Triacetate Fibers Research Articles

Exploring Cellulose Triacetate Nanofibers as Sustainable Structuring Agent for Castor Oil: Formulation Design and Rheological Insights.

Developing gelled environmentally friendly dispersions in oil media is a hot topic for many applications. This study aimed to investigate the production of electrospun cellulose triacetate (CTA) nanofibers and to explore their potential application as a thickening agent for castor oil. The key factors in the electrospinning process, including the intrinsic properties of CTA solutions in methylene chloride (DCM)/ethanol (EtOH), such us the shear viscosity, surface tension, and electrical conductivity, were systematically studied. The impact of the CTA fiber concentration and the ratio of DCM/EtOH on the rheological properties of the gel-like dispersions in castor oil was then investigated. It was found that dispersions with a non-Newtonian response and above a critical concentration (5 wt.%), corresponding to approximately 2-2.5 times the entanglement concentration, are required to produce defect-free nanofibers. The average fiber diameter increased with CTA concentration. Further, the morphology and texture of the electrospun nanofibers are influenced by the ratio of solvents used. The rheological properties of dispersions are strongly influenced by the concentration and surface properties of nanofibers, such as their smooth or porous textures, which allow their modulation. Compared to other commonly used thickeners, such as synthetic polymers and metal soaps, CTA electrospun nanofibers have a much higher oil structuring capacity. This work illustrated the potential of using CTA nanofibers as the foundation for fabricating gel-like dispersions in oil media, and thus exerting hierarchical control of rheological properties through the use of a nanoscale fabrication technique.

Design and fabrication of electrospun mixed-matrix multi-layered membranes containing tri-n-octylphosphine oxide for efficient adsorption of p-cresol

In this study, various types of mixed-matrix cellulose triacetate (CTA) fibrous membranes were prepared by a combined electrospinning and electrospraying process, in which tri-n-octylphosphine oxide (TOPO) powders were incorporated on the surface of the fibers to remove uremic toxin p-cresol by adsorption. The morphology, chemical composition (element analysis), and textural properties of the prepared fibrous membranes were first analyzed. The adsorption ability of various fibrous membranes for p-cresol in synthetic serum was then studied in batch experiments at pH 7.4 and 37 °C. It was seen that the loose structure of the electrospun fibrous membranes was beneficial to the rate of adsorption and the position where the TOPO stayed on the fibers played a crucial role in the availability of TOPO and hence the adsorption performance. The maximum adsorption of p-cresol was 6.45 mmol per gram of TOPO, highlighting the adsorption ability of as-prepared mixed-matrix membranes. Moreover, the electrospun TOPO-coated fibers covered with a thin layer of the electrospun CTA fibers largely improved cell viability. The present results have demonstrated the application potential of electrospun/sprayed mixed-matrix fibrous membranes with TOPO for efficient adsorption of p-cresol.

Structural Characteristics and Properties of Polylactic Acid (PLA) and Cellulose Triacetate (CTA) Fibers for Heat-Not-Burn (HNB) Cigarettes

In this work, two commonly used filter fibers for heat-not-burn (HNB) cigarettes, polylactic acid (PLA) and cellulose triacetate (CTA) fibers, have been extensively investigated by characterizing their morphologies, thermal and wetting properties. It is found that plenty of small pores can be observed in PLA fibers, which can provide more effective surface areas for the adsorption of mainstream smoke than CTA fibers with smooth surface. At the same time, thermal properties results including differential scanning calorimetry data, thermogravimetry data, and thermal conductivities of PLA and CTA fibers indicate that CTA fibers have an amorphous phase, while PLA fibers present a mixture of amorphous phase and crystalline phase with better thermal properties. Additionally, wetting properties demonstrate that PLA fibers have better adsorption properties than CTA fibers.

Cellulose triacetate fiber-reinforced polystyrene composite

The increase in demand for natural fibers in development of the composites has grown rapidly due to the cost-effectiveness, low density, biodegradability, and renewability. The lack of appropriate interfacial bonding between the cellulose fibers and the thermoplastic matrix is one of the disadvantages faced during their application. Also, the properties of composite made of thermoplastic polystyrene (PS) and cellulose acetate fibers are not compatible due to the poor wettability and interfacial adhesion. In the study presented, PS reinforced with cellulose triacetate is being prepared by melt blending in a twin-screw extruder with the induction of fusabond (FB). The influence of the cellulose acetate and FB content on PS composite is being investigated using thermogravimetric analysis, tensile test, dynamic mechanical analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The addition of FB enhances interfacial adhesion demonstrated by the improvement in storage modulus, reduction in damping peak value, and the increase in thermal stability of the composite. The inclusion of FB not only increases the % elongation but also improves the impact strength of the cellulose triacetate-reinforced PS composite under dynamic loading. Moreover, the interaction between PS with cellulose triacetate fiber is indicated by the results of X-ray photospectroscopy and fracture surface morphology. The results show that the addition of FB is suitable for use in cellulose fiber-reinforced PS composite for packaging, automotive, and biomedical applications.

Characterization of Personal Clothing Worn by Pesticide Sprayers in Foumbot Agricultural Area (Cameroon)

Personal protective equipment is intended to protect worker from risks that cannot be eliminated for more effective safety. This study was aimed at evaluating the type of cloth worn by pesticide users in Foumbot agricultural area (West Region of Cameroon) and to identify signs and symptoms related to pesticides effects on human health. A survey was conducted on seventy (70) farmers randomly selected using a questionnaire made up of closed and opened questions. Specimens of cloth were collected, identified and analyzed for the water and vapor absorbency and permeability. The identification was done by burning and solubility tests. Results showed that no farmer used adequate protective clothing, they all presented many pesticide-related signs and symptoms such as dizziness, skin irritation, eye-watering and breathing difficulties; the permeation of clothes that they wear is high with high vapor and water absorbency capacity; they were made up with Cotton fiber, blended cotton fibre, wool, polyester and polyethylene; a local laminated fabric manufactured with Tri-acetate fiber was identified with great capacity of protection. This study raised inappropriate characteristics of protective materials used by farmers in Foumbot agricultural area. However, a local fabric was identified to have been adapted to pesticide applications and may be promoted after further study on the comfortability.

Reinforcement of Artificially Aged Paper Using Electrospun Poly(vinyl alcohol)/Cellulose Triacetate Fibers

Reinforcement of Artificially Aged Paper Using Electrospun Poly(vinyl alcohol)/Cellulose Triacetate Fibers

Electrospun Bilayer of Poly(vinyl alcohol)/Cellulose Triacetate Fibers for Reinforcement of Paper

Electrospun Bilayer of Poly(vinyl alcohol)/Cellulose Triacetate Fibers for Reinforcement of Paper

Enhanced Aerosol Particle Filtration Efficiency of Nonwoven Porous Cellulose Triacetate Nanofiber Mats.

Aerosol particle filtration in most penetrating particle size (MPPS) region is of great challenge for conventional nonwoven filter mats. The present work, therefore, redesigns conventional filter mats by introducing porous structure. A combination of thermally induced phase separation and breath figure mechanism was employed to synthesize porous cellulose triacetate fibers, in conjunction with the volatile solvent methylene chloride. The ambient humidity, the concentration of the polyvinylpyrrolidone (PVP) secondary polymer, and the ethanol cosolvent were all adjusted to modify the Taylor cone formation, jet stability, and fiber porosity. After fiber formation, the PVP was removed to obtain a superhydrophobic material. To distinguish the effect of pores, the performance of porous and nonporous nanofibers having similar sizes was conducted. Tests were performed using various dust particle sizes, and the results show that the collection efficiency of the porous fibers, resulting from particle diffusion, inertial impaction, and interception, was improved. Interestingly, the efficiency of the porous fibers in the MPPS region was exceptionally enhanced (up to 95%), demonstrating that the presence of dynamic pores greatly contributes to particle capture.

Electrospun Cellulose Triacetate Fibers Using DMSO/Chloroform Co-Solvent System

Nonwoven fibers of cellulose triacetate (CTA) were continuously electrospun by using DMSO/chloroform co-solvent system and the size and morphology of fibers were investigated. It was found that the concentration of 8wt% CTA fibers were obtained from DMSO/chloroform with volume ratio of 1:1, 3:2, 2:1, 3:1. The average diameters of CTA fiber was decreased with decreasing chloroform content in the mixed solvent. The minimum diameter of the continuous electrospun cellulose triacetate fibers obtained in this work ranged between 210 and 880 nm.

Crude bacterial extracts of two new Streptomyces sp. isolates as bio-colorants for textile dyeing

Renewed demand for incorporation of natural dyes (bio-colorants) in textile industry could be met through biotechnological production of bacterial pigments. Two new Streptomyces strains (NP2 and NP4) were isolated for the remarkable ability to produce diffusible deep blue and deep red pigment into fermentation medium. Crude mycelial extracts of both strains were used as bio-colorants in conventional textile dyeing procedures avoiding downstream purification procedures. The yields of bio-colorants obtained in this way were 62 and 84 mg per g of mycelia for Streptomyces sp. NP2 and Streptomyces sp. NP4, respectively. Through nuclear magnetic resonance analysis of crude extracts before and after dyeing procedures, it was shown that both extracts contained prodigiosin-like family of compounds that exhibited different dyeing capabilities towards different textile fibers. Polyamide and acrylic fibers were colored to the deepest shade, polyester and triacetate fibers to a noticeable, but much lower shade depth, while cotton and cellulosic fibers stained weakly. These results confirmed that crude bacterial extracts had the characteristics similar to those of ionic and disperse dyes, which was consistent with the identified polypyrrolic prodigiosin-like structures.

Determination of kinetic and thermodynamic aspects of cellulose triacetate dyeing using matching‐index‐of‐refraction absorption spectroscopy

A simple method of analysis is described in which ordinary absorption spectroscopy is employed to measure dye content within cellulose triacetate fibres in order to determine the rate of dyeing for triacetate fabric immersed in infinite dyebaths at various temperatures. The results are analysed to yield values for the activation energy and enthalpy change associated with the transfer of a dye, Disperse Red 13, from a saturated dyebath to the interior of triacetate fibres immersed in that bath.

The structure of electron beam-modified cellulose triacetate

The structure, relaxation, and surface properties of cellulose triacetate (CTA) fibers and films modified by electron-beam irradiation in the absorbed dose range of D = 0−1000 kGy have been studied. The relation of the glass transition and melting temperatures of the irradiated CTA samples with the local density and the fractal dimensionality of the macrochain has been revealed. It has been shown that the radiation-chemical processes associated with the rupture of acetal bonds and the hydrolysis of CTA acetate groups predetermine the change in the structural and relaxation characteristics of the irradiated samples, as well as a nonmonotonic form of the dependence of the density and the surface energy of the films upon the absorbed dose near the threshold value of D = 75 kGy.

Electrospinning of fluorescent fibers from CdSe/ZnS quantum dots in cellulose triacetate

Fluorescent cellulose triacetate (CTA) fibers were prepared by electrospinning solutions of CTA dissolved in an 8 : 2 v/v cosolvent system of methylene chloride (MC) and methanol (MeOH) which contained CdSe/ZnS quantum dots (QDs). The relatively low loading of colloidal nanoparticles was sufficient to impart fluorescence to the fibers but did not significantly alter fiber morphologies, which tended toward smooth surfaces with the occasional longitudinal feature. The fibers were birefringent due to the alignment of the polymer chains which occurred during electrospinning and had widths on the order of a hundred nanometers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Spontaneous elongation of acetate fibres in dimethyl sulfoxide vapors: dynamics, structure, energetics

The effect of a spontaneous change in the size (elongation-partial retraction) of di- and triacetate fibres in DMSO vapors in the 19-60°C range, accompanied by initiation of orientation events in the polymer matrix was detected. Sorption of DMSO vapors by the polymer in self-deformation of the acetate fibre does not obey Fick’s law and is described by extremal swelling curves that indicate the multistage character of the reaction of the sorbate vapors with the polymer. The energetics of spontaneous elongation of cellulose acetate in DMSO vapors was investigated, and the specific work of self-deformation and “negative” longitudinal viscosity were determined. The values of the specific heat was typical of transitions from the isotropic to the LC state. It was found that the stereomeric structure of the polysaccharide changes during a cyclic change in the size of the fibre, confirmed by inversion of the specific optical rotation sign. The data obtained can be described in terms of phase and conformational transitions and the mechanism of reaction of the polymer with the solvent vapors forming the LC phase with it.

Measurements of dye absorption by cellulose triacetate using matching index of refraction absorption spectroscopy

A simple method of analysis has been devised in which the uptake of disperse dyes in triacetate fabrics can be monitored using ordinary absorption spectroscopy. The experimental technique requires that a sample of triacetate fabric be immersed in a liquid having the same index of refraction as the constituent fibres, thus rendering the fabric transparent to visible light. Under these conditions, a dyed sample of fabric may be placed in the cell compartment of an ordinary ultraviolet/visible spectrometer allowing one to measure the absorption spectrum of the dye molecules located within the constituent triacetate fibres of the fabric sample. Values measured for the absorbance of several dyes incorporated within samples of triacetate fabric are shown to satisfy the Beer–Lambert law, thus enabling one to measure the rate of dye uptake by triacetate fabric samples placed in infinite dyebaths.

Ultrafine porous fibers electrospun from cellulose triacetate

Ultrafine porous cellulose triacetate (CTA) fibers were prepared by electrospinning with methylene chloride (MC) and a mixed solvent of MC/ethanol (EtOH) and their intra- and inter-fiber pore structures was investigated. Ultrafine porous CTA fibers electrospun with MC had isolated circular shape pores with a narrow size distribution in the range of 50–100 nm. In the case of ultrafine CTA fibers electrospun with MC/EtOH (90/10 v/v), they had interconnected larger pores in the range of 200–500 nm. These porous structures were induced by phase separation resulting from the rapid evaporation of solvent during the electrospinning process. However, non-porous corrugated fibers were obtained from MC/EtOH (85/15 v/v) and MC/EtOH (80/20 v/v) due to their lower vapor pressure. The pore sizes in ultrafine CTA fibers electrospun with MC showed a bimodal distribution centered at ∼17 and ∼64 nm. CTA fibers electrospun with MC/EtOH (90/10 v/v) showed the greatest porosity due to their larger intra-fiber pores and fiber diameter.

Diffusion and Saponification Inside Porous Cellulose Triacetate Fibers

Cellulose triacetate (CTA) fibers were partially hydrolyzed in 0.054 N solutions of NaOH/H(2)O and NaOMe/MeOH. The surface concentration of acetyl groups was determined using ATR-FTIR. Total acetyl content was determined by the alkaline hydrolysis method. Fiber cross-sections were stained with Congo red in order to examine the interface between reacted and unreacted material; these data were used to estimate the rate constant k and effective diffusivity D(B) for each reagent during the early stages of reaction by means of a volume-based unreacted core model. For NaOH/H(2)O, k = 0.37 L mol(-1) min(-1) and D(B) = 6.2 x 10(-7) cm(2)/sec; for NaOMe/MeOH, k = 4.0 L mol(-1) min(-1) and D(B) = 5.7 x 10(-6) cm(2)/sec. The NaOMe/MeOH reaction has a larger rate constant due to solvent effects and the greater nucleophilicity of MeO(-) as compared to OH(-); the reaction has a larger effective diffusivity because CTA swells more in MeOH than it does in water. Similarities between calculated concentration profiles for each case indicate that the relatively diffuse interface seen in fibers from the NaOMe/MeOH reaction results from factors not considered in the model; shrinkage of stained fiber cross-sections suggests that increased disruption of intermolecular forces may be the cause.

N-arylmaleimide based monomeric and polymeric dyes for cellulose triacetate fiber

A series of monomeric dyes has been prepared by diazotization of 2,6-dibromo-4-nitroaniline and coupled with various N-arylmaleimides. The monomeric dyes were characterized by elemental analysis and IR spectra. The polymeric dyes have been prepared by free radical polymerization of monomeric dyes. They were characterized by IR spectral studies, intrinsic viscosity, molecular weight by vapor pressure osmometry, thermogravimetry analysis and elemental analysis. The purity of all the dyes were checked by thin layer chromatography and they have also been applied on cellulose triacetate fiber as a disperse dye. All the dyes were found to give various color hues with good to very good depth and levelness on the fiber. The percentage dye bath exhaustion and fixation on fiber have been found to be good to very good. The monomeric dyes showed very good fastness properties, and their corresponding polymeric dyes showed excellent fastness to light, washing, perspiration, solvent resistance and sublimation.

Thiadiazole-Based Monomeric and Polymeric Dyes for Cellulose Triacetate Fiber

A series of monomeric dyes was prepared by diazotization of 2-amino-5-mercapto-1,3,4-thiadiazole and coupled with various N-arylmaleimides. The polymeric dyes were prepared by free radical polymerization of monomeric dyes and characterized by IR, intrinsic viscosity, molecular weight by vapor pressure osmometry, thermogravimetry analysis, and elemental analysis. The monomeric dyes were also characterized by elemental analysis and IR spectra. The purity of all the dyes were checked by thin layer chromatography and by application on cellulose triacetate fiber as disperse dyes. All the dyes were found to give various color shades with good-to-very good depth and levelness on fiber. The percentage dyebath exhaustion and fixation on fiber was found to be good-to-very good. The dyeing of monomeric dyes showed very good fastness properties, and their corresponding polymeric dyes showed excellent fastness to light, washing, perspiration, solvent resistance, and sublimation.

Observed versus predicted carboxyhemoglobin levels in cellulose triacetate workers exposed to methylene chloride.

Occupational exposure to methylene chloride, together with carboxyhemoglobin concentrations, has not been studied previously. Carboxyhemoglobin levels were measured in non-smoking employees exposed to varying concentrations of methylene chloride during the manufacture of cellulose triacetate fibers. The observed carboxyhemoglobin levels were compared to predicted concentrations using a pharmacokinetic model. The presence of carboxyhemoglobin in non-smokers exposed to methylene chloride results primarily from the metabolism of methylene chloride in the liver and exhibits a linear dose-response relationship. The observed levels of carboxyhemoglobin in non-smokers at the end of an 8-hour shift depend upon exposures to methylene chloride that day but are independent of occupational exposures on previous days. The observed daily concentrations of carboxyhemoglobin are consistent with predicted concentrations using a pharmacokinetic model. While varying exposure patterns were shown to change the rate of metabolite formation at the end of shift, these same exposure patterns had almost no effect on the total amount of carbon monoxide in the blood. While the present study addresses the relationship between methylene chloride, carbon monoxide, carboxyhemoglobin and ischemic heart disease, it does not address the issue of tumorigenicity, which is also the basis for the current U.S. Occupational Health and Safety workplace exposure limit of 25 ppm. This study provides support for the conclusion that the current American Conference of Governmental Industrial Hygienists 8-hour Threshold Limit Value of 50 ppm adequately protects human health with regard to ischemic heart disease and carboxyhemoglobin formation among non-smokers.