PSI - Issue 14

Vivek Khare et al. / Procedia Structural Integrity 14 (2019) 215–225 Vivek Khare, Shubham srivastava, Sudhir k mle, G.M.Kamath / Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 8. FESEM micrographs (a) 0.5 % MWCNT-PP; (b) 1 % MWCNT-PP; (c) 2 % MWCNT-PP nanocomposites

Figure. 7 and 8. Shows the micrographs of fractured surface of polymers and nanocomposites in 2 µm scale. Samples with 1% functionalized MWCNT loading are found to be better dispersed than 0.5% and 2% samples. However, non-uniformity, MWCNT bundles and agglomerates were observed for 2% samples. 4.4. Dynamic characterization Figure. 9. Shows dynamic testing results of nanocomposites. It was found that – COOH functionalized MWCNT represents increase in storage modulus over pristine MWCNT in all the cases but less than neat PP for 2% sample. However, 2% samples showed decrease in stiffness as compared to neat PP, 0.5% and 1% samples. This could be attributed to formation of large agglomerate beyond 1% concentration as seen from SEM micrographs. Moreover, functionalized MWCNT showed improved stiffness due to fiber polymer bond stretching resulting in effective elastic response, whereas for pristine MWCNT, weak bonds and relatively weaker fiber polymer interaction resulted in lower stiffness as explained by Pegoretti et al. (2004). It was also noted that at elevated temperatures (above room temperature), stiffness of the material decreases still the functionalized MWCNT nanocomposites showcase fine results than pristine MWCNT nanocomposites. However, strength and stiffness decreases with increase in MWCNT loading. Higher concentration resulted in poor performance compared to neat material.