A preliminary investigation into the apparent abhesive effect of stearic acid on cured silicone elastomer

The effect of addition of small amounts of stearic acid on the adhesive properties of polydimethylsiloxane (PDMS) was investigated. Stearic acid reduced the peel strength of bonded aluminium samples with the joint weakening effect increasing with increased loadings. Surface analysis of the peeled surfaces was carried out using XPS, SSIMS and FTIR. This showed that stearic acid did not form a weak boundary layer at the metal–polymer interface as would traditionally be expected. Local Force Microscopy confirmed this, as the surface adhesion of the PDMS increased, rather than decreased, on addition of stearic acid.