A Microscopical Survey of Flame-Resistant Cotton Fabrics

Abstract

Three cotton printcloth fabrics treated for flame resistance with THPOH-NHx, oxidized and nonoxidixed, were studied by light microscopy and by transmission (TEM) and scanning (SEM) electron microscopy. Chars of the treated fabrics were also examined. Staining with Acid Blue I and examination by light microscopy provided a semicluantitative assessment of penetration of nonoxidized THPOH-NHa into yarns and fibers, but was less effective with the oxidized sample. SEM observations indicated polymer build-up on fabric surfaces. Deposits of polymer between fibers were usually heavier around the periphery of the yarn. Laundering removed surface deposits but oxidized samples laundered 50 times were still flame resistant, TEM of ultrathin cross sections showed that no major structural change had occurred in the treated fibers. Both SEM and TEM of fiher char sections indicated that the fibers had become shells on burning. Residue patterns left by treated fiber sections after microincineration suggested that the laulymer had completely penetrated the fibers.