Limiting Oxygen Index LOI

The LOI behavior of phosphorus-containing siliconized epoxy followed the same trend as that of siliconized epoxy system. Epoxy and siliconized epoxy materials cured with the phosphorus diamine curative exhibited the maximum LOI value of 42, which maybe due to the consequence of the char enrichment of phosphorus and the char protecting effect of silicone to exhibit the synergistic effect of both silicone and phosphorus on LOI enhancement [50-54]. Thus simultaneously incorporating silicone and phosphorus into epoxy resin would render these epoxies as flame-retardant polymers and can be rated as the best flame retardant material. 

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Another property, used to compare the flammabiUty of textile fibers, is the limiting oxygen index (LOI). This measured quantity describes the minimum oxygen content (%) in nitrogen necessary to sustain candle-like burning. Values of LOI, considered a measure of the intrinsic flammabiUty of a fiber, are Hsted in Table 2 in order of decreasing flammabiUty. 

Fig. 4. Effect on limiting oxygen index (LOI) of (---) antimony trioxide (---) Flamtard S, and Flamtard H added to (a) the basic unfilled PVC...

When exposed to fire. Teflon PEA contributes Httle in fuel value and is self-extinguishing when the flame is removed. The fuel value is approximately 5.4 MJ/kg (2324 Btu/lb). It passes the UL 83 vertical-flame test and is classified as 94VE-0 according to UL 94. The limiting oxygen index (LOI) by ASTM D2863 is above 95%. 

Elame-spread and smoke-density values, and the less often reported fuel-contributed semiquantitive results of the ASTM E84 test and the limited oxygen index (LOI) laboratory test, are more often used to compare fire performance of ceUular plastics. AH building codes requite that ceUular plastics be protected by inner or outer sheathings or be housed in systems aH with a specified minimum total fire resistance. Absolute incombustibHity cannot be attained in practice and often is not requited. The system approach to protecting the more combustible materials affords adequate safety in the buildings by aHowing the occupant sufficient time to evacuate before combustion of the protected ceUular plastic. 

This statement can be proved very easily by considering four different types of general POP properties and their variability as a function of the side substituents on the polymer skeleton, i.e. glass transition temperature (Tg), morphology, solvent solubility and limiting oxygen index (LOI). The values of these parameters are reported in Tables 5-8. 

Table 8 Limiting oxygen index (LOI) for selected poly(organophosphazenes)...

Some of the other properties of interest for fire hazard assessment cannot be measured with RHR calorimeters. They include flame spread, limiting oxygen index (LOI, or simply oxygen index, 01 both names have been used, but the author s preferred nomenclature is the one used here) and fire endurance. 

Table 2 Char yield, vaporization/decomposition temperatures (7, /7d), limiting oxygen index (LOI) and UL 94 ratings for polymers...

Li etal. (2000a, 2001b) smdied the flammability of wood modified with acetic or propionic anhydrides, finding that this parameter, as determined by limiting oxygen index (LOI), was the same as that found for unmodified wood. Samples were also prepared which were impregnated with sodium silicate prior to anhydride modification. The latter treatment resulted in a decrease in flammability, as shown by an increase in the LOI of the wood. 

The polymer limiting oxygen index (LOI) value is 26,5 which corresponds to that of the isosorbide polyurethanes. It is again higher than that of conventional MDI polyurethanes with similar structure based on 1,4-cyclohexanedimethanol (LOI = 20) and indicates lower flammability of cellobiose polymers,... 

Heats of combustion are not indicators of the tendency to burn or the rate of burning. Other indicators are employed as markers with respect to their tendency to burn. The limiting oxygen index (LOI) is one of these markers. Briefly, the sample, in a predescribed standard... 

Kuila et al. [106] studied the flammability of EVA-LDH nanocomposites with different LDH loading. The results shown in Fig. 59 represent the findings on the limiting oxygen index (LOI) of neat EVA and its nanocomposites. 

PTFE decomposes to TFE with first-order kinedcs and a 347.4-kJ/mol activation energy under vacuum pyrolysis conditions It is extremely flame resistant and does not bum in air Its limiting oxygen index (LOI). the minimum oxygen content of an atmosphere under ambient conditions that sustains combustion, is 96%, which means that it requires almost pure oxygen for combustion... 

ETFE resins do not support combustion in air and have typical limiting oxygen index (LOI) about 30 to 31. LOI depends on monomer ratio in the polymer and it increases gradually as the fluorocarbon content is increased to the alternating composition and then increases more rapidly to the LOI values for FIFE.68... 

A different way to look at extinction is by reducing the oxygen concentration and thus, increasing the characteristic chemical time. This will result in a decrease of the second Damkohler number. This mechanism of extinction is analyzed in a standardized manner by the limiting oxygen index (LOI) [32],... 

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