Cuprammonium Rayon Research Articles

Wastepaper-Based Cuprammonium Rayon Regenerated Using Novel Gaseous-Ammoniation Injection Process.

Rayon is an extremely valuable cellulosic fiber in the global textile industry. Since cuprammonium rayon is more eco-friendly than other types of rayon fabrics, it was synthesized by regenerating α-cellulose isolated from wastepaper using a novel gaseous-ammoniation injection (GAI) process. This was achieved by preparing tetra-ammine copper hydroxide (cuoxam solution) via reacting copper sulfate and sodium hydroxide to produce copper hydroxide that was, finally, ammoniated by injecting the gas directly to the reaction vessel instead of using ammonium hydroxide applied by prior art. After that, the air-dried cellulose was chemically generated by dissolving it in a freshly prepared cuoxam solution and, subsequently, was regenerated by extruding it within a hardening bath constituted mainly from citric acid, producing the cuprammonium rayon (c. rayon). The properties of the fibrous, structural (XRD and mechanical), physical, and chemical features were investigated. It was found that the rayon was produced in a high yield (90.3%) with accepted properties. The fibrous properties of the rayon staple length, linear density, and fiber diameter were found to be 44 mm, 235 Tex, and 19.4 µm, respectively. In addition, the mechanical properties determined, namely tensile strength, elongation at break, modulus of elasticity, and breaking tenacity, were found to be 218.3 MPa, 14.3 GPa, 16.1%, and 27.53 cN/Tex, respectively. Based on this finding, and upon injecting the ammonia gas through the α-cellulose saturated and immersed in the Cu (OH)2 to complete producing the cuoxam solvent, we find that theuse of an injection rate of 120 mL/minute to obtain the highest fibers' tensile strength for the final product of the c. rayon is preferable. Utilization of higher rates will consume more amounts of the ammonia gas without gaining noticeable enhancement in the c. rayon's mechanical quality. Accordingly, the GAI invention rendered the c. rayon favorable for use in making sustainable semisynthetic floss for either insulation purposes or spun threads for woven and nonwoven textile clothing.

Biodegradation of cuprammonium rayon with added coffee grounds produced by wet spinning

This study aims to examine the biodegradation behavior of cuprammonium rayon (CR) with added coffee grounds (CRW) for the sustainable development goals of new products. Biodegradation tests of CRW and CR without coffee grounds (CRWO) were conducted for a 4-week test time. The results show that the respective mass rates of CRW and CRWO at the 4-week test time were 2% and 8%, respectively, implying that the mass rate of CR was affected by the microbial degradation at the CR–coffee ground interface.

Dissolution and Regeneration of the Produced Nano Bacterial Cellulose of Food Industries Wastewaters by a Cost-Benefit Method

This paper applied a simple and cost-benefit method for the production of regenerated bacterial cellulose. The inexpensive production of cellulose with complex media derived from wastewater from food industries such as molasses adds a lot of contaminants to the produced bacterial cellulose, which puts a lot of challenges in cellulose purification. Therefore, the present study aimed to develop an inexpensive strategy for the complete dissolution of the very dirty cellulose produced from the low-cost medium containing molasses and corn steep liquor, and the reconstruction of pure bacterial cellulose that can be used for all types of cellulose. The bacterial cellulose was produced by Gluconacetobacter xylinus BRP2001 in an effective and inexpensive culture media including a mixture of molasses and corn steep liquor, then cuprammonium rayon method as a cost effective approach was modified for quick and complete dissolution of the bacterial cellulose. The main parameters in cuprammonium method such as the value of sodium hydroxide and copper sulfate, the water removal method and dissolution process were optimized by irregular fraction design. In addition to cost, the time of dissolution process of bacterial cellulose was reduced to less than 1 hour which is unprecedented in comparison with other conventional methods. Regeneration of bacterial cellulose for the fabrication of novel regenerated bacterial cellulose was carried out using dilute sulfuric acid. Under the optimum rayon method comprising 3 wt% NaOH/ 6 wt% copper sulfate solution, the diameter of the nanofibers of bacterial cellulose and regenerated bacterial cellulose ranged between 20-80 nm and 60-120 nm, respectively. Also, the crystal sizes of bacterial and regenerated bacterial cellulose were estimated at about 59.74nm and 6.13nm and the crystallinity indexes of bacterial cellulose and regenerated bacterial cellulose were calculated as 89% and 64%, respectively. The mechanical modulus and crystallinity of regenerated bacterial cellulose were significantly reduced because of the disruption of the hydrogen bond.

Ultrasensitive and highly repeatable pen ink decorated cuprammonium rayon (cupra) fabrics for multifunctional sensors

Flexible pen ink/cupra fabrics (PCFs) innovatively prepared by a dip-coating method exhibit ultrasensitive and highly repeatable strain/liquid sensing performance.

Direct hydrolysis of cellulose to glucose using ultra-high temperature and pressure steam explosion

Hydrolysis of two cellulosic materials, i.e. microcrystalline cellulose powder (MC) and cuprammonium rayon fiber (BEMCOT), to glucose was carried out by steam explosion treatment with ultra-high temperature and pressure steam aiming at an effective usage of unutilized cellulosic materials. 50g of cellulosic materials were charged in a sealed reactor (2L) of the steam explosion apparatus kept at steam pressures of 50, 55, 60, and 62atm for a steaming time of 1min. The maximum yield of water soluble sugars, 52.8%, was obtained at a steam pressure of 62atm and a steaming time of 1min for MC. Furthermore, the maximum yield of water soluble sugars, 67.7%, was obtained at a steam pressure of 60atm and a steaming time of 1min for BEMCOT. This water soluble sugars contained 63.1% and 61.0% of glucose, respectively; they are corresponding to 33.3g and 41.0g of glucose contained in 100g of dry steam-exploded cellulosic material.

Cross-sectional Distribution of Crystalline and Fibril Orientations of Typical Regenerated Cellulose Fibers in Relation to their Fibrillation Resistance

The structural distributions and their formation mechanisms, on both the morphological and crystallographic scales of two types of regenerated cellulose fiber, cuprammonium rayon (Cupra) and solvent spun rayon (Lyocell), were studied in relation to fibrillar formation using transmission electron microscopy and electron micro-diffraction analysis. Cupra had a multilayer structure. The outer layer of the fiber had a network structure without distinct fibrils, but with high crystallinity (χc) and crystalline orientation ( Fc), whereas the center of the fiber had a well-developed fibrillar structure with an amorphous state. The high χc in the outer layer probably resulted from the release of both copper and ammonia from the fiber during coagulation. The fibrillar structures in the center could have been formed by the deformation of the network structure along the elongation direction before crystallization took place. Lyocell was crystallographically and morphologically uniform along the fiber radius, with a highly developed fibrillar structure with high χc and Fc. The type of fibrillar formation was closely correlated with the morphological distribution, that is, fibrillation started from layers with a well-developed fibrillar structure.

Platelet Activation during Haemodialysis: Comparison of Cuprammonium Rayon and Polysulfone Membranes

Background/Aim: Haemodialysis-treated patients are at a high risk of developing cardiovascular disease. Part of this risk may be attributable to the type of the dialysis membrane used. We evaluated whether different dialysis membranes differ with respect to platelet activation. Methods: In a randomized crossover trial, the platelet activation was measured in 14 patients treated with two different dialyzers (cuprammonium rayon membrane and polysulfone membrane). We compared the platelet activation over the dialyzer and between dialyzers after several weeks of dialysis. Results: There were no differences between the two dialyzers in platelet activation over the dialyzer. After 2 weeks, however, the expression of CD62P, CD63, and PAC-1 was statistically significantly lower after cuprammonium membrane treatment than after polysulfone membrane treatment (mean fluorescence intensity in arbitrary units 8.0 vs. 11.1, 2.64 vs. 4.01, and 5.61 vs. 9.74, respectively). Conclusion: Dialysis with a polysulfone membrane seems to lead to more platelet activation than dialysis with a cuprammonium membrane.

Measurement with a chemical sensor and a dialysis probe supported by a null method

A kind of null method was introduced to continuous monitoring of chemicals with a dialysis probe and a chemical sensor to construct a system which was not affected by the change of recovery of the probe or sensor drift. Reference solutions with high and low concentrations, a bypass allowing the mixture of the reference solutions to reach the sensor directly without perfusing the dialysis probe, and a three-way valve as well as a feedback control were added to the system. The flow of the reference solutions mixed each other before the three-way valve and then perfused the bypass and the dialysis probe alternately before reaching the sensor. The mixing ratio of the reference solutions was controlled so that the difference of the sensor output between the two paths became smaller than a given threshold. Then, the concentration of the mixture calculated from the ratio was regarded as the concentration of the objective solution. This method was tested in measuring the glucose concentration in vitro using a system consisting of a dialysis probe with a bundle of semipermeable cuprammonium rayon hollow fibers and a glucose sensor. The glucose concentration of the objective solution was measured precisely, even when the performance of the probe declined or the glucose sensor showed a large (nearly 40%) drift, with the largest error of 13.5% between 100 and 200 mg/dl (5.16–11.1 mM). The procedure time to obtain the first output value was between 8 and 16 min.

Prediction of iopromide reduction rates during haemodialysis using an in vitro dialysis system

In clinical studies, it has been difficult to evaluate the influence of haemodialysis (HD) parameters on HD clearance (CL(HD)) and reduction rate (RR) of non-ionic contrast medium during HD sessions. We therefore predicted clinical values of CL(HD) and RR of iopromide, a non-ionic contrast medium, from findings obtained from in vitro experiments, and confirmed that these predictive values were comparable with the actual values in clinical cases. We developed a correlation equation for predicting CL(HD) on the basis of in vitro HD experiments by varying blood flow rates between 100 and 200 ml/min with a cuprammonium rayon dialyser (AM-SD-10H). Total body clearance of iopromide (CL(PT)) was estimated by the Cockroft-Gault equation. The volume of distribution (V(d)) was obtained from the reported value. By using the HD and three pharmacokinetic parameters (CL(HD), CL(PT) and V(d)), we predicted CL(HD) and RR for seven patients undergoing HD after the administration of iopromide. In the in vitro study, the mean values (+/-SD) of iopromide clearance at blood flow rates of 100, 150 and 200 ml/min were 45.35 (2.54), 53.88 (6.46) and 57.61 (4.72) ml/min, respectively. There were highly significant correlations between clearance and blood flow rate (r = 0.975). Although the predicted CL(HD) showed a tendency towards underestimation, a good correlation was found. Predicted RR values were similar to observed values except for one case. The in vitro model used in the present study provides pertinent information about CL(HD) and is helpful for predicting RR during HD in individual patients undergoing HD.

Structure and Properties of Novel Fibers Spun from Cellulose in NaOH/Thiourea Aqueous Solution

Cellulose was dissolved rapidly in a NaOH/thiourea aqueous solution (9.5:4.5 in wt.-%) to prepare a transparent cellulose solution, which was employed, for the first time, to spin a new class of regenerated cellulose fibers by wet spinning. The structure and mechanical properties of the resulting cellulose fibers were characterized, and compared with those of commercially available viscose rayon, cuprammonium rayon and Lyocell fibers. The results from wide angle X-ray diffraction and CP/MAS 13C NMR indicated that the novel cellulose fibers have a structure typical for a family II cellulose and possessed relatively high degrees of crystallinity. Scanning electron microscopy (SEM) and optical microscopy images revealed that the cross-section of the fibers is circular, similar to natural silk. The new fibers have higher molecular weights and better mechanical properties than those of viscose rayon. This low-cost technology is simple, different from the polluting viscose process. The dissolution and regeneration of the cellulose in the NaOH/thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers. This work provides a potential application in the field of functional fiber manufacturing.

Microporous membranes prepared from cellulose in NaOH/thiourea aqueous solution

We successfully prepared novel microporous membranes from cellulose in NaOH/thiourea aqueous solution by coagulating with ammonium sulphate [(NH 4) 2SO 4] aqueous solution with different concentration for 1–20 min. The structure, morphology, water permeability and mechanical properties of the regenerated cellulose (RC) membranes were measured, and the effects of the coagulant concentration and coagulating time on the microporous formation and pore size of the membranes were investigated. The results from Fourier transfer infrared spectroscopy, wide angle X-ray diffraction, scanning electron microscopy (SEM) revealed that the membranes possess homogeneous porous structure on the surface and relatively dense microporous structure in the inner. By changing the coagulation condition, the different apparent average pore diameters (2 r e) observed by SEM were obtained, ranged from 312 to 523 nm for the surface, and from 187 to 320 nm for the cross-section. With an increase of (NH 4) 2SO 4 concentration from 1 to 10 wt.%, the 2 r e, the mean pore diameters (2 r f) measured by flow rate method and water permeability decreased, and then increased as the (NH 4) 2SO 4 content was higher than 10 wt.%. The mean pore size and water permeability of the membranes are significantly larger than those from viscose and cuprammonium rayon process as well as NaOH/urea aqueous solution. Interestingly, the RC microporous membranes coagulated, respectively, with 1 and 10 wt.% (NH 4) 2SO 4 for 5 min exhibited the maximum values of pore size (2 r e = 514 nm, 2 r f = 43.3 nm), as well as the smallest pore size (2 r e = 312 nm, 2 r f = 26.6 nm). This work provides promising potential way to prepare biodegradable membrane materials in the separation technique field.

5-Lipoxygenase-mediated mitochondrial damage and apoptosis of mononuclear cells in ESRD patients

5-Lipoxygenase activity is enhanced in peripheral blood mononuclear cells (PBMC) from end-stage renal disease (ESRD) patients on maintenance hemodialysis (HD), leading to lipoperoxidation and reactive oxygen species formation. These effects are prevented by vitamin E, which inhibits 5-lipoxygenase activity. The present study was designed to test the possibility that 5-lipoxygenase activation might cause mitochondrial damage and cytochrome c release, ultimately leading PBMC to apoptosis. Apoptosis, mitochondrial uncoupling, and cytochrome c release were investigated in PBMC from 16 healthy volunteers and 16 ESRD patients on maintenance HD with cuprammonium rayon (CL-S) membranes in a two-step crossover study: after a four-week treatment with vitamin E-coated cuprammonium rayon (CL-E) membranes, and again after a four-week treatment with oral vitamin E. Compared to healthy controls, PBMC from ESRD patients showed an approximately threefold increase in mitochondrial uncoupling and cytochrome c release (within 4 and 8 hours, respectively), followed by an approximately threefold increase in apoptotic body formation (within 48 hours). Regardless of the administration route, vitamin E reduced mitochondrial uncoupling, cytochrome c release and apoptosis of mononuclear cells, as did the 5-lipoxygenase inhibitor eicosatetraynoic acid. Conversely, the cyclooxygenase inhibitor indomethacin was ineffective. Reported data suggest that the 5-lipoxygenase branch of the arachidonate cascade is only responsible for mitochondrial disruption and apoptosis of PBMC of ESRD patients, and that vitamin E may be helpful in the control of oxidative stress-related disease in these subjects, independent of the administration route.

Response of peripheral blood mononuclear cells in hemodialyzed patients against endotoxin and muramyldipeptide

Microbial fragments of endotoxin (ET) and peptidoglycan (PG) are recognized as pyrogen in dialysate. The aim of this study was to evaluate the effect of contaminated dialysate on peripheral blood mononuclear cells (PBMC) in hemodialyzed patients by measuring production of interleukine 1-beta (IL-1beta) in vitro. Venous blood was withdrawn before dialysis session. The effects of a dialysis membrane, a magnitude of dialysate contamination and a duration of hemodialysis were studied. PBMC was stimulated by the addition of water containing either ET or muramyldipeptide (MDP), the minimum biological activated fragment of PG, or ET+MDP. IL-1beta production of PBMC stimulated by ET or ET+MDP in patients on hemodialysis using a polysulfon (PS) membrane was significantly lower than those using a cuprammonium-rayon (CU) membrane, ethylenevinylalcohol (EVAL) membrane, polymethylmetacrylate (PMMA) membrane, respectively. Among patients on the PS membranes, those who were exposed to dialysate with higher pyrogen contamination had lower PBMC cytokine production than those dialyzed with ultrapure dialysate. Response of PBMC in patients against ET+MDP stimulant decreased with duration of dialysis treatment. This suggested that chronic exposure to ET or MDP during hemodialysis treatment, might cause a tolerance against ET and ET+MDP in PBMC.

Arachidonate cascade, apoptosis, and vitamin E in peripheral blood mononuclear cells from hemodialysis patients

Background: Lipid peroxidation and oxidative stress are enhanced in peripheral blood mononuclear cells (PBMCs) from hemodialysis (HD) patients because of upregulation of the 5-lipoxygenase pathway of the arachidonate cascade. 5-Lipoxygenase activity is specifically inhibited by vitamin E both in vitro and in vivo regardless of its administration route. Methods: The effect of arachidonate cascade enzymes and vitamin E on oxidative stress and apoptosis was investigated in PBMCs from 16 maintenance HD patients treated for at least 6 months with cuprammonium rayon membranes in a two-step crossover study: after a 4-week treatment with vitamin E-coated cuprammonium rayon membranes and again after a 4-week treatment with oral vitamin E. Control PBMCs were obtained from 16 healthy volunteers. Results: Membrane lipoperoxidation, cellular luminescence, membrane fluidity, and leukotriene B4 content were significantly greater in PBMCs from HD patients; lipoxygenase was upregulated, but prostaglandin H synthase (PHS) was not affected. Regardless of administration route, vitamin E partially controlled lipid peroxidation and oxidative stress through direct inhibition of 5-lipoxygenase. Cultured PBMCs from HD patients showed a significant increase in apoptotic cells compared with controls. Vitamin E markedly reduced cell luminescence, membrane fluidity, and apoptosis, whereas the PHS inhibitor indomethacin was ineffective. Similar results were obtained with control PBMCs induced to apoptosis by hydrogen peroxide. Conclusion: Reported data suggest that the 5-lipoxygenase branch of the arachidonate cascade is only responsible for membrane peroxidation, oxidative stress, and apoptosis of PBMCs of HD patients, and administration of vitamin E may be helpful in the control of oxidative stress-related disease in these subjects. © 2002 by the National Kidney Foundation, Inc.

Effect of a nonionic surfactant on Trichoderma cellulase treatments of regenerated cellulose and cotton yarns

It has been shown that some surfactants affect the hydrolysis of cellulose by cellulase. In this study, the effect of the surfactant Tween 20 on the hydrolysis of different cellulosic fibers was investigated and related to the cellulose fiber structure. It was found that this non-ionic surfactant enhanced the enzymatic saccharification of highly crystalline cellulosics such as Avicel, Tencel and cotton but not of cuprammonium rayon. The enhanced saccha-rification effected by the surfactant is attributed to inhibition of non-productive sorption of the endoglucanase of the cellulose surface which gives greater access to the cellulose chain ends by the exoglucanase. Although all three fibers lost tensile strength as a result of the enzymatic treatment, no further decrease was effected by the presence of the surfactant.

Hydrolysis of cuprammonium rayon by endocellulases

The first step in the hydrolysis of cuprammonium rayon with endocellulases was examined and the results were compared with those of hydrolysis with a cellulase complex. Mechanical agitation during endocellulase treatment was effective for the separation of the oligomers from the substrate. The endocellulases removed the intermediately ordered regions in the disordered matrix. The crystalline regions were negligibly affected by the endocellulases, while the cellulase complex considerably deaggregated the surface of the crystallite. The endocellulases enhanced the brittleness of the fabric more than did the cellulase complex. It was assumed that the hydrolysis with the endocellulases proceeded without molecular deaggregation of the fiber. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2543–2547, 2001

Biocompatibility of Hemodialysis Membranes: Interrelations between Plasma Complement and Cytokine Levels

Hemodialysis (HD) membrane biocompatibility is defined as absence of complement activation. We have recently shown that circulating levels of interleukin (IL) 1 and IL-2 predict death and survival, respectively, of HD patients. Studies have assessed IL-1 in treatments with biocompatible and less biocompatible dialysis membranes, but no study has correlated circulating levels of all these immunoreactants. We assessed these immunoreactants, and temperature as an outcome, during HD in patients treated with different membranes. Twelve stable patients, receiving thrice-weekly chronic bicarbonate HD, were randomly dialyzed with three different types of membranes, composed of: Cuprophan, cuprammonium rayon modified cellulose, and Hemophan. Blood was drawn from the arterial line port before (Pre) and 15, 30, and 60 min during and after (Post) HD. Patients’ temperatures were measured before and after each treatment. The plasma concentrations of IL-1 and IL-2 and factors C3a and C5a were assessed by ELISA. There were no differences between baseline levels of any of the immunoreactants in patients treated with different dialyzers. C3a, C5a, and IL-1 levels increased significantly during HD treatments with all three different membranes. C3a, C5a, and IL-1 levels during Cuprophan and Hemophan treatments were significantly higher than the levels during modified cellulose treatment at 30 and 60 min and Post (p < 0.01). For all the immunoreactants, however, the Post levels were higher than the Pre levels. In contrast to IL-1, there were no differences in mean IL-2 levels during treatments when different membranes were compared. There were few correlations of plasma C3a and C5a levels with plasma IL-1 levels, but there was only one treatment time in one dialyzer group during which IL-2 and any of the other factors were correlated. Pre and Post temperature values and percent change in temperature were not correlated with any of the immunoreactants measured. These data show that C3a, C5a, and IL-1 responses are similar, but not identical, during treatments with different membranes. The response of circulating IL-2 levels to treatments is quite different from that of plasma C3a, C5a and IL-1 levels and suggests that these changes are not solely due to treatment factors. Treatment with modified cellulose membranes is associated with a different immunoreactive profile as compared with patients dialyzed using other cellulose membranes. We suggest that circulating IL-1 levels are good biocompatibility markers.

A miniaturized pH and pCO 2 intravascular catheter using optical monitoring and a dual concentric-flow microdialysis approach

Hollow fiber membranes are found to allow the development of extremely small diameter (0.22 mm) probe and catheter-type pH and pCO 2 sensors. These types of sensors can be comparable to the size of fiber optic sensors for these analytes. This work employs a concentric-flow geometry to direct a micro-flow of sweep solutions through hollow fiber membranes made of cuprammonium rayon and silicone. The sweep solutions establish a diffusive equilibrium with the external environment and then flow into optical absorbance cells. The optical system, which is remote from the sensor membranes, consists of two separate transparent capillaries, 555-nm surface-mount LEDs and photodetectors to monitor absorbance changes. In buffer, a ±0.01 pH unit resolution is achieved over the range of 7.02–7.87 with a 5-min 90% response time, and a 1.5-mm Hg pCO 2 resolution is achieved from 0 to 80 mm Hg with a 15-min 90% response time.

Changes in Breaking Strength and Water Retention of Cellulosic Fibers hydrolyzed by Commercial Cellulases.

The changes in weight loss, breaking strength and water retention of the cellulosic fibers; cotton, viscose rayon filament and cuprammonium rayon filament yarns, by the enzymatic hydrolysis were investigated with the commercial cellulase A and cellulase B from Aspergillus niger and from Trichoderma viride, respectively. Under the hydrolysis conditions used in this study, the surface fibrils of cotton and rayon yarns did not easily eliminated. The cellulase B lost weight at faster rate than the cellulase A for all samples: the weight loss increased in the order viscose rayon < cotton < cuprammonium rayon. In all cases, although the fall in breaking strength was totally progressive with increasing weight loss, the relationship between the breaking strength and weight loss appears to be markedly affected by the fine structure of cellulosic fiber. Retention of strength after 240 min incubation time increased in the order cotton < cuprammonium rayon < viscose rayon. It was especially noted, in the case of cellulase B, that there was the range of weight loss which the strength remains constant for all samples. Water retention value of hydrolyzed yarns was found to reach a minimum at initial stages of hydrolysis and then increase at more advanced stages of hydrolysis in all cases.

Investigating the Cuprammonium Rayon Process in a High School Laboratory

We have found the cuprammonium rayon process to be an excellent system for high school independent study. Meeting twice a week provided time for the student-teacher investigation to result in a productive year of study. One can study the shift of the equilibrium to the complex ion, tetraamminecopper(II) hydroxide, and then return to copper(II) hydroxide by adding saturated copper(II) sulfate. The pH dependence of this equilibrium shift is studied as well as the pH dependence of Schweizer's reagent used to dissolve a-cellulose. The methods for rayon fiber formation and rayon disks are described. The fibers in a cuprammonium rayon membrane for a kidney dialysis machine are pictured.