8

Conclusion: By blending modacrylic fibers with aramid fibers, costs are reduced, while the LOI values remain high.

LOI (Limited Oxygen Index) represents the minimum oxygen concentration of an O2 ÷ N2 gas mixture required to sustain combustion of a given material. The materials with higher LOI values are more flame retardant. LOI is determined by ASTM D 2863-77 being expressed as:
(O2 ÷ (O2 + N2)) x 100