I'm currently studying closed cell foams for insulation. At the company where I'm working I was asked if the material holds the same fire resistance once shaped and if they can sell their products with the same UL 94 degree as the one stated on the unshaped material's datasheet. I'm pretty sure the result won't change but I'd like to find some scientific evidence about this. I'm specifically looking for information about foamed closed cell polyethylene, which is bought in rolls and then thermally shaped with a vacuum mold.
Dear Ilaria Dal Maso, I think the thermal conductivity will change as cells collapsing and gas escaping for sure they took place. Another factor may also contribute to the change of the thermal conductivity is that the structure (chain orientation/relaxation, crystallinity, ...) of PE matrix will change. My Regards
Hi;
The vacuum molding process makes the expanded polyethylene more flammable due to the decrease in thermal conductivity that could result, as mentioned by Abdelkader BOUAZIZ to the coalescence and collapse of a certain fraction of the cells during the thermal forming of the materials.
With my best regards
Thank you for your answers, I agree with both of you and I was wondering whether the change in thermal conductivity and cell shape would be great enough to change the flammability class or not. I'll suggest taking UL 94 tests both on raw material and on shaped one. Your help was very much appreciated! Doufnoune RACHIDA Rachida Abdelkader BOUAZIZ
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