Two-step preparation of phosphorus-containing organoclay and its effect on fire-resistant and mechanical properties of the flame-retardant polyethylene composite

In this study, a nanohybrid based on montmorillonite (oMMT2) was prepared through a two-step method using Arquad MCB-80 and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as intercalation agents. The nanohybrid exhibited a basal spacing of 31.5 & Aring;, which contained approximately 12.3% of Arquad MCB-80 and 31.6% of DOPO. Various amount of oMMT2 nanohybrid was incorporated into a flame-retardant polyethylene system containing aluminum trihydroxide and red phosphorus with a constant total additive content of 20 wt%. The dispersibility of oMMT2 in the composite matrix was evaluated by energy dispersive x-ray mapping and x-ray diffraction analyses. At a content of 3 wt% in the nanocomposite, oMMT2 showed a highly exfoliated state, while at a 5% content, a partially exfoliated and intercalated state was observed. A synergistic flame-retardant effect between the nanohybrid and the mixture of aluminum trihydroxide and red phosphorus was found. The nanocomposite loading 3 wt% oMMT2 demonstrated the best flame retardancy, achieving a V-0 rating of the vertical burning test with a limiting oxygen index of 27.6%. Moreover, the addition of the low oMMT2 contents (<= 3 wt%) improved the mechanical properties of the flame-retardant composite. Preparation process of DOPO-containing organoclay and its synergistic flame retardant mechanism with aluminum hydroxide and red phosphorus image