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This paper evaluates the use of an air based atmospheric pressure plasma jet for the activation of carbon fibre epoxy composites. In addition the performance of the jet in the removal of a 5-8 nm thick layer of FreKote 710-NC from the composite surface prior to heat-cured epoxy adhesive bonding was also investigated. The plasma treated composites were examined using thermal infra-red imaging, WCA, profilometry and SEM. A reflectance-IR technique was used to monitor the removal of FreKote as well as changes in the functional chemistry of the plasma treated composite surface. The optimised plasma pre-treatment conditions were identified which help to maximise composite-to-composite adhesive bond strength based on LST. This involved a treatment at a 14 mm nozzle to composite distance and scan rate of 30 mm/s. The air plasma process was bench marked against a manual methanol solvent wipe process, for the removal of FreKote. Both the plasma and the solvent wipe treatments yielded similar composite to composite bond strengths, demonstrating that both were successful in the removal of the FreKote. A comparison was also made between the plasma treated composite and a composite which had been grit blasted using 50 µm aluminium oxide grit. A 7% enhancement in lap-shear strength was achieved with the plasma treatment compared to grit blasting. [ABSTRACT FROM AUTHOR]

Abstract: The hybrid copper oxide–copper sulfate water-splitting thermochemical cycle involves two principal steps: (1) hydrogen production from the electrolysis of water, SO2(g) and CuO(s) at room temperature and (2) the thermal decomposition of the CuSO4 product to form oxygen and SO2, which is recycled to the first step. A four-reaction version of the cycle (known in the literature as Cycle H-5) was used as the basis of the present work. For several of the four reactions, a rotating batch reactor sequence is proposed in order to overcome equilibrium limitations. Pinch technology was used to optimize heat integration. Sensitivity analyses revealed it to be economically more attractive to use a 10°C approach to minimize heat loss (rather than 20°C). Using standard Aspen Plus features and the Peng–Robinson equation of state for separations involving oxygen and sulfur oxides, a proposed flowsheet for the cycle was generated to yield “Level 3” results. A cost analysis of the designed plant (producing 100 million kmol/yr hydrogen) indicates a total major equipment cost of approximately $45 million. This translates to a turnkey plant price (excluding the cost of the high-temperature heat source or electrolyzer internals) of approximately $360 million. Based on a $2.50/kg selling price for hydrogen, gross annual revenue could be on the order of $500 million, resulting in a reasonable payback period when all capital and operating costs are considered. Previous efficiency estimates using Level 1 and Level 2 methods gave the process efficiency in the neighborhood of 47–48%. The Level 3 efficiency computation was 24–25% depending on the approach temperature used for recuperation. If the low quality heat rejected by the process can be recovered and used elsewhere, the Level 3 analysis could be as high as 51–53%. [Copyright &y& Elsevier]