The effect of phosphorus based melamine-terephthaldehyde resin and Mg-Al layered double hydroxide on the thermal stability, flame retardancy and mechanical properties of polypropylene MgO composites

Abstract To improve the flame retardant efficiency of polypropylene (PP) new phosphorus based melamine-terephthaldehyde resin/magnesium oxide (MgO) composite (PMTR@MgO) was synthesized and was used along with sodium dodecyl benzene sulfonate (SDBS) modified Mg-Al layered double hydroxide (LDH) (SDLDH) for fabrication of PP composite and nanocomposites via melt blending method. The X-ray diffraction (XRD) and elemental mapping image results indicated that the nano-layers of LDH were uniformly dispersed in the PP matrix. The thermogravimetric analysis (TGA) results exhibited increasing in Tmax and char residue of the PP systems compared to the neat PP. The cone calorimeter test results indicated that the peak of heat release rate (pHRR) of PP nanocomposites with 20 mass% PMTR@MgO and 5 mass% of SDLDH were decreased to 553 KW/m2, from 834 kW/m² for neat PP. The total heat release (THR) was also decreased from 124 kJ/m2 for this sample to 104 kJ/m2, compared to the neat PP. According to the tensile test results, no significant change was observed in tensile strength of PP systems compared to the neat PP. However, for the sample containing 20 mass% PMTR@MgO and 5 mass% SDLDH, the young’s modulus was increased from 1.74 to 2.89 GPa, along with decrease in elongation at break.