Derivative method allows to observe fine events that are usually hidden in the s DSC- I suggest to repeat the test again.

For porosity , try to do BET test or other related tests.

thanks

Please refer to the paper

Article Understanding the porosity dependence of heat flux through g...

May throw some light. It says that heat transfer coefficient decreases with increase in porosity till a certain extend.

I don't think DSC will work for that; whatever paper I went through, especially for polymers and polymer composite, generally crystallinity, activation energy, the heat of enthalpy, glass transition temperature, and crystalline temperature have been reported.