How much high temp. AIS profile can withstand? What is the melting point of uPVC before a window will give away?

PVC has Vicat softening temperature of 78 to 82 deg. C after which its molecular structure starts degrading. After this point the profile will loose its shape resulting in failure of window. PVC starts to decompose when the temperature reaches 140 °C, with melting temperature
starting around 160 °C. The linear expansion coefficient of rigid PVC is small and has good flame retardancy, the Limiting oxygen index (LOI) being up to 45 or more.