Upon increasing the test temperature, a gradual decrease in flexural strength occurs; in fact, a decrease of 72.5% is reported when the temperature reaches 90 Â°C, as compared to the room temperature samples. Table 1. Properties of epoxy and polyester resins.he relationships between the test temperature and flexural strength of both formulations of polymer mortar are presented in Figures 4 and 5.According to Figure 4, between room temperature and 50 Â°C, only a loss in the ultimate flexural strength is observed.