New poly(ether ether ketone) (PEEK) based composites have been fabricated by the incorporation of single-walled carbon nanotubes (SWCNTs) using melt processing. Their structure, morphology, thermal and mechanical properties have been investigated. Scanning electron microscopy observations demonstrated a more uniform distribution of the CNTs for samples prepared following a processing route based on polymer ball milling and CNT dispersion in ethanol media. Thermogravimetric analysis indicated a remarkable improvement in the thermal stability of the matrix by the incorporation of SWCNTs. Differential scanning calorimetry showed a decrease in the crystallization temperature with increasing SWCNT content, whilst no significant changes were observed in the melting of the composites. The
Several samples of palladium-loaded single-wall carbon nanotubes and palladium-loaded MAXSORB activated carbon were prepared by means of the reaction of the raw carbon support with Pd2(dba)3.CHCl3. When carbon nanotubes were used as the support, the palladium content in the samples reached 13-31 wt % and fine particles of 5-7 nm average size were obtained. In the case of the samples with MAXSORB as the support, the palladium content was higher (30-50 wt %) and the particle size larger (32-42 nm) than in the nanotube samples. At 1 atm and room temperature, the hydrogen capacity of the palladium-loaded samples exceeds 0.1 wt % and is much higher than the capacity of the raw carbon supports (less than 0.01 wt %). The maximum hydrogen capacity at 1 atm and room temperature was found to be 0.5 wt %. A maximum hydrogen capacity of 0.7 wt % was obtained at 90 bar in a palladium-loaded MAXSORB sample, while the capacities for the raw carbon nanotubes and MAXSORB at the same pressure were 0.21 and 0.42 wt %, respectively. At low pressure, it was observed that the H/Pd atomic ratios in the palladium-loaded samples were always higher than in the bulk Pd. The spillover effect is considered as a possible cause of the high H/Pd atomic ratios. On the other hand, the effect of the pressure increase on the spillover was observed to be very low at high pressure and room temperature.
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