Photodegradation and Photooxidation Processes

Interest in polymer photodegradation and oxidation processes is still widespread. Several reviews in this area have 

---

Stabilization of organic coatings against photodegradation and photooxidation is a subject of obvious practical importance. The fundamental processes involved, including spectroscopy, photochemistry, energy transfer, and secondary reactions, have attracted scientists from diverse disciplines into this field. 

Volume 14 deals with all aspects of polymer degradation, classified on the basis of the method of initiation for the process. Thus, Chapter 1 covers thermal degradation, Chapter 2 radiolysis initiated by high-energy radiation such as X- and 7-radiation and electrons, Chapter 3 photodegradation arising from exposure of polymers to visible or ultraviolet radiation and Chapter 4 discusses oxidative degradation, oxidation and photooxidation. 

Abstract A brief overview on the main photoprocesses applied to the treatment of water and wastewater is presented. The photodegradation methods that have been applied to the oxidation of organic pollutants are described. A review on advanced oxidation processes (AOP s) and photooxidation mechanisms in homogeneous and heterogeneous solution is presented and some practical applications discussed. Combinations of biological and chemical treatments are considered to be a good approach to improve the removal efihciencies and reduce costs. 

The photodegradation of para-aramid in an 0 atmosphere allows the differentiation between the accelerated experimental photooxidative conditions from its usual daylight exposure effects. This study illustrated an estimation of the rates of photooxidation of a commercial para-aramid product (i.e., DuPont s Kevlar-29 woven fabric) based on the oxygen-18-labelled carbon dioxide ( CC and CC ) decarboxylated from the sample. The oxygen-18-labelled atoms, which are inserted in the macromolecules, were analyzed for the photodegradation processes. This technique also allows the radial l O-distribution measurement from the fiber surface toward the fiber center. 

In the present paper, we describe how photodegradation of low density polyethylene films was enhanced by uniaxial elongation. An explanation of the enhancement process is given based on the photooxidation and deformation mechanisms, and the photodegradation products. 

---