Your questions are relevant, and indeed crucial, as to whether or not the materials in question provide the required isolation, safely
, down to the lowest frequency of interest for the design load.
Rather than get bogged down in the theoretical engineering (and dimensional units) may I suggest that you talk to a provider of the type of isolation products that you need? I am not sure what country you are in, however, here is a link to a UK company that specialises in products for isolation of structures:- Sylomer®
. I have studied noise and vibration isolation formally, however, it is not my specialisation and I
would wish to consult the professionals who have
made it their business to specialise in. After all, whatever you build, you need to have the confidence that it stays built.
There is a also a mine of technical information on this site, so if you do indeed wish to study the science more deeply I am sure it will be enlightening and open up additional lines of study. I hope this helps.