Location: Cotton Chemistry and Utilization ResearchTitle: Natural fire-defense of raw white and brown cotton fibers evidenced by suppressed unzipping depolymerization
Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2016
Publication Date: N/A
Technical Abstract: Pre-cleaned (scoured or scoured/bleached), cotton-based materials, whose utilization has greatly been enhanced in support of environmental sustainability, burn rapidly, causing a difficulty in controlling the spread of fire. This high burning rate is primarily associated with the unzipping depolymerization of cellulose, which produces a highly flammable levoglucosan. In this study, we have shown that the depolymerization process for white cotton was significantly suppressed in the presence of its naturally occurring inorganic salts; a great reduction in the yield of levoglucosan was observed at elevated temperatures by pyrolysis-gas chromatography/mass spectrometry (PY-GC/MS). Consistently, a noticeable change in the thermal reaction of cellulose after scouring raw white cotton was shown by thermogravimetric (TG), differential TG, and microscale combustion calorimetric analyses and was confirmed by examining intermediate gaseous and solid byproducts using FT-IR and solid state CP/MS 13C NMR, respectively. The role of inorganic salts was further confirmed by the retarded burning behavior of naturally pigmented brown cotton fiber, which contains a larger amount of inorganic salts and condensed tannins. The nonwoven fabrics made of brown cotton fiber did not support an open flame in 45' flammability tests, and the additional adsorption of inorganics by tannins increased a limiting oxygen index.