In this study, the potential of conductive polymer composites based on graphite‐filled polymer blend for achieving high‐performance polymer electrolyte membrane fuel cell (PEMFC) bipolar plates (BPs) was investigated. Maleic anhydride grafted polypropylene‐compatibilized polypropylene (PP)/epoxy blend was selected as the matrix due to its good combination of mechanical strength and ductility, and its potential to form a co‐continuous morphology, which promotes the selective distribution of the filler in one of the polymer phases and formation of high electrical performance‐CPCs. PP/epoxy/graphite composites, with varying amounts of graphite, were prepared by melt mixing followed by compression molding, and then characterized. The results obtained showed that in‐plane and through‐plane electrical conductivities increased with an increase in graphite content while the flexural strength increased with graphite content up to a maximum value of 54.36 MPa at 70 wt% graphite, and then decreased to 40.16 MPa at 80 wt% graphite. The PP/epoxy/80 wt% graphite composite has the most promising combination of properties for BP application. While the PP/epoxy/80 wt% graphite composite exhibited in‐plane and through‐plane conductivities (68.03 and 3.211 Scm−1, respectively) that are still below the targets set by the United States Department of Energy (DOE), its flexural strength and modulus (40.16 and 11.47 GPa, respectively), density (1.77 gcm−3), and water absorption (0.098%) satisfy the DOE targets.
A series of developments have been made in synthesizing Carbon Nanotubes (CNTs) by Catalytic Vapour Deposition (CVD) methods since its discovery as a possible route to the large scale and high quality production of CNTs. In this study, CNTs were synthesized continuously in a swirled floating catalytic chemical vapour deposition reactor using acetylene as carbon source, ferrocene as catalyst, with argon and hydrogen as carrier gases within the temperature range of 900-1050 degrees C. The effects of pyrolysis temperature, acetylene flow rate, hydrogen flow rate, and ratio of flow of acetylene to hydrogen on the rate of production of CNTs were investigated. The CNTs produced were purified with dilute nitric acid and the nature and quality of the CNTs were analysed by TEM, Raman spectrometer, EDX, and TGA. Results obtained revealed that a mixture of single and multi wall carbon nanotubes were produced continuously with a maximum yield rate of 0.31 g/min at 1000 degrees C and a flow ratio of acetylene to hydrogen of one to five.
Conductive polymer composites (CPCs) are very promising candidate materials for bipolar plates (BPs) in polymer electrolyte membrane fuel cells (PEMFCs). However, a major challenge facing application of CPCs in PEMFC BPs is the difficulty in achieving high electrical conductivity while maintaining adequate mechanical strength. Therefore, a good balance between electrical conductivity and mechanical strength is critical in the development of high-performance CPC BPs. In this study, CPCs consisting of polypropylene (PP)/epoxy blend filled with graphite were investigated for application as BP material, which will combine electrical conductivity and mechanical strength that meet the performance requirements for PEMFC BPs. The CPCs, with 30 – 80 wt% graphite powder, were produced by melt mixing followed by compression molding. The morphology, in-plane electrical conductivity, and flexural strength of the composites were investigated using the scanning electron microscopy, four-point probe method, and three-point bending test, respectively. The results obtained were compared with the technical targets for PEMFC BPs by the United States Department of Energy (DOE). All the PP/epoxy/graphite composites exhibited flexural strength that satisfies the DOE target of > 25 MPa while the composite with 80 wt% graphite content showed the best in-plane electrical conductivity.
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