Thermal stability, flame retardancy and rheological behavior of ABS filled with magnesium hydroxide sulfate hydrate whisker

Abstract

Halogen-free and flame-retardant acrylonitrile–butadiene–styrene copolymer (ABS) composites were prepared using magnesium hydroxide sulfate hydrate (MHSH) whisker as a flame retardant, and the effect of zinc stearate (ZnSt2) as a dispersion additive on the morphology and properties of the ABS/MHSH composites was studied. The morphology observation by using scanning electronic microscope (SEM) indicates that the addition of zinc stearate could improve the dispersion of the MHSH whisker in ABS matrix. Cone analysis results show that the heat release rate (HRR) and mass loss rate (MLR) of the composites decrease considerably with increasing MHSH whisker content. The composite with zinc stearate has lower HRR than the composite without zinc stearate, indicating the better dispersion of MHSH whisker could improve the flame retardancy of ABS composites. SEM observation results show that the char residue of ABS/MHSH composites retain its fibrous appearance. Thermogravimetric analysis (TGA) shows that the presence of MHSH enhanced thermal stability of the composites obviously. The viscoelastic behavior of the composites was measured by using a parallel plate rheometer. With increasing MHSH whisker content, the viscosity, storage modulus of the composites increase at low frequency zone, and ABS/MHSH composites exhibit more distinct solid-like response at terminal zone than ABS. The presence of zinc stearate leads to slight increases in the storage modulus.