Thermal, mechanical and viscoelastic properties of compatibilized polypropylene/multi-walled carbon nanotube nanocomposites

Polymer composites containing nanofillers are among the most promising research fields for advanced materials. Carbon nanotubes (CNTs) are considered an ideal inclusion for polymer nanocomposites due to superior electrical, thermal, and mechanical properties which can be explained with the unique atomic structure of the nanotubes. Multi-walled carbon nanotubes (MWCNTs) are used as extremely strong nano-reinforcements for composites to produce a new generation of fiber-reinforced plastics with better application properties. In this experimental study, PP/MWCNT polymer nanocomposites with nanofiller concentrations in the range of 0.05–1 wt% MWCNT and the maleic anhydride amount from 0 to 7.5 wt% were investigated. An experimental study is conducted to examine the influence of MWCNT and compatibilizer contents on the thermal, mechanical, and viscoelastic properties of polypropylene (PP)/MWCNT nanocomposites. Extruded samples are characterized by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and microindentation tests. Standard Berkovich indentation test determined by residual surface impression method based on load–displacement curves was used. DSC results show an increase in the crystallization temperature of maleinated PP with the increase of MWCNT contents proving the nucleation effect of CNTs. DMTA results prove the good modification properties of maleic anhydride in MWCNT/PP nanocomposites at 0.05 wt% nanotubes concentration. Elastic moduli, obtained from both DMTA and microindentation, are compared to investigate the difference between surface and bulk mechanical properties of nanocomposites with increasing nanotubes concentration. Measured values of elastic moduli are within comparable ranges, but the absolute values are different.