Distribution Analysis of Hydroxyl Groups in Polymers by Derivatization-Electron Probe X-ray Microanalysis

Abstract

An analytical method, referred to as “derivatization-electron probe X-ray microanalysis (XMA)”, has been developed to determine the distribution of small amounts of hydroxyl groups formed by the oxidation and the hydrolysis of polymers. A suitable condition for a derivatization reaction with hydroxyl groups in polymers was investigated. It was found that hydroxyl groups in polymers were derivatized selectively using gas-phase esterification with trichloroacetic anhydride (TCAA). The most suitable amount of TCAA in a 50-ml vial was 50 µl. After setting a sample in the vial without directly contacting the reagent, by heating the reagent and the sample at 60°C for 90 min, the highest reaction yield and selectivity were obtained. By derivatization-XMA using this reaction condition, a distribution measurement of small amounts of hydroxyl groups in the polymer became feasible. Actual applications to a depth analysis of degraded polyethylene and polyester proved that the present method is useful for the characterization of polymers and for the study of polymer degradation.