SURFACE EFFECT OF FLAME TREATMENTS ON POLYPROPYLENE .2. SIMS (FABMS) AND FTIR-PAS STUDIES

Static secondary ion mass spectroscopy (fast atom bombardment mass spectroscopy), (SIMS (FABMS)) and fourier transform infrared-photo-acoustic spectroscopy (FTIR-PAS) studies have been performed on samples of polypropylene subjected to different flame treatments. SIMS spectra can identify the site of oxidation in the methyl pendant groups because of the decrease in the intensity of the methyl fragment in positive-ion spectra. The behaviour of surface concentrations of hydroxyl, formyl and carboxyl groups as a function of the number of flame treatments has also been observed, leading to an hypothesis supporting the effectiveness of hydroxyl groups in promoting paint adhesion. FTIR-PAS spectra did not show evident changes on passing from untreated to flame-treated samples. This negative evidence implies a limited depth of oxidation of some 10 to 20 nm.