Abstract
Rigid polyurethane foams filled with alumina trihydrate (ATH) exhibit, in comparison with non-filled foams, higher fire resistance when evaluated using the oxygen index (O.I.) test method.
The hydrate particle size within a certain range, does not have any effect on the oxygen index. The efficiency of the treatment increases with the concentration of ATH in the foam and, by using simultaneously flame resistant agents containing phosphorous, it is possible to obtain polyurethane foams with O.I. of the same order of those of polyisocyanurate foams.
Thermogravimetric analysis has shown that the ATH does not modify the thermal-oxidative degradation in the polymer.
The reduction in the smoke density of the ATH filled foams can be attributed to the action in gas phase of an intermediate in the ATH decomposition process and to the slower thermal-oxidative degradation of the polymer.
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