Development and characterization of surface functionalized hierarchical carbon fiber reinforced hybrid polypropylene composites.

Light-weight hybrid composites of relevant industrial applications were prepared using surface functionalized hierarchical carbon fibers (f -CF), silane treated hollow glass microspheres (HGM), and a blend of polypropylene (PP) and maleic anhydride-grafted-styrene ethylene butylene styrene as the base polymer matrix. The f -CF were prepared by coating amine functionalized carbon nanotubes onto silane treated CF using an ultrasonic assisted electrophoretic deposition technique to improve fiber-matrix interfacial adhesion. For hybrid composition of 20 wt.% f -CF and 10 wt.% HGM, the tensile strength and modulus improved by ∼141 and ∼536% over neat PP while flexural strength and modulus increased by ∼118% and ∼583% respectively. Impact strength of 11.06 kJ/m² was obtained and uniform dispersion and distribution of f -CF and HGMs was observed in Scanning electron microscope (SEM) images. Desirable reduction in density and melt viscosity along with improvement in composite stiffness were observed due to addition of HGM filler. Compared to PP, the crystallization temperature increased by ∼12°C while a maximum decrease of ∼5°C in melting temperature was obtained for the hybrid composites. Crystallinity of the hybrid composites decreased with an evident β crystal formation brought in by the nucleation. [ABSTRACT FROM AUTHOR]