Effect of Filler Functionalization on the Thermo-Mechanical behavior of Polypropylene Nanocomposites

Abstract Present study is an experimental attempt to characterize the thermo-mechanical behavior of Thermoplastic polymer nanocomposites (PNC) surface functionalized with multi walled carbon nanotubes (MWCNT). Nanocomposites with two grades of MWCNT, pristine and –COOH functionalized were fabricated with isotactic polypropylene (iPP) and results were compared. Nanocomposites Films with 0%, 0.5%, 1% and 2% MWCNT loadings were prepared by conventional solution casting method followed by isothermal quasi static uniaxial tensile tests at constant strain rates of 0.1/min, cyclic tensile tests at strain rate of 0.1/min and isochronous creep characterization at stress levels of 0.2, 0.5, 1, 2, 5, 7, 10, 12 and 15 MPa performed on Tinius-Olsen Universal Testing machine to monitor strength and stiffness of the material and obtain the threshold of stress and time at room temperature to observe the transition from linear to nonlinear viscoelastic regime. Dynamic characterization at constant frequency of 1 Hz, temperature ramp 0-100°C, was performed to obtain storage modulus under dynamic loading conditions on Dynamic mechanical analyzer (DMA). It was reported that incorporation of functionalized MWCNT increases the strength, failure strain, reduces creep strain and increases stiffness of nanocomposites as compared to those with pristine-MWCNT up to 1% concentration. Moreover, it was also observed that loading under 1MPa and 5 seconds, the material behaves linearly. Prior to the testing, thermal stability of materials was monitored by Thermo-gravimetric analysis.