Limiting oxygen index flammability properties

Flame retardance is another important property and is defined by different test methods. Some of the small-scale methods include horizontal flame spread (FMVSS 302, ASTM D-1692) vertical flammability (ASTM D-3014, so-called Butler Chimney Test), limiting oxygen index (ASTM D-2863), and smoke density (ASTM D-2840). 

Polysulfones are transparent (though often slightly yellow), have low flammability (limiting oxygen index typically 38), and bum with little smoke production. Typical properties of some of the commercial polysulfones are shown in Table 4.31. 

Another property used to compare the flammability of textile fibers is the limiting oxygen index (LOI). This measurement quantity describes the minimum oxygen content (%) in nitrogen necessary to sustain candle-like burning. Values of LOI, considered a measure of the intrinsic flammability of a fiber, are listed in Table 12.28 in order of decreasing flammability. Acrylic fibers, it can be seen, are similar in flammability to cotton. Modacrylics, on the other hand, are somewhat less flammable than any of the synthetics, except 100% PVC, and are substantially less flammable than cotton and wool. 

The preliminary study on the flammabihty of HUP-MMT compositions was performed by the determination of limiting oxygen indexes (LOI). The flame retardance was affected by styrene content in the resin and the type of clay used (Table 9.3). An additional amount of styrene has been added to some compositions in aim to improve the casting properties on the other hand the excess styrene makes the cured compositions more flammable due to the increased content of polystyrene (LOI = 18) and decreased of HUP (LOI = 24). The cured compositions containing MMT-Na as well as organoclays with DMDTA and ADA, showed... 

The flammability addresses the following questions (1) how readily the material ignites when exposed to a flame or heat source (2) once ignited, whether it continues to burn (3) how rapidly the fire spreads across a surface and (4) how much heat is released by the combustion and how fast. The main reaction properties that quantify these various parameters are the time-to-ignition, the limiting oxygen index (LOI), the flame spread rate and the heat release rate (HRR). 

---