Liquid Ammonia Treatment Research Articles

Cellulose polymorphs and physical properties of cotton fabrics processed with commercial textile mills for mercerization and liquid ammonia treatments

We report the detection of cellulose polymorphs, using spectroscopic and diffraction techniques, in cotton fabrics treated with commercial textile mill processes designed for better dyeing and mechanical properties. Vibrational sum frequency generation (SFG) spectroscopy analysis of cotton is known to be selective and sensitive to the crystalline cellulose portion in the sample. The SFG analysis results were compared with the results from conventional analytical techniques such as X-ray diffraction (XRD) and infrared (IR) spectroscopy. The XRD detection of a small fraction of cellulose II present in the partially-mercerized fabric was difficult, while SFG and IR analysis indicated the partial conversion of cellulose I to II without significant reduction of the cellulose crystallinity. Processing the cotton fabric with the liquid-ammonia treatment mill caused partial conversion of cellulose I to III and significant reduction of the overall crystallinity of cellulose. All XRD, SFG, and IR techniques were able to monitor this conversion. When the cotton fabric was treated with the partial mercerization process first and then the liquid-ammonia process, both cellulose II and cellulose III were produced and identified with SFG. But XRD and IR failed to detect the presence of cellulose II in the mercerized and ammonia-treated fabric. The polymorphic changes found in the SFG, XRD, and IR analyses provided insights into the physical property changes of cotton fabric after commercial mercerization and liquid-ammonia treatment processes.

Evaluation of liquid ammonia treatment on surface characteristics of hemp fiber

In this study, we investigated the effects of liquid ammonia treatment on the surface characteristics of hemp fibers. We determined the elemental composition, morphological structure, roughness, and wettability of fiber surface using techniques such as electron spectroscopy for chemical analysis, scanning electron microscopy, atomic force microscopy, and contact angle measurements. The lignin coverage on the hemp surface was calculated from the O/C ratio and the C1 content. The results show that lignin removal from the fiber surface was significantly greater than that from the fiber bulk. After the treatment, the O/C ratio of hemp fibers increased, and cellulose was exposed. The proportion of O2 species that contributed to formation of hydrogen bonds increased; this further increased the number of hydrophilic groups in the hemp fibers, improving the fiber wettability. The liquid ammonia treatment did not change the large dislocation structures in hemp fibers, but the removal of noncellulosic materials from the fiber surface increased the roughness of the fiber surface.

Liquid ammonia treatment of (cationic) nanofibrillated cellulose/vermiculite composites

AbstractLiquid ammonia was used to treat films of nanofibrillated cellulose (NFC), trimethylammonium‐modified NFC (TMA‐NFC), and their composites with vermiculite. Crystal structure, mechanical properties, water vapor permeation and water vapor adsorption of the resulting materials were investigated. Upon treatment, the crystal structure of (TMA‐)NFC both in presence and absence of vermiculite changed from cellulose I to III. With the exception of TMA‐NFC/vermiculite composites, pronounced effects on the addressed mechanical properties arose after exposure of the materials to ammonia. Furthermore, treatment of composite films with ammonia led to a distinct decrease in water vapor permeation. Remarkably, TMA‐NFC/vermiculite composites films show the best water vapor barrier properties, highest tensile strength and highest elastic modulus after treatment with liquid ammonia. This is regarded to be at least partially a consequence of electrostatic attraction between the positively charged ammonium groups in TMA‐NFC and the anionic silicate layers of vermiculite. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013

Titania Coated Mica via Chemical Vapour Deposition, Post N-doped by Liquid Ammonia Treatment

Abstract TiO 2 films were successfully grown on synthetic mica powders via Chemical Vapor Deposition (CVD). The CVD rig is a cold-walled design that allows surface coverage of a powder to be successfully achieved. The TiO 2 was produced by the reaction between TiCl 4 and Ethyl Acetate. The powder produced could be successfully N-doped using post liquid ammonia treatment. The TiO 2 powder produced could have potential applications in self-cleaning surfaces or antimicrobial paints.

The effects of yarn number and liquid ammonia treatment on the physical properties of hemp woven fabrics

The effects of yarn number and liquid ammonia (L/A) treatment on the physical properties of woven fabrics prepared with pure hemp spun yarns were investigated. As a result of L/A treatment, the crystal structure of hemp fiber was changed from cellulose I to the mixtures of cellulose III and cellulose I and its crystallinity was slightly decreased by 13 %. The crease recovery of hemp fabric treated with L/A was improved upto 78 %. The washing shrinkage of hemp fabric treated with L/A decreased significantly to less than 0.4 %, while the washing shrinkage of hemp fabric prepared with the fined yarn was superior to that of hemp fabric prepared with the coarsed yarn. Especially, the wicking speed and drying ratio of hemp fabrics treated with L/A were higher than those of the untreated as yarn number increased. However, it was found that there is no significant effect on the UV protection of the L/A treated hemp fabrics.

Effects of alkaline or liquid-ammonia treatment on crystalline cellulose: changes in crystalline structure and effects on enzymatic digestibility

BackgroundIn converting biomass to bioethanol, pretreatment is a key step intended to render cellulose more amenable and accessible to cellulase enzymes and thus increase glucose yields. In this study, four cellulose samples with different degrees of polymerization and crystallinity indexes were subjected to aqueous sodium hydroxide and anhydrous liquid ammonia treatments. The effects of the treatments on cellulose crystalline structure were studied, in addition to the effects on the digestibility of the celluloses by a cellulase complex.ResultsFrom X-ray diffractograms and nuclear magnetic resonance spectra, it was revealed that treatment with liquid ammonia produced the cellulose IIII allomorph; however, crystallinity depended on treatment conditions. Treatment at a low temperature (25°C) resulted in a less crystalline product, whereas treatment at elevated temperatures (130°C or 140°C) gave a more crystalline product. Treatment of cellulose I with aqueous sodium hydroxide (16.5 percent by weight) resulted in formation of cellulose II, but also produced a much less crystalline cellulose. The relative digestibilities of the different cellulose allomorphs were tested by exposing the treated and untreated cellulose samples to a commercial enzyme mixture (Genencor-Danisco; GC 220). The digestibility results showed that the starting cellulose I samples were the least digestible (except for corn stover cellulose, which had a high amorphous content). Treatment with sodium hydroxide produced the most digestible cellulose, followed by treatment with liquid ammonia at a low temperature. Factor analysis indicated that initial rates of digestion (up to 24 hours) were most strongly correlated with amorphous content. Correlation of allomorph type with digestibility was weak, but was strongest with cellulose conversion at later times. The cellulose IIII samples produced at higher temperatures had comparable crystallinities to the initial cellulose I samples, but achieved higher levels of cellulose conversion, at longer digestion times.ConclusionsEarlier studies have focused on determining which cellulose allomorph is the most digestible. In this study we have found that the chemical treatments to produce different allomorphs also changed the crystallinity of the cellulose, and this had a significant effect on the digestibility of the substrate. When determining the relative digestibilities of different cellulose allomorphs it is essential to also consider the relative crystallinities of the celluloses being tested.

Effect of Different Ways of Ammonia Removal on the Fine Structure and Properties of Hemp Fibers

Liquid ammonia treatment can improve the properties of a hemp fiber and widen its application in textiles. This study investigated the effects of different ways of NH3 removal on the fine structure and properties of hemp fibers, including thermal property and dyeing behaviour. It was found that, of the three ways of ammonia removal, removal of ammonia with glacial acetic acid resulted in the highest transition of cellulose Ⅰinto cellulose Ⅲ and removal ammonia with water resulted in the lowest transition of cellulose Ⅰinto cellulose Ⅲ. Removal of ammonia with water also resulted in better thermal stability and higher dye uptake than the other ways of ammonia removal. Of the three ways of ammonia removal, removal of ammonia by evaporation resulted in the lowest dye uptake.

Effect of Alkali Treatment on the Tensile and Impact Properties of Ramie Plied Yarn-Reinforced Green Composites

Effect of alkali-treatment on the mechanical properties of a ramie plied yarn reinforced green composite was investigated, using NaOH solutions with various concentrations. The composites reinforced with NaOH-treated yarns decrease in strength and Young's modulus if the concentration of the solution is equal to 12wt% or more. It was proved from X-ray diffraction analysis that these decreases were closely related with a decrease in the index of crystallinity and a crystalline transformation from cellulose I to cellulose II of the yarns. On the other hand, fracture strain of the NaOH-treated yarn composites increased largely, as compared to that of the untreated yarn composite. In this study, furthermore, the effect of liquid ammonia (NH3) treatment on the mechanical properties of the green composite was investigated. The results showed that the NH3-treated yarn composites showed higher tensile strength and fracture strain, as compared to those of the untreated yarn composites, but their Young's modulus decreased. It was considered that such changes were concerned to a change in the yarn structure, as well as a crystalline transformation from cellulose I to cellulose III and the less index of crystallinity.

Improving Quality of Linen-Cotton Fabrics with Liquid Ammonia Treatment

ABSTRACT Liquid ammonia treatment (water-based process) was applied in a large-scale production for improving quality of cotton/linen (warp/weft) fabrics. Results prove that liquid ammonia treatment is beneficial especially for improving dimensional stability, abrasion resistance and appearance after washing. The swelling treatment has also a positive effect on the crease recovery property, however, the final CRA are still unsatisfactory. Furthermore, liquid ammonia strengthens the warp and weakens the weft yarns and increases the breaking elongation especially in weft direction. Perceptible color difference exists between the ammonia treated fabrics and their non-treated counterparts. The swelling treatment does not cause chain fragmentation in cellulose derived from either cotton warp or linen weft yarns.

Dyeing Property of Subtropical Plant Fibers Treated with Sodium Hydroxide or Liquid Ammonia

Six kinds of subtropical plant fibers, Hibiscus, Pineapple, Okra, Plantain, Banana and Agave were treated with liquid ammonia (NH3) and 11% sodium hydroxide (NaOH) solution. The water absorption and dyeing property were measured. Generally water absorption decreased by the liquid ammonia and sodium hydroxide treatments. From the microscopic observation of the fiber dyed with a C.I. Direct Blue 1, it is obvious that the dye penetrates extremely by the NaOH treatment for every fiber. Also it is clear that dye penetration brings about not only from the surface of the multicell fiber but also through the crack in the fiber. Dyeing rate and equilibrium dye uptake increased considerably by the NaOH treatment for all fibers. On the other hand, NH3 treatment caused a decrease of the dyeing rate for Plantain and Banana, and other fibers increased the rate compared with the untreated ones. The effect of the NH3 treatment for dyeing behavior is smaller than that of the NaOH treatment.

Effect of Ammonia Fiber Expansion (AFEX) and Silane Treatments of Corncob Granules on the Properties of Renewable Resource Based Biocomposites

Development of economically and ecologically attractive composite technologies is possible through the use of renewable biomass based resources such as polymeric matrices and reinforcement filler materials. The processability and physical properties of these composite materials are very important parameters for product performance. This study develops the enabling technology needed to transform corncobs, an abundant agricultural residue from the corn grain industry, into reinforcement filler material for manufacturing biocomposites. We have successfully fabricated biocomposite materials from poly(lactic acid) (PLA) and corncob granules (CCG) that were produced by a microcompounding molding system. To ensure appropriate interfacial interactions between the matrix and composite material, surface properties of the biocomposite filler must be modified accordingly. CCG-matrix adhesion was promoted by surface modifications using ammonia fiber expansion (AFEX), liquid ammonia treatment, and silane treatment. The final composite materials have improved mechanical and thermomechanical properties such as high flexural properties, high impact strength, and modulus at higher temperature. The surface morphology, as indicated by scanning electron microscopy (SEM), showed good dispersion of CCG in the PLA matrix. Modification of the CCG surface showed an improved adhesion and dispersion within the matrix. Overall, the results demonstrated the potential of CCG as reinforcement filler material for a renewable source based polymeric matrix.

Effect of Liquid Ammonia on the Fine Structure of Linen Fabrics

It has recently been shown that liquid ammonia treatment (water-based process) is very effective in improving the wrinkle recovery, dimensional stability, and resistance to abrasion of the all-linen fabrics. In this study the changes in the fine structure were characterized by measuring the crystallinity and sorption properties of the linen fabrics. In addition, the effect of liquid ammonia on the surface properties of the linen fibers was investigated. X-ray analysis showed that liquid ammonia treatment did not significantly affect the ratio of crystalline and amorphous regions, but a partial recrystallization occurred in the crystalline part, resulting in mixed cellulose I and III lattices in the linen substrates. Although the moisture regain and iodine sorption capacity of the treated linen substrates increased, water retention values, however, were decreased significantly by the intracrystalline swelling treatment.

Ammonia‐gas and liquid ammonia treatments of silk fabric

AbstractSilk fabric, Habutae, was treated with 100% ammonia‐gas under atmospheric pressure and at pressures of 2, 4, and 6 kgf/cm2, and with liquid ammonia at −33°C. The effects of the treatment were investigated on the basis of the X‐ray diffraction, DSC thermogram, moisture regain, water absorption, dyeing property, and mechanical property of the fabric. Crystallinity and equilibrium dye uptake were increased apparently by the liquid ammonia treatment, whereas effect of the ammonia‐gas treatment was less than the liquid ammonia treatment. KES (Kawabata Evaluation System) shearing, bending, and tensile parameters were obtained. The modulus G, B, and hysteresis widths 2HG, 2HG5, and 2HB were decreased with the ammonia‐gas treatment. On the contrary, the liquid ammonia treatment increased the parameters considerably. Therefore, it seemed that the ammonia‐gas treatment is effective in enhancing the soft hand of the silk fabric. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3487–3492, 2006

The Liquid Ammonia Treatment of Cotton Fibers-Structural Changes of Cotton Fibers after Liquid Ammonia and Hot Water Treatment-

Five kinds of cotton fabrics were treated using a practical liquid ammonia unit and consequently treated with hot water at 70°C or 130°C for two hours. The lattice type, the washing shrinkage, the water retention, the moisture absorbency, the dry and wet crease recovery angle and the bending repulsion were measured. Five data items for each measurement were averaged and analyzed. Due to the hot water treatment after liquid ammonia treatment, the dry crease recovery angle and the bending repulsion were decreased; on the other hand, the water retention, the wet crease recovery angle and the moisture absorbency were increased. These changes represent a rearrangement of the hydrogen bonding from a non-swollen state to a swollen state and stabilization of the fiber shape in the swollen state. Through this stabilization, a decrease in the washing shrinkage is thought to occur. The changes of the lattice type by the hot water treatment occurred a little at 70°C and occurred largely at 130°C. On the other hand, the washing shrinkage and other physical properties changed largely at 70°C. These results suggest that the decrease of washing shrinkage and the changes in the other properties depend mainly on the changes in the amorphous region.

The Liquid Ammonia Treatment of Cotton Fibers-Comparison and Combination with Mercerization using a Practical Unit-

Three kinds of cotton fabrics were treated using a practical mercerizing unit under conventional conditions. No change in the lattice type of cellulose was found against the common understanding of mercerization. The reason for this phenomena is thought to be as follows; the mobility of the cellulose molecules in the cotton fabrics is restricted by the construction of the fabrics and the conversion to sodium cellulose as well as conversion from sodium cellulose to cellulose _are hindered. Other physical properties though, were obviously changed by the mercerization. The pore volume increased, water retention decreased, moisture absorbency increased, wet crease recovery increased, dye uptake increased and the bending repulsion increased. In the case of a combination with liquid ammonia treatment, the changes in the water retention, moisture absorbency and crease recovery were enhanced; the pore volume decreased and the changes in the dye uptake and bending repulsion were reduced. Therefore, the combination of mercerization and liquid ammonia treatment should be used depending on the required purpose of the finishing.

The Changes of the Structure and the Propertles of Cotton Fibers through the Liquid Ammonia Treatment

The Changes of the Structure and the Propertles of Cotton Fibers through the Liquid Ammonia Treatment

The Liquid Ammonia Treatment of Cotton Fibers-The Structural Changes of Cotton Fibers under Various Treatment Conditions in Practical Units

The structural changes of cotton fibers by practical liquid ammonia treatment under four different conditions were investigated. Two liquid ammonia units were used, one of which had one drying cylinder and the other had two cylinders. The running speed of each unit was set at high or low. In each unit, the lattice type I did not decrease even after long ammonia wetting, and as the drying time increased, the lattice typeIII increased, the amorphous region also decreased. Therefore, regarding practical liquid ammonia treatment, the changes in the crystal structure are thought to occur as follows: Almost all cellulose changes to ammonia cellulose after short ammonia wetting, and along with the removal of the ammonia, the lattice type III increases, the amorphous region decreases and the residual ammonia cellulose converts to the lattice type I. It was found that after liquid ammonia treatment the pore volume corresponding to the PEG radius over 1.1nm and the water retention decrease, the dry and wet crease recovery angle, the tear strength, the tensile strength and the dye uptake increase. The degree of decrease or increase depends on the degree of drying respectively.

The Liquid Ammonia Treatment of Cotton Fibers-The Structural Changes of Cotton Fibers under Different Methods of Liquid Ammonia Removal-

There are two major methods in liquid ammonia treatment, which are the ammonia dry process and the ammonia wet process. In the ammonia dry process, liquid ammonia is applied on the fabrics and is removed by heating, whereas in the ammonia wet process, the ammonia is removed by water. The differences of the effects between these two processes were investigated precisely using continuous practical units and a discontinuous laboratory unit. The X-ray diffraction patterns of the finished samples were quite different between the two processes: only the cellulose I type was found in the ammonia wet process samples, while both of cellulose I and III types were found in the ammonia dry process. Pore distribution analysis by liquid chromatography also showed different results between the two processes. Various other properties though were not substantially different. The slight differences found were as follows: the higher crease recovery angle in the ammonia dry process, and the harder hand and the higher dyeabillity in the ammonia wet process.

Liquid Ammonia Treatment of Regenerated Cellulosic Fabrics

Liquid ammonia is effective at improving the strength, shrink resistance, and hand of cotton fabric. In this study, we apply a liquid ammonia (NH3) treatment to three regenerated cellulosic fabrics—rayon taffeta, cupro taffeta, and polynosic broadcloth— and subsequently process these with hot water and dry heat. We investigate the effect of the processes on crystal form, crystallinity, moisture regain, water absorption, and dyeing properties. Also, the mechanical properties of the NH3-treated fabrics are measured in relation to fabric hand. The diffraction intensity profiles of the rayon taffeta are unchanged by the NH3 treatment and subsequent heat processing. The profile of cupro taffeta is not changed by the NH3 treatment, but it is transformed to cellulose IIIII by subsequent hot water and dry heat processes. On the other hand, although the profile of polynosic broadcloth is transformed to cellulose IIIII by the NH3 treatment, the profile is not changed by hot water and dry heat. Furthermore, fabric crystallinity decreases with the NH3 treatment and increases somewhat after the hot water and dry heat processes. Water absorption and equilibrium dye uptake decrease with the NH3 treatment. Excellent washing shrinkage resistance is obtained with the NH3 treatment. The shearing and bending parameters of the rayon and cupro fabrics decrease somewhat with the NH3 treatment, so this treatment of regenerated cellulosic fabrics is effective at improving hand as well as washing shrinkage.

Polymorphism of cellulose I family: reinvestigation of cellulose IVI.

Polymorphs of cellulose I, III(I), and IV(I) have been investigated by X-ray diffraction, FT-IR, and solid-state (13)C NMR spectroscopy. Highly crystalline cellulose III(I) samples were prepared by treating cellulose samples in supercritical ammonia at 140 degrees C for 1 h, and conventional cellulose III(I) samples were prepared by liquid ammonia treatment. The cellulose IV(I) sample of highest crystallinity was that prepared from Cladophora cellulose III(I) in supercritical ammonia, followed by the sample treated in glycerol at 260 degrees C for 0.5 h, whereas the lowest crystallinity was observed in ramie cellulose prepared by conventional liquid ammonia treatment followed by glycerol annealing. In general, the perfection of cellulose IV(I) depends on the crystallinity of the original material: either of the starting cellulose I or of the cellulose III(I) after ammonia treatment. The product thus obtained was analogous to cellulose I(beta), which is what it should be called rather than cellulose IV(I). If the existence of the polymorph cellulose IV(I) is not accepted, the observations on which it has been based may be explained by the fact that the structure termed cellulose IV(I) is cellulose I(beta) which contains lateral disorder.