Halloysites/polypropylene nanocomposites with different nanotubes contents were prepared by diluting a masterbatch containing 30 wt.% halloysites with polypropylene (PP). Unmodified (HNTs) and quaternary ammonium salt treated (QM-HNTs) halloysite nanotubes were used. Both degree of crystallinity and crystallization temperature increase upon addition of halloysites into PP, thus indicating a potential nucleation effect induced by the nanotubes. An homogeneous distribution and dispersion of nanotubes was observed throughout the PP matrix, with a slightly better dispersion in the case of modified QM-HNTs compared to unmodified HNTs. Mechanical tests in tension, bending and notched impact demonstrated that strength and modulus of the nanocomposites significantly increase with addition of halloysites without significant loss of ductility. An halloysite content of 6 wt.% appears as an optimum. Modified halloysites (QM-HNTs) lead to globally better performances due to strong interfacial interaction between the polymer matrix and the nanotubes

Multi-wall carbon nanotubes (MWNTs) filled polypropylene (PP) nanocomposites were prepared through diluting a PP/MWNT masterbatch in a PP matrix by melt compounding with a twin screw extruder. Polypropylene grafted maleic anhydride (PP-g-MA) was used to promote the carbon nanotubes dispersion. The effect of PP-g-MA addition on the rheological, mechanical and morphological properties of the nanocomposites was assessed for different MWNTs loadings. Scanning electron microscopy (SEM) has shown that nanotubes are distributed reasonably uniformly. A better dispersion and good adhesion between the nanotubes and the PP matrix is caused by wrapping of PP-g-MA on MWNTs. When PP-g-MA is added, dynamic moduli and viscosity further increases compared to PP/MWNT nanocomposites. The rheological percolation threshold drops significantly. Tensile and flexural moduli and Charpy impact resistance of the nanocomposites also increases by the addition of PP-g-MA. The present study confirms that PP-g-MA is efficient to promote the dispersion of MWNTs in PP matrix and serves as an adhesive to increase their interfacial strength, hence greatly improving the rheological percolation threshold and mechanical properties of PP/MWNT nanocomposites

In this work, three-dimensional (3D) printing system based on fused deposition modeling (FDM) is used for the fabrication of conductive polymer nanocomposites. This technology consists in the additive multilayer deposition of polymeric nanocomposite based on poly(lactic acid) (PLA) and graphene by means of a in house made low-cost commercial bench-top 3D printer. Further, 3D printed PLA/graphene nanocomposites containing 10 wt% graphene in PLA matrix were characterized for their mechanical, electrical and electromagnetic induction shielding properties of the nanocomposite. Furthermore X-ray computed micro-tomography analyses showed that printed samples have good dimensional accuracy and are significantly closer to the predefined design and the results of scanning electron microscopy (SEM) printed samples showed a uniform dispersion of graphene in PLA matrix The proposed material has uniquely advantageous when implemented in 3D printed structures, because incorporation of multifunctional graphene has been shown to substantially improve the properties of the resulting nanocomposite.