|Delhom, Christopher - Chris|
|Montalvo Jr, Joseph|
|von Hoven, Terri|
|Santiago Cintron, Michael|
Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2015
Publication Date: 9/9/2015
Citation: Hinchliffe, D.J., Condon, B.D., Delhom, C.D., Chang, S., Montalvo Jr, J.G., Madison, C.A., Reynolds, M.L., Von Hoven, T.M., Santiago Cintron, M. 2015. Physical and combustion properties of nonwoven fabrics produced from conventional and naturally colored cottons. Textile Research Journal. 85(16):1666-1680.
Interpretive Summary: The fibers of naturally colored cottons (NCCs) are naturally occurring and include pigmentations that range from cream to dark brown, various shades of green, and reddish to rust. NCCs are a natural alternative to conventional chemical dyeing which generates a significant waste stream. NCC’s however have achieved limited commercial success due to less than optimal fiber properties and restricted processing needs. In addition to natural color, some brown colored cotton fibers possess inherent flame retardancy (FR) properties that would allow brown fibers to be utilized in specific end use application, particularly in nonwovens textiles. There has been conflicting speculation in the scientific literature as to the exact nature of the FR of brown cotton fibers, including the trace metal elemental content of the fibers. Here we report the effects on physical and combustion properties as a function of processing brown cotton and conventional white cotton fibers into nonwovens fabrics. Nonwovens production parameters included needlepunching (NP), hydroentanglement (H-E), and post-processing chemical treatments such as scouring and bleaching. Physical and combustion properties were measured during processing by standardized testing procedures for fiber quality, flammability, heat release during combustion, elemental analysis, and fiber water content. The results suggest a multi-faceted and synergistic combination of physical and compositional properties that give increased FR to brown cotton fibers that include higher levels of elements known to impart FR properties; higher water content at moisture equilibrium; and unknown factors potentially related to coloration. Nonwoven NP fabrics produced from brown fibers in the natural, greige state also passed standardized testing requirements for use in fire sensitive components in automotive interiors and aircraft interiors without the addition of chemical FR additives.
Technical Abstract: A comparative study was conducted to identify the effects of processing parameters on physical and combustion properties of needlepunched (NP) and hydroentangled (H-E) nonwoven fabrics produced from fibers of a standard Mid-South white fiber cotton and a naturally colored brown fiber cotton. The flammability testing indicated a significantly higher degree of flame retardancy (FR) present in fabrics produced from brown cotton fibers compared to white cotton fibers. Thermal testing by microscale combustion calorimetry (MCC) revealed significantly lower heat release capacity, lower peak heat release rate, and total heat release from brown fibers compared with white fibers. The ash content was also significantly higher in brown fiber samples following complete pyrolysis which suggested higher levels of inorganic elements in the brown fibers. Elemental analyses revealed that brown cotton fibers had higher levels of elements such as phosphorous and magnesium, which are known to impart FR properties. Wet processing by H-E reduced FR in brown fabrics, which also correlated with a reduction in phosphorous. However, brown H-E fabrics still maintained significantly higher FR than white H-E fabrics. Water content analysis at moisture equilibrium by Karl Fischer titration indicated higher water levels in brown fibers, particularly greige brown fibers, which correlated with increased FR. Processing parameters such as specific energy of hydroentanglement did not significantly affect combustion of the two fabric types. Scouring of the brown fiber fabrics reduced, but did not remove coloration, while scouring and bleaching removed the brown color completely. Scouring alone, or scouring and bleaching, completely removed the higher FR properties of the brown fiber fabrics. The results indicate that the mechanism of FR in brown cotton fibers is dependent on multiple compositional factors that may include elements with FR properties, water content, and compounds related to coloration. Nonwoven NP fabrics produced from brown fibers also passed standardized testing requirements for use in fire sensitive components in automotive interiors and aircraft interiors without the addition of chemical FR additives.