Comparative study on the thermal stability, flame retardancy and smoke suppression properties of polystyrene composites containing molybdenum disulfide and graphene

Abstract

As a graphene-like layered nano-material, molybdenum disulfide (MoS₂) has gained intensive attention from the materials fields. In our research, MoS₂ and graphene sheets (GNS) were used as nanofillers to prepare polystyrene (PS) composites by masterbatch-melt blending. The morphology, thermal stability, fire resistance and smoke suppression properties of the PS composites were studied. The aim of our present study is to compare the effect of MoS₂ and GNS on the thermal stability, fire resistance and smoke suppression properties of the PS composites. The cone test results indicate the PS/GNS composites exhibited superior flame retardance over PS/MoS₂ composites. The results from TGA exhibits that the addition of MoS₂ improved the thermal stability and char residues of the PS composites more obviously, When adding 3 wt% MoS₂, T_−5%, T_−10% and T_−50% of the composites are increased to 371, 390 and 428 °C, which are 39, 43 and 31 °C higher than those of PS/3% GNS composites. TG-IR results show that the main decomposition products of PS/MoS₂ and PS/GNS composites are aromatic compounds and alkenyl units which are similar to those of pure PS. However, less flammable gas products are released relative to pure PS which further leads to the inhibition of smoke. The improvements in the thermal stability, fire resistance and smoke suppression properties of the PS composites are attributed to good dispersion, physical barrier effects of layered nanofillers and the presence of MoS₂ which can promote char formation.