Vacuum Properties of the Open Cell Foams

To fully exploit the insulating performances of the open cell PU foams, pressure in the panel has to be kept preferably below 1.0 Pa during its life. To achieve this demanding target, the foam must be 100% open celled and with a very low outgassing rate. 

In spite of the increasing use of open cell PU foam, data from the literature on its vacuum properties are quite scarce. 

To estimate the outgassing contribution, specific tests can be carried out using high vacuum benches equipped with a quadrupole mass spectrometer. 

For each gas species, the amount released by the sample at a given time is obtained by simply multiplying the test volume (V) by the gas partial pressure (q (t) = Pi V, qi(t) is the outgassing rate (Pa-l/h) at time t, P being the measured i-th partial pressure). 

The experimentally determined q value for each gas species can be interpolated over time according to the semi-empirical law quoted in the literatnre [16]  

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