Flame retardancy and pyrolysis behavior of an epoxy resin composite flame‐retarded by diphenylphosphinyl‐POSS

Abstract

To reduce the flammability of epoxy resin (EP), a flame retardant (designated as D‐POSS) containing diphenylphosphinyl and polyhedral oligomeric silsesquioxane (POSS) was constructed by aminopropyl‐isobutyl POSS and diphenylphosphinyl chloride. The chemical structure of D‐POSS was fully characterized, then it was used to enhance the flame retardancy of EP. When the flame‐retardant EP composite contained 4 wt% D‐POSS, its limiting oxygen index value was 29.0% and it achieved UL 94 V‐1 rating. Also, its peak of heat release rate (pk‐HRR), total heat release (THR) and total smoke production were decreased by 35.3%, 30.3%, and 38.3%, respectively. Moreover, the results from cone calorimeter disclosed that diphenylphosphinyl group and POSS group in D‐POSS showed a strong synergistic effect in inhibiting pk‐HRR, THR, and smoke production, promoting the charring formation of EP material, and forming an intumescent char layer. Additionally, the theoretical THR reduction of flame‐retardant EP composite was calculated by the equation deduced from the standard, and it was almost same with the practical THR reduction. Notably, some silicon oxide enriched on the residue's surface. The phenomenon led to form a double‐layer residue that consisted of white yarn‐like outer char and normal intumescent inner char. This double‐layer residue was contributed to enhance EP composite's flame retardancy.

Tuning morphology of siloxane bond‐based polybenzoxazines by controlling the sol–gel and curing processes

“…On the other hand, the directed synthesis of Si O Si bond‐based nanostructures for obtaining POSS has also become an important branch of hybrid sol–gel chemistry. [ 17,40,42,47,48 ] However, POSS exhibits problems associated with the synthesis, since it requires long reaction times, and the yields are often low. Blends from polybenzoxazine and POSS showed low miscibility, generating materials with heterogeneous morphologies.…”

“…Therefore, the POSS R groups have been modified in order to obtain miscible polybenzoxazines‐POSS composites. [ 40,48,49 ]…”

Effects of a composite flame retardant system on the flame retardancy and mechanical performance of epoxy resin adhesive

“…Epoxy resins (EP) possess many merits including high thermal stability, water resistance, electrical and chemical resistance, and good adhesion to many materials. [1][2][3] Consequently, the epoxy resins are widely applied in the fields including the aerospace, electronics and electrical appliances, building materials, coatings, and automotive industry. 4,5 Due to their superior adhesive performance, epoxy resins are often used in electronic packing and sealants.…”

The P/Si synergistic effect enduing epoxy resin with improved flame retardancy and outstanding mechanical properties

“…31 Meanwhile, silicon-containing modifiers are also constantly being studied, for that they may enhance the flame retardancy without sacrificing strength of epoxy resins. [32][33][34][35][36][37] However, the mechanical properties of epoxy resin may be compromised when too many modifiers are introduced for flame retardancy, which greatly reduces its use value. 15,17 Therefore, it is very necessary to find a way to get the flame retardancy and mechanical properties improved at the same time.…”