Polymer limiting oxygen index values

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,... 

Mechanisms of Fire-Retardant Action 315 Table 17.1 Limiting oxygen index values for selected polymers [29],... 

This polymer has a good strength for a flexible silicone polymer coupled with the good heat resistance which may be expected from its components, together with an outstanding value for the limiting oxygen index of 48. 

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 15 Limited oxygen index (LOI) values at 20 °C for polymers...

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... 

The degree of flammability of a polymeric material may be predicted from its chemical structure. One of the most valuable criteria in fire research, the so-called limiting oxygen index (LOI) may be estimated either from the specific heat of combustion or from the amount of char residue on pyrolysis. Since both quantities can be determined if the chemical structure is known, also the LOI can be estimated. An approximate assessment of the LOI value direct from the elementary composition of the polymer is also possible. 

A four-ply graphite cloth laminate based on polymer (e) was fabricated. Limiting oxygen index of this laminate was determined according to ASTM D2863-74 and was found to be 71%. Similar values for the graphite cloth laminates fabricated from 9,9-bis(p-maleimidophenyl)fluorene have been obtained earlier (2). 

Fire retardancy of fabrics treated by using the same procedure as given above was evaluated by limiting oxygen index (LOI) measurements according to ISO 4589-2 (Tsafack et al., 2004). The results obtained for the acrylates phosphates and phosphonates monomers show that LOI values increase with the relative phosphorus content in the monomer and therefore in the grafted polymer. This can be explained by the fact that phosphate monomers compared to phosphonate monomers are subject to more chain transfers that lead to highly cross-linked polymers and decrease the flammability (Tsafack et al., 2(X)4). 

Table 11.19 Limited Oxygen Index (LOI) Values at 20°C for Polymers"...

Polyphosphazenes have low inflammability, very high values of limiting oxygen index (LOI) equal to 24-65, and evolve no toxic gases during burning. Most of them do not burn and some are used as additives to other polymers as flame... 

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