The influence of alkali pretreatments in lyocell resin finishing – Fiber structure

Manian, Avinash P.; Abu-Rous, Mohammad; Lenninger, Margit; Roeder, Thomas; Schuster, K. Christian; Bechtold, Thomas

doi:10.1016/j.carbpol.2007.07.020

Cited by 21 publications

(11 citation statements)

References 17 publications

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“…1,2 However, the strong swelling propensity of lyocell fibers in alkali solutions 3 changes substrate properties and may lead to alterations in the accessibility and reactivity of lyocell for chemicals and reagents and influence its performance in subsequent treatments. 4,5 In earlier work, 6,7 we examined the influence of alkali pretreatments on the performance of lyocell fabrics in subsequent resin finishing treatments. Fabric samples were pretreated with sodium hydroxide (NaOH; 120 g/L) or KOH (250 g/L) and resinfinished with a dimethyloldihydroxyethylene urea (DMDHEU) based product.…”

Section: Introductionmentioning

confidence: 99%

Alkali pretreatment and resin finishing of lyocell: Effect of sodium hydroxide pretreatments

Kongdee

Manian

Lenninger

et al. 2009

J of Applied Polymer Sci

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Lyocell fabric samples were pretreated with 2-8 mol/L sodium hydroxide (NaOH) and then resin-finished with dimethyloldihydroxyethylene urea, dimethyl dihydroxyethylene urea, and dimethylol urea based products. The resin-finishing treatments caused changes in the substrate properties, such as reduced accessibility, improved crease recovery, and reduced work of rupture and abrasion resistance. Differences were observed between resin-finished substrates as a function of the crosslinker type, and they were attributed to the influence of the crosslinker content and crosslink length in the substrates. The alkali pretreatments influenced the effects of resin finishing. A significant enhancement of the crosslinker penetration appeared within the substrates pretreated with 4 mol/L NaOH. Pretreatments with 6 and 8 mol/L NaOH also enhanced the crosslinker penetration, but the depth of catalyst penetration appeared to exceed that of the crosslinker; leading to demixing between the two components within the substrates. The penetration depth of a direct dye, C.I. Direct Red 81, appeared lower than that of the crosslinker in the alkali-pretreated substrates. Pretreatments with NaOH in the range of 4-8 mol/L appeared to create gradients of accessibility within fibers and yarns of lyocell fabrics, with the depth of reagent penetration increasing in the following order: C.I. Direct Red 81 < crosslinker < catalyst.

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Section: Introductionmentioning

confidence: 99%

Alkali pretreatment and resin finishing of lyocell: Effect of sodium hydroxide pretreatments

Kongdee

Manian

Lenninger

et al. 2009

J of Applied Polymer Sci

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“…We examined their effects on later crosslinking with a widely used agent, dimethyloldihydroxyethylene urea (DMDHEU) (Manian et al 2006(Manian et al , 2008. Fabric pieces crosslinked after alkali pretreatment exhibited lower tensile strength, lower abrasion resistance and lower crease recovery as compared to pieces crosslinked without pretreatment, although all pieces were treated with the same crosslinker formulation and all exhibited the same crosslinker content.…”

Section: Introductionmentioning

confidence: 99%

Alkali pretreatments and crosslinking of lyocell fabrics

et al. 2017

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Lyocell fabrics were pretreated with NaOH, KOH and LiOH and subsequently crosslinked with three urea-formaldehyde based crosslinkers DMDHEU, DMeDHEU and DMU. The mechanical properties varied with the alkali concentration in fabrics crosslinked after pretreatment with 2-8 mol/l NaOH and 4 mol/l LiOH. In fabrics crosslinked after pretreatment with 2-8 mol/l KOH and 1-3 mol/l LiOH, in contrast, the mechanical properties were relatively insensitive to the alkali concentration. The difference in effects is attributed to the alkali influence on the accessibility of crosslinker in fiber structures. The NaOH and 4 mol/l LiOH pretreatments increase the accessibility of crosslinker but the KOH and 1-3 mol/l LiOH pretreatments do not appear to change accessibilities to the same extent. The results underscore the importance of alkali choice and process control in the pretreatments of lyocell. Both NaOH and KOH may be used to good effect. However, lyocell is more sensitive to changes of alkali concentration in NaOH treatments as compared to KOH pretreatments. Thus, the use of NaOH in pretreatments of lyocell will require a greater degree of monitoring and control of alkali concentrations as compared to when KOH is used.

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“…Carboxyl content of lyocell fabric measured by the Technical Association of the Pulp and Paper Industry (TAPPI) Test method T 237 did not change significantly following 3 M NaOH treatment. This was attributed to the decrease in carboxyl content due to dissolution of short chain-length components from the cellulose (being compensated by an increase in the carboxyl content due to oxidative degradation during alkali treatment (Manian et al 2008)). …”

Section: Resultsmentioning

confidence: 98%

“…The Vp and Dp values for lyocell fabric was reported to be 0.60 cm 3 /g and 38 Å , respectively which increased after 3 M NaOH treatment. However the Op value (320 m 2 /g) decreased following this treatment (Manian et al 2008). Accessible total pore volume of lyocell yarns were increased by 4% NaOH treatment (Kasahara et al 2004).…”

Section: Pore Structurementioning

confidence: 96%

“…Wakelin et al stated that X-ray diffraction measures order while chemical methods such as infrared are based on the number of available sites on the surface of crystallites (Wakelin et al 1959). No significant differences in IR crystallinity indices of untreated and 3 M NaOH treated lyocell fabric were reported (Manian et al 2008). Figure 7 shows the depth of FWA diffusion into untreated and 2.5 M NaOH treated lyocell fibers as a function of dyeing time.…”

Section: Pore Structurementioning

confidence: 96%

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Changes in the intra- and inter-fibrillar structure of lyocell (TENCEL®) fibers caused by NaOH treatment

et al. 2008

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Some effects of NaOH treatment at concentrations of up to 8 M on (1) the porous structure, (2) the degree of swelling, (3) carboxyl content using methylene blue sorption and 9H-fluoren-2-yl-diazomethane (FDAM) methods, (4) dyeing, (5) the molecular weight distribution measured by gel permeation chromatography (GPC), (6) crystallinity determined by wide angle X-ray diffraction (WAXD) and (7) the tensile properties of lyocell fibers were investigated. The porous structure of fibers was visualised using fluorescence microscopy and transmission electron microscopy (TEM) on fiber cross-sections and was also studied by inversion size exclusion chromatography (ISEC). Mean pore diameter and pore area of fibers were not changed by NaOH treatments. The pore volume increased above 2.5 M NaOH. NaOH-treated samples showed higher dye uptake, higher swelling, but lower carboxyl and moisture content and increased crystallinity. As the NaOH concentration increased, the depth of colour following dyeing with C.I. Direct Red 81 also increased due to deep penetration of alkali into the fiber. In general, fiber properties were distinctly different in the ranges 0 to approximately 3 and 3-8 M NaOH.

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The influence of alkali pretreatments in lyocell resin finishing – Fiber structure

Cited by 21 publications

References 17 publications

Alkali pretreatment and resin finishing of lyocell: Effect of sodium hydroxide pretreatments

Alkali pretreatment and resin finishing of lyocell: Effect of sodium hydroxide pretreatments

Alkali pretreatments and crosslinking of lyocell fabrics

Changes in the intra- and inter-fibrillar structure of lyocell (TENCEL®) fibers caused by NaOH treatment

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