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Fourier transform infrared (FTIR) spectroscopy and wide‐angle X‐ray scattering (WAXS) investigations of isotactic polypropylene (iPP)–vapor‐grown carbon nanofiber (VGCNF) composites containing various amounts of VGCNFs ranging between 0 and 20 wt %. are reported. The FTIR investigations were focused on the regularity bands of iPP. The FTIR data indicated a drop in the isotacticity index as the concentration of nanofibers was increased; this suggested a decrease in the crystallinity. WAXS measurements revealed a dominating α1 phase, with a small admixture of γ phase or mesophase. The loading of the polymeric matrix with carbon nanofibers (CNFs) did not induce significant changes in the morphology of the polymeric matrix. A weak decrease in the size of α crystallites upon loading of CNFs was noticed. The experimental data obtained by FTIR spectroscopy supported the WAXS data. Spectroscopic data (a drop in the isotacticity index as estimated by FTIR spectroscopy and the ratio between the crystalline and total areas of WAXS lines assigned to iPP) failed to confirm the enhancement of the degree of crystallinity of polypropylene upon loading by nanofibers. However, whereas both techniques can identify with a high accuracy vibrations in ordered domains (FTIR spectroscopy) and the crystalline structure, including the lattice parameters and the size of crystallites (WAXS), difficulties in the correct assessment of the baseline and of amorphous components may result in important errors (typically >5%) in the estimation of the degree of crystallinity of the polymeric component. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Nanocomposites have been obtained by dispersing various amounts of vapor grown carbon nanofibers within isotactic polypropylene. Thermal investigations done by differential scanning calorimetry and dynamic mechanical analysis revealed the effect of the vapor grown carbon nanofibers on the melting, crystallization, α, and β relaxations. Direct current electrical features of these nanocomposites have been investigated and related to the thermal features of these nanocomposites. The effect of the loading with carbon nanofibers on the electrical properties of these nanocomposites is discussed within the percolation theory. The percolation threshold was estimated at about 5.5% wt carbon nanofibers. The temperature dependence of the direct current conductivity is analyzed in detail and it is concluded that the electronic hopping is the dominant transport mechanism. A transition from one‐dimensional hopping towards a three‐dimensional hopping was noticed as the concentration of carbon nanofibers was increased from 10% wt to 20% wt carbon nanofiber. The possibility of a differential negative resistivity is suggested. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45297.

Raman spectroscopy investigations on nanocomposites obtained by dispersing halloysite within isotactic polypropylene are reported. A detailed analysis of the modifications of the regularity band associated to the polymeric matrix is presented. The Raman lines assigned to the polymeric matrix are broadened and weakened as the loading with halloysite is increased. The analysis of Raman lines indicates that the polymeric matrix becomes less crystalline upon the loading with halloysite and that the nanofiller is experiencing a weak dehydration upon dispersion within the polymeric matrix, probably due to the related thermal processing used to achieve the dispersion of halloysite.