7
Figure 6
TGA thermogram of TPVs based on ENR/EVA/PP blends with the various of ENR/EVA ratio
Figure 5,6 shows TGA thermograms of pure ENR, pure EVA and dynamically cured NR/EVA/PP blends
.
It
is seen that the pure ENR showed a single degradation step at degradation temperature of approximately 380°C.
However, pure EVA shows double degradation stages with an degradation temperature at 370°C in the first stage
which corresponds to the degradation of vinyl acetate moieties with emitting acetic acid. The second degradation step
was related to the main chain
degradation with degradation temperature of 483°C. It is seen that
the double
degradation stages were also observed in the TPVs with various blend ratios. That is, increasing proportions of EVA
phase in a range of 15 to 30 wt% caused an increase of the degradation temperatures from 468 to 475°C for the 2nd
degradation stage. This is attributed to the degradation of the EVA phase that occurs at a higher temperature than in
the case of the ENR-25. This proves the ability of EVA to improve thermal stability of dynamically cured
ENR/EVA/PP blends.
Morphological studies
Figure 7
SEM micrograph of TPVs based on ENR/EVA/PP blends with the various of ENR/EVA ratio
60/0/40
45/15/40
30/30/40
15/45/40
0/60/40
