Effect of aging on Raman spectroscopy analyses for flexible polyvinyl chloride

For polymers, including flexible polyvinyl chloride, aging processes play a crucial role in determining their long-term performance and function in various applications, especially those exposed to harsh environmental conditions. Aging effects are analyzed using several tools, including Raman spectroscopy, which is an effective tool for detecting molecular and structural changes in the polymer structure, providing a detailed analytical picture of the degradation behavior as a result of aging. The present study investigates the effect of aging on the structural properties of flexible PVC, taking into account the effect of sample thickness on the results of Raman spectroscopy. The results of 2 and 4 mm thick flexible PVC samples produced by extrusion, immediately after production and after one year of production, after being stored at room temperature without being exposed to harsh external conditions were analyzed to study natural aging. The characteristic Raman peaks associated with plasticizer leaching, chain splitting, and oxidation, as well as the SEM images, were analyzed and the obtained results correlated with the sample thickness. Thicker samples showed a lower rate of detectable chemical changes in the polymer structure, attributed to slower oxygen diffusion and lower chlorine release rate compared to thinner samples exposed to the same environmental conditions. Therefore, it is essential to consider the sample thickness factor in Raman spectroscopy analyses, as it greatly affects the sensitivity and interpretation of the results.