Modification of poly(vinyl chloride) by mefenamic acid in presence of micro metallic oxides as self photostabilizer

Abstract

To date, many approaches have been made to stabilize the chemical structure of PVC when exposed to sunlight in outdoor usage. This work includes utilizing mefenamic acid (1 % per polymer weight) as a new photo stabilizer unit to adjust PVC to enhance resistance to change under UV exposure. Modification by attaching a new unit that contains an aromatic substance could protect the polymer from UV light due to its ability to absorb it. Positive results were obtained, as the interaction between mefenamic acid and PVC succeeded, using the FTIR technique to characterize the chemical structure of the product. FTIR spectrum of modified PVC shows the disappearance of (OH) band in the region above 3200 cm⁻¹ which is clear evidence that the connection between the polymer and mefenamic acid has happened through the OH group. In addition, we have investigated the influence of microparticle metallic oxides such as TiO₂, and Cr₂O₃, using only 1 % per modified polymer weight, on the photodegradation process of PVC materials. Several approaches have been utilized to investigate the photo-stability of studied materials which are FTIR functional group indices, weight-loss percentage, microscopic images, SEM, and AFM. They demonstrated that modified PVC gives better stability after exposure to UV in comparison to unmodified PVC. It's interesting to note that adding titanium dioxide to modified PVC has increased the amount of UV protection by acting as a UV shielding agent and blocking the light's path to the polymer. Thus, chromium oxide has demonstrated the opposite findings because it functions as a photo-catalytic reagent that accelerated the photo-degradation process. This result may be interpreted as the decomposition of waste PVC, which poses a major threat to the marine ecosystem.