The effect of addition of Multiwall Carbon Nanotubes on the vibration properties of Short Glass Fiber reinforced polypropylene and polypropylene foam composites

Abstract The objective of this paper was to investigate the effect of addition of Multiwall Carbon Nanotubes (MWCNTs) with different values of weight percentage (0.5%, 1%, and 1.5%) on the vibration and morphological properties of Short Glass Fiber (SGF) (10, 20, and 30 wt.%) reinforced polypropylene (PP) and the polypropylene foam composites. Nanocomposites were first compounded by using the melt-compounding technique in a twin-screw extruder. Then, azodicarboxamide was added as a foam agent to investigate the foaming behavior of the samples. The free vibration behavior of the samples under clamp-free boundary conditions was studied via Operational Modal Analysis (OMA). In order to confirm the experimental results, the Euler-Bernoulli beam theory was employed to calculate the values of the natural frequencies. The results of analyses indicated that the theoretical natural frequencies had a significant correlation with the experimental results within 18% mean error level. The experimental results showed that addition of SGF particles to the PP and PP foam would significantly increase the natural frequencies, but it would in return decrease the damping factor. The results also indicated that, with addition of MWCNTs to the samples, the damping factor and natural frequencies of the PP and SGF/PP composites would increase. The highest increase in the natural frequencies amounted to 118.8%, which resulted from combination of 20 wt.% SGF and 1 wt.% MWCNT. On the other hand, the highest increase in the damping factor amounted to 68.9%, which resulted from combination of 20 wt.% SGF and 1.5 wt.% MWCNT.