Liquid Ammonia Treatment Research Articles

Transfer Law and Influence of Water Molecules in Cotton Fabric After Liquid-Ammonia Treatment

Transfer Law and Influence of Water Molecules in Cotton Fabric After Liquid-Ammonia Treatment

A fast and effective way to measure the inner pore size distributions of wetted cotton fibers and their pretreatment performance using time-domain nuclear magnetic resonance

This study reports the findings from using time-domain nuclear magnetic resonance (TD-NMR) to analyze the pore structures of cotton fibers. Cotton fibers, which swell and soften in water, present challenges for conventional pore measurement techniques. TD-NMR overcomes these by measuring the transverse relaxation time (T2) of water protons within the fibers, indicative of internal pore sizes. We established a T2-to-pore size conversion equation using mixed cellulose ester membranes. This enabled differentiation between strongly bound, loosely bound, and free water within the fibers, and detailed the water distribution. A method for measuring the pore size distribution of wet cotton fiber was developed using TD-NMR. We then examined how various pretreatments affect the fibers' internal pores by comparing their pore size distribution and porosity. Specifically, caustic mercerization primarily enlarges the porosity and size of larger pores, while liquid ammonia treatment increases porosity but reduces the size of smaller pores. This research confirms TD-NMR's utility in assessing cotton fabrics' wet processing performance.

Effect of Liquid Ammonia on the Structure and Properties of Superfine Wool Fibers

Superfine wool fiber has a soft and luxurious texture, excellent moisture absorption and is warmer and more comfortable than ordinary wool. Liquid ammonia, which has exceptional permeability, exerts a certain modification effect on the surface scales of wool in the finishing and processing of wool fabric, thereby enhancing its wear performance. However, limited research has been conducted on the impact of liquid ammonia on valuable wool fibers such as superfine wool and cashmere. In this article, superfine wool tops were treated with continuous liquid ammonia finishing equipment and the effects of liquid ammonia on the microstructure and surface morphology of superfine wool fiber were investigated. In addition, the changes in length, fineness, anti-felting, and dyeing properties of superfine wool fiber after liquid ammonia treatment were examined. The results demonstrated that the interstitial integrity of intercellular substance of superfine wool was compromised following treatment with liquid ammonia, which had a greater tendency to infiltrate cortical cells and induce alterations in wool structure and performance. Furthermore, the surface scales of superfine wool were damaged after treatment with liquid ammonia, leading to improved anti-felting and dyeing properties.

Effect of liquid ammonia and protease on surface modification and shrink resistance of wool

In order to improve the surface properties of wool fiber, the wool fabric was treated with liquid ammonia and protease treatments successively. The results showed that liquid ammonia pretreatment could cause certain damage to the surface structure and disulfide bonds in keratin, which enhanced the action of protease on wool surface and catalytic hydrolysis of the cuticle. The joint treatment of liquid ammonia and protease changed the secondary structure of wool. The content of α‐helix and random crimp increased, while the content of β‐sheet decreased. In addition, the shrink resistance of wool fabric was significantly improved without obvious losses in tensile strength and elongation. The combination of liquid ammonia and protease treatments provides a potential new method for the surface modification and eco‐friendly shrink‐resistant finishing of wool and further widens the application of liquid ammonia in textile industry.

Synergetic Effects of Liquid Ammonia, Protease, and Polyurethane Nano-Emulsion on Improving Shrink Resistance of Wool

In order to enhance the shrink-resistant properties of wool to achieve a machine washable effect, the effect of water-soluble polyurethane polymer on a worsted wool fabric which was modified by liquid ammonia and protease was investigated. The worsted wool fabric was pretreated by a continuous liquid ammonia finishing machine and then treated by protease, followed by polyurethane nano-emulsion coating. The results showed that, after liquid ammonia and protease treatment, the surface scales of wool were seriously damaged, even partly peeling off, and the disulfide bond content of the wool decreased while the active group content of the wool increased. Furthermore, after polyurethane finishing, the surface scale and the gap between the scales were covered with a thin film, and the area shrinkage reached 3.1% when the concentration of polyurethane was 20 g/L, showing an effective improvement in the shrink resistance of the worsted fabric. As far as our knowledge goes, this is a systematic report on the synergistic effect of liquid ammonia, protease, and polyurethane on the shrink resistance of wool fiber, and provides a new method for the commercial application of shrink-resistant finishing of wool fabric.

Liquid-Ammonia-Mediated Dyeing Process of Wool at a Lower Temperature

Liquid ammonia as a non-aqueous medium has many physical properties close to water, such as small molecular weight and strong permeability. It has been widely used for the ecological processing of cellulosic fibers to improve their luster, softness and dyeing properties. However, there are few reports on the dyeing of wool treated with liquid ammonia, especially at a lower temperature. Herein, a continuous liquid ammonia finishing machine was used to batch process wool followed by dyeing in a commonly-used wool dyeing machine. The results showed that many scale flakes and some cuticle cracking were seen on the fiber surface, and the disulfide bonds of cystine were broken down after liquid ammonia treatment, which promoted the diffusion of dyestuff into the fiber. Moreover, the uptakes and K/S value of wool dyed with Lanaset and Lanasol CE dyes were higher than the untreated wool, and the dyeing temperature could decrease to 85 °C, while the degree of fiber strength reduction merely decreased by 3–5%. Furthermore, for the reactive dyes, the dyeing temperature can reduce to 70 °C with the chemical auxiliaries Miralan LTD, while the degree of strength reduction decrease by 8–10%. Liquid ammonia treatment can be used for dyeing at a lower temperature than boiling temperature (100 °C), reduce energy consumption and reduce the degree of fiber strength reduction of wool. The method shows considerable to great value and is significant in providing a feasible approach for the industrial application of low-temperature dyeing technology.

Influence of liquid ammonia on the structure of wool fiber

Liquid ammonia treatment of worsted fabric was carried out by a continuous liquid ammonia finishing machine, and the effects of liquid ammonia on wool surface morphology, chemical structure and crystallinity were studied and corresponding mechanism was discussed in detail. The results showed that liquid ammonia made the surface scales of wool remove partially and decreased the content of hydrophobic lipid layer and hydrophobic property. After liquid ammonia treatment, the secondary structure of wool macromolecule was changed, manifested in increased α-helix and decreased β-sheet; the disulfide bonds were broken to form cysteine sulfonate, cysteic acid and cystine oxides. Liquid ammonia increased the content of α-crystallization, causing an increase in the crystallinity of wool. As our knowledge goes, this is the most systematic report to date on the effect of liquid ammonia on the structure of wool fiber, and provides a novel medium for the modification of wool in a large scale. Furthermore, it also provides a theoretical basis for the commercial application of liquid ammonia as a non-aqueous medium in wool textile industry.

Influence of Sequential Liquid Ammonia and Caustic Mercerization Pre-Treatment on Dyeing Performance of Knit Cotton Fabric.

A two-stage sequential pretreatment including caustic mercerization (CM) and liquid ammonia (LA) treatment was applied to investigate the influence on dyeing performance and handle of knit cotton fabric, and the relationship between dye size and dyeing properties. Various techniques were applied to characterize all the treated fabrics. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses of the treated fabrics confirmed that both sequential treatments decreased the crystallinity of cotton fabric more than only the CM or LA treatment. The pattern of cellulose I was transferred to a mixed configuration of cellulose II and cellulose III after the CM/LA or LA/CM treatment. Thermal performances measured by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) techniques showed that the thermal stability of the treated cotton only marginally decreased. The wicking height increased after the sequential CM/LA treatment, indicating that the hydrophilicity of the fabric increased. The dye absorption and color uniformity were better for the reactive dye with a smaller molecular weight (Reactive Red 2) compared with the one with a larger molecular weight (Reactive Red 195). The total dye fixation efficiency (T%) increased to 72.93% and 73.24% for Reactive Red 2 dyeings of CM/LA- and LA/CM-cotton fabric from 46.75% of the untreated fabric, respectively; the T% increased to 65.33% and 72.27% for Reactive Red 195 dyeings of CM/LA- and LA/CM-cotton fabric from 35.17% of the untreated fabric, respectively. The colorfastness and dye exhaustion and fixation percentages of the samples were enhanced after the treatments. Furthermore, compared to the single CM or LA treatment, the softness handle properties were further improved after the fabrics were sequentially treated by CM/LA. The developed pre-treatment of CM/LA can be used in the textile industry to promote the dyeability, handle, and mechanical properties of knit cotton fabrics.

Post-treatment of reactive dyed cotton fabrics by caustic mercerization and liquid ammonia treatment

Post-treatment of reactive dyed cotton fabrics by caustic mercerization and liquid ammonia treatment

Effects of LAT on chemical structure and enzymatic hydrolysis of crop straw

Objective This study aims to investigate the effects of liquid ammonia treatment (LAT) pretreatment on the hydrolysis resistance of biomass and the enzymatic hydrolysis rate of lignocellulosic biomass. Method Four different types of lignocelluloses biomass, namely wheat straw (Triticum aestivum), alfalfa (Lotus corniculatus), sorghum straw (Sorghum bicolor), and their mixture (mass ratio 1∶1∶1), were pretreated by LAT method, and the effect of LAT on their chemical structure changes was studied by using thermo gravimetric analysis (TGA), Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), and scanning electron microscope (SEM). Then, the effect of pretreatment temperature and enzymatic hydrolysis time on the enzymatic hydrolysis conversion rates of glucan and xylan in the four raw materials was investigated. Result LAT had a significant effect on the chemical structure of biomass materials. After this pretreatment, the relative content of glucan, xylan, and arabinan in four types of lignocelluloses biomass slightly decreased. The relative content of O and H decreased because some functional groups containing O and H dropped off. The crystallinity decreased slightly, while the surface pore structure significantly increased, and the availability of enzymes in the chemical structure of biomass increased. The optimum pretreatment temperature of wheat straw and mixture was 90 ℃, while that of alfalfa and sorghum straw was 110 ℃. The enzymatic hydrolysis rates of glucan and xylan increased with the increase of enzymatic hydrolysis time. Among the four types of lignocelluloses biomass, the highest enzymatic hydrolysis rate of glucan obtained at the optimal enzymatic hydrolysis condition was wheat straw, followed by the mixture, sorghum straw, and alfalfa. The enzymatic hydrolysis rate of xylan ranging from large to small was sorghum straw, wheat straw, the mixture, and alfalfa. Conclusion LAT can improve the enzymatic hydrolysis efficiency of lignocellulosic biomass, especially that of wheat straw and sorghum straw. [Ch, 8 fig. 2 tab. 24 ref.]

Effect of Ammonia Based Deprotonation on the variable range hopping conduction in Polypyrrole Nanotubes

This paper reports the facial synthesis of polypyrrole (PPy) nanotubes by an anionic azo dye {sodium 4-[4-(dimethyl-amino)-phenyldiazo] phenylsulfonate} assisted chemical oxidation method and their deprotonation by liquid ammonia treatment. Scanning and transmission electron microscopy studies reveal the synthesis of PPy nanotubes of diameters ∼155 nm and their lengths are found to be about 2–3 μm. The deprotonation of PPy nanotubes by liquid as well as gaseous ammonia has been experimentally confirmed by Raman and FTIR studies. These spectroscopic techniques suggest the proton transfer based mechanism for deprotonation of the PPy nanotubes. The deprotonation of PPy nanotubes has also been confirmed through the electrical measurements carried out in the presence of ammonia gas at different ppm levels. Furthermore, the effect of deprotonation on the charge transport properties of PPy nanotubes has also been investigated. The temperature dependent conductivity measurements are performed on both the pristine as well as deprotonated (by liquid ammonia) PPy nanotubes in a wide range of temperature (77–400 K) and analyzed for different conduction mechanisms. However, both the samples are found to follow Mott's variable range hopping conduction process in three dimensions (3D-VRH) for the charge transport. The conduction properties of both the samples are further investigated in terms of Mott's 3D-VRH variables such as Mott's characteristic temperature, hopping distance, hopping energy, and density of states, etc.

Diffusion behaviors of liquid ammonia in the cellulose based on molecular dynamics simulation

PurposeIn the textile industry, liquid ammonia treatment is an important way to modify the structure of natural fibers. The purpose of this paper is to reveal the diffusion behaviors of liquid ammonia in cellulose.Design/methodology/approachTo analysis the diffusion behaviors of liquid ammonia in cellulose, the cellulose model and the system of ammonia and cellulose are built. Infrared spectrum is carried out to test the model of cellulose, which is found to agree with experiment. Diffusion coefficients, free volume and hydrogen bonds are discussed to explain diffusion behaviors.FindingsThe results demonstrate that diffusion coefficients and free volume of systems rise with increasing temperature. The diffusion coefficients of ammonia are larger than those of water, a result in agreement with free volume. To understand the mechanism of diffusion, the numbers of hydrogen bonds are tracked. It is found that without ammonia, intrachain hydrogen bonds decrease with the increase of temperature, which indicate that the structural stability of cellulose is deteriorated. And the increased interchain hydrogen bonds show that swelling properties of cellulose become better with the increase of temperature. After ammonia treatment, the numbers of intrachain hydrogen bonds remain stable, indicating that the structure stability of cellulose chain is maintained. But, there is a substantial rupture of interchain hydrogen bonds, ammonia molecule destroys the hydrogen bond network between the original cellulose molecular chains, which intensifies the activity of cellulose molecular chains and enlarges the distance between cellulose molecular chains, showing good swelling properties.Originality/valueThe research findings give a detailed information about the diffusion behaviors of liquid ammonia in cellulose, which provide the theoretical evidence for liquid ammonia treatment.

Low liquid ammonia treatment of wheat straw increased enzymatic cell wall polysaccharide degradability and decreased residual hydroxycinnamic acids

Ammonia treatment of lignocellulose improves carbohydrate degradability, however, low ammonia dose treatment effects and mechanisms are hardly considered. This study describes low dose ammonia treatment of wheat straw in a statistical design of experiments (Taguchi design) to evaluate the effects of ammonia concentration, treatment time and the Solid:Liquid ratio on structure, composition and enzymatic degradability of the residual fractions. The results showed that low ammonia concentration (≤2 w/w % NH3) resulted in a high carbohydrate recovery (>80%) coupled enzymatic hydrolysis of 50% of xylan and 40% of glucan of the treated material using a (hemi-) cellulase enzyme cocktail. This effect coincidences with the relative decrease in ferulic acid by 10% and coumaric acid by more than 50% analysed via pyrolysis-GC–MS, measured as 4-vinyl-phenol and 4-vinyl-guaiacol, respectively. Our findings show that lowering ammonia concentration increased the effect of treatment time on the enzymatic degradability of the residual fraction.

ChemInform Abstract: Reduction of Manganese Dioxide by Dissolved Lithium in Liquid Ammonia for Li‐Mn‐O Spinels.

AbstractLi1.12Mn1.88O4 spinel is synthesized by reduction of MnO2 by lithium dissolved in liquid ammonia (‐33 °C) and subsequent heat treatment (600—700 °C, 5—10 h).

Effect of liquid ammonia treatment on the pore structure of mercerized cotton and its uptake of reactive dyes

Structural changes in mercerized cotton by liquid ammonia (LA) treatment were investigated and correlated with changes in dyeability of cotton fabrics with reactive dyes. The pore structures of mercerized cotton and mercerized-liquid ammonia (M-LA) treated cotton were characterized by inverse size exclusion chromatography (ISEC). Results showed that when the mercerized cotton was subjected to LA treatment, cumulative accessible volume of smaller pores (e.g., 25.2 Å) increased, whereas that of the larger pores (e.g., 56.7 Å) decreased. These results might be related to the changes in the amorphous region of cotton fiber. The decrease in crystallinity of cotton fiber would increase accessible volume of smaller pores. The larger pores might be compressed by extrusion during swelling of microfibrils or elementary fibrils in water. The change in dyeability of fabrics with reactive dyes of various molecular weights could be rationalized using the observed changes in pore structure. Results also showed that ISEC was more suitable than the method employing Chrastil's diffusion equation for analyzing the pore structure of cotton fiber.

Evaluation of liquid moisture management properties on hemp woven fabrics treated with liquid ammonia

The effects of yarn number and liquid ammonia (L/A) treatment on the liquid moisture management properties (such as wetting time, absorption rate, maximum wetted radius, spreading speed, accumulative one-way transport capability, and overall moisture management capability) of hemp woven fabrics were evaluated by using a moisture management tester on the basis of AATCC test method 195-2011. As a result of the L/A treatment, the crystal structure of hemp fiber was changed from cellulose I into a mixture of cellulose III and cellulose I and its crystallinity was slightly decreased from 66.1% to 57.4%. From scanning electron microscopy analysis, hemp fabric looked swollen and bulked after L/A treatment. The liquid moisture management properties of the L/A-treated hemp woven fabrics showed much better results compared with the untreated ones. Overall moisture management capacity values increased as the yarn number increased and the values of the L/A-treated hemp samples are higher than those of untreated ones. This research could be valuable for the improvement of liquid moisture management properties of hemp woven fabrics.

Effects of liquid ammonia treatment on the physical properties of knit fabric

The cellulosic knit fabric must be treated by NaOH solution in silket process to modify dyeability, luster, physical property, etc. But the silket treated knit fabric has a stiff touch, and must be treated with much of silicone softener. But it has bad durability of laundry. And the silket process has a problem that must discharge a lot of alkaline wastewater. In case of woven fabrics, as an alternative to silket process, liquid ammonia process was developed and this process is eco-friendly because the used ammonia is recovered by 98%. But the knit fabrics are not applicable to the conventional liquid ammonia process because they have selvedge curling problem and are very sensitive to tension. Recently, Korea High Tech Textile Research Institute(Korea) and Lafer SPA(Italy) worked together to develop the new liquid ammonia process for knit fabrics. In the present study, the physical properties of knit fabric after the newly-developed liquid ammonia treatment were investigated. The basic physical properties of knit fabric were measured using the Kawabata evaluation system. In addition, the dyeability, dimensional stability, eco-friendliness were investigated. The results showed that liquid ammonia treatment gave improved physical properties, which can be attributed to fast and uniform swelling, to knit fabric and resulted in a dimensional stability. The knit fabric treated in liquid ammonia showed a darker colour and unique appearance. Above all, the knit fabric treated in liquid ammonia had softer touch and superior gloss than the knit fabric of silket process. The new liquid ammonia process for knit fabrics will become the highest quality standard for knits and will be considered the preferred finish also thanks to eco-friendliness.

Mechanical properties and hand evaluation of hemp woven fabrics treated with liquid ammonia

The effects of liquid ammonia (L/A) treatment on the mechanical properties and hand of 100 % hemp woven fabrics were investigated by the KES-FB (Kawabata Evaluation System for Fabric). Tensile energy and tensile resilience were increased by the L/A treatment. Bending and shearing values such as bending rigidity, bending moment, shear stiffness, shear hysteresis of the L/A treated fabrics were lower than those of the untreated ones. Compressional linearity and compressional energy were decreased while the compressional resilience was increased by the L/A treatment. From the hand evaluation, the primary hand values as well as total hand value of the hemp fabric were markedly increased by the L/A treatment, especially when yarn number was fine. Therefore, L/A treatment was found to be an effective method of improving the flexibility and softness of hemp woven fabrics.

Effects of biowashing and liquid ammonia treatment on the physical characteristics and hand of denim fabric

The changes in the physical characteristics and hand of denim fabric through aftertreatments such as biowashing using only neutral cellulase enzyme and liquid ammonia treatment were investigated. The basic physical properties of denim were measured using the Kawabata evaluation system for fabric. The results showed that biowashing increased softness and created a fade‐out effect with natural colour; however, it reduced strength and elastic recovery as a result of damage to the cellulose by the enzyme. On the other hand, liquid ammonia treatment gave improved physical properties, which can be attributed to fast and uniform swelling, but resulted in a darker colour. Therefore, a combination of liquid ammonia treatment with biowashing is desirable in order to obtain a good fade‐out effect while achieving softness, smoothness, and elastic recovery.

Optimization of Liquid Ammonia Treatment for Enzymatic Hydrolysis of Miscanthus sinensis Anderss

Miscanthus biomass yield high, high photosynthetic efficiency, fast growth, easy breeding, widely distributed, is suitable as raw materials for the production of fuel ethanol. In this paper, the method of the pretreatment of liquid ammonia for Miscanthus, using the pretreatment of liquid ammonia to overcome biomass recalcitrance, adding cellulase enzyme, and the monosaccharide content is determined by using high performance liquid chromatography (HPLC). Effect of pretreatment process on the enzyme solution effect of awn, conducts the research to the water processing rate, temperature, residence time, amount of ammonia, the amount of H2O2 parameters. Data shows that, in the moisture content of 80%, temperature 130?C, loading amount of ammonia 2:1, residence time 10 min, the glucan and xylan enzyme conversion rate are 73.23% and 73.28% respectively. After a mass balance, dry base mans per 100 g can get glucose 28.96 g and xylan 17.25 g.