SPATIALLY-RESOLVED IN-SITU ANALYSIS OF POLYMER ADDITIVES BY 2-STEP LASER MASS-SPECTROMETRY

Two-step laser mass spectrometry has been employed for the direct in-s itu analysis of a variety of additives in different polymers. Because of the high sensitivity and optical selectivity of this approach, mass spectra can be obtained directly from the polymer material. The effec ts of CO2 laser irradiation (lambda=10.6 mu m) on samples of poly(oxym ethylene) (POM), poly(vinyl chloride) (PVC), polypropylene (PP), and p oly(ethylene terephthalate) (PET) and the mechanism of additive desorp tion have been examined. Several hydroxyphenylbenzotriazole (Tinuvin) UV stabilizers as well as a phenolic antioxidant (Santo White) were su ccessfully detected in typical industrial polymers. The detection limi t for Santo White antioxidant in POM was found to be as low as 28 ppm. Finally, depth profiling by stepwise CO2 laser ablation was carried o ut for a POM injection bar containing 0.1 wt % antioxidant. These spat ially resolved measurements established that the near surface concentr ation of antioxidant was 40% lower than in the bulk.