Short Fiber Length Research Articles

Enhanced Electromagnetic Interference Shielding in Cement Composites Utilizing Carbon Fiber Clustered Networks with Dual Different Lengths

Electromagnetic interference (EMI) shielding is crucial for radio frequency ranges, particularly around 1 GHz, to ensure the functionality and security of electronic devices and wireless communications especially within building materials. The inherent properties of typical metallic materials, such as their heavy weight and high cost, make them less suitable for mass production, particularly in the construction applications. Herein, we present a novel approach to improve EMI shielding efficiency of cement composites by incorporating two types of carbon fibers with distinct lengths as fillers and optimizing the clustering network among these fillers. By precisely controlling the length and proportion of long (mother) and short (anchor) carbon fibers, we demonstrate that a 7:3 ratio of 6 mm mother fibers to 2 mm anchor fibers yields optimal shielding efficiencies, delivering 65.3 dB at a low radio frequency (1 GHz) and 44.5 dB in the high X-band frequency range (8.2 – 12.4 GHz). Significantly, two-dimensional matrix simulations corroborate the geometric modifications occurring between fillers as the length and ratio of carbon fibers are altered, showing excellent agreement with our experimental results. Combined with an intriguing approach to fine-tune the clustered network of carbon fibers, this study highlights the critical role of filler geometry within the matrix in developing high-performance EMI shielding materials, offering new insights for the design of advanced EMI shielding solutions.

Investigation of Impact Behaviour of Sisal Fiber Reinforced Phenol Formaldehyde Composites

Short Sisal fiber reinforced Phenol Formaldehyde resin composites are prepared with varied fiber lengths (5 mm and 10 mm) and for varied weight fraction (20%, 25% and 30%) of the fibers. Here in this work, Sisal fiber is used as reinforcement. Since it is abundantly available in nature and majority of it is getting wasted without being used as reinforcement in engineering applications. Over the last thirty years composite materials, plastics and ceramics have been the dominant emerging materials. The 10 mm fiber length reinforced composite shown improved mechanical properties than 5 mm fiber length reinforced composite. Increase in impact strength is seen when the fiber content in the composite is increased from 20% to 25% and 25% to 30%. The fiber strength, for different fiber lengths and fiber volume fraction, the work of fracture is proportional to the fiber length and fiber volume fraction. Although results show increment in impact strength with fiber volume fraction, proportionality is not demonstrated. This suggests that there are other mechanisms that affect the impact strength of the composites. Crack propagation is the predominant toughening mechanism in notched impact test. Improvement in impact strength characterizes that fibers as stress transferring medium are able to absorb impact energy effectively. Good interaction with crack increases the energy needed for further crack formation and propagation. The exceptional case could be due to low fiber content and relatively short fiber length so that the energy is not dissipated effectively. Weak interfacial bonding of natural fibers is mainly due to incompatibility of hydrophobic matrix and hydrophilic fiber. High moisture absorption causes dimensional changes of natural fibers as well.

Realizing 0.7 dB/m gain in O + E band by promoting BACs-P formation in bismuth-doped phosphosilicate fiber with double-pass configuration.

The long fiber length required for the amplification of bismuth-doped fiber (BDF) has hindered its practical application. In this paper, we propose and demonstrate a feasible method to improve the active absorption of bismuth active centers (BACs) by optimizing the drawing conditions, achieving a high gain with a short fiber length. The bismuth-doped phosphosilicate fiber (BPSF) preform was fabricated by the modified chemical vapor deposition (MCVD) process and drawn into fiber under nine different conditions. The results indicate that the active absorption of BACs increases as the drawing temperature increases and the drawing speed decreases within these drawing parameters. Meanwhile, the corresponding gain per unit length is improved. Furthermore, a maximum gain of 31.6 dB at 1350 nm with the >20 dB gain wavelength range of 1311-1401 nm was achieved in a double-pass double-pump configuration, using only 45 m BPSF. Meanwhile, the -3 dB bandwidth was 1328-1370 nm. The gain per unit length is 0.7 dB/m, which, to the best of our knowledge, is the highest gain per unit length reported for the BPSF.

Green-reinforced clay sandy soil with natural fibers

Several studies focus on enhancing soil strength through the incorporation of natural or synthetic fibers. However, there is limited published data on the effectiveness of rice husk in soil reinforcement. The use of rice husk as a reinforcing material is supported by the fact that rice is one of the most produced and consumed cereals globally. In this article, we analyze the behavior of a clayey soil from southern Brazil with the addition of 0.5, 0.75, and 1% rice husk (RH), comparing it to coconut coir (CC) and curauá fibers (CU). In unconfined compressive strength tests (UCS), increases in soil strength of 20, 40, and 140% were observed for RH, CC, and CU, respectively, compared to pure soil. From consolidated undrained triaxial compression tests, both unreinforced soil and soil reinforced with 1% RH, CC, and CU were examined. The triaxial tests revealed an increase in the internal friction angle of 72 and 98%, alongside a decrease in cohesion of 57 and 94% due to the addition of CC and CU, respectively, in terms of effective stress. In contrast, RH did not significantly enhance the soil’s behavior, likely due to its shorter fiber length.

Development of wavelength dispersion measurement method using Fresnel reflection of fiber under test at both end faces

The phase shift method is generally used for wavelength (chromatic) dispersion measurement of optical fibers. However, the phase shift method requires a long fiber under test (FUT) of several hundred meters or more to obtain high temporal resolution. Therefore, measuring specialty fibers with short production lengths and amplification fibers that absorb light at specific wavelengths used for fiber lasers is difficult with this method. We have developed a method to measure the beat spectrum, by incident, an incoherent tunable light source (I-TLS) composed of amplified spontaneous emission (ASE) to a FUT. The FUT constitutes a Fabry–Perot resonator using Fresnel reflections at both end faces of the fiber. Chromatic dispersion can be calculated from the wavelength dependence of the refractive indices of the FUT, enabling measurement with short fiber lengths. The standard deviation of the chromatic dispersion @1550 nm was 0.352 ps/(nm km) based on five measurements of a FUT of approximately 3 m. The error between the manufacturer's measurement of chromatic dispersion @1550 nm, and the average value measured in this study was measured at 0.56%, indicating that it can be measured with very high accuracy.

Genome-wide association studies of bundle and single fiber length traits reveal the genetic basis of within-sample variation in upland cotton fiber length.

Within-sample variation in cotton fiber length is a major factor influencing the production and quality of yarns. The textile industry has been searching for approaches of improving the long fiber fraction and minimizing the short fiber fraction within a cotton sample to produce superior fiber and yarn quality. USTER® High Volume Instrument (HVI) has been widely used for a rapid assessment of cotton fiber length traits from a fiber bundle. However, its effectiveness for genetic studies has been questioned due to the indirect estimations of the cotton fiber traits that cannot be measured from a fiber bundle. To overcome the limits of the HVI fiber length traits, we utilized the Advanced Fiber Information System (AFIS) measuring fiber length traits directly from individual fibers based on weight or number. Comparative fiber length analyses showed AFIS provided higher sensitivity in detecting the fiber length variations within and among cotton samples than HVI. The weight-based AFIS length traits were strongly correlated with the corresponding HVI lengths, whereas the number-based AFIS mean length showed a relatively weaker correlation with the HVI lengths. Integrations of the weight based-length traits with genome-wide association studies (GWAS) enabled classifying the QTLs specifically associated with long, mean, or short fiber length traits and identified a false positive associated with the indirectly estimated HVI short fiber trait. Unlike the weight based-AFIS length traits, the number-based AFIS length trait did not show a negative correlation with a weight related-HVI property, and identified a single QTL that was not detected by the corresponding HVI trait. These results suggested that integrating the AFIS method with GWAS helped discoveries of the genome loci involved in the within-sample variation in cotton fiber length and characterizations of the fiber length QTLs.

High-temperature resistant boron nitride-based coatings for specialty silica optical fibers

h-BN is well known for its thermal stability. h-BN coated silica optical fibers were manufactured. The coating solution is compatible with optical fiber drawing process, which allows the preparation of tens of meter of h-BN coated fibers. In addition, it is possible to use this coating material for the preparation of short length fiber samples in a post-production approach. Bentonite acts as a binder and allows the adhesion of h-BN to the silica optical fiber. The thermal stability of this protected optical fiber has been demonstrated over a short period of time (several hours) up to 900 °C and over a long period of time (1500 h) up to 800 °C in air. Moreover, the coated optical fiber can resist up to 1000 °C in neutral atmosphere (tested over 6 h).

Muscle Architecture Properties of the Deep Region of the Supraspinatus: A Cadaveric Study.

The supraspinatus is most frequently involved in rotator cuff tears, a common orthopaedic condition. However, the architecture of this muscle has been described only for the superficial, anterior, and posterior regions. To determine the muscle architecture of the deep supraspinatus. Descriptive laboratory study. Muscle architecture measurements were collected from 25 cadaveric supraspinatus specimens (13 intact [without tendon tears], 3 with partial-thickness tears, 9 with full-thickness tears). The muscle was divided into deep, superficial anterior, and superficial posterior regions. Pennation angle, raw and normalized fiber length, and sarcomere length and number were compared using repeated-measures analyses of variance. First, mean architecture measurements were compared between regions using only the intact specimens (n = 13). The deep region had a lower mean pennation angle (3.3° ± 1.0°) compared with the posterior region (11.0° ± 3.9°; P < .0001), which in turn had a significantly higher pennation angle compared with the anterior region (7.6 ± 2.6°; P = .0005). Normalized fiber lengths in the deep region were 21.1% (P = .0052) and 34.5% (P < .0001) shorter than the posterior and anterior normalized fiber lengths, respectively. Sarcomere lengths in the deep region were longer (3.4 ± 0.2 μm) compared with the posterior (3.1 ± 0.2 μm; P = .0012) and anterior (3.2 ± 0.2 μm; P = .0390) regions. Sarcomere numbers also decreased in the deep region by 21.2% (P = .0056) and 34.2% (P < .0001) compared with the posterior and anterior regions, respectively. The deep supraspinatus had significantly lower pennation angles, shorter fiber lengths, and fewer but longer sarcomeres in series compared with other subregions within the muscle. These structural differences suggest a functionally unique "submuscle" within the supraspinatus. Understanding the architecture of the supraspinatus muscle can provide insight into muscle function in health and disease. Specifically, this deep submuscle may play a different role in rotator cuff function than the rest of the muscle.

Tensile and Impact Properties of Woven Glass Fibers/Epoxy Composites Filled with Short Glass Fibers

Glass fiber/polymer composites are widely utilized in many structural applications because of their high specific strength and stiffness-to-weight ratios. In this study, woven glass fiber/epoxy was hybridized with short glass fibers of different lengths (2, 4, 6, 2+4, 2+6, and 4+6 mm) and contents (3, 6, 9, and 12 wt%) to produce hybrid woven SGF/epoxy composites. Variations in the thickness, fiber volume fraction, density, and void content of the prepared composites were determined. Mechanical tests such as tensile and Charpy impact tests were conducted. Compared to the woven fabric composites without short glass fibers (control samples), the tensile strength increased by approximately 13% at an optimum weight fraction of 3 wt% using short glass fiber lengths of 4 mm. Meanwhile, the incorporation of short glass fibers into the woven glass composites decreased the tensile modulus for all lengths. The maximum enhancement in the impact strength (approximately 14%) was achieved by the hybrid composite samples reinforced with 4 mm of short glass fibers at 3 wt%. This hybrid composite offers 18% and 20% improvements in the specific tensile and impact strengths, respectively. In summary, filling the woven fabric composites with specified short fiber contents and lengths can increase their mechanical performance when resin-rich regions are reinforced with short fibers without forming relatively thick interleaves between the woven fabric plies

Preparation and characterization of high load‐bearing needled composite preform based on novel ordered short fiber network needling method

AbstractNeedled preform and its composite using felt and base cloth stacked needled have small fiber volume fraction and relatively weak mechanical properties, which are difficult to meet the service requirements of structural and functional integrated components of high‐speed aircraft. Responding to this issue, this paper proposed a new method for preparing high load‐bearing needled composite preform based on ordered short fiber network needling. The high load‐bearing needled preforms were prepared by designing different structural parameters of ordered short fiber network and forming process parameters, and then preform structure was characterized and mechanical properties were tested. The results showed that using ordered short fiber network as carrier of the short fibers, the formed needled fiber bundles were longer and denser, volume content of needled fiber bundles and mechanical properties of needled preform were greatly improved, and needled fiber bundles volume content of ordered short fiber network reinforced needled preform was 1.5 times and 46.3 times that of half‐cut cloth and felt respectively. Compared with traditional felt needled preform and half‐cut cloth needled preform, the interlaminar peeling strength of the ordered short fiber network reinforced needled preform increased by up to 246.4% and 49.2%, respectively. The tensile strength of ordered short fiber network reinforced needled preform was 12.9% higher than that of half‐cut cloth in X‐axis direction. In addition, the effects of ordered short fiber network structure, short fiber length, areal density and needling density on the needled preform structure and properties were also revealed.Highlights High load‐bearing needled composite preform was prepared based on novel ordered short fiber network needling method. The needled fiber bundles formed by using ordered short fiber network were longer and denser, and their volume content was 46.3 times that of felt needled preform. The interlaminar peeling strength of the ordered short fiber network reinforced needled preform increased by up to 246.4%. The tensile strength of ordered short fiber network reinforced needled preform was 12.9% greater than half‐cut cloth in the X‐axis direction.

Effect of fiber characteristic parameters on the synergistic action and mechanism of basalt fiber asphalt mortar

Basalt fiber has been shown to significantly improve the performance of asphalt mixtures and extend the lifespan of roads. However, more research is needed to investigate the characteristic parameters of basalt fiber when used in asphalt mortar and asphalt mixture. In order to enhance the reinforcing effect of basalt fiber on asphalt mixture and understand how it works, this study examines the properties of asphalt mortar mixed with basalt fiber with different characteristic parameters. Nine types of basalt fibers with varying characteristic parameters were selected for this work, including three lengths (3 mm, 6 mm, 12 mm) and three diameters (7 μm, 16 μm, 25 μm). The properties of asphalt mortar mixed with basalt fiber with different characteristic parameters were tested. High-temperature properties were characterized using the ZSV and MSCR tests; medium-temperature properties were characterized using the LAS test; low-temperature properties were characterized using the BBR and direct tensile tests. In addition, the effects of fiber characteristics on the viscosity, structural integrity and interfacial properties of asphalt mortar were analyzed through the bond strength test, Rigden porosity test and fiber monofilament drawing test. The results demonstrate that basalt fiber can improve high-temperature properties significantly in asphalt mortar while being greatly influenced by its characteristic parameters. Specifically, fibers with a length of 6 mm and a diameter of 7 μm exhibit superior reinforcement effects. Fatigue life results indicate that basalt fiber enhances fatigue resistance in asphalt mortar as well; furthermore, the influence exerted by fiber characteristic parameters aligns consistently with that observed for high-temperature performance. Although the BBR test results indicate that fiber incorporation has minimal impact on its enhancement, the direct tensile test results demonstrate a significant improvement in the toughness of asphalt mortar due to fiber reinforcement. The addition of basalt fiber enhances the bond strength of asphalt mortar. According to Einstein viscosity formula, the viscosity of asphalt mortar decreases with shorter fiber lengths and larger diameters. Incorporating basalt fiber can enhance the proportion and strength of structural asphalt in asphalt mortar. When comparing fibers with equal diameter or length, an increase in either parameter initially improves the strength of structural asphalt but eventually leads to a decline. Results from monofilament fiber drawing tests and theoretical critical embedding length confirm that a 6 mm fiber length is most beneficial for enhancing the performance of asphalt mortar. Basalt fiber exhibits significant potential for improving various properties of asphalt mortar and provides a favorable reference for optimizing the selection of basalt fiber.

Load-bearing behavior of short-fiber-reinforced textile-reinforced concrete for a wrapping process

In the research project titled Wrapping process for highly fiber-reinforced concrete using the example of a pump sump (WiFaPu), a new production process for components made of short-fiber-reinforced textile-reinforced concrete was developed. The idea of wrapping concrete continuously around a formwork evokes high-level requirements on the workability of concrete while matching reinforcement properties. In this study, the load-bearing behavior of wrappable short-fiber-reinforced textile-reinforced concrete with an uncoated textile reinforcement made of AR-glass is investigated via tensile and bending tests. The concrete inserted into the wrapped layers by casting, laminating or spraying and the short fiber content and warp/weft direction of the uncoated fabric have a major influence on the load-bearing behavior of the tested specimens with regard to the utilized tensile strength and crack spacing. Members produced by inserting the concrete in a spraying or laminating process showed low tensile strength and unsatisfactory cracking patterns in the warp direction of the fabric due to the lacing of rovings, which led to lower matrix penetration. For rovings in the weft direction without lacings, higher utilized tensile strengths and fine crack patterns are observed. The casting of specimens leads to significantly higher utilized textile tensile strengths if the reinforcement is slightly tightened in the formwork. Compacting fine-grained concrete leads to better roving penetration than does the spraying process. The addition of short fibers generally benefits the cracking pattern and partially compensates for the negative effects of the textile weave on the utilized tensile strength as well as on the warp direction of the crack pattern. The load increase in tensile and bending tests is proportional to the increase in short fiber content and fiber length. Finally, the influence of different coatings is examined for another uncoated textile reinforcement made of AR-glass with a more favorable textile weave. The utilized tensile strength of the reinforcement is almost doubled when impregnated with a fine cement suspension and directly installed in the formwork and cast. An impregnation process such as this can also be integrated into the wrapping process.

Effects of artificial management on culm properties of Dendrocalamus brandisii.

The artificial cultivation and management were extensively carried out in Dendrocalamus brandisii stands. However, the influences of artificial management on the anatomical and chemical characteristics of the bamboo culms were unknown. In this study, the fiber morphology, chemical composition and sugar accumulation of the D. brandisii culms with management and without management were compared in order to determine the influences of artificial management on bamboo culms. The results indicated that artificial management had a significant influence on the fiber morphology, resulting in shorter fiber length, larger L/T ratio, and smaller W/Lu value. However, the management not only increased the contents of moisture, ash, SiO2, and extractive, but also increased the holocellulose contents and decreased the lignin contents, as compared to those without management. Moreover, the management significantly increased the endogenous carbohydrates storage in the culms so as to improve the shoot production. The bamboos under management conditions could still be utilized as a raw material for papermaking. This provided a theoretical basis for the artificial management of D. brandisii stands.

Formaldehyde-free bio-composites based on Pleurotus ostreatus substrate and corn straw waste

Corn straw-based board has great potential for the protection of forest resources, waste recycling, and sustainable economic development. However, corn stalk-based board has poor mechanical properties due to its short fiber length and poor water resistance because of the presence of numerous hydrophilic hydroxyl functional groups in its structure. Natural mycelium originating from waste Pleurotus ostreatus substrate is a hydrophobic bio-adhesive. In the present study, formaldehyde-free corn stalk/P. ostreatus substrate bio-composites were prepared using the hot-pressing technique without the addition of any chemical adhesive. The mechanical properties and water resistance of the prepared bio-composites were excellent. The highest internal bonding strength (IBS) of 2.16 MPa and the minimum thickness swelling (TS) of 18.3% were observed, which are beyond the national standards for particleboard in China. These bio-composites were prepared using a simple, green, and convenient manufacturing method to promote their popularization and application. The method may, therefore, be used as a novel technical measure to resolve the problem of overuse of forestry resources and waste disposal.

Characterization of holocellulose extracted from agricultural and food processing byproducts via ecofriendly delignification pulping process

AbstractThis study investigated an ecofriendly peracetic acid delignification process to extract holocellulose from various fiber rich plant‐based byproducts (coconut palm spathe/leaf, apple pulp, wine grape pomace, hazelnut shell, and hemp fiber/hurd), and evaluated their physicochemical, morphological, and thermophysical properties in comparison with commercial cellulose nanofibers produced from wood. Holocellulose from coconut palm spathe has long fiber (~846.7 μm), whereas that from wine grape pomace and hazelnut shell exhibits a cylinder shape of particles with short fiber length (~123.8 and ~ 71.1 μm, respectively). Biofilms cast from apple pulp and hemp fiber holocellulose have higher degradation temperature (361 and 358°C, respectively) than biofilms from other materials, thus more thermally stable. All biofilms demonstrate high UV absorbance, and the biofilm cast from apple pulp holocellulose is transparent with smooth surface. Fourier‐transform infrared spectroscopy analysis confirms the presence of cellulose and hemicellulose as the main components in the biofilms, along with traces of residual lignin that remained after the extraction process. This study demonstrates that holocellulose with varied cellulose morphology and polymeric characteristics could be extracted depending on the type of byproducts and be employed to produce sustainable packaging materials.

Preparation of novel silica-clay mineral aerogel nanocomposites with outstanding thermal insulation performance

Monolithic silica-based aerogels, produced with tetraethoxysilane (TEOS), reinforced with aramid fibers and incorporating aluminosilicates were prepared for the first time. The nanocomposites were obtained by varying the amount and type of aramid fibers and replacing a part of the synthetic Si (up to 35 wt% of Si) of TEOS by natural aluminosilicates, kaolin and palygorskite. The effects of the type and amount of both fiber and mineral in the materials key properties were investigated. Most samples displayed very low volumetric shrinkages during ambient drying (<5%), high porosity (∼90%), and low bulk densities, down to 120 kg m−3. Composites with both minerals exhibited superinsulating thermal performance, with thermal conductivity reaching values as low as 22 mW m−1 K−1, while also showing excellent thermal stability. The mechanical properties of the designed clay mineral-silica aerogels can be tailored, since the addition of short length fibers (Kevlar pulp) produces stiffer composites, while the longer fibers (Teijinconex) lead to more flexible ones.

Preparation of Filter Paper from Bamboo and Investigating the Effect of Additives.

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size.

Mathematical Modelling of Scission Electrospun Polystyrene Fibre by Ultrasonication Scission

This study investigates the effects of time and diameter on the final scission length of the electrospun polystyrene (PS) fibres, whereby the fibres were ultrasonicated for 1, 2, 3, 4, and 8 minutes. The ultrasonic probe stimulates bubble cavitation followed by bubble implosion as scission occurs. Factors affecting the scissionability of the electrospun PS fibres are primarily the diameter of the fibre and the sonication run time. The scission final fibre length range is approximately 23.7 µm to 1.1 µm. SEM images show that the fibre breaks into shorter lengths as sonication run time increases. Conversely, fibre diameter exhibits a positive relationship with fibre length. The model gives an R-squared value of 0.44 and 0.59 for linear and non-linear regression, thus suggesting that the non-linear model provides a better fit for the data. The validation of the model is achieved by conducting a hypothesis test. Through hypothesis testing, the mean of the experimental average final length value and the predicted average fibre length from the regression model were not significant, indicating that the model can generally predict a relatively accurate average final fibre length value. The model derived from this study enables researchers to estimate the time required to sonicate the PS fibre (with a specific diameter) to achieve the short fibre length needed in their application. As research progresses, refining the model and incorporating additional parameters will be essential to ensure the broad reliability and applicability of these models across a variety of practical contexts.

Improving performance of bamboo fluff pulp by liquid hot water pretreatment and combination with longer fibers

Bamboo has several disadvantages as a raw material for the preparation of fluff pulp, including short fiber length, a high proportion of hemicellulose and high levels of fines and non-fibrous cells. Here, the proportion of hemicellulose was reduced by liquid hot water (LHW) pretreatment. The bamboo was then kraft cooked, screened through a 100 mesh screen plate to remove fines and non-fibrous cells, and bleached to prepare bamboo pulp fibers. Changes in the functional groups and crystallinity after LHW pretreatment were investigated by Fourier-transform infrared spectroscopy and X-ray diffraction. Analysis of the cross-sectional and surface morphology of the bamboo before and after pretreatment and of the surface morphology of the fluff pulp by field emission scanning electron microscopy showed that LHW pretreatment effectively removes hemicellulose from the bamboo. Combination of the bamboo pulp fibers with softwood fiber or cotton linter fiber produced a fluff pulp fiber with improved strength and water absorption. The new bamboo-cotton and bamboo-wood mixed fiber fluff pulps outperformed a branded commercial fluff pulp.

Fiber optic refractive index sensing using an inline dual semi-distributed interferometer

In this work, we present a fiber optic refractive index (RI) sensor based on a dual inline semi-distributed interferometer (SDI) device. The SDI is formed within a telecom-grade optical fiber by simply splicing a short length of a high-scattering fiber; the presence of a high density of scattering centers induces a distributed cavity effect, forming a low-finesse interferometer. Here, we propose an approach based on two serial SDIs, with few millimeters spacing between the two cavities; the outer SDI encodes the changes of surrounding RI, while the inner probe is RI-insensitive and can be used as a reference. Experimental analysis shows that the dual-SDI device has RI sensitivity of 111.2–466.2 dB/RIU with RI-sensitive mode, and 0.4–3.7 dB/RIU with RI-insensitive mode, with a ratio up to 1165.5 between sensitive and insensitive modes. In addition, the Vernier effect can be interrogated by detecting the wavelength shift of the narrow spectral lines, with sensitivity of 0.303 nm/RIU.The dual-SDI structure maintains the same fabrication ease of a single SDI, since all process is made through splicing and cleaving fibers with a telecom-grade fiber. The key advantage is the availability of modes having both high and near-zero RI sensitivity, which therefore can be used for a referenced RI detection as an in-situ probe.