Structure/Property Relationships in Polypropylene Nanocomposites

  • Linda Thiraphattaraphun

Student thesis: Phd


In this work, structure/property relationships in polypropylene (PP) nanocomposites have been investigated for different nanofillers. Nanofillers of modified clay based on montmorillonite (MMT) and multi-wall carbon nanotubes (MWNTs) have been selected and incorporated to the PP matrix as either single nanofillers or hybrid nanofillers. Melt mixing via a twin screw extruder and further moulding by injection moulding have been used to prepare PP nanocomposites. Moreover, the dilution of MWNT masterbatch has been used to prepare PP/MWNT and PP/clay/MWNT nanocomposites. Three types of the PP nanocomposites have been obtained: PP/clay, PP/MWNT and PP/clay/MWNT nanocomposites. In all three types of the PP nanocomposites, alpha- and -PP crystals were observed in the wide angle X-ray diffraction (WAXD) patterns. Furthermore, the addition of nanofillers to the PP did not appear to affect the PP orientation. Slight PP orientation in the PP nanocomposites was shown in the two-dimensional X-ray diffraction (2D-XRD) patterns. Mixed clay layers were combined in the PP/clay and PP/clay/MWNT nanocomposites and investigated by WAXD as well as transmission electron microscopy (TEM). In addition, the aggregated and individual MWNTs were present in both the PP/MWNT and PP/clay/MWNT nanocomposites TEM images. A rough fracture surface with cracks was revealed from the scanning electron microscopy (SEM) images of the three types of PP nanocomposites. Polarized optical microscopy (POM) micrographs were taken at different temperatures during cooling in a hot stage and revealed the limitation of PP spherulite growth upon adding the nanofillers to the PP. The incorporation of nanofillers was found not to affect the glass transition temperature (Tg) of PP which investigated by dynamic mechanical analysis (DMA). However, the increase of both the peak melting temperature (Tm) and the peak crystallization temperature (Tc) of PP with adding the nanofillers was shown by differential scanning calorimetry (DSC) thermograms. In addition, the nanofillers also have been shown to act as nucleating agents. The thermal stability of PP in a nitrogen atmosphere was enhanced by the nanofillers when examined by thermogravimatric analysis (TGA). DMA and tensile testing were performed and showed that the nanofillers act as reinforcement for the PP. The distribution, orientation and deformation of MWNTs in the PP/MWNT and PP/clay/MWNT nanocomposites have been followed by Raman spectroscopy. Significant shifts of the Raman G'-band from the MWNTs was obtained during deformation of the MWNT nanocomposites and the hybrid clay/MWNT nanocomposites as the stress transfer from the PP matrix to the MWNTs has occurred. A correlation between calculated modulus from deformation and measured modulus from DMA and tensile testing has been found for PP/MWNT and PP/clay/MWNT nanocomposites. Finally, the PP nanocomposites have been considered for use in packaging applications.
Date of Award1 Aug 2014
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorRobert Young (Supervisor)


  • Raman spectroscopy
  • Mechanical properties
  • Clay
  • Polypropylene
  • Carbon nanotubes

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