Utilization of brown cottons for enhanced flame retardance

Authors: Kimmel, Linda; Campbell, Jacqueline; Delhom, Chris; White, Leslie; Yachmenev, Valeriy; NEGULESCU, IOAN - LOUISIANA STATE UNIV.

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2003
Publication Date: 4/15/2003
Citation: Kimmel, L.B., Campbell, J.H., Delhom, C.D., White, L.A., Yachmenev, V., Negulescu, I. 2003. Prospective utilization of brown cottons for enhanced flame retardance. National Cotton Council Beltwide Cotton Conference. p. 2217.

Interpretive Summary: The range of micronaire of the colored cotton is great. However, some pigmented fibers exhibit fiber length, strength, uniformity, and other characteristics suitable for commercial use. The thermal and flammability responses of selected brown cottons are reported for a set of needled nonwovens. Initial horizontal and vertical tests of flammability are reported. Data suggest these particular brown cottons are better thermal insulators than the green cotton and demonstrate that they also tend to burn more slowly. Thermogravimetric analyses evidence that the amounts of char residues coincide with the rates of burning. Fiber color intensifies with many wet processes. Preliminary extractions by select polar aprotic solvents reduce the horizontal flame resistance of the brown cotton, concomittant with an observed color shift but not its removal. The thermal characteristics of these cottons are changed by the extraction, with significant differences observed in the resulting TGA curves and char yields. Work is underway to analyze the post-extractuon materials and solution with the hope of better explaining the witnessed color responses. The variation inherent in the nonwoven textiles precludes drawing definitive conclusions at this time. A follow-up study will test the flammability of heavyweight knits and woven fabrics.

Technical Abstract: Whereas cotton is not typically flame resistant, its desirable attributes such as hand and absorbency make it the preferred fiber for certain apparel applications. Improved flame retardance would substantially boost the market for this natural fiber. Several researchers have reported on the superior flame resistance of naturally colored brown cotton as compared to white cottons. This study compares the properties of selected green and brown cottons with those of a collection of colored cotton obtained from domestic and international sources. The data reveals that the pigmented fibers tend to be shorter and weaker than white cotton. The range of micronaire of the colored cotton is great. However, some pigmented fibers exhibit fiber length, strength, uniformity, and other characteristics suitable for commercial use. The thermal and flammability responses of selected brown cottons are reported for a set of needled nonwovens. Initial horizontal and vertical tests of flammability are reported. Data suggest these particular brown cottons are better thermal insulators than the green cotton and demonstrate that they also tend to burn more slowly. Thermogravimetric analyses evidence that the amounts of char residues coincide with the rates of burning. Fiber color intensifies with many wet processes. Preliminary extractions by select polar aprotic solvents reduce the horizontal flame resistance of the brown cotton, concomittant with an observed color shift but not its removal. The thermal characteristics of these cottons are changed by the extraction, with significant differences observed in the resulting TGA curves and char yields. Work is underway to analyze the post-extractuon materials and solution with the hope of better explaining the witnessed color responses. The variation inherent in the nonwoven textiles precludes drawing definitive conclusions at this time. A follow-up study will test the flammability of heavyweight knits and woven fabrics.