Thermal degradation and combustion behaviors of flame retarded glass fiber reinforced polyamide 6 composites based on cerium hypophosphite

In this work, cerium hypophosphite (CeHP) was synthesized and characterized by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) test. CeHP presented rod-like morphological feature with good thermal stability. Subsequently, CeHP was added into glass fiber reinforced polyamide 6 (GFPA) to develop flame retardant glass fiber reinforced polyamide 6 composites (FR-GFPA). The flame retardancy of FR-GFPA composites was characterized by limiting oxygen index (LOI), Underwriters Laboratories 94 testing (UL-94), microscale combustion calorimeter, and cone calorimeter test. FR-GFPA composite with 20 wt% CeHP loading passed UL-94 V0 rating with a high LOI of 26.5 vol%. Cone Calorimeter test showed that peak of heat release rate (PHRR) and total heat release (THR) of FR-GFPA composites were reduced 27.1% and 21.1% compared with those of GFPA. The mechanical measurement revealed that the tensile strength first increased and then decreased with the increase of CeHP loading. With 15 wt% CeHP loading, the tensile strength of FR-GFPA composite was 43.0% higher than GFPA. TGA and char residue characterization revealed that the addition of CeHP could significantly promote the formation of condensed char residue. The FR-GFPA composites obtained herein exhibited superior combined properties of fire resistance, thermal stability, and mechanical properties, demonstrating that CeHP will be a promising candidate for preparing high performance polyamide composites. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers