Properties Of Resulting Fibers Research Articles

Rapid Improvement of Fiber Tensile Properties via In Situ Biomimetic Robotic Pulling and Bayesian Optimization

For fiber technology, new approaches such as biomimetic materials, such as silks, are being intensively explored, providing new solutions for a variety of industries, including textiles, composites, and biomedical engineering. New approaches for spinning or these materials are needed. Despite recent advances in enhancing fiber tensile properties, achieving significant improvement in tensile properties remains a tedious and challenging task, suffering from little to no controlled extrusion process and difficult optimization in high‐dimensional parameter spaces. Herein, a novel robotic biomimetic pulling method that can rapidly enhance fiber tensile properties surpassing current methods in both speed and resulting fiber properties is shown. Using a controlled fiber‐pulling device with in situ tensile measurements and adaptive optimization based on Bayesian Optimization, fiber strength exceeding 300% of the traditional full factorial design method within just a few experimental iterations is reached. The rapid experimental method presents a potential avenue for enhancing the performance of artificial fibers across diverse industries and applications.

Medicinal plants as a cellulose source for the fabrication of poly(lactic acid) composites: A mini-review

More recently, natural polymers produced by living organisms have received considerable attention due to their unique properties such as eco-friendliness, biodegradability, and biocompatibility. These polymers possess similar properties to conventional plastics, making them suitable potential plastic substitutes for sustainable development and conservation of finite oil resources. Poly(lactic acid) (PLA) is comparable to commonly used plastics but is inferior, thus limited applications. However, PLA can benefit from the incorporation of various polymer components with complementary properties to yield improved physical properties. The fabrication of fully bio-based nanocomposites such as that of PLA and cellulose is of particular interest to research scientists. Incorporating organic fillers such as nanocellulose in a PLA matrix gives rise to improved composite properties. Because plant cell walls comprise semicrystalline cellulose molecules embedded in matrices, the crystalline portion of the stiff chains extracted from medicinal plants is currently exploited for potential filler roles. In this review, the use of medicinal plants in bio-based composite applications is covered. Several medicinal plants as sources of cellulose, different cellulose extraction methods, as well as the resulting fiber properties, are discussed. Although tremendous progress has been made in developing biocomposites, a lot of research still needs to be carried out.

Surfactant Molecular Properties Control Location in Emulsion Electrospun Fibers and Dictate Resulting Fiber Properties

Surfactant Molecular Properties Control Location in Emulsion Electrospun Fibers and Dictate Resulting Fiber Properties

Regulating the dissolving system of ultra‐high molecular weight polyethylene to enhance the high‐strength and high‐modulus properties of resultant fibers

AbstractThe molecular weight loss of ultra‐high molecular weight polyethylene (UHMWPE) fibers is extremely serious in comparison with raw materials due to the high temperature and strong shearing during dissolving process. In this study, decalin was introduced as preswelling solvent and the dissolving system was regulated to improve the solubility of UHMWPE in paraffin oil without severe degradation so as to prepare UHMWPE fibers with high molecular weight retention and low entanglement. UHMWPE was preswelling in decalin with different content, the mass ratio of decalin to UHMWPE were 1:1, 1.5:1, 2:1, 2.5:1, and 3:1. All UHMWPE fibers were prepared by gel‐spinning and hot‐drawing. UHMWPE fibers possess the highest molecular weight after preswelling of UHMWPE in decalin (with a mass ratio of 3:1 to UHMWPE, namely UPE/dec‐s‐3 sample). What's more, the entanglement of UHMWPE fibers gained from UPE/dec‐s‐3 sample has been observably diluted in comparation to that from UPE‐neat and other swollen samples. More importantly, the tensile strength and modulus of UHMWPE fibers obtained from UPE/dec‐s‐3 sample can reach 31.41 and 1446.26 cN/dtex, increased by 15.1% and 14.3% compared with UPE‐neat fibers, respectively. Besides, the thermal and crystallization behavior of UHMWPE fibers prepared from swollen UHMWPE have also been boosted.

Preparation Smallest PVA/Binahong Leaf Nanofiber for Wound Dressing Applications by Varying Electrospinning Variable using Taguchi Method

Binahong leaf is one of the herbal plants known to have interesting properties such as accelerating wound healing, anti-bacterial, etc. Converting Binahong leaves into fiber will increase their effectiveness because they are easier to absorb. The electrospinning method is used to convert Binahong polymers into Binahong fibers. The Taguchi method is used for experimental design with three factors and three levels. The resulting fiber properties vary with each variation factor. The smallest fiber obtained was 459,993 nm with tip and collector distance, voltage, and weight% PVA, respectively, 8 cm, 20 kV, and 8% (98.6922 P). Wound dressing by using Binahong nanofiber is possible.

Highly phosphorescent hollow fibers inner-coated with tungstate nanocrystals

In order to develop luminescent microtubes from natural fibers, a facile biomimetic mineralization method was designed to introduce the CaWO4-based nanocrystals into kapok lumens. The structure, composition, and luminescence properties of resultant fibers were investigated with microscopes, x-ray diffraction, thermogravimetric analysis, and fluorescence spectrometry. The yield of tungstate crystals inside kapok was significantly promoted with a process at high temperature and pressure—the hydrothermal treatment. The tungstate crystals grown on the inner wall of kapok fibers showed the same crystal structure with those naked powders, but smaller in crystal size. The resultant fiber assemblies demonstrated reduced phosphorescence intensity in comparison to the naked tungstate powders. However, the fibers gave more stable luminescence than the naked powders in wet condition. This approach explored the possibility of decorating natural fibers with high load of nanocrystals, hinting potential applications in anti-counterfeit labels, security textiles, and even flexible and soft optical devices.

Mass and controlled fabrication of aligned PVP fibers for matrix type antibiotic drug delivery systems

Recent advances in fiber technology and engineering, for nano- and micro-meter scaled materials, have focused largely on developments surrounding the electrospinning (ES) technique. Although this process enables the engineering of complex fibrous structures; the inability to yield industrial scale production through existing ES techniques becomes a bottle-neck and critical feature. Furthermore, in several advanced engineering remits (such as healthcare) the role of fiber alignment, layering and morphology is also paramount. In this study the development of a enhanced spinneret device for the up-scaled production of aligned fibers is demonstrated. Compared to conventional centrifugal electrospinning (CES) techniques, a relatively greater production rate of fibers is achieved at reduced rotation speeds and also excludes the use of needles during the process. The impact of experimental process parameters such as rotation speed (60–90rpm), working distance (9–14cm) and solution concentration (15–30w/v%) on resulting fiber properties were investigated using commercial polymeric drug delivery excipient polyvinyl pyrrolidone (PVP). Mass production of fibers is demonstrated and the impact of specifically aligned ultrafine drug-fiber matrices on drug release behavior is shown. For this, the antibiotic tetracycline hydrogen chloride was spun alongside PVP (5w/w%) as the matrix material. The spinneret device provides an enhanced approach for active embedded fiber production on a scale favorable to industry (120g/h) when using optimized process parameters (70rpm and 15kV for the four-pore system). Furthermore, the in-situ method permits control on fiber alignment and overall mat thickness providing tailored fabrication for specific applications or drug dosage requirements (e.g. active dissolution behavior for fibrous drug delivery systems).

Manufacture and performance of O-carboxymethyl chitosan sodium salt/cellulose fibers in N-methylmorpholine-N-oxide system

A series of O-carboxymethyl chitosan sodium salt (NaCMCh) with different degree of substitution (DS) of -CH2COONa agent were successfully prepared by altering the reaction temperature and time. Both fourier transform infrared spectroscopy (FTIR) and 13C-Nuclear Magnetic Resonance (13C-NMR) were used to study the structure of NaCMCh. And the impact of DS on the antibacterial activity of NaCMCh was investigated. Then, the NaCMCh with optimal antibacterial activity was selected to prepare NaCMCh/cellulose fibers in N-methylmorpholine-N-oxide (NMMO) system. The structure, crystallization behavior, thermal property and morphology of obtained fibers were carefully studied with FTIR, Wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermal gravimetric (TG) and scanning electron microscope (SEM), respectively. Meanwhile, the antibacterial activity as well as mechanical properties of resultant fibers was also investigated. The results demonstrated that the fibers had strong antibacterial activity against Escherichia coli (E. coli), acceptable mechanical properties and good water retention.

Strong, Light, Multifunctional Fibers of Carbon Nanotubes with Ultrahigh Conductivity

Broader applications of carbon nanotubes to real-world problems have largely gone unfulfilled because of difficult material synthesis and laborious processing. We report high-performance multifunctional carbon nanotube (CNT) fibers that combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. These fibers consist of bulk-grown CNTs and are produced by high-throughput wet spinning, the same process used to produce high-performance industrial fibers. These scalable CNT fibers are positioned for high-value applications, such as aerospace electronics and field emission, and can evolve into engineered materials with broad long-term impact, from consumer electronics to long-range power transmission.

Fiber Structure Development and Mechanical Properties in Continuous Drawing and Annealing of Poly (phenylene sulfide) Filament

Poly(phenylene sulfide) (PPS) multi-filaments were continuously drawn and annealed. The maximum values of birefringence, crystallinity, tensile strength and Young′s modulus in the drawn and annealed PPS filament were 249×10−3 ‚ 27%, 5.3 cN/dtex and 64 cN/dtex‚ respectively. The orientation-induced crystallization was observed at 150×10-3 of birefringence. The crystal orientation factor f′ was estimated by wide angle X-ray diffraction. The λnet was estimated by the strain shifting of true stress - true strain curve to the master curve. The orientation estimated by the λnet differed from that estimated by birefringence. The fiber structure development and the mechanical properties of resultant fibers were discussed in terms of orientation parameters, which were birefringence‚ network draw ratio (λnet) and crystal orientation factor (f′). The birefringence shows a good correlation with the Young’s modulus. On the other hand, λnet shows a good correlation with the tensile strength. The f′ shows good correlations with both Young′s modulus and tensile strength‚ however‚ they tend to saturate at high f′. The melting temperature of PPS changed from 280.1oC to 288.7oC with the increase of birefringence and λnet.

Effect of the Control of Polymer Flow in the Vicinity of Spinning Nozzle on Mechanical Properties of Poly(ethylene terephthalate) Fibers

Abstract In the melt spinning of PET, effects of the variation of flow behavior in the vicinity of spinning nozzle on the mechanical properties of as-spun fibers and drawn fibers were investigated. The variation of flow behavior was introduced by the change of spinning nozzle diameter and by the irradiation of CO2 laser to the spin-line at a position immediately below the spinneret. The curve representing the correlation between strength and elongation at break of as-spun fibers shifted toward the upper-right direction by the applications of small diameter nozzle and laser irradiation, indicating that the toughness of as-spun fibers was improved. The two-stage continuous drawing of as-spun fibers with various draw ratios revealed that the correlation between strength and elongation of drawn fibers also shifted toward the upper-right direction by the application of small diameter nozzle and laser irradiation. In other words, improved toughness in the as-spun fibers was preserved in the drawn fibers. Accordingly, by the drawing of the as-spun fibers prepared by the combination of small-diameter nozzle and laser irradiation, high-strength and high-toughness PET fibers with the tensile strength of 1.68 GPa (12.1 cN/dtex) and the elongation at break of 9.1% was obtained. Numerical simulation of the melt spinning process incorporating the effects of nozzle diameter variation and laser irradiation heating indicated that the maximum Deborah number in the spin-line decreased by the applications of small diameter nozzle and laser irradiation heating. Accordingly, it was speculated that the variation of the state of molecular entanglement caused by the difference of polymer flow in the melt spinning process has significant effect on the mechanical properties of resultant fibers.

Effect of CO2 Laser Irradiation in Spinline on Mechanical Properties of Poly(ethylene terephthlate) Fibers

In the melt spinning of high molecular weight poly(ethylene terephthalate), spinline immediately below the spinning nozzle was heated by irradiating the CO2 laser with the intention of controlling the physical and mechanical properties of resultant fibers. In comparison with the fibers prepared without the laser irradiation, as-spun fibers obtained with laser irradiation showed higher elongation at break and higher tenacity. Higher elongation was attributed to lower tensile stress in the spinline caused by the increase of spinline temperature. Drawn fibers were produced from thus prepared as-spun fibers at various draw ratios. When the drawn fibers with similar elongation at break were compared, fibers prepared with the laser irradiation showed steeper increase in the stress-strain curve in the region of low strain, and showed higher tenacity as a result. On the whole, plot of the relation between tenacity and elongation at break of each fiber shifted toward higher tenacity and higher elongation in case of fibers prepared with the laser irradiation, indicating that the toughness of the fibers were improved. Numerical simulation of the melt spinning process incorporating the effect of laser irradiation suggested that temperature increase by the laser irradiation was at most about 70 degree in the spinning conditions adopted in this study. It was also confirmed that the heating of the spinline immediately below the spinneret led to steeper decrease of spinline diameter in the region near the spinneret, and reduction of strain rate and decrease of tensile stress in the region of lowered spinline temperature. These changes in the thinning behavior of the spinline were speculated to be the origin of the changes in the mechanical properties of laser irradiated fibers.

The influence of air‐gap conditions on the structure formation of lyocell fibers

The influence of an air gap on the formation of a filament spun from a solution of cellulose in N-methylmorpholine N-oxide was studied. A number of parameters were investigated, principally, air-gap length, temperature, and humidity and the water content in the polymer solution. Their effect on the draw-down profile and orientation of the filament in the air gap was determined and compared to the structure and properties of the resulting fibers. It is shown that all these parameters have a strong influence on the structure formation process. Depending on the combination of parameters used, the phenomenon of draw resonance may or may not be observed. The results indicate that the cooling of the filament is driven by two simultaneous processes. Modifying the parameters studied also causes significant changes to the resulting fiber properties, but the fiber structures, measured by birefringence and wide-angle X-ray diffraction, appear almost identical. © 1996 John Wiley & Sons, Inc.

Preparation of high performance PET fiber by solution spinning technique

AbstractHigh molecular weight poly(ethylene terephthalate) (PET, IV = 3.30 dL/g) was extruded in attempts to prepare high performance fiber using the solution spinning method. Solution preparation, fiber coagulation, and mechanical properties of resultant fibers were examined. An as‐spun fiber exhibited high deformability when appropriate coagulation conditions were used. Tenacity and modulus of the resultant drawn fibers achieved 12.9 and 230 gpd, respectively, at draw ratio above 10. © 1995 John Wiley & Sons, Inc.

Structure and properties of mesophase pitch carbon fibre with a skin-core structure carbonized under strain

Coal tar mesophase pitch fibres stabilized at 270° C to different extents were carbonized under strain by the constant load or constant length, using different heating rates, and further graphitized at 2500° C. Shallow and moderate stabilization provided a skin-core structure in the resultant fibres which exhibited higher orientation, tensile modulus, and better graphitizability after calcination at 1300° C and graphitization at 2500° C than deep stabilization. The tensile strength and modulus of the graphitized fibre was significantly improved through the strained carbonization when the stabilization was performed to a moderate extent. The strain tended to give an onion-like alignment in the fibre to improve the preferred orientation of carbon planes. Larger load and more rapid heating during carbonization modified the structure and properties of resultant fibres through a significant longitudinal elongation. The stabilization extent of pitch fibres governs the mobility or fusibility of mesogen molecules at the carbonization which allows their better alignment by the strain.

Formation properties of solid‐state extruded high density polyethylene fibers

AbstractExtrusion rates have been measured for high density polyethylene fibers prepared by solid‐state extrusion through a conical die with maximum draw ratio of 52, using constant pressure and temperatures ranging from 0.12 to 0.49 GPa and 60° to 140°C and molecular weights from 5 × 104 to 6 × 106. The processing variables are reported in terms of an apparent elongational viscosity. The logarithm of the extrusion rate was proportional to the applied pressure. Deviation from the Eyring theory of viscosity was found, since lowering of the extrusion temperature to 60°C produced an anomalous decrease in the extrusion rates. The anomaly was explained by the increased friction between die and polymer, the pressure dependence of the yield stress, and by the pressure dependence of the α‐relaxation mechanism. Apparent activation energies of 60 and 100 kcal/mole were calculated for the solid‐state extrusion in the region 100°–130°C and 80–100°C. Three modes of deformation were observed for each extrusion, consisting of an unsteady state, a second stage of drawing in which the extrusion rate approached a constant value, and a fracture region. The first mode corresponded to orientation and rotation of the crystalline lamellae, as shown by the rapid increase and plateau region of the crystalline and noncrystalline orientation functions. During the second stage of deformation, the apparent elongational viscosity ηE increased linearly with draw ratio, as did the modulus, and this mode was found necessary for the attainment of high modulus fibers. The second mode of deformation was associated with the deformation of the crystalline lamellae and strain hardening in which ηE‐approached that for a glass. Strain hardening readily occurred with decreasing temperature, and increasing draw ratio and molecular weight. Continuous extrusion producing uniform modulus fibers was only possible when the maximum draw ratio of the die was less than the fiber draw ratio, where strain hardening occurred. The third mode of deformation limited the maximum modulus obtainable and consisted of fracture or kink planes oblique to the fiber axis. The relations between the processing variables used in the solid‐state extrusion and the resulting fiber properties are discussed.