Functionalized sepiolite intercalated graphene nanostructure reinforced polypropylene composites: Colloids and Surfaces A: Physicochemical and Engineering Aspects

The present work developed hybrid polypropylene (PP) ternary composites using PP with different contents of amine-functionalized sepiolite intercalated graphene (f-Sep-Gr) nanofillers through the melt blending method. The amine functionalization on sepiolite intercalated graphene (Sep-Gr) nanostructure was carried out using 3-amino propyl triethoxyl silane. Fourier Transform-Infra Red (FT-IR), X-ray Photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis confirmed the successful functionalization of the amine group into Sep-Gr. Transmission Electron Microscopy (TEM) analysis also confirmed that the amine functionalization didn't disturb the Sep-Gr morphology. Maleic anhydride graft polypropylene (PP-g-MA) was employed as an interfacial compatibilizer to enhance the dispersion of f-Sep-Gr into the continuous PP phase via a perfect covalent bond interaction. X-ray diffraction (XRD) analysis showed a complete distribution of f-Sep-Gr into the PP/PP-g-MA blend matrix, and the intercalated structure of f-Sep-Gr was not adversely disturbed in the composite. Melt rheological analysis revealed that the composite consisting of the lower content of f-Sep-Gr (0.5 wt%), resulting in a viscous behavior, and a further increase in the content of f-Sep-Gr into the PP/PP-g-MA blend showed viscoelastic solid-like behavior. Differential scanning calorimetry (DSC) analysis revealed that the f-Sep-Gr did not accelerate the melt-crystallization process of PP. In addition, thermogravimetry analysis (TGA) showed that the thermal stability of PP/PP-g-MA/f-Sep-Gr composites improved as a function of f-Sep-Gr content. A small amount of f-Sep-Gr (0.5 wt%) increased Young's modulus and impact strength of the PP matrix, which is about 123% and 266%, respectively, compared to pure PP. TEM analysis ensured the incorporation of a small fraction of f-Sep-Gr into the blend matrix, forming a three-dimensional network structure in the composite.