Investigation on thermal properties and flame retardancy of glass-fiber reinforced poly(butylene succinate) composites filled with aluminum hypophosphite and melamine cyanurate

Herein, this paper perhaps reports for the first time that a series of glass fiber reinforced poly(butylene succinate) composites (GRPBS) using the flame-retardant system composed of aluminum hypophosphite (AHP) and melamine cyanurate (MC) are fabricated by melt blending method. When the composite is loaded of 20 wt% AHP/MC with mass ratio about 2:1, it achieves UL-94 V-0 rating with the value of limited oxygen index (LOI) significantly increasing to 30%. Meanwhile, the thermo-gravimetric analysis also well proves that the composite can produce more char residues because of the addition of AHP, however, its thermal stability would slightly decreases. In addition, the results obtained from micro-scale combustion calorimetry testing reveal that total heat release and peak of heat release rate for GRPBS composites combined with AHP and MC both significantly reduce, and the similar results are easily found in cone calorimeter testing. Additionally, the residues after LOI testing are further investigated by Fourier transform infrared spectrometry and scanning electron microscopy, which definitely confirm the formation of the compact char layer with crater-like structure. Mechanism analysis indicates the significant enhancement of flame-retardant efficiency principally benefits from the cooperative work dominated by AHP and MC.