Expanding Foam Insulation

Just as it sounds, open cell foam allows flow through its cells and therefore does not make a very good choice in some applications. So, you need to include some comments as to your application requirements.

Glass fiber could also be considered as open cell but it is not a foam and it has very different properties but it can be compressed for insertion and then allowed to expand.

Chemical makeup and properties will vary widely for the temperature range you may need to cover. So, if you want good answers, you will need to include more information such as wall thickness, temperature difference, humidity factors, etc.