Modulus Of Fibers Research Articles

Optimizing toughness and cost-effectiveness in one-part geopolymers via fiber reinforcement: A comprehensive investigation of PVA, PE, and glass fibers

This study explores developing and characterizing a one-part geopolymer, an innovative and sustainable construction material. The effects of incorporating polyvinyl alcohol (PVA), polyethylene (PE), and glass fibers (GF) on the toughness of slag and fly ash-based one-part geopolymer mortars were investigated through compressive, three-point flexural, and four-point bending tests. The findings demonstrate that fiber incorporation reduces fluidity and compressive strength due to increased porosity, lower elastic modulus of fibers, and weak interfacial bonding. However, fibers significantly enhance damage resistance and toughness via crack bridging and load transfer mechanisms. Formulations with 2 % PVA fibers and combinations of 1 % PVA with 1 % PE fibers and 1 % PVA mixed with 0.5 % PE and 0.5 % GF demonstrate excellent toughness. Notably, the latter two fiber blends achieve 14 % and 10 % cost reductions, respectively, compared to using only PVA fibers, making them economically viable for large-scale applications. Scanning electron microscopy and X-ray diffraction provided insights into the toughening mechanisms, including crack bridging, fiber pull-out, and enhanced stress distribution within the geopolymer matrix. Digital image correlation techniques further elucidated the fibers' role in improving the post-cracking behavior and structural resilience under load.

The role of constitutive properties on the longitudinal compressive strength of composites

The longitudinal compressive strength of fibre-reinforced composites is often a limiting factor for structural design. This paper uses micromechanical finite-element analyses to examine how the constitutive properties of the matrix, fibres, and interface affect the composite’s strength. For a typical carbon/epoxy composite, the matrix shear strength has a larger effect than the modulus; a linear-elastic perfectly-plastic approximation of the matrix shear curve may overestimate the composite’s strength by over 15%. A pressure-dependent and dilatant matrix plasticity response may strengthen the composite by 30%, considering current uncertainties in friction and dilation angles of epoxy matrices. The finite shear modulus of carbon fibres may weaken the composite by more than 10%. Considering a cohesive interface using traction–separation laws significantly affects the predicted response of the composite, even for interfaces stronger than the matrix. Opportunities for improving the characterisation, modelling and performance of the constituents in terms of matrix plasticity, fibre shear modulus, and interface response are discussed.

Irradiation multi-scale damage and interface effects of 3D braided carbon fiber/epoxy composites subjected to high dose γ-rays

The serious damage caused to 3D braided carbon fiber (CF)/epoxy (EP) composites in high-energy irradiation environments is a pressing research topic that has not yet been reported. This study analyzed the γ-irradiation multi-scale damage of the matrix, interfaces, and near-interface regions in 3D braided CF/EP composites with three different braiding angles (18°, 28°, 38°) at atomic, microscopic, and macroscopic scales. The molecular structure and atomic charge information alterations of epoxy matrix were characterized using soft X-ray absorption spectroscopy (sXAS). When the irradiation dose reached 1000 KGy, the compressive strength of composites decreased by 20.88 %, 18.07 %, and 16.60 %, respectively, with an increase in the braiding angle. Micro-CT observation, along with statistical computing, confirmed that irradiation causes interface damage and increases the defect volume of 3D braided composites. Nanoindentation was used to compare the modulus of carbon fiber, interface, near-interface regions and matrix in irradiated composites and the function of CF/resin interface as an irradiation defect capture site in the irradiation resistance of resin-matrix composites has been newly established. In addition, the mechanism behind the effect of braiding angle on macroscopic properties was also analyzed.

The synergy of the matrix modification and fiber geometry to enhance the thermo‐mechanical properties of basalt fiber‐polypropylene composites for automotive applications

AbstractBasalt fiber reinforced polypropylene composites with two initial fiber lengths (3.2 and 6.4 mm) were fabricated using twin‐screw extrusion compounding. In the case of composites with smaller initial fiber length, basalt fibers predominantly served as nucleating agents for polypropylene thereby resulting in an increase in the degree of crystallinity. The addition of polypropylene‐g‐maleic anhydride (PP‐g‐MA) caused the matrix to become amorphous, which was due to the establishment of a fiber–matrix interphase. This behavior was different for the composites with relatively larger initial fiber length especially at higher fiber content. The reduction in fiber length in the composites caused a decrease in crystallinity, as this hindered the ability of the polypropylene matrix to form crystals. Addition of PP‐g‐MA established a fiber–matrix interphase thereby synergistically contributing to the increased matrix amorphousness of the basalt fiber reinforced polypropylene composites with 6.4 mm initial fiber length. Reduced fiber length due to processing also accelerated the thermal degradation of the composites with an initial fiber length of 6.4 mm. However, the reduction in fiber length due to processing resulted in increased fiber orientation, which contributed to the improvement in tensile and flexural properties of the basalt fiber reinforced polypropylene composites with an initial fiber length of 6.4 mm. At 30% fiber content, the tensile strength and modulus of basalt fiber reinforced matrix modified polypropylene composites with 6.4 mm initial fiber length improved by 18% and 13% as compared with the composites with 3.2 mm initial fiber length.

Optimization, Sodium Hydroxide and Plantain Fibres: Mechanical Properties of Unsaturated Polyester Composites for Transtibial Prosthetic Socket

Low mechanical behaviors of natural fibres in the reinforcement of polymer composites have remain an issue of concern. This study is aimed at investigating the effect of NaOH treatment on the mechanical properties of plantain fiber for the transtibial prosthetic sockets made of polyester resin. Plantain fiber was extracted from the plantain bast using water retting techniques. The fibres were modified using alkaline treatment method of 5 – 25% for variable time of 30 to 150 minutes. It was optimized using 3-level Factorial design (3-LCD) of response surface methodology based on tensile properties of treated fibres. The polyester composites of plantain and glass fibers were prepared using hand-layup techniques. Instron Universal testing machine-3369 model was used to determine the tensile and impact properties of fibers and polyester composites. Rockwell hardness tester-RBHT/S-39 model was used to determine the hardness property. The optimum process conditions of 5 % NaOH for 119 minutes improved plantain fiber tensile strength, modulus, strain, energy, and extension by improved by 102.03, 208.07, 9.70, 210.52 and 205.73 %, respectively. The ultimate tensile strength and modulus was obtained at 10 and 12.5% fiber loading. The hardness and impact strength of NaOH modified unsaturated polyester composites was marginally more than 3.51 and 10.69% of glass fiber reinforced unsaturated composites, respectively, at 12.5% fiber loading. FTIR analysis revealed the improvement in mechanical properties. Thus, NaOH modified plantain fiber unsaturated polyester composites serves as a better alternative for making transtibial prosthetic socket.

Investigation of forming process and deformation mechanisms of 3D warp interlock fabric

This article introduces a modeling method aimed at predicting the internal geometric structure of 3D warp interlock fabric. Inspired by the digital element method, the method employs truss elements to model the yarns as fiber bundles, and considers their material properties. This technique allows for predicting the microstructure of 3D woven fabric based on simple input characteristics. By varying the elastic modulus of virtual fibers, the friction coefficient between fibers, and the tension load at the ends of yarns, and designing compression molding molds to compress the fabric into shape, the virtual fiber fabric predicted the influence of variables on the fabric. The study found that the structure of the samples obtained through CT scanning is generally consistent with the structure of the virtual fiber fabric. The elastic modulus has a relatively minor impact on the fabric structure, whereas the friction coefficient and tension load significantly affect the cross-sectional shape of the yarns. During compression molding, deformation within the mold leads to interlayer fabric slippage and changes in the cross-sectional shape of the fabric. This suggests the feasibility and applicability of virtual simulation testing methods for analyzing the behavior of various types of 3D woven fabrics.

Study of Mechanical and Surface Properties of Multi-Walled Carbon Nanotube Grafted Flax Fiber and Its Composites

ABSTRACT The modification method of grafting multi-walled carbon nanotubes (MWCNT, abbreviated as CNT in this paper) on the surface of flax fibers was investigated, i.e. CNT were grafted onto the surface of flax fibers by silane coupling agent under the action of ultrasonic waves to form covalent bonding. The tensile strength of CNT grafted flax fiber is 22% higher than that of untreated flax fiber monofilament. The tensile strength of FFRP composites after CNT grafting treatment increased by 14.2%; however, the tensile modulus of single fiber and composites did not show a significant increase, the interfacial shear strength of the fiber-resin is 38.3% higher than that of untreated filament. The improvement of the contact angle after grafting was investigated by observing the surface morphology, and the surface of flax filament was characterized by scanning electron microscopy and atomic force microscopy. Also the elemental changes of the flax single fiber surface before and after the treatment were analyzed using X-ray photoelectron spectroscopy. The results showed that the tensile strength of flax single fibers, its composites, and interfacial shear strength of fiber-matrix was improved after CNT grafting treatment but the increase of modulus was not obvious.

Polymer Physics behind the Gel-Spinning of UHMWPE Fibers.

Gel-spinning of ultra-high molecular weight polyethylene (UHMWPE) fibers has attracted great interest in academia and industry since its birth and commercialization in the 1980s, due to unique properties such as high modulus, low density, and excellent chemical resistance. However, the high viscosity and long relaxation time greatly complicate processing. In industry, solvents, like decalin and paraffin oil, usually disentangle the physical networks and promote final drawability. From extruding the polymer solution to post-solid-stretching, many polymer physics problems that accompany high-modulus fiber gel-spinning should be understood and addressed. In this review, by detailed discussions about the effect of entanglements and intracrystalline chain dynamics on the mechanical properties of UHMWPE, theoretical descriptions of the structure formation of disentangled UHMWPE crystals, and the origin of high modulus and strength of final fibers are provided. Several physical intrinsic key factors are also discussed, revealing why UHMWPE is an ideal material for producing high-performance fibers.

Assessment of the anisotropy development of mechanical properties of pitch-based carbon fibers

Carbon fiber XN-P9 derived from anisotropic pitch was heat treated at different temperatures (2000, 2500, and 3000℃) and the mechanical properties of those single filament in various directions were tested with some methods we have developed. The anisotropy of the mechanical properties of those pitch-based carbon fibers was evaluated to be developed by heat treatment. As a comparison, the properties of carbon fiber XN-05 derived from isotropic pitch were also tested. The ratio of the longitudinal tensile modulus to the shear modulus of XN-05 fiber was approximately 3. In contrast, for pristine XN-P9 fiber, the longitudinal tensile modulus was more than nine times greater than the shear modulus, and the difference between these moduli increased with the elevating heat treatment temperatures. It was suggested that the anisotropy of mechanical properties of pitch-based carbon fibers was developed by heat treatment. In compressive deformation in the transverse direction to the fiber axis, a yielding and a softening was clearly observed with the elevating heat treatment temperature. The effect of anisotropy development on the span-length dependence of flexural modulus obtained from the three-point bending test of the single filament was assessed.

Skeletal muscle stiffness is altered by age and fatigue at the cellular level

Advanced age is associated with increased skeletal muscle stiffness at the cellular and whole-tissue levels. In older adults, fatigue increases falls risk. Our lab has previously observed fatigue-induced reductions in skeletal muscle cellular stiffness in younger adults, prompting the question of whether the same occurs in older adults. If so, it is possible that fatigue-induced reduction in cellular stiffness of older adults would reduce the rate of tendon loading and/or increase tissue compliance, ultimately contributing to increased falls risk. Therefore, the OBJECTIVE of the present study is to measure cellular passive and active stiffness in younger and older adults across fatigue conditions to test the hypothesis that fatigue induces tissue compliance that predisposes older adults to falls. Methods: 11 untrained males and females (7 younger, 20±1 yrs.; 4 older, 74±4 yrs.) performed unilateral knee extensions to fatigue, followed by bilateral biopsy of the Vastus Lateralis providing fatigued (F) and non-fatigued (NF) samples. Single fibers (146 younger, 130 older) were passively stretched to 156% initial length and passive modulus was calculated as the slope of the resulting stress-strain curve. Separately, Residual Force Enhancement (RFE) was measured in a subset of fibers (9 younger, 40 older) to assess passive contributions (titin) to active (actin-myosin) stretch. Main effects (age/fatigue) on passive modulus and RFE were tested via linear mixed model and t-tests, respectively. Results: Passive modulus was increased with age (p=0.04) and reduced by fatigue in both the younger (p<0.01) and older (p<0.01) participants. In a subset of fibers, RFE was increased in older women compared to younger (p<0.01) and older men (p<0.01). No main effect of fatigue on RFE was detected (p=0.49). However, RFE trended towards reduction with fatigue in a younger male (p=0.13) and was significantly reduced by fatigue in myosin heavy chain (MHC) I fibers from an older male (p=0.02). CONCLUSION: In agreement with existing literature, cellular passive modulus was higher in older versus younger adults. Additionally, fatigue reduced passive modulus in skeletal muscle fibers from both older and younger adults. Though no main effect of fatigue on RFE was detected, these results suggest that cellular RFE measures are age- and fiber-type specific. This work was supported by funds from the Wu Tsai Human Performance Alliance. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Experimental free vibration and tensile test results of a five-layer sandwich plate by comparing various carbon nanostructure reinforcements with SMA

Considering to need for the sensitive and destructive industries for high stiffness and low weight, an experimental free vibration and tensile test results of a five-layer sandwich plate by comparing various carbon nano structures reinforcements with SMA is discussed. The effect of various reinforcements, including carbon nanostructures (carbon nanotubes (CNT), carbon nanorods (CNRs), Graphene platelets (GPLs)) and nitinol shape memory alloy (SMA) wire on the vibration behavior of a five-layer sandwich plate with a foam core is investigated. The purpose and novelty of this work are to compare the effect of different reinforcements on the vibrations of a five-layer plate so that by using this comparison, one can choose the best reinforcements according to the needs of the desired industry and more suitable economic conditions. Considering a 1 % weight fraction of epoxy resin, GPLs, CNTs, and CNRs increase Young's modulus of face sheets by 30 %, 25 %, and 5.8 %, respectively. In this work, a five-layer sandwich structure model can be suggested, and numerically analyzed. The special advantage novelty of this research compared to previous research is the construction of this five-layer model. This is a simple modeling structure for the construction and preliminary examination of structures with five layers experimentally. Also, the composite structure is made by the vacuum pump method, which does not have the disadvantages of the manual method, and the method is completely optimal. At first, the Young's and shear moduli of unidirectional glass fiber (UGF) are calculated by performing a tensile test. To examine all aspects of the construction of five-layer structures during construction, in this article first, the face sheets are made separately using resin, UGF, and various reinforcements, and then the layers of face sheets and the cores are connected using glue. In the following, the equations of motion for the sandwich plate are derived using refined first-order shear deformation theory (RFSDT) by employing Hamilton's principle. Using the Halpin-Tsai equation and the extended rule of mixture, the mechanical properties of the reinforced composite face sheets are obtained. According to the Brinson model, the constitutive equations of the SMA are presented. The influence of various parameters such as side ratio, thickness ratio, weight fraction of CNRs, CNTs, GPLs and SMA wire, fiber angle, and temperature changes on dimensionless fundamental frequency is also represented. Also, the natural frequency of orthotropic plates by considering reinforcements is higher than that without considering reinforcements. By increasing the aspect ratio (a/h), the dimensionless natural frequency increases, while the natural frequency decreases. For two-layer square angular asymmetric laminated sheets (-θ/θ), the minimum dimensionless natural frequency occurred at the fiber placement angle approximately equal to 26 and 64°. The highest frequency is related to the sandwich plate in that its face sheets have higher strength and stiffness because it is placed further from the middle plane. Also, the highest frequency is related to the sandwich plate, whose face sheets are reinforced with GPLs.

Effect of high temperature annealing on microstructure and mechanical properties of Morlion735 alumina fiber

Continuous alumina fiber-reinforced alumina (Al2O3/Al2O3) composite is a very promising candidate for thermal structural materials in aerospace vehicles and other applications. Alumina fibers used in Al2O3/Al2O3 composites play a crucial role in enhancing their mechanical properties and thermostability. In this article, the effect of annealing on the tensile strength and microstructure of Morlion735 alumina fiber was investigated. The results showed that the phase transformation occurs at 1147 °C, resulting in a mullite phase with an orthogonal lattice structure. As the annealing temperature increases, the crystal domain size of the mullite gradually increases. Both the phase transformation and the increasing crystal domain size lead to more lattice defects, which significantly affect the tensile strength and tensile modulus of alumina fibers. A 0.67 GPa reduction in tensile strength (from 1.14 GPa to 0.47 GPa) was observed when the annealing temperature increased from 1200 °C to 1400 °C. Weibull statistical analysis revealed that as the annealing temperature increased, the tensile strength dispersion of Morlion735 fiber also increased. This can be attributed to the volume-dependent flaw distributions. These results provide an in-depth understanding of the tensile strength evolution mechanism under high temperatures.

Failure analysis of glass fiber and basalt fiber reinforced polymer composites under an extreme environment with high‐temperature, high‐pressure and H2S/CO2 exposure

AbstractFiber‐reinforced polymers composites (FRPs) are widely used in the industrial field, but their failure mechanism in extreme environments is usually unclear. In this work, the effect of high‐temperature, high‐pressure and H2S/CO2 extreme environment, similar to oil and gas field conditions, on raw fibers and unidirectional FRPs was investigated. The results showed that the glass fibers (GFs) suffered extensive degradation with the presence of metal sulfides in the precipitate, whereas basalt fibers (BFs) showed localized degradation. The flexural modulus of glass fiber reinforced polymer composite (GFRP) after degradation decreased by 28.8% compared to 25.6% for the basalt fiber reinforced polymer composite (BFRP). The interlaminar shear strength and flexural strength of the BFRP decreased by 20.3% and 24.7% respectively. In contrast, the GFRP had a reduction of 55.2% in flexural strength after degradation. Finite element method (FEM) analysis showed that the GFRP exhibited severe cohesive interface damage, while the primary failure mode of BFRP remained essentially unchanged with a combination of fiber damage and cohesive interface damage. This study confirms the superior degradation resistance of BF/BFRP over GF/GFRP in the simulated environment and highlights its promising application potential in oil and gas field service.Highlights Filament winding was used to fabricate the GFRP and BFRP. Revealed distinct surface morphology changes in GFs and BFs under simulated oil and gas field conditions. Superior degradation resistance of BFRP over GFRP was found in the extreme environment. Demonstrated superior chemical stability and mechanical properties of BFRP over GFRP. Used FEM to investigate the failure modes of FRPs before and after exposure.

Effects of macro basalt fibers on the tensile behavior of ultra-high performance concrete

Macro basalt fibers (MBF), which is also named as basalt fiber reinforced polymer (BFRP) minibar, is a novel kind of fiber manufactured with BFRP. This work studied the effects of MBF on the tensile behavior of ultra-high performance concrete (UHPC) and proposed some MBF optimization recommendations based on the experimental results. Nine kinds of UHPC with MBFs and two kinds of UHPC with steel fibers or polypropylene (PP) fibers were designed for the tests of fiber distribution, density, compressive and tensile behavior. According to test results, UHPC with MBFs showed a more ideal fiber distribution compared to UHPC with steel fibers and PP fibers. For the samples with MBFs, UHPC with 3 % twisted MBFs had the highest compressive strength, tensile strength and ultimate tensile strain, which were 138.9 MPa, 8.14 MPa and 1714 με, respectively. Compared to UHPC with steel fibers, UHPC with MBFs had slightly lower density and mechanical properties, but a similar stain-stress relationship. Thereby, the linear-exponential softening model was adopted to show the tensile stain-stress relationship of UHPC with MBFs. Based on the test results, three recommendations for optimizing MBF, which contained reducing fiber diameter for larger aspect ratio, optimizing fiber shape for higher fiber-UHPC bonding behavior and increasing the fiber modulus, were proposed to improve the mechanical properties of UHPC with MBFs.

Characteristics and Comparative Study of Sodium Hydroxide Treated Banana Fiber Reinforced Composite Material

Environmental issues have become a worldwide crisis because of the high rate of pollution and changing climate patterns. Due to innovations and discoveries, the need for materials is increasing day by day. Here, composite materials can be substituted for any other mono-clinic materials fulfilling the requirements of those particular materials. However, the maximum composite materials are man-made or artificially fabricated fibers. These are not environmentally friendly and bio-degradable, which creates an environmental hazard. So, scientists are trying to fabricate composite materials from eco-friendly and green resources. The main advantages of natural fibers are their low cost, easy availability, and low density. Besides these acceptable specific properties, ease of separation, increasing energy recovery, carbon-oxide neutrality, and recyclable properties are increasing the popularity of natural fiber. In this study, we have used mainly two types of banana fiber for preparing the composite specimens, especially highlighting the hybrid fiber, which is made by mixing those two types of fiber: “Shobri” and “Champa” banana fibers. These names are renowned locally in Bangladesh. In this study, polyester and MEKP are used as matrix and hardener sequentially. We have accomplished a chemical treatment process. The treating process was accomplished in the alkaline medium with two different molar concentrations of NaOH. These are 1% and 5% solutions of NaOH. After the treatment neutralization process was performed with a 1 gm/L acetic acid solution. In addition, two distinct mechanical tests— the bending and tensile tests—were carried out. The results indicated that the hybrid fiber treated with 1% NaOH had the highest tensile properties; its Young’s modulus was around 625 MPa and its tensile strength was approximately 36.42 MPa. The tensile strength and Young’s modulus of Champa banana fiber treated with 1% and 5% NaOH solutions were the lowest, respectively. Approximate values are 1.82 GPa and 18.3 MPa. The flexural strength of hybrid fiber treated with 1% and 5% NaOH was the highest and lowest in that order. 69.2 MPa and 56.21 MPa, respectively, are their values. Regarding flexural modulus, Champa fiber treated with 5% and 1% NaOH exhibits the highest and lowest values, measuring roughly 4 and 1.82 GPa, respectively.

The splitting tensile strength and impact resistance of concrete reinforced with hybrid BFRP minibars and micro fibers

Basalt fiber reinforced polymer (BFRP) minibar is a novel kind of macro fiber, which is high-performed, green and durable. This study aimed to use hybrid BFRP minibars and micro fibers to control cracks of concrete from micro size to macro size, ultimately improving the mechanical properties of concrete. The compressive strength, splitting tensile strength and impact resistance of concrete reinforced with hybrid BFRP minibars and various micro fibers were tested and evaluated. The micro fibers contained micro basalt fibers, polyvinyl alcohol (PVA) fibers and steel fibers. Test results showed that the hybrid fibers provided significantly positive synergistic effects on the impact resistance, compressive and splitting tensile strength of concrete. Micro fibers improved the microcrack resistance capacity of concrete that increased with micro fiber content and modulus, but most of fractured during the development process of microcracks owing to their tiny size, showing little contribution to macrocrack resistance. BFRP minibar showed the pull-out failure, and the force preventing BFRP minibar from pullout bridged macrocracks, improving the macrocrack resistance capacity of concrete., but they seldom improved the microcrack resistance capacity of concrete because of its large size. Hybrid fibers improve the sustained resistance to crack during the whole crack development process owing to the synergistic contribution of hybrid fibers. Thereby, the concrete reinforced with hybrid 1.5% BFRP minibars and 0.75% micro steel fibers showed the highest compressive strength, splitting tensile strength and final-fracturing impact life under the failure probability of 30%, which were 22% 29% and 415% higher than those of concrete with mono 1.5% BFRP minibars. The method, which is that using hybrid macro fibers and micro fibers with high modulus and proper content to reinforce concrete, supports for further improving the mechanical properties of concrete in practice.

Fiber Flexibility Reconciles Matrix Recruitment and the Fiber Modulus to Promote Cell Mechanosensing.

The mechanical interaction between cells and the extracellular matrix is pervasive in biological systems. On fibrous substrates, cells possess the ability to recruit neighboring fibers, thereby augmenting their own adhesion and facilitating the generation of mechanical cues. However, the matrices with high moduli impede fiber recruitment, restricting the cell mechanoresponse. Herein, by harnessing the inherent swelling properties of gelatin, the flexible gelatin methacryloyl network empowers cells to recruit fibers spanning a broad spectrum of physiological moduli during adhesion. The high flexibility concurrently facilitates the optimization of fiber distribution, deformability, and modulus, contributing to the promotion of cell mechanosensing. Consequently, the randomly distributed flexible fibers with high moduli maximize the cell adhesive forces. This study uncovers the impact of fiber recruitment on cell mechanosensing and introduces fiber flexibility as a previously unexplored property, offering an innovative perspective for the design and development of novel biomaterials.

Avocado Pruning Residues for the Formulation of Bio‐Based Polyethylene/Fiber‐Based Biocomposites for Sustainable Food Packaging

AbstractThe extensive use of non‐biodegradable bioplastics and fossil‐based plastics in food packaging presents a significant environmental challenge. Consequently, there has been a growing interest in exploring agricultural biomass as a potential source for formulating biocomposites for packaging due to the substantial amount of lignocellulosic residue generated. This study explores the utilization of avocado pruning residue (APR) for isolating lignocellulose fibers and their application as replacement and reinforcement material for bio‐based polyethylene (BioPE) composites. The results obtained reveal that a concentration of 9% (w/w) of maleic anhydride‐grafted‐polyethylene (MAPE) shows the most effective fiber–polymer interaction, resulting in a significant improvement of 25.47% in the mechanical properties. Biocomposites with varying fiber concentrations, ranging from 10% to 40% (w/w), are prepared and assessed for their macro‐ and micromechanical properties. The results demonstrate a substantial 49% increase in tensile strength and a remarkable 325% enhancement in Young's modulus for biocomposites containing 40% (w/w) fiber content. Furthermore, micromechanical analysis provides insights into the intrinsic strength and modulus of avocado fibers, with values of ≈437 MPa and 33 GPa, respectively. This research contributes to the development of sustainable and eco‐friendly alternatives for food packaging, reducing the reliance on fossil‐based plastics, and promoting the utilization of agricultural waste.

Experimental Study on Single Fiber Tensile Properties of Sisal Fibers Using a Digital Image Correlation Method as a Strain Measurement

ABSTRACT The development of natural fibers in engineering applications requires an accurate measurement of their dimensional characteristics and mechanical properties. Fiber cross-sectional area (CSA) obtained from lateral dimensional measurements should consider the specific cross-sectional shape (CSS) of the fibers and their wide lengthwise variations. In this study, the dimensional measurements of water-retted and unretted sisal fibers were conducted by laser scanning microscopy (LSM) and calculation-based methods. Single fiber tensile tests were performed using the digital image correlation (DIC) method. Results show that the diameters of water-retted and unretted fibers measured by LSM were 233 ± 45 µm and 236 ± 42 µm, respectively. The diameters of water-retted and unretted fibers obtained by calculation were 192 ± 17 µm and 178 ± 20 µm, respectively. The tensile strengths of water-retted and unretted fibers were 679 ± 118 MPa and 718 ± 106 MPa, respectively. The strain at failure and elastic modulus of water-retted and unretted fibers were 2.0 ± 0.6% and 34 ± 8 GPa, as well as 1.5 ± 0.2% and 48 ± 6 GPa, respectively. Water retting seems to predominantly influence the strain at failure and elastic modulus of sisal fibers, as confirmed by the ANOVA analysis.

Estimation of transverse thermoelastic properties of polyimide fibers based on micromechanical models

The determination of the thermoelastic properties of polyimide (PI) fibers is important for their applications, however, these properties are difficult to measure directly, especially the transverse thermoelastic properties. Here, the transverse thermoelastic properties of PI fibers, including transverse Young's modulus (2.12 GPa), shear modulus (0.94 GPa), Poisson's ratio (0.05), and coefficient of thermal expansion (45.68 μm/m°C), were estimated by combining dynamic and static thermo-mechanical techniques, as well as various relevant micromechanical models. The transverse Young's modulus of PI fibers was only 1/46th of the longitudinal one, and the transverse coefficient of thermal expansion of PI fibers was positive, unlike the longitudinal one, which was negative, showing the typical anisotropy of PI fibers. Finally, the thermoelastic properties of the PI fibers were in turn used to predict the thermoelastic behavior of the PI fiber-reinforced composites, thus validating their effectiveness.