Getting the right thermal and mechanical properties for rubber is difficult, since there are so many factors that come into play. Obviously, things like cure time and temperature matter, but even with those held constant, there can be huge variations from one material to the next related to temperature, strain level, loading rate, and type (obviously, there's tensile and compression tests, but there are many others also). I know that there are various on-line databases which claim to have generic rubber constants and coefficients, but in my experiences, they usually differ quite a bit from your own material when you try to use these numbers for FEA analysis. To really get a hold of elastomer properties, you need to get your material tested, and use that data for FEA. Most programs (ABAQUS, MSC.Marc, ANSYS) all do a pretty good job integrating data by now, and various labs (such as Axel Products) work closely together with them to get precisely this type of data.