Metallic ferrites as flame retardants and smoke suppressants in flexible poly(vinyl chloride)

Abstract

Two metallic ferrites LaFeO 3 and BiFeO 3 were successfully synthesized and compared with ZnFe 2 O 4 used as flame retardants and smoke suppressants for flexible poly(vinyl chloride) (PVC). The flame-retardant and smoke-suppressant properties of flame-retarded PVC were evaluated using the limiting oxygen index, smoke density rating, and cone calorimeter tests. The results indicate that BiFeO 3 is an excellent flame retardant and smoke suppressant for flexible PVC. Under 30 kW m -2 radiation, the peak value of heat release rate of 20 phr PVC/BiFeO 3 was reduced by 44.8 % as compared to neat PVC, and the total smoke produced and average specific extinction area of 20 phr PVC/BiFeO 3 were reduced by 54.8 and 52.3 %, respectively. The char residues of the PVC samples were analyzed by SEM and Raman spectra, which suggested the incorporation of ferrites can induce the formation of char layer. This effect combined with the gaseous phase effect of BiFeO 3 , and hence PVC/BiFeO 3 has the best flameretardant and smoke-suppressant properties.

Synergistic flame retardant effects of activated carbon and molybdenum oxide in poly(vinyl chloride)

“…The former is produced by the defect‐induced vibration mode, i.e. the unorganized carbon specific absorption band, whereas the latter corresponds to E 2g modes of sp bonds of carbon atoms in graphite layers . Figure shows the Raman diffusion spectra of the char residues of the PVC composites at 500 °C under nitrogen.…”

“…Poly(vinyl chloride) (PVC) is a general plastic with one of the highest yields in the world, and is widely used in building materials, industrial products, daily necessities, etc., because of its valuable properties, such as chemical resistance, flame retardancy, abrasion resistance, superior mechanical and physical properties and low cost . Usually, PVC can be divided into rigid, semi‐rigid and flexible, based on the various amounts of plasticizer additives.…”

Reduction in smoke emitted and fire hazard presented by flexible poly (vinyl chloride) through novel synthesis of SnO2 supported by activated carbon spheres

“…A large proportion of these applications demand flexibility and are therefore well served by the unique attributes of flexible PVC (fPVC). However, the flammable nature of fPVC restricts its application in certain areas; large amounts of heat and toxic smoke are released by the combustion of PVC which, in certain circumstances, could lead to heavy casualties and property losses in the event of a fire . Reducing the fire hazard presented by fPVC is, therefore, a subject of great concern.…”

Synthesis of nano-flame retardant and its use as a promising substitute of antimony trioxide in flame retardant flexible poly(vinyl chloride)

“…However, the conventional plasticizers used in the manufacture of flexible PVC detract from this outstanding fire resistance. These plasticizers also promote a particular combustion mechanism that ends up generating a significant amount of dense and dark smoke [11]. The limiting oxygen index (LOI) is the minimum concentration of oxygen in the mixture with nitrogen that will support combustion of a polymer.…”

“…smoke suppressing effects of ferrites in PVC. Several ferrites including ZnFe 2 O 4 , MgFe 2 O 4 , NiFe 2 O 4 and CuFe 2 O 4 were synthesized and added into flexible PVC [65].Subsequently, LaFeO 3 and BiFeO 3 were also synthesized and used as flame retardants and smoke suppressants for flexible PVC[11]. Afterwards, Xu and co-workers further employed thermogravimetric analysis-Fourier transform infrared spectroscopy (TG-FTIR) and X-ray photoelectron spectroscopy (XPS) to understand flame-retardant mechanism of flexible PVC filled with metallic ferrites[8].…”