Dear Kaisan, proofs and methods for heat and liquid ageing of rubber seals are normed by international Standards like ISO 1817 and ASTM D 471-95. Usually the experimental setup are based on DSC (differential scanning calorimetry). Regarding accelerated ageing estimation, the most used method is Arrhenius formula.
Have a look to this https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwj1m-bM9MXXAhWBiRoKHVISDWUQFghdMAk&url=http%3A%2F%2Fprod.sandia.gov%2Ftechlib%2Faccess-control.cgi%2F2007%2F076781.pdf&usg=AOvVaw2NC6JdRkiTtA1_R4bCc4Cb