Influence of long-chain alkylamine-modified graphene oxide on the crystallization, mechanical and electrical properties of isotactic polypropylene nanocomposites

• Alkyl amines with varying chain length are grafted to graphene oxide (GO) surface.
• Grafting of alkyl amines are corroborated using standard characterization tools.
• Improvement in properties are observed on loading modified GO in PP nanocomposites.
• Grafting of alkylamine in GO resulted in strong interfacial interactions in PP matrix.

Long chain alkylamines with varying chain length were chemically grafted to the graphene oxide (GO) surface via two types of reactions: (i) amidation reactions between amine groups and carboxylic acid sites of GO and (ii) reactions between amine and epoxy groups on the surface. Successful grafting of alkylamines was confirmed using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Raman spectroscopic studies revealed that grafting of long chain alkylamines does not affect the graphitic structures of GO. These chemically modified GOs with varying loading amounts were incorporated in a polypropylene (PP) matrix in the presence of maleic anhydride-g-polypropylene (MA-PP) compatibilizer through a melt processing technique. X-ray diffraction (XRD) and differential scanning calorimetric (DSC) studies revealed that the loading of alkylamine modified GO resulted in significant improvement in crystallization characteristics with significant variation in orientation parameters of crystalline phases on increasing the chain length of the grafted alkylamines. Owing to the strong interfacial interactions between alkylamine-grafted GO and polymer, significant enhancement in mechanical and electrical properties was observed when compared to pristine, GO-filled PP composites.

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