Optimization of the mechanical properties of polypropylene-based nanocomposite via the addition of a combination of organoclays

The properties of polypropylene (PP) nanocomposites are dependent on the quaternary ammonium salt in the montmorillonite (MMT). A nanocomposite with C-15A, which has a high cation exchange capacity (CEC), exhibits an increase in its impact properties, while one prepared with C-20A, which has a low CEC, shows an increase in the flexural modulus. In order to obtain enhancements in both properties, PP nanocomposites were prepared using a combination of 1:1 of C-15A/C-20A. X-ray, TEM, thermal properties, dynamical mechanical analysis (DMA), and mechanical tests were used to evaluate the properties of this novel mixture. Nanocomposites of partially exfoliated morphology were obtained, especially when 5 wt% of poly(propylene-graft-maleic anhydride) (PP-g-MA) was used. The mechanical tests showed that the use of a 1:1 mixture of C-15A/C-20A caused a simultaneous gain of approximately 12% in flexural modulus and a five times higher impact strength. In addition, the dispersion of the clay was more homogeneous, with the absence of agglomerated structures that were present when either the individual C-15A or C-20A was used. The DMA results showed that while the organoclay improved the modulus of PP, the Tg was decreased slightly.