FLOW SORPTION CALORIMETRY, A POWERFUL TOOL TO INVESTIGATE THE ACID-BASE CHARACTER OF ORGANIC POLYMER SURFACES

Flow sorption calorimetry (FSC) can be a useful tool to estimate the L ewis acid-base behaviour of the surface of organic polymers with less than 1 m(2)/g surface area. Polyethylene powders grafted with differen t amounts of acrylic acid have been chosen as samples. The surface of the powders was investigated by means of X-ray photoelectron spectrosc opy (XPS) at first and than brought into contact with the strong elect ron donor triethylamine in a special FSC measuring system. The heat of tile displacement isotherm together with the surface excess isotherm of triethylamine adsorbed onto the powders was determined. The results obtained with FSC and XPS were well correlated and gave a comprehensi ve picture of the acidic surface character of modified polyethylene.