How much the fabric grammage may affect cotton combustion?

The present article is addressed to investigating the effect of different fabric grammages (mass per area unit) on cotton combustion. To this aim, 100, 200 and 400 g/m² cotton fabrics were tested when exposed to (1) two different heat fluxes (25 and 35 kW/m²) under a cone calorimeter, (2) a methane flame in horizontal or vertical flame spread tests or (3) a propane flame in Limiting Oxygen Index tests, and (4) when pyrolysed and further oxidised in pyrolysis-combustion flow calorimetry (PCFC). The collected results demonstrated a precise relationship between fabric grammage and cotton combustion behaviour. Indeed, when exposed to a 35-kW/m² heat flux, the higher the fabric grammage, the higher the total heat release during combustion was; the opposite trend was observed when the same fabrics were pyrolysed and further oxidised in PCFC. This finding was ascribed to the different scenarios described by these instrumentations; indeed, the cone calorimeter was able to reproduce cotton combustion in a well-ventilated context in the presence of air (thus, oxygen), while PCFC only represented the combustion of pyrolysis products. However, both techniques indirectly evidenced a linear dependence of char formation as a function of fabric grammage: the higher the fabric grammage, the larger the amount of char formed was. The same trend was also observed during horizontal and vertical flame spread tests. In conclusion, the present article is intended to show how cotton combustion may be affected by fabric grammage as well as how such behaviour is influenced by the experimental conditions in which it is investigated.