Polymer Photodegradation Followed by Infrared: A Tutorial

Abstract

Since the first scientific study published by August Wilhelm Hofmann at 1861, where he found the role of oxygen in the degradation of weathered materials, a lot of progress has been made regarding the understanding of the mechanisms that lead to the polymer degradation. In this work, it was proposed a protocol to study the photochemical degradation of polymers using as probes the absorption of hydroxyl, carbonyl, and vinyl, as followed by the infrared spectroscopy. As a result, it is possible to assess the evolution of the chemical groups associated with the polymer degradation comparing the absorption as a function of degradation time, for films with the same thickness, or comparing the absorption of the chemical groups associated with the polymer degradation related to a reference band, for polymer or pieces with different thicknesses. We discuss also the general mechanism of photodegradation for polyolefins; the difference between using the area of the band vs the intensity of the peak; and the construction of a lab-made ageing chamber, and the role of each part.