Green Fiber Research Articles

Straight recycled green fibre pull-out behaviour in an ultrahigh performance concrete composite matrix UHPC

This article presents the study of the pull-out method and the behavior of the cementitious matrix under loading. Using finite element analysis to investigate the interfacial debonding performance allows us to grasp the experiment’s estimated values. The mechanical bonding is determined using a Scanning Electron Microscopy SEM image. The slippage during the pull-out load varies depending on the cementitious matrix grade and whether the recycled steel strand is hooked at specific angles (Inclination angle). The relationship between monotonic loading and steel fiber diameter was found to be a direct proportion. To comprehend the bonding and debonding between surfaces, as well as the shear experience under loading, both studies find the correlation between theoretical and experimental results to be satisfactory. All aspects were discussed in relation to the effective use of a finite element method in analysis.

Potential application of a green fiber laser in laser display systems.

This study explores the application of optical fiber lasers in display systems by integrating a P r3+-doped green all-fiber laser into a laser projection display system. As a control group to compare the results, a 520nm semiconductor green laser diode module was integrated, similar to the experimental group. The color gamut and speckle performances were studied and compared. The results showed that the experimental group performed slightly better in the color gamut volume. The speckle contrast decreased rapidly in the experimental group when power increased. To our knowledge, this is the first study to apply a fiber laser to a laser display system. The results shed light on developing laser display systems with fewer or no speckle reduction elements.

Properties and Structure of Thermoplastic Polyvinyl Alcohol/Polyamide Sea-Island Fibers.

Ultra-fine fibers derived from sea-island fibers have attracted great attention due to their excellent overall performance. However, green and efficient splitting of sea-island fibers is still a challenging task. In this work, thermoplastic polyvinyl alcohol (TPVA) was prepared by the physical blending of plasticizer. The modified TPVA showed a high decomposition temperature (285 °C) and a wide thermoplastic processing window. This made TPVA match well with polyamide 6 (PA6) to form conjugated melts at 250 °C. Corresponding PVA/PA6 sea-island fibers were first reported to realize water-splitting instead of alkali-extraction of "sea" polymers. The effects of sea/island mass ratios and different spinning speeds on the properties of PVA/PA6 sea-island pre-oriented yarn (POY) were investigated. A higher spinning speed enhanced the orientation-induced crystalline behavior of fiber, therefore increasing the tensile strength of fibers. As the increase of spinning speed from 1000 to 1500 m/min, the crystalline degree of corresponding POYs increased from 9.9 to 14.3%. The plasticizer in PVA did not diffuse to the PA matrix during spinning. However, PVA could induce the crystallization of PA6 via interfacial hydrogen bonding. When the spinning speed was 1500 m/min, and PVA/PA6 was 7:3, the tensile strength reached the highest value of 1.67 cN/dtex. The uniform diameters of ultra-fine PA6 fibers (2-5 μm) were obtained by an environment-friendly water-splitting process. The "sea" phase (TPVA) in sea-island fiber could be removed quickly by boiling water treatment in 3 min. This green and energy-saving sea-island fiber splitting technique is of great significance in reducing CO2 emissions during the preparation of super-fine fibers.

Eco-friendly PVA-LYS fibers for gold nanoparticle recovery from water and their catalytic performance.

In this work, we grafted lysine on PVA electrospun fibers, using a green preparation technique. The resulting fiber mats were proposed for gold nanoparticles (AuNPs) removal from water. The efficiency of three fibers with different lysine amounts (10, 20, and 30%) was investigated. The incorporation of amino groups in PVA fibers was firstly proved by FTIR, SEM, and elemental analysis, confirming the presence of lysine. Among the three different fibers, PVA-LYS 30% has shown the best removal efficiency, reaching 65%, at pH equal to 5. Adsorption isotherms were studied and showed that the Langmuir model is the best model fitting our experimental results, with a maximum adsorption capacity of 20.1mgg-1. Metal-ligand interactions and electrostatic attraction between protonated amino groups of lysine on the fibers and negatively charged, citrate capped, AuNPs are the main proposed mechanisms for AuNP adsorption on the fibers. Sustainability of AuNPs adsorbed on these fibers has been checked through their reuse as catalyst for the reduction of 4-nitrophenol to 4-aminophenol. The process was completed within 60min, and their reusability showed more than 99% efficiency after 5 reduction cycles. Our results prove that green PVA-LYS fibers can extract nanoparticles from water, as low cost-effective and eco-friendly adsorbent, and contribute to the promotion of a circular economy approach, through their reuse as catalyst in the reduction of pollutants.

Impact of distinct alkaline treatment on natural plant fibre reinforced polymer composites

The primary goal of this research work is to enhance the mechanical behaviour of luffa, coir and sisal fibre reinforced polymer composites, which had undergone diverse chemical processing. The selected green fibres were subjected to a variety of alkaline treatments at varied concentration of 5% NaOH, 3% KOH and 7% Ca(OH)2 for 4, 2 and 6 h, respectively. The hand lay-up method was used to prepare the nine distinct samples. It was found that the composites with highest wt.% of coir and luffa fibres which underwent NaOH treatment resulted in highest tensile strengths of 10.946 and 14.425 MPa. However, Ca(OH)2 treatment proved to be better for composites containing 20% sisal fibres. Similarly, 20% NaOH treated coir fibre reinforced composite exhibited better flexural stress and modulus, whereas Ca(OH)2 treatment led to increase in flexural stress and modulus for composites containing 20% sisal fibres. The impact strength of the composites containing highest percentage of coir fibres that is, 20% was higher for all alkali treatments. Composite containing 20% NaOH treated coir fibres exhibited maximum interlaminar shear strength. Overall, NaOH treatment of coir, Ca(OH)2 treatment of sisal and KOH treatment of luffa fibre significantly improved the mechanical behaviour of the composites.

Microplastics released from artificial turf applied as hedge walls: Their aging-induced properties and uptake by grass carp, mussels and earthworms

An emerging source of MPs in China is artificial turf applied as hedge walls (ATHWs), which have been increasingly used mainly in enclosing construction sites as well as beautifying the municipal landscape. However, the specific ecological risks caused by MPs released from ATHWs (ATHW-MPs) are still unknown. In the present study, we investigated the amount and aging-induced properties of green fibers (GMPs) and the backing materials (BMPs), released from the ATHWs; as well as their potential uptake by animals. Grass carp (Ctenopharyngodon idellus), mussels (Mytilus edulis) and earthworms (Eisenia fetida) were used as animal test species. Outdoor exposure for 180 days made ATHWs more prone to embrittlement and disintegration, leading to 4.58 ± 1.96 % weight loss of the grass panels. More and finer particles and fibers were released by an external shear force from the outdoor exposed panels than from panels exposed to artificial UV-light. The aging process altered the surface properties of both GMP and BMP such as zeta potential, surface roughness, specific surface area and chemical groups, which may change their interaction with chemicals and species in the environment. All the studied species tended to ingest more fine particles (<40 µm) of BMPs. As a kind of microfibers, GMP were ingested by some grass carp and mussels but not by earthworms. Ingestion of MPs increased at higher MP-exposure concentrations. Although most of BMPs were partly egested by animal species after 3 d intestinal cleansing; 10 %, 44 % and 22 % of ingested BMPs remained in grass carp, mussels and earthworms, respectively. Aging of ATHW cause more and finer shed MPs, therefore, the sources and quality of the raw materials and producing process must be strictly controlled. We suggest that industry should develop or pay attention to the materials that are more resistant to aging; assess and inform the life cycle of the ATHWs in the instructions, and remind users to avoid free exposure of the backing material during installation.

Two-in-One Spider Silk Protein with Combined Mechanical Features in All-Aqueous Spun Fibers.

Major ampullate (MA) spider silk reveals outstanding mechanical properties in terms of a unique combination of high tensile strength and extensibility, unmatched by most other known native or synthetic fiber materials. MA silk contains at least two spider silk proteins (spidroins), and here, a novel two-in-one (TIO) spidroin was engineered, resembling amino acid sequences of such two of the European garden spider. The combination of mechanical and chemical features of both underlying proteins facilitated the hierarchical self-assembly into β-sheet-rich superstructures. Due to the presence of native terminal dimerization domains, highly concentrated aqueous spinning dopes could be prepared from recombinant TIO spidroins. Subsequently, fibers were spun in a biomimetic, aqueous wet-spinning process, yielding mechanical properties at least twice as high as fibers spun from individual spidroins or blends. The presented processing route holds great potential for future applications using ecological green high-performance fibers.

Flexural behavior of green RC beams with disposable glasses fibers in a marine environment

Using supplementary cementitious materials (SCMs) in concrete improves mechanical behavior and decreases the environmental pollution resulting from cement as a generator of greenhouse gases. On the other hand, the addition of disposable glasses as fibers to concrete can reduce cracking, increase ductility, and decrease environmental pollution too. Therefore, it seems that by the simultaneous use of SCM and plastic waste fiber in producing green concrete structures can reduce environmental pollution, improve mechanical behavior, and delay the cracking process, especially in marine. To achieve this objective, in the current research program, the effects of adding 0.5 % and1 % disposable glass fibers in form of ring or strip on the flexural behavior of ordinary green reinforced concrete (GRC) beams containing 10 % metakaolin/zeolite as SCMs were investigated at 28 and 180 days in the tidal environment of the Oman sea. According to the results, the cracking load (Pcr) of GRC beams was decreased up to 25 % and 32 % by adding ring and strip fibers, respectively. Moreover, adding fibers to GRC beams increased the maximum load capacity (Pmax) and flexural toughness (T) up to 28 % and 48 %, respectively. Also, green fiber reinforced concrete (GFRC) beams containing strip fibers had greater Pmax and T than ring fibers. Furthermore, metakaolin GFRC beams had higher Pcr, Pmax, and T than zeolite by 7 %, 9 %, and 7 %, respectively. Considerating the results, addition of ring fibers to the GRC beams increased the pre-cracking stiffness (SFpr) more than the strip fibers and decreased the post-cracking stiffness (SFpo).

Pyrolysis process for boron nitride fiber derived from tris(methylamino)borane: Evolution of the molecular structure

AbstractTo provide molecular‐scale insight into the structural evolution from tris(methylamino)borane to boron nitride (BN) fiber during the chemical thermal‐treating process, polymeric green fiber is cured in hot synthetic air at 300°C and then treats to 400, 600, 800, and 1000°C in ammonia. The chemical composition and structure of the volatile compounds and residual products are analyzed during the pyrolysis process for the polymeric green fiber. It is demonstrated that oxygen can be used to cure polymeric green fiber rapidly under the premise of ensuring a final fiber content of less than 1 wt% carbon and 2 wt% oxygen while maintaining the fiber tensile strength at 1000°C. The molecular structure evolution during the pyrolysis process for polymeric green fiber after oxygen curing is determined. Specifically, in hot synthetic air, introducing oxygen and releasing methylamine generates a B–O six‐membered ring structure in the polymer in the first stage. Then, the removal of methyl results in the formation of a B–N–O network in hot ammonia. Afterward, nitridation of the B–O six‐membered ring promotes the evolution of the B–N six‐membered ring structure with the release of water and carbon dioxide. Finally, the growth and rearrangement of the BN structure are achieved.

Inorganic composite coagulant for wool scouring wastewater treatment: Performance, kinetics and coagulation mechanism

Wool is perceived to be a clean and green natural fibre. However, raw wool contains substantial amounts of contaminants that must be removed in a wool scouring process before the wool can be used as a textile fibre. Coagulation is the first step for scouring wastewater treatment. But the role of inorganic coagulants in increasing sludge density for scouring wastewater treatment remains unclear. This work systematically prepared a series of inorganic composite coagulants (polyaluminium ferric silicate (PAFS)) and investigated their efficiency for treating wool scouring wastewater. Compared with conventional coagulants, polyaluminium chloride (PAC) and polyferric sulfate (PFS), PAFS showed improved coagulation performance over a wider pH range (3–7), achieving higher removal rates of 97 % and 99 % for chemical oxygen demand (COD) and turbidity, respectively. In addition, PAFS showed its advantages for practical wastewater treatment, including fast floc settling rate, increased sludge density (with a reduced sludge volume) and low floc moisture content. This optimized PAFS was successfully obtained in a scaled-up process. Zeta potential tests revealed that PAFS coagulated colloidal particles by the synergistic action of electro-neutralization and adsorption bridging. This work has practical implications for increasing the efficiency of wastewater treatment and reducing the environmental impact of wool scouring.

Direct generation of 3.17 mJ green pulses in a cavity-dumped Ho3+-doped fiber laser at 543 nm

High-energy pulsed lasers in the green spectral region are of tremendous interest for applications in space laser ranging, underwater detection, precise processing, and scientific research. Semiconductor pulsed lasers currently are difficult to access to the so-called “green gap,” and high-energy green pulsed lasers still heavily rely on the nonlinear frequency conversion of near-IR lasers, precluding compact and low-cost green laser systems. Here, we address this challenge by demonstrating, for the first time to the best of our knowledge, millijoule-level green pulses generated directly from a fiber laser. The green pulsed fiber laser consists of a 450 nm pump laser diode, a Ho3+-doped ZBLAN fiber, and a cavity-dumping module based on a visible wavelength acousto-optic modulator. Stable pulse operation in the cavity-dumping regime at 543 nm is observed with a tunable repetition rate in a large range of 100 Hz–3 MHz and a pulse duration of 72–116 ns. The maximum pulse energy of 3.17 mJ at 100 Hz is successfully achieved, which is three orders of magnitude higher than those of the rare-earth-doped fiber green lasers previously reported. This work provides a model for compact, high-efficiency, and high-energy visible fiber pulsed lasers.

Using Tween 80 in pretreatment, enzymatic hydrolysis, and fermentation processes for enhancing ethanol production from green coconut fiber

Using Tween 80 in pretreatment, enzymatic hydrolysis, and fermentation processes for enhancing ethanol production from green coconut fiber

Pre-oxidation of cellulose controlled by the nitrogen-phosphorus compound catalyst to prepare fibers with ultra-high flame retardancy

Cellulose fibers are a class of green fibers that are widely used. But its flammability makes it a very high fire risk. According to inference, glycine and phosphoric acid may have the function of binding each other and capturing cellulose pyrolysis fragments. This is of great significance for the exploration of the hypothesis that the oxidation process of cellulose can be regulated by adding catalysts so that the oxidized fibers have high carbon yield and ultra-high flame retardancy. In this study, a compound catalyst was prepared with glycine and phosphoric acid in a particular ratio for the first time, and the chemical structure of lyocell fiber during pre-oxidation was adjusted with a specific step-by-step heating system to prepare flame-retardant fiber. The results of flammability testing showed that the limiting oxygen index (LOI) of the oxidized fibers unexpectedly jumped to 66.4%, more than three times higher than that of lyocell fibers with an LOI of only 18%. The UL-94 grade also directly reached the highest level (V-0). This means that the study produced fibers with excellent flame retardancy with a simple method, which to some extent verified the previous hypothesis. Furthermore, based on the abundant XPS and FT-IR data, a unique mechanism for the synergistic flame retardancy of N and P based on the phosphoramide structure is also proposed. This study provides a new method for broadening the application scope of cellulose-based products in the field of fire risk.

Cotton green fiber promotes suberin synthesis interfering cellulose deposition in the secondary cell wall

Naturally green cotton (NGC) represents one of two commercialized naturally colored cottons, but its application is limited in the textile industry for inferior productivity and fiber quality of NGC cultivars. NGC fiber deposits substantial suberin at maturation, possibly related to fiber green coloration. The effects of suberin deposition on fiber development and fiber yield and quality are still to be elucidated. In the present study, the green fiber gene (Lg) in upland cotton (Gossypium hirsutum L.) was cloned using map-based method. It was found that Lg encoded an R2R3-MYB transcription factor, promoting suberin synthesis and deposition in cotton fiber via regulating multiple suberin structural genes. Suberin accumulated in green fibers continuously from the beginning of the secondary cell wall synthesis, along with significantly inhibited cellulose deposition, leading to dramatically decreased fiber strength and lint percentage. Our data demonstrated that suberin accumulation significantly interfered with cellulose deposition in fiber secondary cell wall, which conferred low yield and inferior fiber quality to green-fiber cottons.

Study of using different colors of fluorescent fibers as optical antennas in white LED based-visible light communications.

A fluorescent fiber can be used as an optical antenna in visible light communication (VLC) for simultaneous optical filtering and light concentration and therefore to build a compact receiver. Since its light concentration principle is based on fluorescence, it can exceed the étendue limit and achieve both a high concentration gain and a wide field-of-view (FOV). In addition, because the photoluminescence (PL) lifetime of the fluorophore is typically only several nanoseconds, it can support high-speed data transmissions. When a fluorescent fiber antenna is used in a white light-emitting diode (LED)-based VLC system, the transmission performance highly depends on how the absorption and emission spectra of the fluorophore are associated with both the spectrum of the LED and the responsivity of the silicon photodetector. In this paper, we analyze the performance of several different commercially available fluorescent fibers. We show that, when the data rate is low or the transmission distance is long, since the light emitted from a red fluorescent fiber is associated with high silicon responsivities, it can result in high signal-to-noise ratios (SNRs) at the receiver output and therefore lead to low transmission error rates. In contrast, when the data rate is high or the transmission distance is relatively short, the bandwidth dominates the overall performance and consequently the green fluorescent fiber has better performance since it only absorbs the light emitted from the blue LED rather than the light emitted from the yellow phosphor.

Initial discovery of microplastic pollution in Mnemiopsis leidyi (Ctenophora: Lobata)

The production of plastics has exponentially increased over time such that the observation of microplastics in the oceans has become a major concern given how frequently these particles and marine biota may interact. Microplastics can be ingested by diverse species, including invertebrates, which can lead to physical damage due to their small size and potentially chemical damage related to the ingestion of monomers, polymeric additives, or adsorbed chemicals. This study reports on the first evidence of microplastics in Mnemiopsis leidyi. Microplastics were described by type, quantified, and had their chemical composition identified. In total, 328 samples of microplastic (MP) candidates were observed: blue fibers were the most abundant, followed by black, red, and green fibers as well as blue fragments. Three types of microplastics were chemically identified as polyurethane, unplasticized polyvinylchloride, and polyethylene polylauryllactam. Overall, this study demonstrated that Mnemiopsis leidyi have the capacity to incorporate microplastics. Although more studies are needed, Mnemiopsis leidyi is relatively abundant on the Atlantic coast and should be recommended for use as a bioindicator for microplastics.

Surfactant Assisted In Situ Synthesis of Nanofibrillated Cellulose/Polymethylsilsesquioxane Aerogel for Tuning Its Thermal Performance

Back Cover: In article 2200628, Pradip K. Maji and co-worker show that the thermal conductivity depends upon solid and gaseous conductivity. The red and blue color gradients in aerogel slab distinguish hot and cold region. Green color fibers and spherical particles symbolize nanofibrillated cellulose and polymethylsilsesquioxane, respectively. The navy blue color air molecules diffuse into aerogel pores due to Knudsen effect. The structure of aerogel slab represents the thermal insulator.

Reutilization of different bamboo residue fiber as sustainable asphalt modifier: performance evaluation and parameter recommendation.

The large-scale application of bamboo has led to the production of enormous amounts of waste in the form of bamboo residue. In order to reuse the bamboo residue, three types of bamboo fiber (sinocalamus affinis fiber (SAF), green bamboo fiber (GBF), and phyllostachys pubescens fiber (PPF)) extracted from bamboo residues were studied. The properties of bamboo fiber modified asphalt were evaluated by ductility test, cone penetration test, rheologicaltest, and low-field nuclear magnetic resonance (LF-NMR) test. Furthermore, the dispersion properties of bamboo fiber were analyzed by dispersion uniformity test. The results show that the mechanical and high-temperature properties of the bamboo fiber modified asphalt are obviously improved while the low-temperature crack resistance is only slightly weakened. Meanwhile, the signal intensities of SAF modified asphaltand GBF modified asphalt are basically the same before and after aging. It proved the viscosity is not changed much, which verified the good anti-aging properties of SAF modified asphaltand GBF modified asphalt. However, PPF is the best dispersed uniformly in the asphalt. The maximum allowable length and dosage of bamboo fibers is recommended as follows: SAF (9mm, 2.0%), GBF (6mm, 1.5%), and PPF (6mm, 2.0%). The application of bamboo residue in asphalt not only emphasizes the recycling value of bamboo residue waste but also provides an optional natural fiber material for asphalt pavement construction, which meets the requirements of sustainable development.

Varietal performance of jute based on yield and yield contributing characters under the Terai region of Province -1 Nepal

A research experiment was conducted to know the varietal performance of some jute varieties at the farm of Jute Research Programme, Itahari, Sunsari, Nepal, during the jute growing period in 2019 and 2020. A total of fifteen tossa jute varieties viz. CO-58, JRCM-2, JRO-524, JRO-2407, SM-100, JRO-204, NJ-7010, Mahabij, JBO-2003H, JRO-7835, YA-41, Itahari-2, OM-1, JRO-632 and KEN-DS-058 were used as experimental crops. The experiment was laid out in Randomize Complete Block Design (RCBD) with three replications, and each replicate had 12 lines with an inter and Intra row spacing of 25 cm and 5 to 7cm, respectively. Varietal performances of jute showed statistically significant variation for all the traits. Among the tested varieties, the jute variety NJ-7010 showed the tallest plant height (366 cm), highest basal diameter (20.6 mm), bark thickness (1.7 mm), leaf width (4.8 cm), petiole length (4.7cm), lowest disease incidence (2.5 %) respectively. However, the variety JRCM-2 and JRO-524 showed the highest leaf length (15.1 cm), while the variety JRO-524 showed the lowest pest incidence (4.2 %). Furthermore, the jute variety NJ-7010 also showed greater results on various yield characters viz. green leaf weight (17.3 ton/ha), green plant weight (100.3 ton/ha), green fibre weight (44.7 ton/ha), green stick weight (57 ton/ha), dry fibre weight (7.2 ton/ha), dry stick weight (17.3 ton/ha). Thus, the jute variety NJ-7010 understood superiority in growth, yield, and yield-attributing traits. Therefore, the jute variety NJ-7010 could be a more successful, productive variety than other tested varieties in the terai region of Province-1 Nepal.

Upgrading Paper-Grade Pulp as Dissolving Pulp for Lyocell Fiber Preparation

Lyocell fiber has emerged as a new generation of green fiber due to its preparation process and unique properties in comparison with viscose fiber. The raw material for the preparation of Lyocell fiber has a great impact on the quality of the finished product. However, unlike viscose-grade dissolving pulp, there is no evaluation system for Lyocell-grade dissolving pulp, making it difficult to assess the quality of the raw material. This study examined the approach to upgrade the paper-grade pulp to dissolving pulp for the preparation of the raw material for Lyocell fiber. Under the sequence of caustic extraction, acid treatment, and enzymatic treatment, the pulp was prepared with competitive properties compared to the commercial Lyocell-grade dissolving pulp. The assessment of prepared pulp was also accomplished by characterizing the pulp properties, the dissolution properties, and the spinnability and stability of Lyocell solution using the prepared sample. In addition, the dissolution mechanism and influencing factors of pulp in the system were elucidated, providing a theoretical basis for upgrading paper-grade pulp to dissolving pulp for Lyocell fiber production.