Preparation Of Fibers Research Articles

Preparation and characterization of zein electrospun fibers loaded with savory essential oil for fruit preservation

Using electrospun fibers from edible and biodegradable polymers has been a dynamic approach to postharvest technology in the past decade. The current research aimed at making zein electrospun fibers with savory essential oil (SEO) at several concentrations (0 %, 5 %, 10 %, and 20 % w/v) to study the effect of the fibers on the shelf life of tangerine and banana fruits. SEM results indicated that zein electrospun fibers had flat, consistent, and tubular morphology. It is demonstrated that the mean diameter of zein electrospun fibers increased parallel to the increase in SEO concentration. FTIR spectroscopy revealed hydrophobic interactions between SEO and zein. X-ray diffraction patterns indicated that at higher concentrations of the SEO, the crystallinity of zein electrospun fibers increased from 67 % to 69 %. Calorimetric findings of differential scanning demonstrated that the Tg of zein electrospun fibers increased from 85.9 ºC to 238.8 ºC. Through the Bernauer-Emmitte-Teller application, the mesoporous condition of electrospun fibers were described. Tensile strength analysis demonstrated that a higher concentration of SEO in the zein mat caused a significant increase in TS, YM, and EB values (p < 0.05). SEO loaded zein electrospun fibers effectively inhibited the growth of E. coli (Gram-negative) and S. aureus (Gram-positive). The SEO loaded zein electrospun fibers affected the storage of banana and tangerine through a storage period of 7 and 28 days, respectively. The results suggested that SEO loaded zein electrospun fibers are suitable for the preservation of tangerine, but are unsuitable for banana. These findings indicated that edible and biodegradable electrospun fibers are effective biopackages for non-climacteric fruits.

Group Replacement-Rearrangement-Triggered Linear-Assembly Nonaqueous Precipitation Synthesis of Hydroxyapatite Fibers.

A novel method for hydroxyapatite fiber preparation with highly large-scale production prospects is of paramount importance but remains particularly difficult. Here, group replacement-rearrangement-triggered linear-assembly nonaqueous precipitation synthesis has been proposed for hydroxyapatite fibers under mild conditions. Pure hydroxyapatite fibers can be fabricated taking disodium hydrogen phosphate, calcium acetate, and glycerol as the phosphorus source, calcium source, and solvent, respectively. Single hexagonal crystal structures of hydroxyapatite fibers growing along the c-axis and preferential growth of the (002) crystal plane similar to the layered stacking structure of an adult bone have been confirmed by XRD refinement tests and calculation, TEM electron diffraction calibration, and FE-SEM. Highly active carbonate apatite is further demonstrated by EDS, FT-IR, Raman spectroscopy, and XPS. Unsaturated P-O and O-Ca bonds at both ends of the hexagonal-sheet assembly unit in a high-polarity nonaqueous glycerol environment without strongly coordinated OH- confirm the solution spontaneous linear assembly to form the single hydroxyapatite fibers.

Preparation and fluorescence performance of high elastic core-shell structure composite fibers based on electrospun nanofibers

Fluorescent fibers with light weight and good mechanical properties provide exciting opportunities for the development of flexible optical sensing textiles. This could accelerate the realization of the wearable technology goal of functional and large area display. Here, we synthesized a polyimide containing 20% pyrene group (Py-20) with excellent fluorescence and thermal properties. Then, fluorescent composite fibers with core–shell structure were prepared by using Py-20 electrospun membrane as surface layer and polyurethane (TPU) fiber as inner layer. The diameter and thickness of surface fluorescent fibers was 500 nm and 100 μm, respectively. Polarized infrared spectra analysis proved that the aggregation of polymer molecular chains in electrospun fiber could be reduced effectively. The DR (DR = I∥/I⊥) values of polymer film and electrospun fibers were 0.7553 and 0.5955, respectively. Therefore, the fiber samples exhibited higher fluorescence intensity than the polymer film. The maximum photoluminescence peaks of electrospun and composite fibers were located at about 595 nm. In addition, thanks to interlaced layered structure of electrospun fibers, the fluorescent composite fiber maintained a relatively uniform morphology at 40.84% (strain) and 4.96 MPa (stress). Importantly, this Py-20/TPU composite fiber could meet the complex weaving process of yarns and display bright yellow-orange colors under ultraviolet light irradiation. Thermal analysis exhibited that the initial decomposition temperature (Td) of composite fiber in the air could reach to 269 °C. This fiber material will become a competitive candidate in smart textiles with the excellent luminescence, mechanical and thermal properties.

Salicylic Acid Release from Syndiotactic Polystyrene Staple Fibers

Films and fibers of syndiotactic polystyrene (sPS), being amorphous or exhibiting nanoporous crystalline (NC) or dense crystalline phases, were loaded with salicylic acid (SA), a relevant non-volatile antimicrobial molecule. In the first section of the paper, sPS/SA co-crystalline (CC) δ form is characterized, mainly by wide angle X-ray diffraction (WAXD) patterns and polarized Fourier transform infrared (FTIR) spectra. The formation of sPS/SA δ CC phases allows the preparation of sPS fibers even with a high content of the antibacterial guest, which is also retained after repeated washing procedures at 65 °C. A preparation procedure starting from amorphous fibers is particularly appropriate because involves a direct formation of the CC δ form and a simultaneous axial orientation. The possibility of tuning drug amount and release kinetics, by simply selecting suitable crystalline phases of a commercially available polymer, makes sPS fibers possibly useful for many applications. In particular, fibers with δ CC forms, which retain SA molecules in their crystalline phases, could be useful for antimicrobial textiles and fabrics. Fibers with the dense γ form which easily release SA molecules, because they are only included in their amorphous phases, could be used for promising SA-based preparations for antibacterial purposes in food processing and preservation and public health. Finally, using a cell-based assay system and antibacterial tests, we investigated the cellular activity, toxicity and antimicrobial properties of amorphous, δ CC forms and dense γ form of sPS fibers loaded with different contents of SA.

Preparation of high acidity coefficient slag wool fiber with blast furnace slag and modifying agents

Preparation of high acidity coefficient slag wool fiber with blast furnace slag and modifying agents

Negative Charges Introduced Near the IT Helix of Cardiac Troponin T Stabilize the Active State of Actin Filaments.

The disordered and basic C-terminal 14 residues of human troponin T (TnT) are essential for full inhibition of actomyosin ATPase activity at low Ca2+ levels and for limiting activation at saturating Ca2+. In previous studies, stepwise truncation of the C-terminal region of TnT increased activity in proportion to the number of positive charges eliminated. To define key basic residues more closely, we generated phosphomimetic-like mutants of TnT. Phosphomimetic mutants were chosen because of reports that phosphorylation of TnT, including sites within the C terminal region, depressed activity, contrary to our expectations. Four constructs were made where one or more Ser and Thr residues were replaced with Asp residues. The S275D and T277D mutants, near the IT helix and adjacent to basic residues, produced the greatest activation of ATPase rates in solution; the effects of the S275D mutant were recapitulated in muscle fiber preparations with enhanced myofilament Ca2+ sensitivity. Actin filaments containing S275D TnT were also shown to be incapable of populating the inactive state at low Ca2+ levels. Actin filaments containing both S275D/T284D were not statistically different from those containing only S275D in both solution and cardiac muscle preparation studies. Finally, actin filaments containing T284D TnT, closer to the C-terminus and not adjacent to a basic residue, had the smallest effect on activity. Thus, the effects of negative charge placement in the C-terminal region of TnT were greatest near the IT helix and adjacent to a basic residue.

Effect of bamboo unit morphology on the preparation of bamboo fibers by steam explosion

Steam explosion is an attractive technology due to its low energy consumption and low environmental impact; however, there is still relatively limited research to improve the extraction efficiency of bamboo fibers. Here, the effects of the morphology of bamboo units on the extraction efficiency of bamboo fibers by steam explosion were fully examined. Based on the differences in morphology of raw materials, five types of bamboo units (bamboo strip, tangential bamboo sliver, radial bamboo sliver, bamboo bundle, and bamboo particle) were selected for steam explosion treatment. The characteristics of bamboo units and the resulting bamboo fibers as well as extraction efficiency were investigated by scanning electron microscopy, specific surface area analysis, fiber yield and aspect ratio calculation, color difference analysis, infrared spectroscopy, and tensile testing. Moreover, the mechanisms behind the improvement in the extraction efficiency of fibers from bamboo units have also been explored. The results showed that the unit morphology of raw materials greatly influenced the preparation of bamboo fibers by steam explosion. The effective fiber yield of bamboo bundles could reach 60.85%, which was 42.51% higher than bamboo strips. The tensile strength and modulus of steam exploded fibers from bamboo bundles could be as high as 531.79 MPa and 23.15 GPa without compromising the fiber properties too much. This is because the specific structure of bamboo bundles was able to facilitate the entry of steam for fiber separation without causing excessive damage to the fibers, showing the most effectiveness. The improvement of the extraction efficiency of steam explosion through tuning the properties of bamboo units is conducive to the cost-effective and efficient preparation of controlled-form bamboo fibers. The results in this work provide fundamental information for the further utilization of fiber extraction by steam explosion.

Investigating of the influence of zinc oxide nanoparticles morphology on the properties of electrospun polyvinyl alcohol/chitosan (PVA/CS) nanofibers

In recent years, investigating of the effect of nanoparticles with different morphologies in therapeutic applications has attracted the attention of many researchers. In this research, the effect of adding zinc oxide nanoparticles with a completely new morphology in the improving the properties of PVA/CS nanofibers as a wound dressing are investigated. Zinc oxide nanoparticles were synthesized using the co-precipitation method. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential (ZP), and dynamic light scattering (DLS) were used to characterize the synthesized particles. Using Experimental Design software resulted in the preparation of defect-free nanoscale fibers and beads by optimizing factors such as voltage, feed rate and PVA/CS mixing ratio. After determining the optimal conditions, several weight percentages of ZnO nanoparticles with pyramidal rod and star-like morphologies were introduced to the electrospinning solution. The properties of the fabricated nanofibers were also analyzed by SEM, FTIR, tensile testing, thermal analysis, antibacterial testing, and in vivo wound healing in mice. The tensile tests revealed that the addition of zinc oxide nanoparticles with pyramidal rod morphology increased the mechanical strength of PVA/CS nanofibers, while star-like ZnO decreased the mechanical strength. Furthermore, incorporating ZnO in PVA/CS nanofibers greatly enhances their heat resistance. The antibacterial test results revealed that fibers containing zinc oxide nanoparticles have significant antibacterial activities. In vivo wound healing tests demonstrated that PVA/CS/ZnO nanofibers enhanced wound healing compared to PVA/CS nanofibers. Histopathological investigation revealed that epidermal regeneration is complete in samples containing ZnO nanoparticles. The present study shows that PVA/CS nanofibers containing zinc oxide nanoparticles with pyramidal rod morphology have great potential in wound healing.

A comprehensive review on the use of natural fibers in cement/geopolymer concrete: A step towards sustainability

The construction industry is shifting towards environmentally friendly products due to the rising demand for non-renewable raw materials, their high energy consumption, and, most importantly, their detrimental environmental effects. High levels of solid waste produced by raw materials release dangerous gases like nitrous and Sulphur oxides, which are very harmful to the environment. In recent years, the usage of fibers has tremendously increased to make significantly robust structures. For sustainable, waste-free development, manufactured fibers can be replaced with natural fibers without compromising on the requirements. This study considers various natural fibers like basalt, coconut/coir, banana, sugarcane bagasse, hemp, kenaf, bamboo, jute, sisal, abaca, and cotton, and their effects on fresh and hardened concrete have been discussed. This article also reviews the composition, preparation, and processing procedures of various natural fibers, and their potential applications in building materials are highlighted. Future research avenues are identified, and possible negative impacts and limitations are discussed. Our findings confirm the feasibility of standard concrete using natural fibers in cement or geopolymer concrete. Lastly, this review compiles insights from numerous sources to aid academia and the construction industry in developing eco-friendly materials.

Study of metakaolin geopolymer composites reinforced by clean broom-like bristle bamboo fibers

Natural fiber-reinforced geopolymer (GP) is gaining popularity in the construction and building materials industries due to its natural renewability, accessibility, low cost, and excellent mechanical properties. In light of this, an investigation was conducted on the effect of bamboo fiber (BF) loading and fiber pretreatment methods on final composites. Mechanical tests showed that compared to pure GP, the compressive strength and flexural strength of GP composites were slightly negatively affected by the addition of either untreated or alkali-treated BFs. However, the loading of KH550 significantly improved the mechanical properties of GP with the addition of alkali-treated BFs more than untreated BFs. Scanning electron microscopy (SEM) analysis illustrated that the employment of KH550 effectively improved the interfacial performance between the BF and GP matrix. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) tests demonstrated the successful synthesis of GP and that the addition of KH550 had little effect on the main crystal structure and chemical composition of GP. This study provides a new method of bamboo fiber preparation and the feasibility of applying it to reinforce GP.

Pultrusion preparation and properties of continuous glass fiber reinforced polylactic acid thermoplastic composites

AbstractContinuous glass fiber (CGF) reinforced polylactic acid (PLA) thermoplastic composites (CGF/PLA) were prepared through the pultrusion process. The effects of processing temperature, tension, traction speed and CGF weight content on the tensile strength of CGF/PLA were carefully studied and systematically optimized. The results indicated that the tensile strength and storage modulus of the CGF/PLA were the highest and respectively reached up to 186.4 MPa and 17.5 GPa when the processing temperature was 220°C, the tension force was 11 N, the traction speed was 3 r/min and the CGF content was about 40.0 wt.%. In addition, it was found that the tensile strength of CGF/PLA increased with the rise of the processing temperature and CGF content. Those above results demonstrated that this pultrusion fabrication strategy of CGF/PLA could promote a low‐cost and high‐strength method for the industrial fabrication of CGF/PLA with desired properties, and thus opening possibilities for the rational design and pultrusion preparation of CGF/PLA.

Preparation of stereocomplex polylactic acid fiber and evolution of crystal structures

Stereocomplex polylactic acid (ScPLA) fibers were successfully prepared by mixing equal mass melts of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) by melt spinning process. The evolution of crystal structures of ScPLA fibers was investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results show that the homogeneous crystal (Hc) will be converted to stereocomplex crystal (Sc) as the heat setting temperature (HT) increases. The crystallinity curves of Hc and Sc cross into an “X” and the cross point is near the melting point of the Hc. The temperature range to form ScPLA fiber with fully stereoscomplex structures is 187 ℃ to 197 ℃ and the maximum Sc content is about 60%.

Preparation and mechanical properties of ultra-high strength superalloy fibers

GH4169 superalloy fibers with ultra-high strength and ultra-fine grain (UFG) were fabricated by cold deformation and low temperature annealing, which provides a simple and effective method for preparation of UFG materials. In this study, the fibers were cold-drawn for 13 times and then cold-rolled 25 passes. Finally the annealing experiment is carried out on the cold-rolled samples. The fiber area was reduced by 97% and the grain size reaches 66 nm after cold deformation. In the subsequent annealing 450 ℃ for 30 min, the grain size was further reduced to 42 nm and the tensile strength of the fiber increases to about 2.05 GPa. The increase of the superalloy fiber energy storage and decrease of the curvature of the grain boundary lead to the low-temperature phase transformation. By controlling the annealing condition, these precipitation nanoparticles keep stable, the superalloy fibers are further refined and thus obtain higher strengthening superalloy fibers.

Sorbent-coated carbon fibers for direct air capture using electrically driven temperature swing adsorption

•Sorbent-coated carbon fibers exhibit rapid temperature swing by Joule heating •The DAC system can fully regenerate in under 10 min •Wind-driven DAC modules recover CO2 product from the air at ∼82% purity •The cost of CO2 from this wind-driven DAC system is projected to be ∼$160/tonne Direct air capture (DAC) by electrically driven temperature swing adsorption (ETSA) is an emerging technology due to its simplicity and ease of pairing with renewable electricity energy sources. Herein, we describe the preparation of sorbent-coated carbon fibers via roll-to-roll process that exhibit 400 ppm CO2 adsorption of ∼1.2 mmol gfiber−1. The fibers exhibit Joule heating upon application of a potential, reaching CO2 regeneration temperatures within 1 min. DAC modules show fast electrothermal CO2 desorption with directly applied electric potential, releasing the adsorbed CO2 six times faster than externally driven thermal desorption. The simplicity and modularity of the sorbent-coated carbon fibers and their rapid adsorption/desorption cycling by ETSA have the potential to improve the productivity of DAC systems. A techno-economic analysis of a pilot-scale ETSA-DAC system projects an overall cost of about 160 $ tCO2−1, with convective energy losses to the ambient accounting for only 7% of the Joule heating input during desorption. Direct air capture (DAC) by electrically driven temperature swing adsorption (ETSA) is an emerging technology due to its simplicity and ease of pairing with renewable electricity energy sources. Herein, we describe the preparation of sorbent-coated carbon fibers via roll-to-roll process that exhibit 400 ppm CO2 adsorption of ∼1.2 mmol gfiber−1. The fibers exhibit Joule heating upon application of a potential, reaching CO2 regeneration temperatures within 1 min. DAC modules show fast electrothermal CO2 desorption with directly applied electric potential, releasing the adsorbed CO2 six times faster than externally driven thermal desorption. The simplicity and modularity of the sorbent-coated carbon fibers and their rapid adsorption/desorption cycling by ETSA have the potential to improve the productivity of DAC systems. A techno-economic analysis of a pilot-scale ETSA-DAC system projects an overall cost of about 160 $ tCO2−1, with convective energy losses to the ambient accounting for only 7% of the Joule heating input during desorption.

Preparation and characterization of nanocellulose fiber (CNF) by biological enzymatic method

In this paper, using Styphnolobium japonicum, Cryptomeria fortunei and Pinus yunnanensis as raw materials, cellulose (CE) was first extracted by chemical method (CM1) and biological enzymatic method 2 (BM2), and then further prepared into nanocellulose fiber (CNF) by biological enzymatic method 1(CPM (CPM stands for cellulase and pectinase)). The CE and CNF were characterized by FTIR, XRD, SEM, DSC and TG. The results showed that the CNF prepared by CM1-CPM was cellulose type II, CNF prepared by BM2-CPM was cellulose type I. The best crystallinity of the CNF prepared by CM1-CPM reached 74.1% ( C. fortunei CNF), the best yield was 24.0% ( S. japonicum CNF) and the minimum average diameter was 62.6 nm ( C. fortunei CNF). However, the best crystallinity of CNF prepared by BM2-CPM reached 80.1% ( C. fortunei CNF), the best yield was 27.4% ( C. fortunei CNF), and the minimum average diameter was 31.6 nm ( C. fortunei CNF). And also, the thermal degradation analysis of the CNF prepared from the three raw materials revealed that the CNF prepared by BM2-CPM had better thermal degradability. Finally, the thermal stability analysis of the C. fortunei CNF was carried out, and it was found that the residual mass of CNF prepared by BM2-CPM was 48%, while the residual mass of C. fortunei CNF prepared by BM1-CPM was 22%, which showed the C. fortunei CNF prepared by BM2-CPM had better thermal stability. Therefore, the properties of nanocellulose prepared by BM2-CPM are optimal.

Preparation of SiCN ceramic fibres via UV irradiation curing polysilazane

Preparation of SiCN ceramic fibres via UV irradiation curing polysilazane

The Multi-layer Distributed Pressure Washing Process and Permeability of Viscose Fiber Roll

Viscose fiber is widely used in the production of medium and high-grade fabrics. Pressure washing of fiber roll is an important post-treatment process for viscose filament production, and multi-layer distributed pressure washing is the key equipment for washing fiber roll. In order to reduce the energy consumption of viscose fiber production and preparation, improve the economic benefits of enterprises, and respond to the goal of national green chemical industry, this paper introduces the pressure washing process and the permeability of fiber roll, which provides support for the uniform washing of fiber roll.

Preparation of para-aramid aerogel fiber structurally colored by light scattering through wet spinning and supercritical drying

This research is an investigation of the preparation conditions for para-aramid aerogel fibers that are structurally colored by Rayleigh scattering, an angle-independent structural color. It is well known that structural color has the angle dependence of colors. However, there is currently a desire for materials with angle-independent structural color. During the fibers’ spinning process, the microstructures of the fibers are generated. The effect of spinning conditions is investigated by measuring the optical properties of the wet gel fibers. The neutralization speed of negatively charged PPTA fibrils has a significant impact on the formation of the dense microstructure. Spinning under the fast neutralization speed condition makes it possible to achieve the blue-colored fiber derived from Rayleigh scattering. The influence of neutralization speed on the microstructure of the fibers is confirmed by FE-SEM characterization. Furthermore, spinning using a narrow inner diameter needle decreases the whiteness component derived from Mie scattering of the fibers, resulting in a more vivid blue color. The angle-independent structurally colored fibers hold great promise for application in clothing, interiors, and industrial materials.

Evaluations of Sisal Fiber as Biosorbent for online Preconcentration and Determination of Cu and Mn coupled to MP AES using the Analytical Greenness Metric Approach

Biorsorbents can be used to pack minicolumns for the preconcentration of trace elements and thus improve the detection limits of some techniques. A biosorbent is efficient when presents binding sites as carbonyls, amines, and carboxylic groups, among others. Thus, natural materials as the sisal fiber (Agave sisalana) may be a good candidate. Sisal fiber demonstrated good performance for Cu preconcentration when it was impregnated with alizarine fluorine blue (AFB). However, very good results were reported for the first time by our group with this column, without the use of additional reagents for both, Mn and Cu determinations in water samples by using microwave plasma atomic emission spectroscopy (MP AES). In this paper a comparison of the sisal fiber preparation with and without impregnation with AFB is presented and discussed in terms of the figures of merit, including precision, trueness, limits of detection and quantification. In addition to that, the number of determinations without the need of replacement of the solid phase was evaluated. Results demonstrated that the impregnation of sisal fiber with AFB does not leads to an improvement in the analytical performance. Analytical Greenness Metric Approach (AGREE) was used to evaluate the greenness of both methods and results obtained were similar. Despite this, the method without impregnation of the fiber has some remarkable advantages, that contributes to Green Analytical Chemistry (GAC), related to the lifetime of the sorbent, not considered in the AGREE tool.

Dynamic mechanical properties, interface structure evolution and deformation behaviors of PVA-carbon fiber reinforced concrete with negative Poisson’s ratio design

Based on the advantages of negative Poisson's ratio (NPR) materials in controlling deformation and absorbing energy, this paper combines NPR design with the preparation of fiber reinforced concrete (FRC) to optimize the anti-dynamic load performance of FRC. In this paper, a helical auxetic yarn (Hay) with NPR effect is obtained by wrapping carbon fiber (CF) on polyvinyl alcohol fiber (PVAF) at a certain angle, and it is mixed into concrete in different forms to obtain auxetic fiber concrete. In order to explore the influence of auxetic fiber on the anti-dynamic load performance of concrete, split Hopkinson pressure bar (SHPB) test and dropping ball impact test are carried out on different FRC. The impact resistance of FRC under different impact velocities is tested, and the impact resistance behavior of FRC is analyzed by digital speckle correlation method (DSCM). The results show that in SHPB test, the anti-impact strength of the layered auxetic fiber concrete is 19.1 % higher than that of the plain concrete (PC), and its fracture energy is increased by 25.8 %. In the dropping ball impact test, its fracture energy is 5 ∼ 9 times that of PC. In addition, the results of scanning electron microscopy (SEM) and DSCM test show that the incorporation of auxetic fiber has a positive effect on improving the generation and development of internal cracks in concrete, which is expected to provide a reference for the application of NPR materials in explosion resistance, penetration resistance and impact resistance of building structures.