Effect of Ammonium Polyphosphate in Combination with Zinc Phosphate and Zinc Borate on Thermal Degradation and Flame Retardation of Polyamide 6/Clay Nanocomposites

In this paper, PA6/clay nanocomposites containing flame retardant additives such as ammonium polyphosphate (AP760), zinc phosphate and zinc borate were prepared by melt blending method. The resulting nanocomposites were characterized by X-ray diffraction and Fourier Transform Infrared spectroscopy (FTIR). X-ray diffraction patterns indicated the formation of intercalated structure in PA6 nanocomposites. FTIR analysis of residues obtained at 400°C revealed the formation of aromatic carbonaceous char and the presence of nitrile chain ends in the degradation products of PA6 composites. Thermogravimetric analysis and UL-94 test were performed to determine thermal stability and flammability of nanocomposites. Synergistic effects were observed on addition of zinc borate with AP760 in PA6/clay nanocomposites for increasing thermal stability by 38°C. The PA6/AP760 composite containing 20 wt% of AP760 without clay achieved flame retardancy with V-2 rating in UL-94 test.