Establishment of an efficient and accurate thermal stability evaluation method based on machine vision and its application in PVC thermal degradation

Efficiency and accuracy are two major criteria for evaluating a test method. The thermal stability evaluation of PVC materials is now mainly based on the color change of PVC samples and Congo red test paper with manual observation as the main method, which is inefficient and imprecise. In this work, a machine vision-based evaluation system was developed to address the issues of low efficiency and poor accuracy in evaluating PVC thermal stability. During the degradation process, the color change recognition characteristics of PVC film samples and Congo red test paper were determined by analyzing the RGB SUM value and the R value, respectively. In comparison to manual observation, the machine vision-based evaluation system is more objective, efficient and accurate, and it is particularly suitable for evaluating PVC samples with similar thermal stability. Moreover, this study also resolves the issue of color mutation during the window period of the thermal stability test, and obtains the thermal degradation evolution trend through the color value change curve. This method holds great importance and application potential in guiding the processing or reprocessing of PVC materials. An efficient and accurate PVC thermal stability evaluation method based on machine vision was established.