The effect of macrostructure and stability on the flammability of non-woven fabrics

The most flame retardants and non-combustible non-woven fabrics are made of oxidized and carbon fibres due to their strong thermal stability. The burning of non-woven fabrics consists of complex combustion mechanisms: their surface, micro and macrostructures together define their combustion features. By microstructure, we mean oxidized polyacrylicnitrile fibres, which finally constitute the base material of the macrostructure. The macrostructure represents the different forms of the product, in which the material results during production. In this paper, the effect of the macrostructure of non-woven fabrics on flammability has been studied. It has experimentally shown that by defining the oxygen index, we can demonstrate the surface and thickness inhomogeneity, which is invisible or cannot be detected by mechanical tests. A feature of non-combustible non-woven fabrics is that their flammability depends on their thickness and area weight; however, the combustion phenomena of felt fabrics depend primarily on their macrostructure. Different oxygen contents have different combustion phenomena, thus an oxygen index can be assigned to each one. Thermoanalytical test results clearly showed the temperature at which the thermal decomposition of the fibres begins, which gives the surface flame when combusted.