THERMAL-DECOMPOSITION BEHAVIOR OF POLYAMIDE FIRE-RETARDANT COMPOSITIONS CONTAINING MAGNESIUM-HYDROXIDE FILLER

The thermal analysis of polyamides modified with magnesium hydroxide f ire retardant filler is studied. Using combined TGA, DSC EGA and on-li ne FTIR techniques, it is shown that on thermal breakdown magnesium hy droxide exerts a significant pro-degraditive action on polyamides, att ributed to water release and resulting hydrolysis of the polymer chain . Evolved gases released are shown to be water, carbon monoxide, carbo n dioxide, ammonia and various hydrocarbon fragments. Similar results are obtained for both filled and unfilled PA compositions. However it is evident that in PA-6,6, polymer degradation occurs before magnesium hydroxide breakdown, whereas there is much greater overlap between th ermal decomposition of PA-6 and the fire retardant filler.