Crystalline Fibers Research Articles

Carbon fibers from polypropylene: Structural evolution of precursor fiber during stabilization and carbonization

Utilizing polypropylene (PP) fibers as the precursor material, Polypropylene-based carbon fibers (CFPP) were obtained by carbonization after sulfonation cross-linking with sulfuric acid. First, the mechanism of structural evolution of sulfonated PP fiber (SFPP) during carbonization was investigated at temperatures between 500 °C-1300 °C. According to the results, the chemical structure, as well as the carbon structure transformation of SFPP, depending on the carbonization temperature, i.e., the removal of organic functional groups, the fusion to small aromatic structures, and the transformation to ordered carbon structures. The carbon content of the carbon fibers obtained at 1300 °C was as high as 93.4 %. Subsequently, various PP fibers with different diameters and crystalline structures were prepared by melt spinning and subsequent thermal-drawing treatment, and the relationship between their structures and the properties of CFPPs was investigated. The sulfonation reaction rate of PP fibers increased as the sulfonation reaction proceeded and was synergistically regulated by the crystalline structure and fiber diameter. The CFPP with a smaller diameter exhibited a more homogeneous skin-core structure, together with higher overall graphitization, smaller graphite layer spacing, and better graphite microcrystalline structure, and thus its conductivity and mechanical properties of the carbon fiber were significantly improved. The mechanical properties and volume resistivity of the prepared CFPP reached 338.6 MPa and 4.91×10−5 Ω·m, respectively.

Ultrastable N-Type Semiconducting Fiber Organic Electrochemical Transistors for Highly Sensitive Biosensors.

Organic electrochemical transistors (OECTs) have attracted increasing attention due to their merits of high transconductance, low operating voltage, and good biocompatibility, ideal for biosensors. However, further advances in their practical applications face challenges of low n-type performance and poor stability. Here, it is demonstrated that wet-spinning the commercially available n-type conjugated polymer poly(benzimidazobenzophenanthroline) (BBL) into highly aligned and crystalline fibers enhances both OECT performance and stability. Although BBL is only soluble in high-boiling-point strong acids, it can be wet-spun into high-quality fibers with adjustable diameters. The BBL fiber OECTs exhibit a record-high area-normalized transconductance (gm,A) of 2.40 µS µm-2 and over 10 times higher figure-of-merit (µC*) than its thin-film counterparts. More importantly, these fiber OECTs exhibit remarkable stability with no noticeable performance attenuation after 1500 cycles over 4h operation, outperforming all previously reported n-type OECTs. The superior performance and stability can be attributed to shorter π-π stacking distance and ordered molecular arrangement in the fibers, endowing the BBL fiber OECT-based biosensors with outstanding sensitivity while keeping a miniaturized form factor. This work demonstrates that, beyond new material development, developing new fabrication technology is also crucial for addressing the performance and stability issues in n-type OECTs.

Investigation Mechanical Properties of Polypropylene Composite with Difference Composition of Nucleating Agent Based Sorghum Fiber

The purpose of this research is to investigate the mechanical effects of polypropylene using sorghum fiber as nucleating agent. Alkalization, bleaching, and acid hydrolysis are all used to chemically modify sorghum fiber. This modified sorghum fiber was then mixed with polypropylene as a polymer matrix for 10 minutes in a rheomix at 100 rpm at 165°C and molded in a hot press. The results of this study suggest that acid hydrolysis can improve the crystallinity and compatibility of sorghum fiber. Furthermore, at 23.44 MPa, the optimum mechanical characteristics of a mixture of polypropylene and micro fibrillated cellulose (MFC) from sorghum fiber were achieved from 0.5% MFC resulting from acid hydrolysis.

Hollow Hafnium Oxide (HfO2) Fibers: Using an Effective Combination of Sol-Gel, Electrospinning, and Thermal Degradation Pathway.

In recent years, hafnium oxide (HfO2) has gained increasing interest because of its high dielectric constant, excellent thermal stability, and high band gap. Although HfO2 bulk and film materials have been prepared and well-studied, HfO2 fibers, especially hollow fibers, have been less investigated. In this study, we present a facile preparation method for HfO2 hollow fibers through a unique integration of the sol-gel process and electrospinning technique. Initially, polystyrene (PS) fibers are fabricated by using electrospinning, followed by dipping in a HfO2 precursor solution, resulting in HfO2-coated PS fibers. Subsequent thermal treatment at 800 °C ensures the selective pyrolysis of the PS fibers and complete condensation of the HfO2 precursors, forming HfO2 hollow fibers. Scanning electron microscopy (SEM) characterizations reveal HfO2 hollow fibers with rough surfaces and diminished diameters, a transformation attributed to the removal of the PS fibers and the condensation of the HfO2 precursors. Our study also delves into the influence of precursor solution molar ratios, showcasing the ability to achieve smaller HfO2 fiber diameters with reduced precursor quantities. Validation of the material composition is achieved through thermogravimetric analysis (TGA) and energy-dispersive spectroscopy (EDS) mapping. Additionally, X-ray diffraction (XRD) analysis provides insights into the crystallinity of the HfO2 hollow fibers, highlighting a higher crystallinity in fibers annealed at 800 °C compared with those treated at 400 °C. Notably, the HfO2 hollow fibers demonstrate a water contact angle (WCA) of 38.70 ± 5.24°, underscoring the transformation from hydrophobic to hydrophilic properties after the removal of the PS fibers. Looking forward, this work paves the way for extensive research on the surface properties and potential applications of HfO2 hollow fibers in areas such as filtration, energy storage, and memory devices.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat.

Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken. The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups. All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Dodecyl methacrylate (DM) dispersion-assisted surface modification approach for increasing crystallinity of coir fibers

Coir fiber crystallinity is crucial since it widens the range of possible uses for natural fiber. To increase the crystallinity of coir fiber, the study describes an easy-to-use, simple-to-implement method that is cost-effective, eco-friendly, and highly productive. With the help of dodecyl methacrylate disperson, hydrocarbon molecules of varying chain lengths are covalently attached to the surface of coir fibers, modulating their surface wettability. There are a few different long-chain hydrocarbon compounds employed, including n-butyl methacrylate, n-octyl acrylate, and dodecyl methacrylate (DM), but DM has shown to be the most effective. The degree of grafting yield alteration is determined gravimetrically. It has been found that grafting yields of 28–30 wt.% can be used to convert hydrophilic coir fibers into water repellent crystalline fibers (water contact angle 148°). A total of 15 nm of dispersion, a disperson rate of 2 nm/min, DM concentration of 20%, and water content of 10% are fixed as key reaction parameters. Thermal and mechanical analyses show no significant changes in the fiber structure during alteration. The grafting and changes in surface wettability are well supported by the surface morphology of pure and modified coir fiber, which can be seen using scanning electron microscopy.

Hydrophilic Modification of Polylactic Acid Fiber and the Usage of Natural Dye for Multi-Levered Improvement of the Fabric Staining Depth and the Stability Effect.

Polylactic acid (PLA) fiber is a degradable material with good environmental friendliness for textile applications. However, the main problems of difficult dyeing of PLA fibers were: high crystallinity to the adsorption of dyes, more ester and methyl groups producing non-hydrophilic problems, long chains making dyes difficult to penetrate, and producing a low dyeing rate. Here, we attempted to change the crystallinity of the PLA fiber to a lower degree from hydrophobic to hydrophilicity property variation, destroy the long chain structure to grant more staining sites, and improve the PLA fiber staining depth and the resilience dyeing effect with deep eutectic solvent (DES) treatment and natural dyes. We discovered that a controlled DES treatment process could make PLA fibers less crystallized, help amorphous areas form, and break up long chains, which lead to more dye sites. After DES treatment, the crystallinity decreased from 56.12 to 29.86%, and the instantaneous water contact angle decreased from 108.79 to 64.39°. The DES-treated PLA fabric exhibited a higher K/S value of 15.14 for natural dyes under specific conditions. The fabric, which had remarkable fastness characteristics and wash resistance, could endure frequent laundering and fulfill the demands of everyday use. Moreover, the fabric had good antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans and possessed a certain level of biocompatibility with fibroblasts. This DES treatment and natural dye combination method offered a new strategy for improving PLA fabric staining depth and color fastness, making it a promising option for low-carbon environmental protection in the textile industry.

Physical properties, morphology and crystallinity of Typha leaf fibers processed by different extraction treatments

The effect of different extraction processes on the properties of Typha leaf fibers was investigated. In this work, manual decortications (FNT), NaOH alkali treatment (FT), sea water retting (FM) and a combined treatment (FC) including NaOH plus enzyme Pectinex Ultra SPL were compared. After the extraction process, morphological structure was examinated, physical and mechanical properties were also discussed. Scanning electron microscopy results revealed that extraction of Typha leaf fibers by NaOH plus enzyme led to removal of surface impurities and non-cellulosic materials. According to X-ray diffraction results, crystallinity index of (FC) was improved after enzymatic process by 57% compared to manual decorticated fibers. Tenacity of Typha fibers improved after different extraction methods when compared to manual decortications. Especially sea water retting process (FM) showed an increase of 82% higher tensile strength. Moreover, attenuated infrared spectroscopy analysis revealed that chemical retting, sea water process and combined treatment caused change of chemical composition by disappearing and/or attenuation of some bands which belong to hemicelluloses and lignin compounds. Also, chemical constituents’ analysis presents lignin fraction and alpha cellulose equal to 8.13% and 69.8% respectively for (FC).

Fabrication of highly crystalline titanium-containing SiC fibers with different boron contents exhibiting excellent electromagnetic wave absorption

Fabrication of highly crystalline titanium-containing SiC fibers with different boron contents exhibiting excellent electromagnetic wave absorption

Enhancing mechanical performance of biodegradable automotive composites with EPO and graphene

Recent strides in composite manufacturing technology have sparked a widespread embrace of natural fiber composites in engineering applications, exemplified by flax fiber. The crux of this development centers on the creation of an environmentally friendly composite, utilizing alkali-treated flax fiber reinforcement and poly lactic acid (PLA) as the polymer matrix through a hot compression technique. The investigation into water absorption unveils that alkaline treatment augments the hydrophobic nature and enhances the crystallinity of flax fibers, resulting in improved adhesion between the reinforcement and polymer matrix. The introduction of 5% wt of epoxidized palm oil (EPO) as plasticizers not only counters brittleness but also elevates thermal stability. Further enhancements are achieved through the addition of 0.5 wt% of graphene nanoparticles as nano-fillers, culminating in superior mechanical properties. This research places a focal point on a thorough mechanical characterization of these green composites, encompassing tensile, flexural, and impact properties, along with an assessment of inter-laminar shear strength. A detailed analysis of dimensional stability is conducted, while morphological scrutiny is performed using scanning electron microscopy. This study marks a significant leap towards sustainable engineering, presenting innovative natural fiber green composites that exhibit heightened mechanical and environmental performance.

Liquid crystalline elastomer self-oscillating fiber actuators fabricated from soft tubular molds.

The self-oscillation of objects that perform continuous and periodic motions upon unchanging and constant stimuli is highly important for intelligent actuators, advanced robotics, and biomedical machines. Liquid crystalline elastomer (LCE) materials are superior to traditional stimuli-responsive polymeric materials in the development of self-oscillators because of their reversible, large and anisotropic shape-changing ability, fast response ability and versatile structural design. In addition, fiber-shaped oscillators have attracted much interest due to their agility, flexibility and diverse oscillation modes. Herein, we present a strategy for fabricating fiber-shaped LCE self-oscillators using soft tubes as molds. Through the settlement of different configuration states of the soft tubes, the prepared fiber-shaped LCE oscillators can perform continuous rotational self-oscillation or up-and-down shifting self-oscillation under constant light stimuli, which are realized by photoinduced repetitive self-winding motion and self-waving motion, respectively. The mechanism of self-oscillating movements is attributed to the local temperature oscillation of LCE fibers caused by repetitive self-shadowing effects. LCE self-oscillators can operate stably over many oscillating cycles without obvious performance attenuation, revealing good robustness. Our work offers a versatile way by which LCE self-oscillators can be conveniently designed and fabricated in bulk and at low cost, and broadens the road for developing self-oscillating materials for biological robotics and health care machines.

PREPARAÇÃO DE BIOCOMPÓSITO À BASE DE AMIDO TERMOPLÁSTICO REFORÇADO COM FIBRAS DE EUCALIPTO: AVALIAÇÃO DO EFEITO DO TAMANHO DAS FIBRAS NAS PROPRIEDADES MECÂNICAS E DE SORÇÃO

PREPARATION OF BIOCOMPOSITE BASED ON THERMOPLASTIC STARCH REINFORCED WITH EUCALYPTUS FIBERS: EVALUATION OF FIBERS SIZE EFFECT ON MECHANICAL AND SORPTION PROPERTIES. This study investigated the preparation of a thermoplastic starch-based (ATP) biocomposite reinforced with eucalyptus fibers (FE), focusing on how fiber size affects the properties. The natural fibers were chemically processed using alkaline and bleaching treatments of eucalyptus bark. Subsequently, they were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to evaluate alterations in fiber composition and crystalline structure. Samples of biocomposites were prepared with a fixed fiber content (20 wt.%) and variations in particle size (dp): ATP/FE600 (600 μm ≤ dp < 1180 μm), ATP/FE250 (250 μm ≤ dp < 600 μm), and ATP/FE75 (75 μm ≤ dp < 250 μm). The samples were characterized by optical and scanning electron microscopy, mechanical tests, moisture absorption, and swelling analysis. Results indicated significant effects of fiber size on the biocomposite properties. Notably, the larger fibers present in ATP/FE600 exhibited superior tensile strength and elastic modulus, while this sample demonstrated reduced moisture absorption and swelling tendencies. Microscopic images revealed enhanced matrix-fiber adhesion in ATP/FE600, highlighting the importance of proper fiber size. The optimization of fiber size emerges as a relevant strategy for improving the mechanical attributes and mitigating moisture/water absorption tendencies in starch-based thermoplastic biocomposites, contributing to sustainable and high-performance materials.

Effect of fiber content on mechanical properties of carbon fiber-reinforced polyether-ether-ketone composites prepared using screw extrusion-based online mixing 3D printing

The mechanical properties of carbon fiber-reinforced polyether-ether-ketone (CF/PEEK) composites are closely related to the fiber content. However, the low fiber content (typically below 20 wt%) that can be prepared by current material extrusion limits the application of the composites. In this work, CF/PEEK composites with up to 50 wt% carbon fiber content were manufactured using a custom-made screw extrusion-based online mixing 3D printhead. The impact of fiber loading on the rheological and flow characteristics of the composites was thoroughly examined initially. Subsequently, the influence of fiber content on the crystallinity and mechanical behavior of 3D-printed parts before and after annealing was further explored. The results indicated that adding CF and annealing significantly enhanced the strength and modulus of the 3D-printed composites within a fiber content range of 10 wt% to 40 wt%, compared to those of pure PEEK. At 40 wt% CF, the tensile and flexural strengths of the samples reached their maximum values at 135.9 MPa and 251.2 MPa, respectively, which were enhanced by 94% and 111% compared to those of the unannealed pure PEEK specimens. Also, these properties are the highest values achieved in 3D-printed short CF/PEEK composites. The mechanical properties of composites are affected by various factors such as fiber content, crystallinity, and internal pore defects when the fiber content is less than 20 wt%. However, when the fiber content exceeds 20 wt%, the influence of crystallinity on the mechanical properties becomes less significant. This study further explores the potential application of CF/PEEK composites and provides a novel approach for composite preparation.

Functional properties and optimization of dietary fiber concentrate from sago hampas using response surface methodology

Sago hampas, whose major components are fiber and starch, is an underutilized by-product generated from starch extraction of sago stems. In order to increase its added value and applications, sago hampas could be developed into dietary fiber concentrate. This research purposed to obtain the optimum condition of enzymatic hydrolysis process of sago hampas to isolate the dietary fiber components. A central composite design of response surface methodology (RSM) was used to optimize processing variables, namely, sago hampas slurry concentration (0.1–0.2 kg/kg), reaction time (45–135 min), and enzyme concentration in the substrate (10–35 mL/kg). Enzymatic hydrolysis using α-amylase at 108 °C was employed to remove starch components (becoming maltodextrin), escalate dietary fiber content, and modify the crystallinity of fiber. The goals of optimization were to maximize total dietary fiber (TDF), water-holding capacity (WHC), and oil-holding capacity (OHC) of the dietary fiber concentrate and to maximize dextrose equivalent (DE) of the maltodextrin solution obtained. The optimum process condition was found when the variables sago hampas slurry concentration, reaction time, and enzyme concentration were 0.14 kg/kg, 121 min, and 25 mL/kg, respectively. The optimal condition was verified by laboratory experiment resulting in TDF, WHC, OHC, and DE of 92.98 %, 26.34 g of water per g of sample, 5.64 g of oil per g of sample, and 10.37 %, respectively. TDF increased while the starch decreased significantly following conversion to dietary fiber. It is associated with the improvement in the functional properties of dietary fiber. The OHC, cation exchange capacity, emulsifying activity, swelling capacity, and solubility all exhibited significant increases. The morphological structure of the dietary fiber concentrate revealed a fiber matrix degradation with a high level of fiber porosity while the crystallinity was decreased from 61 % to 42 %. The properties of dietary fiber concentrate indicate appropriate parameters for food industry applications.

Viologen-based supramolecular crystal gels: gelation kinetics and sensitivity to temperature.

Supramolecular crystal gels, a subset of molecular gels, are formed through the self-assembly of low molecular weight gelators into interconnecting crystalline fibers, creating a three-dimensional soft solid network. This study focuses on the formation and properties of viologen-based supramolecular crystalline gels. It aims to answer key questions about the tunability of network properties and the origin of these properties through in-depth analyses of the gelation kinetics triggered by thermal quenching. Experimental investigations, including UV-Vis absorption spectroscopy, rheology, microscopy and scattering measurements, contribute to a comprehensive and self-consistent understanding of the system kinetics. We confirm that viologen-based gelators crystallize by forming nanometer radius hollow tubes that assemble into micro to millimetric spherulites. We then show that crystallization follows the Avrami theory and is based on pre-existing nuclei. We also establish that the growth is interface-controlled, leading the hollow tubes to branch into spherulites with fractal structures. Finally, we demonstrate that the gel properties can be tuned depending on the quenching temperature. Lowering the temperature results in the formation of denser and smaller spherulites. In contrast, the gel's elasticity is not significantly affected by the quench temperature, leading us to hypothesize that the densification of spherulites occurs at the expense of connectivity between spherulites.

Smart Films Produced by Electrospinning of Poly(butylene-adipate-co‑terephthalate)/poly-(ε-caprolactone) for Controlled Delivery of Ibuprofen

Wound dressing devices composed of microfibers of poly(butylene-adipate-co-terephthalate) and poly-(ε-caprolactone) incorporated with ibuprofen were obtained by electrospinning technique. The effect of ibuprofen concentration (0, 10, and 20% m m-1) on morphology, spectroscopic, and thermal characterization was evaluated. The fibers containing ibuprofen presented beads and revealed no uniformity. The spectroscopic analysis showed signals that reveal the ibuprofen incorporation on fibers. At the same time, X-ray diffraction spectroscopy indicated a difference in the fiber crystallinity depending on drug concentration, where a lower crystallinity was verified by the film containing a greater concentration incorporated. Rheological measurements revealed that films were more plastic in greater ibuprofen incorporation. Contact angle characterization revealed that ibuprofen solubilization on composite surfaces increased the film wettability. Finally, the fibers promoted the controlled release of ibuprofen, promoting morphological changes in polymeric matrices. The material developed can be used in future biomedical applications.

In situ production of bacterial nanocellulose-activated carbon composites from pear juice industry wastewater by two new Komagataeibacter intermedius and Komagataeibacter xylinus isolates for heavy metal removal

Fruit juice industry generates a large amount of wastewater, which contains substantial waste activated carbon for juice turbidity removal. Due to the low concentrations of useful compounds in the wastewater, the cost for the extraction is extremely high. Two new bacterial nanocellulose (BNC) producing strains were isolated and identified. These strains produced 6.11 and 1.38 folds BNC from pear juice wastewater than from a conventional medium, respectively. BNC spontaneously encapsulated the suspended waste activated carbon particles during the fermentation, flocculating and collecting the particles without additional filtration or centrifugation processes. FE-SEM, FT-IR, TGA and XRD showed that the fiber diameters, chemical structure, thermal stability and crystallinity of BNC produced from the pear juice wastewater supernatant was similar to that from the conventional medium. FE-SEM revealed the three-dimensional package structure of the BNC-activated carbon composite, and XRD showed that the crystallinity of the composite was improved up to 86%. The BNC-activated carbon composite exhibited excellent adsorption performance towards heavy metals, and the maximum adsorption capacities for Cu2+ and Zn2+ were 20.71 mg/g and 76.92 mg/g within 60 min, respectively. Especially, compared to activated carbon, the adsorption capacity of the composite for Zn2+ was improved for 25.01%. This study utilized pear juice wastewater as an alternative medium to produce BNC at lower cost, and reduced BOD and wastewater treatment costs. Additionally, BNC encapsulated residual activated carbon left over in the wastewater, preventing dust pollution and enabling recycling of the waste activated carbon, and formed a composite with excellent heavy metal absorption capacity.

EFFECTS OF COMBINED CHEMICAL AND HYDROTHERMAL PRETREATMENT ON PAPYRUS CELLULOSE STRUCTURE

"Papyrus (Cyperus papyrus L.) is a lignocellulosic plant suitable for many applications when properly pretreated. This study explores the potential of a two-stage pretreatment (combining hydrothermal and chemical methods) on the characteristics of cellulose fibers derived from papyrus. One-stage and two-stage pretreatments were compared, utilizing sodium hydroxide (NaOH) and ferric chloride (FeCl3) chemical solutions at a 3% (w/v) concentration. Chemical pretreatment was employed for one-stage processing, while hydrothermal pretreatment was introduced prior to chemical pretreatment. As the liquid hot-water process intensified, significant changes in chemical composition and morphology occurred. Hydrothermal pretreatment partially eliminates hemicelluloses and lignin, while increasing the cellulose content and enhancing fiber crystallinity. Following the pulping and bleaching stages, it was determined that the FeCl3-based two-stage pretreatment exhibited the greatest potential for cellulose recovery and hemicelluloses and lignin removal, yielding the highest crystallinity index."

Quantification of collagen fiber properties in alcoholic liver fibrosis using polarization-resolved second harmonic generation microscopy

Liver fibrosis is assessed mainly by conventional staining or second harmonic generation (SHG) microscopy, which can only provide collagen content in fibrotic area. We propose to use polarization-resolved SHG (PR-SHG) microscopy to quantify liver fibrosis in terms of collagen fiber orientation and crystallization. Liver samples obtained from autopsy cases with fibrosis stage of F0–F4 were evaluated with an SHG microscope, and 12 consecutive PR-SHG images were acquired while changing the polarization azimuth angle of the irradiated laser from 0° to 165° in 15° increments using polarizer. The fiber orientation angle (φ) and degree (ρ) of collagen were estimated from the images. The SHG-positive area increased as the fibrosis stage progressed, which was well consistent with Sirius Red staining. The value of φ was random regardless of fibrosis stage. The mean value of ρ (ρ-mean), which represents collagen fiber crystallinity, varied more as fibrosis progressed to stage F3, and converged to a significantly higher value in F4 than in other stages. Spatial dispersion of ρ (ρ-entropy) also showed increased variation in the stage F3 and decreased variation in the stage F4. It was shown that PR-SHG could provide new information on the properties of collagen fibers in human liver fibrosis.

A step towards tuning the jute fiber structure and properties by employing sodium periodate oxidation and coating with alginate

This paper outlines a novel simple protocol for tuning the structure and properties of jute using sodium periodate (NaIO4) oxidation and coating with alginate. When compared to the raw jute, fabrics oxidized with a 0.2 or 0.4 % NaIO4 solution for 30–120 min exhibited an increased aldehyde group content (0.185 vs. 0.239–0.398 mmol/g), a significantly increased negative zeta potential (from −8.57 down to −20.12 mV), a slight disruption of fiber crystallinity, 15.1–37.5 % and 27.9–49.8 % lower fabric maximum force and stiffness, respectively. Owing to the removal of hydrophobic surface barrier, decreased crystallinity index and the presence of micropores on the fabrics' surfaces, oxidized fabrics have a 22.3–29.6 % improved ability for moisture sorption compared to raw fabric. Oxidized fabrics characterized by very long wetting times and excellent antioxidant activities (> 98 %), can find applications as hydrophobic packaging materials. To further extend the utilization of jute in biocarpet engineering such as water-binding geo-prebiotic supports, oxidized fabrics were coated with alginate resulting in 7.9–24.9 % higher moisture sorption and 352–660 times lower wetting times than their oxidized counterparts. This modification protocol has never been applied to lignocellulosic fibers and sheds new light on obtaining jute fabrics with tuned structure and properties intended for various applications.