Metal‐organic frameworks derived ZnO@MOF@PZS flame retardant for reducing fire hazards of polyurea nanocomposites

Abstract

Transition metal as flame retardant has attracted intense interests in recent years. In this work, ZnO@MOF@PZS was prepared via hydrothermal and polycondensation methods. ZnO nanoflowers played the role as a template for growth of MOF@PZS and zinc source for formation of MOF. Subsequently, the obtained ZnO@MOF@PZS was mixed into polyurea (PUA) to investigate its flame retardancy and toxicity suppression properties. The cone calorimeter test (CCT) showed that ZnO@MOF@PZS significantly improved the flame retardancy of PUA composites. The addition of 3 wt% ZnO@MOF@PZS into PUA could result in peak heat release rate (PHRR), total heat release (THR) and total CO production (TCO) of 28.30%, 19.59% and 36.65%, respectively. The result of universal testing machine showed that ZnO@MOF@PZS‐add PUA had better mechanical properties. It is notable that the improved flame retardant properties for PUA composites are mainly attributed to ZnO@MOF@PZS promoting the formation of dense char residue.

An Organometallic Flame Retardant Containing P/N/S–Cu2+ for Epoxy Resins with Reduced Fire Hazard and Smoke Toxicity

“…This suggests that the DCSA-Na (Cu) may facilitate the curing reaction of EP because the remaining N−H bond after the Schiff base reaction can facilitate the curing of EP, and the presence of the metal ions can be used as an effective catalyst to facilitate the curing process of EP. 15 It can be seen from Figure 3b that irrespective of the addition of DCSA-Cu or DCSA-Na, they have less effect on the overall curing process of the EP due to their lesser addition. In general, the addition of a small amount of DCSA-Cu to the epoxy matrix has a little effect on the curing process.…”

“…The curing exothermic peak of 5 wt % loading of DCSA-Cu occurs at 146 °C, which was a 14 °C decrease from pure EP. This suggests that the DCSA-Na (Cu) may facilitate the curing reaction of EP because the remaining N–H bond after the Schiff base reaction can facilitate the curing of EP, and the presence of the metal ions can be used as an effective catalyst to facilitate the curing process of EP . It can be seen from Figure b that irrespective of the addition of DCSA-Cu or DCSA-Na, they have less effect on the overall curing process of the EP due to their lesser addition.…”

“…Though these phosphorus and nitrogen organic flame retardants can effectively enhance the flame-retardant performance of EP, they have less effect on the release of smoke during the burning of EP. Metal oxides and their hydroxides can be used as inorganic flame retardants to effectively improve the smoke suppression performance of polymeric materials, − but owing to their low flame-retardant efficiency, it has to be added in large quantities to obtain the fireproof effect, which seriously damages the mechanical properties of polymeric materials . Much research has been conducted to show that the combination of metal ions introduced into flame retardants can successfully reduce the smoke emissions from the burning of compound materials − and catalyze the conversion of toxic gases, significantly reducing environmental pollution.…”

Recent advances in metal-family flame retardants: a review

“…Wang et al prepared ZnO@MOF@PZS by hydrothermal method and polycondensation method. 80 The synthetic route is shown in the Fig. 10(b) .…”