Impact on Poly(Vinyl chloride) of trimethoprim schiff bases as stabilizers

Poly(vinyl chloride) PVC materials are used in many industrial and household outdoor applications which exposed to sunlight ultraviolet. This exposure motivates photo-degradation of the PVC and hence, reduces its life time and leads to undesirable physical properties. Herein, three new Schiff bases containing a trimethoprim moiety were investigated as photo-stabilizers for poly(vinyl chloride) against photo-decomposition. Merely 0.5% by weight of these Schiff bases was mixed with the polymer to form blend films with thickness of (40 µm). The films were irradiated for a period of time from 0 to 300 h and the irradiation impact on the PVC stabilization was monitored every 50 h. The efficiency of these additives as photo-stabilizers was investigated as a function of different parameters during the course of irradiation, such as weight loss, growing carbonyl and alkene groups as well as the surface morphology of the prepared films. The changes during irradiation were obvious for the blank films in comparison to the films containing the new additives. Therefore, these Schiff bases were found to act as photo-degradation inhibitors through reducing the elimination of hydrogen chloride molecules and as free radical scavengers or peroxide decomposers.