Effect of degree of sulfonation on the performance of adsorbent SAPO-34/S-PEEK composite coatings for adsorption heat pumps

A composite adsorbent coating on Al6061 aluminum substrate, based on SAPO34 zeolite filler and sulfonate poly (ether-ether ketone) (S-PEEK) matrix is proposed for sustainable energy saving technologies. The effect of sulfonation degree on the mechanical and physical chemical properties of the composite coating was assessed by synthesizing four batches with a degree of sulfonation of the matrix ranging from about 40%–50%. The degree of sulfonation was measured by titration and confirmed by thermogravimetry and FTIR analysis. For each batch of S-PEEK four coatings at increasing SAPO-34 filler content (in the range 80−95 wt.%) were realized. The composite coatings were homogenous and almost defect free. The mechanical performances, evaluated by scratch and pull-off tests, highlighted that all batches exhibited a suitable behavior for adsorption heat pumps application in mobile systems. Best results were observed by using a relatively high sulfonation time of S-PEEK. Obtained coating exhibited indeed very good adhesive and cohesive properties as well as high water vapor uptakes.