Rayon Fibers Research Articles

A comparative study of regenerated bamboo, cotton and viscose rayon fabrics. Part 2: antimicrobial properties

Since regenerated bamboo fibres (also referred to as bamboo viscose) became commercially available in 2006, consumers have been bombarded with contradictory information regarding products made of these fibres, their potential end-uses and their properties. On the one hand, manufacturers and marketers make broad claims about the antimicrobial and environmentally friendly characteristics of products made of regenerated bamboo, while, on the other hand, there is an outcry from consumer watchdogs that many of these claims are false and have not been properly proven. Very little information is available about the validation of these properties through scientific research studies. It is also evident that information about natural bamboo and regenerated bamboo fibre products is often confusing. Regenerated bamboo (also referred to as bamboo viscose or bamboo rayon) is manufactured from natural bamboo fibres in a regeneration process by which bamboo pulp is refined from the stems of the bamboo plant in a process similar to that used to manufacture viscose rayon fibres. The severity of this process has led to scepticism as to whether the antimicrobial properties of the bamboo kun remain unchanged in regenerated bamboo fibres. The question has been raised as to whether residual chemicals on the spun fibres could be the cause of antimicrobial properties. The main objective of this study was to investigate the claim that regenerated bamboo fibres have inherent antimicrobial properties as a result of the bamboo kun present in the raw material from which the fibres are regenerated. For this purpose, the antimicrobial properties of regenerated bamboo fabric were compared to those of viscose rayon and cotton fabrics. The results confirmed that cotton fabric (used as a control) exhibited no antimicrobial activity. However, the antimicrobial effect of the regenerated bamboo and viscose rayon samples was significantly higher than that of the cotton sample, for both Gram-positive bacteria and Gram-negative bacteria. The claims made concerning the bacteriostatic or antimicrobial properties of regenerated bamboo could thus not be proven as false. Statistically, the regenerated bamboo fabrics did not perform better than the viscose rayon fabrics in our tests and did not kill all the bacteria in the solution. No evidence was found that regenerated bamboo fibre fabrics are superior to other regenerated cellulose fibres such as viscose rayon, nor that the antimicrobial properties of natural bamboo remain unchanged in regenerated bamboo fibres.

Zinc extraction from sulfate media with bis(2,4,4-trimethylpentyl)dithiophosphinic acid in the absence and in the presence of electron donor additives

The paper presents data on zinc extraction from sulfate solutions with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR, trade mark CYANEX 301) diluted with nonane and kerosene in the absence and in the presence of electron-donor additives (L). Trialkyl amine (TAA), trialkyl phosphine oxide (TAPO), tributyl phosphate (TBP), and n-octanol were used as additives.Using the zinc distribution data and spectral methods, it was shown that, in the absence of additives, zinc extraction with CYANEX 301 proceeds by a cation exchange mechanism. The composition of the extracted compound in the organic phase was found to be ZnR2. In all cases, the introduction of additives into the organic phase results in a decrease in zinc extraction, which is probably due to a decrease in the extractant activity resulting from the interaction between HR and L. The degree of extraction decreases in the series HR without additives>HR+n-octanol>HR+TBP>HR+TAPO>HR+TAA.In the HR+TAA system, with increasing aqueous acidity, a change in the mechanism of zinc extraction from cation exchange to binary extraction takes place. In this case, the counter ion (bisulfate ion) is extracted together with the cation (zinc).The mixtures of HR with TAA could be of interest for zinc recovery from various industrial solutions, for example, in the processing of viscose rayon fibre solutions for the separation of zinc from calcium, for purification of zinc solutions from manganese, etc. Unlike the system containing only dithiophosphinic acid, both effective zinc extraction and its effective stripping with dilute solutions of sulfuric acid are possible for the HR+TAA system.

Preparation and Properties of Viscose Rayon/O-carboxymethyl Chitosan Antibacterial Fibers

Antimicrobial viscose rayon/O-carboxymethyl chitosan fibers (VCMFs) were manufactured by spinning the mixture of O-carboxymethyl chitosan (O-CMCS) xanthate and cellulose xanthate via the viscose process. The structure, morphology and mechanical properties were investigated by infrared, scanning electron microscopy, transmission electron microscope and tensile test. The results show that the blend fibers of cellulose and O-CMCS were satisfactorily prepared and the two polymers were mixed homogeneously. VCMFs display striation along the fiber similar to those of viscose rayon fibers, and their mechanical properties are close to that of viscose rayon. With O-CMCS blended, VCMFs showed good moisture absorption and antibacterial activity against E.coli.

Preparation and Characterization of the Blended Film from Silk Fibroin and Regenerated Cellulose Fiber Residue

This research studied the preparation of the blended film from Bombyx mori silk fibroin with the regenerated cellulose obtained from rayon fiber residue, the industrial waste fiber. The β-sheet structure of silk fibroin was observed while the regenerated cellulose possessed cellulose II crystalline form. The infrared spectra of the blends showed changes in shape and intensity of IR absorption frequency characteristics in the region of 3500-3300 cm-1 as compared with those of the starting materials, pure silk fibroin and cellulose. This indicates the occurrence of the intermolecular interactions between the –OH groups of cellulose and silk fibroin by forming hydrogen bond. The tensile properties of the blends with cellulose content lower than 50 % could not be measured due to the weakness of the prepared film. The stronger and more flexible film was obtained with increasing the regenerated cellulose content. The study on the effect of NaCl and CaCl2 salt addition aiming to establish a porous structure to the blends was also investigated.

Properties and structure of MWNTs/cellulose composite fibers prepared by Lyocell process

AbstractLyocell fiber is a new kind of regenerated cellulose fiber and expected to replace the Rayon fiber to be not only used in the textile field but also used in the fields of industry and aerospace after being modified. In this work, the multi‐walled carbon nanotubes (MWNTs)/Lyocell composite fibers were prepared under different draw ratios by dry‐wet spinning and their electrical properties, mechanical properties, and structure were investigated. It was found that an appropriate amount of MWNTs could be dispersed homogeneously in the Lyocell matrix and could improve the mechanical and thermal properties of composite fiber. The results of wide angle X‐ray diffraction (WAXD) showed that the MWNTs in the composite fiber almost aligned along the axis of the fibers and the orientation of MWNTs increased with the increasing draw ratio. Furthermore, it was found that more MWNTs content and lower draw ratio could improve the electrical conductance of the composite fiber. The composite fiber containing 5 wt % MWNTs has a volume conductivity of 8.8 × 10−4 S/cm, which is five orders higher than that of pure Lyocell fiber. These results indicate that the MWNTs/Lyocell composite fiber has potential applications in the areas of precursor of carbon fiber and conductive fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Development on the Multi-Component Blending Yarn of Hemp/ Anti Bacteria Fine Rayon/Micro-Porous Polyester Fiber

The hemp, anti-bacteria fine rayon and micro-porous polyester fiber were select to spin into the multi-component blending yarn by ring spinning process. The performances of these fibers were analysed, the spinning process were presented. The multi-component blending yarn of Hemp/Anti bacteria fine rayon/micro-porous polyester fiber of excellent was spun successfully, and the performance of yarn was examined and discussed.

Rendering Rayon Fibres Antimicrobial and Thermal-Responsive via Layer-by-Layer Self-Assembly of Functional Polymers

A thermal-responsive polymer was prepared by partially acetalyzing poly(vinyl alcohol) (PVA). The completely reversible polymer aggregation and dissolution occur above and below a low critical solution temperature (LCST) for the aqueous solution of the modified PVA. The partially acetalized PVA (APVA) with higher molecular weight and higher degree of acetalysis exhibited a lower LCST transition and was used as an anionic polymer for polymer complexation. Water-soluble polymer, cationic polyhexamethylene guanidine hydrochloride (CPHGH) with antimicrobial property, was also prepared. In conjunction with APVA, CPHGH created the unique antimicrobial polymer multilayers on the surfaces of rayon fibres via layer by layer (LbL) assembly. AFM images revealed that the particles generated by multilayers became larger after the material was treated at 60°C; while the roughness of the surfaces was increased as the layer number increased and then decreased. Moreover, antimicrobial tests also demonstrated that the rayon fiber assembled with (CPHGH/APVA) multilayers exhibited higher antimicrobial activity against E. coli and s. aureus.

Influence of esterification crosslinking structures of rayon fibers with 1,2,3,4‐butanetetracarboxylic acid on tensile properties

Abstract1,2,3,4‐Butanetetracarboxylic acid (BTCA) was applied to crosslink amorphous regions of cotton‐type rayon fibers via anhydride‐mediated esterification for the purpose of a molecular‐level control over macroscopic properties. Formation of intrafiber crosslinked structures of the rayon fibers was a facile and efficient method to diminish swelling degree and enhance tensile properties. Crosslinking was conducted under a series of curing temperature and various dosages of BTCA with the presence of sodium hypophosphite as the catalyst for anhydride formation. It was found that crosslinking conditions, both the curing temperature and dosage of the crosslinking agent, made notable impacts on the crosslinking behaviors of the rayon fibers. The dry and wet tensile strength of the rayon fibers were optimized for both the dosage of the crosslinking agent and the curing temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Drafting Force Forecasting Using Genetic Programming

Genetic programming was used to find out a mathematical model for drafting force from drafting process parameters on the drawing frame, which fits the experimental data as much as possible. The study used rayon fibers as the raw material in the mini-draw frame. The process parameters on the draw frame such as front roller speed, front roller draft, back roller speed and back roller draft as variables were investigated. The paper used the principle that there is linear relationship between drafting force and deformation from the strain gauges in the sensor. The data obtained from online measurement device was used for training and testing on the genetic programming. A comparison between experimental and predicted data was done. The results show very good agreement between the experimental and predicted values. Furthermore, this article shows that genetic programming can provide further use for setting up the machine process parameters without requiring an expert in the field.

A semi-analytical model for simulating fluid transport in multi-layered fibrous sheets made up of solid and porous fibers

Direct simulation of fluid transport in fibrous media consisting of swelling (i.e., fluid-absorbing) and non-swelling (i.e., solid) fibers is a challenge. In this work, we have developed a semi-analytical modeling approach that can be used to predict the fluid absorption and release characteristics of multi-layered composite fabrics made up of swelling and non-swelling fibrous sheets. The simulations presented here are based on a numerical solution of Richards’ equation. Two different fibrous sheets composed of non-swelling (PET) and swelling (Rayon) fibers with different Solid Volume Fractions (SVFs) and thicknesses were arbitrarily chosen in this study for demonstration purposes. The sheets’ capillary pressure and relative permeability are obtained via a combination of numerical simulations and experiment. In particular, the capillary pressure expression for non-swelling media is obtained from the analytical expressions that we previously developed via 3-D microscale simulations, while the capillary pressure for swelling media is obtained via height rise experiments. The relative permeability expressions for both swelling and non-swelling media are obtained from the analytical expressions previously developed via 3-D microscale simulations, which are also in agreement with experimental correlations from the literature. On the macroscale, simulation results are reported for fluid transport in bi-layered composite fabrics, and comparison is made between the performances of these fabrics in terms of the order in which the layers are stacked on top of one another. A higher rate of absorption was observed when the layer in contact with the fluid is that comprised of swelling fibers. A similar study was conducted for motion-induced fluid release from the composite fabrics when partially-saturated with a fluid. It was shown that less fluid release is expected when the swelling sheet is placed in contact with the surface.

Water sorption of denture base resin reinforced with different fibres

This study determined the changes in water sorption property of a denture base resin reinforced with five types of fibre. E-glass, polyester, rayon, nylon 6 and nylon 6/6 fibres were cut into 2, 4 or 6 mm lengths, and added into resin at 3 wt-%. Fifteen specimens were prepared for each length of reinforcing fibres, and for control specimens without fibre, using a mould with 10 × 10 × 2 mm dimensions. Water sorption test was performed according to ISO Specification 1567:1999 for the immersion periods of 1 day, 1 week and 4 weeks (n=5). Results showed that water sorption profiles of all groups were time dependent, and that different lengths of the same fibre material affected sorption values non-linearly. The use of different fibres in varying lengths also had a significant effect on water sorption capacity of the resin. The highest sorption value was recorded from the specimens reinforced with 4 mm rayon fibres after for 4 week immersion.

Molecular Orientation in Dry and Hydrated Cellulose Fibers: A Coherent Anti-Stokes Raman Scattering Microscopy Study

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with spontaneous Raman scattering microspectroscopy and second harmonic generation (SHG) microscopy to interrogate the molecular alignment in dry and hydrated cellulose fibers. Two types of cellulose were investigated: natural cellulose I in cotton fibers and regenerated cellulose II in rayon fibers. On the basis of the orientation of the methylene symmetric stretching vibration, the molecular alignment of cellulose microfibrils is found to be conserved on the micrometer scale. Whereas the molecular orientation in cotton shows modest variability along the fiber, the alignment of the cellulose units in rayon is highly consistent throughout the fiber. The ordered alignment is retained upon fiber hydration. Upon hydration of the cellulose fibers, an anisotropic electronic contribution is observed, which indicates an ordered incorporation of water molecules into the fiber structure. The third-order and second-order electronic polarizability of cellulose I are directed along the axis of the polyglucan chain. No second-order optical response is observed in cellulose II, supporting the antiparallel arrangement of the polyglucan chains in regenerated cellulose.

A comparative study on the graft copolymerization of acrylic acid onto rayon fibre by a ceric ion redox system and a γ-radiation method

Functionalization of rayon fibre has been carried out by grafting acrylic acid (AAC) both by a chemical method using a Ce 4+–HNO 3 redox initiator and by a mutual irradiation (γ-rays) method. The reaction conditions affecting the grafting percentage have been optimized for both methods, and the results are compared. The maximum percentage of grafting (50%) by the chemical method was obtained utilizing 18.24 × 10 −3 moles/L of ceric ammonium nitrate (CAN), 39.68 × 10 −2 moles/L of HNO 3, and 104.08 × 10 −2 moles/L of AAc in 20 mL of water at 45 °C for120 min. For the radiation method, the maximum grafting percentage (60%) was higher, and the product was obtained under milder reaction conditions using a lower concentration of AAc (69.38 × 10 −2 moles/L) in 10 mL of water at an optimum total dose of 0.932 kGy. Swelling studies showed higher swelling for the grafted rayon fibre in water (854.54%) as compared to the pristine fibre (407%), while dye uptake studies revealed poor uptake of the dye (crystal violet) by the grafted fibre in comparison with the pristine fibre. The graft copolymers were characterized by IR, TGA, and scanning electron micrographic methods. Grafted fibre, prepared by the radiation-induced method, showed better thermal behaviour. Comparison of the two methods revealed that the radiation method of grafting of acrylic acid onto rayon fibre is a better method of grafting in comparison with the chemical method.

A comparative study of regenerated bamboo, cotton and viscose rayon fabrics. Part 1: selected comfort properties

Regenerated bamboo, also known as bamboo viscose, is a man-made cellulose fibre that has recently appeared on the market as an apparel and home-furnishing textile. The products are marketed as having exceptional properties such as superior comfort and hand, as well as antimicrobial properties. Apart from the claimed “cool feeling”, the comfort properties referred to in the promotion of bamboo viscose fabrics can generally be ascribed to most cellulose fibres or fabrics. The purpose of this study was to investigate whether the moisture management and thermo-physiological properties of regenerated bamboo fabrics differ significantly from those of cotton and viscose rayon fabrics. A knitted regenerated bamboo fabric was compared to cotton and viscose rayon fabrics of comparable construction by using the results of objective measurements. Test apparatus used included the WALTERTM sweating manikin to measure thermal resistance, water vapour permeability, water absorbency and the moisture permeability index, the ALAMBETA instrument to measure thermal resistance and absorption and the PERMETEST instrument to measure water vapour permeability. To compare the structure of the regenerated bamboo fibre with that of cotton and viscose rayon fibres, the longitudinal character and cross-section of fibres were studied using scanning electron microscopy (SEM). Results confirmed that regenerated bamboo fibre fabrics have excellent moisture and temperature management properties. Contrary to the expectations created, however, no empirical evidence was found in this study, when properties pertaining to comfort were compared, to confirm that regenerated bamboo fibre fabrics are superior to those made of cotton and viscose rayon.

Postmenopausal breast cancer and occupational exposures

ObjectiveTo determine whether exposures in the workplace to organic solvents and to other agents, such as polycyclic aromatic hydrocarbons, are associated with increased risks of developing postmenopausal breast cancer.MethodsBetween 1996...

Spinnability of low‐substituted hydroxyethylcellulose sodium hydroxide aqueous solutions

AbstractEthylene oxide was used to etherify alkali cellulose with a low substitution degree to replace carbon disulfide to generate cellulose xanthogenate by viscose technology. The resultant low‐substituted hydroxyethylcellulose (LSHEC), with molar substitution of 0.49, was used to attempt to spin LSHEC fibers under spinning and coagulation conditions identical to those used for industrial rayon fibers. The spinnability of LSHEC was investigated by the variation of the storage modulus, loss modulus, and complex viscosity with the concentration of the LSHEC spinning solutions and temperature. It was found that the dissolution of LSHEC in sodium hydroxide aqueous solutions was an exothermic process, whereas the gelation of LSHEC was an endothermic process. Spinning conditions, comprising the concentration of the spinning solutions and corresponding spinning temperatures, were derived from the gelation onset curve theoretically. Moreover, combinations of the concentration of the spinning solution and the temperature of the coagulation bath could be predicted by the gelation onset curve. Finally, LSHEC fibers were prepared under the spinning conditions based on the gelation onset curve. The as‐spun LSHEC fibers had dry and wet tensile strengths of 1.59 and 0.47 cN/dtex, respectively, with a 0.30 ratio of the wet tensile strength to the dry tensile strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

合成繊維・再生繊維集合体の圧縮応力緩和特性

In this paper, the compressive stress relaxation properties of twelve kinds of cylindrical fiber assembly made of synthetic fibers such as polyester fibers and poly(trimethylene terephthalate) (PTT) fibers, and regenerated fibers such as cupro-ammonium rayon (cupra) fibers and lyocell fibers are investigated experimentally with regard to sleeping comfort. The results are obtained as follows.(1) Experimental curve of Sγ , residual stress ratio for all samples is expressed approximately by following empirical equation for t > 102 sec.Sγ=σ/σ0= K(a0 - ln t)where, σ : stress at time t (Pa), σ0: initial stress (Pa), t : time(s), K and a0 : constants determined by fiber type and measurement condition.(2) Stress relaxation rate represented by K of regenerated fiber assembly made of cupra and lyocell fibers is high compared to that of synthetic fiber assembly made of polyester and PTT fibers.(3) Compression stress relaxation phenomena of regenerated fiber assembly is expressed by following equation derived from Eyring′s non-linear two element visco-elastic model for 0 < t < 104 sec.Sγ=σ/σ0= K ln [coth {1/2(2e-a0t + B)}]where, K, a0 and B are constants determined by fiber type and measurement condition. In contrast, compression stress relaxation phenomena of synthetic fiber assemblies are not expressed by this equation.(4) Compression stress relaxation phenomena of synthetic fiber assembly are expressed by following empirical equation for 0 < t < 104 sec. σ = βt-α. where, σ : stress at time t (Pa), t : time (s), α and β are constants determined by fiber type and measurement condition.

Characteristics of microbubbles generated by porous mullite ceramics prepared by an extrusion method using organic fibers as the pore former

Porous mullite ceramics with unidirectionally oriented pores were prepared by an extrusion method using rayon fibers as the pore formers and the characteristics of microbubbles generated by these porous ceramics were investigated. The 1200 mm long ceramics were tubular and of thick or thin types of 20–30 mm inner diameter and 30–50 mm outer diameter, respectively. The thin and thick samples had porosities of 47 and 49% and average pore radii of 7.8 μm. The gas permeabilities of the thick and thin samples were 4.1 × 10 −14 and 5.4 × 10 −14 m 2, respectively. Microbubbles were generated by introducing N 2 gas through the ceramic tube by immersing it into water. The minimum pressure (bubble point pressure) for generation of microbubbles was 20 kPa, much lower than for other bubble-forming methods. The average microbubble radii ranged from about 70 to 105 μm at flow rates of 0.15–0.25 L/min in the thin sample and 0.3–0.7 L/min in the thick sample. These bubble sizes are much smaller than calculated for a Fritz-type bubble such as generally formed by bubbling from pores and/or orifices. However, the present bubble sizes agree well with the calculated value based on nanobubbles, indicating that bubble formation occurs by mixing the gas with water in small pores. Since microbubbles enhance the dissolution rate of a gas phase in water, they are potentially useful for improving water environments, especially oxygen-deficient water. The effectiveness of gas dissolution in water was confirmed by determining the dissolution behavior of CO 2 gas using these porous ceramics.

Influence of Low Temperature Plasma Treatment on the Properties of Tencel and Viscose Rayon Fibers

Two regenerated cellulosic fibers, namely, Tencel and viscose rayon fibers, were modified by means of low temperature plasma (LTP) treatment using oxygen gas. The morphological changes in fiber structure were assessed by a scanning electron microscope, which revealed the formation of ripplelike structures on the treated fiber surface. The ripplelike structures oriented at a direction perpendicular to the fiber axis were developed gradually with increasing LTP treatment time. The LTP treatment not only reduced the tenacity and elongation at break but also increased the percentage of moisture regain of Tencel and viscose rayon fibers. Moreover, the percentage of crystallinity of the LTP-treated fiber assessed by an X-ray diffraction analysis was found to be reduced. In addition, the color of the LTP-treated fiber surface was changed to yellow due to the effect of oxidation caused by the oxygen LTP.

The design and testing of a dual fiber textile matrix for accelerating surface hemostasis.

The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions.