Effect of Dispersion Method on the Thermal and Wear Properties of Graphene Nano Platelet Filler Modified Polyurethane

  • Author / Creator
    Al-Rahman,Mohammad Rizwan
  • Polyurethane is used in various applications, for example as liner for piping systems, pipelines, pressure vessels and valve trims, where it may be subjected to elevated temperature as well as high rate of erosion. At elevated temperatures, polyurethane erodes at a faster rate. In this research, the aim was to investigate the erosive wear and improve the thermal conductivity of polyurethane and find a correlation between the thermal and wear properties of polyurethane that is reinforced by graphene. Two different dispersion methods (Three Roll Milling and Sonication Dispersion) were explored to find their effect on the overall thermal and wear performance of polyurethane, as well as the quality of distribution and exfoliation of the graphene filler nanoparticles. Thermal conductivity and wear performance of polyurethane at elevated temperatures were evaluated and compared for both three roll milling and sonication dispersion process separately. Experiments were performed with a filler loading ranging from 0% to 4% by weight and at temperatures of 22ºC, 60ºC and 100ºC. Dispersion by three roll milling method provided a higher degree of alignment, as determined by characterizing the samples using XRD analysis and SEM imaging, compared to that under sonication method. The alignment of graphene particles affected the thermal conductivity of polyurethane, which resulted in an anisotropic higher thermal conductivity in the axial direction. Overall, a higher thermal conductivity was achieved with an increase in graphene filler content. The bulk isotropic thermal conductivity of the samples prepared by three roll milling method also increased for all the three tested temperatures with increase in filler loading. However, with an increase in temperature, there was no noticeable change in the thermal conductivity. With temperature rising from 22ºC to 100ºC, the erosion rate of pure polyurethane increased by nearly 30-fold. By embedding graphene as a reinforcement, the final erosion rate, when compared to that of pure polyurethane at 100°C, was reduced by 76.14% when using three roll milling method for dispersion, and by 71.3% when using sonication process for dispersion. This suggests that samples prepared by three roll milling method demonstrated better performance with respect to wear due to reinforcing particles being aligned in the through thickness direction in the samples. Evaluation of the surface morphology indicated that the pure polyurethane samples underwent ductile erosion with plastic deformation. By dispersing graphene, the mode of erosion had a ductile to brittle transition. Thus, it was found that graphene can be used as a reinforcement to increase the wear performance of polyurethane at elevated temperatures. Thus, this finding also opens new possibilities for use of polyurethane in other applications.

  • Subjects / Keywords
  • Graduation date
    Spring 2020
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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