranes show enhanced thermal stability, the initial decomposition temperature (Ti) of phenoxy occurred at 276 oC while in case of PNC3 and PRC3, Ti was found at 318 and 298 oC respectively as shown in table 15. Similarly, final decomposition temperature (Tf) of phenoxy, PNC3 and PRC3 were observed at 433, 479 and 458 oC respectively. The enhancement in the thermal stability of PNC3 could be attributed to the better compatibility and intercalation of polymer matrix within the silicate galleries of 3 wt% organically modified red mud. Similarly, from fig.28 and table 15, it was observed that PNC2 showed higher Ti and Tf as compared to the PRC1 and PRC2, thereby showing higher thermal stability comparatively.

In general, major weight losses were observed in the range of 275-500 oC for Phe and polymer nanocomposite films, which may be correspondent to the structural decomposition of the polymer backbones at higher temperatures. After 500oC, all the curves became flat and mainly the inorganic residue (i. e. Al2O3, MgO, and SiO2 etc.) remained.

Sample

Ti (o C)

Tf (o C)

Ash (%)

Pure Phe

276

433

3.2

PRC1

287

439

6.33

PRC2

293

443

7.97

PNC2

312

454

8.23

PNC3

318

479

11.30

PRC3

298

458

14.15

Table 15. Degradation temperature and ash content of Pristine Phe and the Phe- nanocomposite membranes