The combined effect of organic phoshphinate/ammonium polyphosphate and pentaerythritol on thermal and fire properties of polyamide 6-clay nanocomposites

The PA6/organoclay nanocomposites with organic phosphinate (OP) or ammonium polyphosphate (APP) and pentaerythritol (PER) flame retardant additives were prepared by melt blending process using a twin screw extruder. The structure and morphology of nanocomposites formed were studied by X-ray diffraction and transmission electron microscopy, which indicated that the clay (Cloisite 30B) was intercalated and/or exfoliated into the PA6 matrix. Thermal behaviour was evaluated by thermogravimetric analysis. The small shift in TG curve to lower temperature in the initial stage of degradation on addition of OP to PA6 shows the mild catalysing effect of OP on degradation of PA6 in the presence of clay whereas the onset temperature of degradation of PA6 on addition of equal amount of APP is found to be decreased by about 100 °C due to decomposition of APP and strong catalysing effect of phosphoric acid released from APP. The cone calorimeter test showed that on addition of 15% OP and 5% 30B to PA6 have reduced the PHRR by 77%. From thermal and combustion behaviour, PA6/OP/30B sample having 5% 30B and 15% OP is found more effective in reducing burning propensity of PA6.