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Scanning electron microscopic studies of wool/intumescent char formation
Thermal analytical studies of synthesized mixtures of powdered wool, wool/flame retardant viscose blended fiber/intumescent combinations and intumescent-coated fabrics have shown previously that while enhanced volatilization occurs during char formation below 400 deg C, the chars formed showed higher-than-expected oxidative resistance up to temperatures beyond 700 deg C. Scanning electron microscopy was used to study these interactions and showed that over the temperature range 250 deg C to 450 deg C, charred residues from wood-containing samples coated with intumescent and without intumescent exhibit significant changes in wool fiber morphology. Wool fibers first appear to swell and then develop an axial defect. Further swelling occurs to yield a swollen and pod-like morphology at higher temperatures, and splitting of the cuticle along the axial defect allows the largely liquid degraded wood keratin interior to escape and wet neighboring surfaces. The presence of intumesent flame retardant appeared to inhibit the rupture of the wool cuticular membranes, possibly via enhanced crosslinking of the keratinous protein accompanied by enhanced volatile formation in the 250 deg C to 350 deg C region. The subsequent rupture stage (> 350 deg C) enables the intumescent to act upon the emerging liquefied pyrolyzing keratin core of the fibers, providing a second high volatilization stage to accompany complex char formation with adjacent cellulosic fibers.
Scanning electron microscopic studies of wool/intumescent char formation
Thermal analytical studies of synthesized mixtures of powdered wool, wool/flame retardant viscose blended fiber/intumescent combinations and intumescent-coated fabrics have shown previously that while enhanced volatilization occurs during char formation below 400 deg C, the chars formed showed higher-than-expected oxidative resistance up to temperatures beyond 700 deg C. Scanning electron microscopy was used to study these interactions and showed that over the temperature range 250 deg C to 450 deg C, charred residues from wood-containing samples coated with intumescent and without intumescent exhibit significant changes in wool fiber morphology. Wool fibers first appear to swell and then develop an axial defect. Further swelling occurs to yield a swollen and pod-like morphology at higher temperatures, and splitting of the cuticle along the axial defect allows the largely liquid degraded wood keratin interior to escape and wet neighboring surfaces. The presence of intumesent flame retardant appeared to inhibit the rupture of the wool cuticular membranes, possibly via enhanced crosslinking of the keratinous protein accompanied by enhanced volatile formation in the 250 deg C to 350 deg C region. The subsequent rupture stage (> 350 deg C) enables the intumescent to act upon the emerging liquefied pyrolyzing keratin core of the fibers, providing a second high volatilization stage to accompany complex char formation with adjacent cellulosic fibers.
Scanning electron microscopic studies of wool/intumescent char formation
Davies, P.J. (author) / Horrocks, A.R. (author) / Miraftab, M. (author)
Polymer International ; 49 ; 1125-1132
2000
8 Seiten, 7 Bilder, 2 Tabellen, 19 Quellen
Article (Journal)
English
| British Library Online Contents | 2000
| British Library Online Contents | 2001