Surface Modification Of Multi-Scale Cuprous Oxide With Tunable Catalytic Activity Towards Toxic Fumes And Smoke Suppression Of Rigid Polyurethane Foam

The development of flame retardant rigid polyurethane foam (RPUF) composites with low smoke toxicity emission, as well as excellent mechanical properties remains a huge challenge. Herein, a facile wet chemical approach was proposed for the preparation of cuprous oxide (Cu2O) crystals with different sizes, i.e. approximately 5 nm, 100 nm and 1 mu m in lateral size, which were confirmed by X-ray diffraction and transmission electron microscopy. The effect of Cu2O crystals on the combustion behavior of RPUF was evaluated by cone calorimetry and steady state tube furnace tests. Significant reduction in peak carbon monoxide (CO) production rate (by 41.2%, 67.6% and 27.9%) and total smoke production (21.6%, 16.1% and 12.2%) were realized by the incorporation of 2 wt% Cu2O into the RPUF matrix in addition to a slight reduction in peak heat release rate. Notably, nano-sized Cu2O with high specific surface area is beneficial for the complete combustion of RPUF and the conversion of CO to carbon dioxide (CO2), involving the reduction of Cu2+-Cu+-Cu0 by degraded gases and the oxidation of Cu0-Cu+-Cu2+ by oxygen. This work demonstrated that submicron-sized Cu2O is an effective smoke and toxic gases suppressant for RPUF, which is expected to find practical applications in polymeric materials.