Multiwalled carbon nanotubes-based polypropylene composites: Influence of interfacial interaction on the crystallization behavior of polypropylene

Abstract

Composites of polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) were prepared via melt-mixing utilizing Li-salt of 6-amino heaxanoic acid (Li-AHA) modified MWCNTs in the presence of a compatibilizer (polypropylene-g-maleic anhydride; PP-g-MA). Improved interaction between the anhydride group of PP-g-MA and the amine functionality of Li-AHA was confirmed via FTIR and Raman spectroscopic analysis. A higher glass transition temperature (Tg) of the PP phase has been observed in these composites as compared to pristine MWCNTs based composites. The crystallization temperature (Tc) of the PP phase was increased as a function of pristine MWCNTs concentration in PP/MWCNTs composites indicating hetero-nucleating action of MWCNTs. However, Tc value was decreased in the presence of Li-AHA modified MWCNTs indicating the adsorbed Li-AHA on the MWCNTs surface. Moreover, Tc value was higher in the presence of Li-AHA modified MWCNTs with PP-g-MA as compared to that of without PP-g-MA, suggesting the desorbed Li-AHA from the MWCNTs surface due to melt-interfacial reaction. Further, MWCNTs were extracted by hot vacuum filtration technique from PP/MWCNTs composites containing Li-AHA and PP-g-MA. The isothermal crystallization kinetics showed a variation in crystallization behavior of the PP phase in the corresponding composites as compared to the “extracted MWCNTs.” POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers