A semi-analytical model for effective conductivity of parallelogram-periodic fibrous composites with circular inclusions

Triacetin (TA) is a solvent commonly used in pharmaceutical and food applications, and as a plasticizer in bioplastics such as poly(lactic acid) (PLA) and cellulose acetate (CA). L-lactide is the monomer used in the ring-opening polymerization of PLA. The structure of TA emulsions stabilized by a cellulose hydrogel (CH) was imaged in this study. The emulsions were prepared by mechanical homogenization or a two-step process with subsequent high-pressure homogenization (HPH). The two-step process yielded smaller TA droplets and a more homogeneous CH dispersion. The images demonstrate that emulsion stabilization is due to CH particles adsorbed at the TA-water interface. The ester hydrolysis of TA and a lactide/TA solution by two industrially important lipases, from Candida rugosa (CRL) and Burkholderia cepacia (BCL), was investigated, assessing the effect of CH as an emulsion stabilizer. Mechanically homogenized TA emulsions were effectively hydrolyzed. Lactide was found to inhibit the enzymatic hydrolysis of TA. This inhibition was mitigated by CH for CRL-catalyzed hydrolysis but not for BCL catalysis. These results indicate a synergistic effect of CH stabilization on the interfacial activation of CRL. Thise effect may also be relevant for the biodegradation of bio-derived plastics and their fibrous cellulose composites.

• Comparative assessment of mechanical, thermal, and chemical recycling reveals clear trade-offs in fiber recovery and energy demand. • Life cycle evaluation shows recycled HDPE, PET, and carbon fibers outperform virgin materials in cost and environmental impact under policy incentives. • Hybrid recycling with process control achieves ∼90% fiber quality retention while reducing overall processing costs. • AI- and IoT-enabled monitoring improves traceability, process efficiency, and circular-economy performance. Fibrous polymer composites are widely used in aerospace, automotive, and renewable energy due to their lightweight and high-strength properties. Traditional linear production and disposal methods, however, cause resource depletion and environmental impacts. This review critically synthesizes circular economy strategies for fibrous polymer composites, integrating material selection, additive manufacturing, and recycling pathways. Mechanical, thermal, and chemical recycling methods are compared in terms of fiber recovery (60–90%), energy consumption (0.5–5.0 MJ/kg), and economic feasibility, highlighting trade-offs between efficiency and scalability. Agro-based and synthetic fibers are evaluated for their performance and sustainability potential. Implementable strategies such as design-for-disassembly, hybrid recycling, AI-driven material traceability, and policy–industry collaboration are discussed to enhance circularity. By providing a systems-level framework linking composite design, end-of-life management, and industrial application, this review identifies critical research gaps, informs sustainable composite development, and offers policy-relevant guidance to promote environmental and economic benefits. By emphasizing recycling, renewable fibers, and resource-efficient design, this study supports the advancement of cleaner, more sustainable composite materials.

Loading Rate Dependent Mode I Fracture in Fibrous Cementitious Composites: Insights from Digital Image Correlation Method

This paper presents a solution to the plane doubly periodic problem of loading an infinite, isotropic, elastic plane with a hexagonal packing of elliptical inclusions. The plane is subjected to one of three types of remote loading: uniaxial tension along one of the inclusion’s axes or pure shear. The regular hexagonal unit cell contains a single elliptical inclusion with its axes perpendicular to the cell boundaries. The size of the inclusion is significantly larger than the plate thickness. The solution is constructed by reducing the problem to finding complex potentials from the boundary conditions, which are derived from the equality of normal forces and displacements in the matrix and the inclusion. This is achieved using conformal mapping techniques and the method of Muskhelishvili. The influence of non-central inclusions is accounted for via a small parameter method. As a result, a system of linear algebraic equations is derived for solving the considered doubly periodic problem, and solutions for several specific cases are obtained. The results were verified against a numerical solution obtained by the finite element method in the Abaqus software package. The solution to this problem serves as a model for the loading of a fibrous composite, which makes it highly relevant. A relatively small number of works in mechanics are devoted to fibrous composites, with most publications focusing on the analysis of experimental studies or numerical solutions. Therefore, this analytical solution possesses significant scientific value.

Abstract Piezomagnetic-piezoelectric composites can be applied to fabricate devices controlled both magnetically and electrically, and thus draw increasing attentions recently. The present paper aims to develop a computational methodology using the imperfect interface model
to characterize the thin transition layers within such fibrous smart composites to quantitatively evaluate their influence on the magnetoelectric effects. First, the thin transition layers within a practical multi-phase smart composites are reformulated based on continuum mechanics as a general imperfect interfaces of null thickness, across which both the primary and secondary physical quantities suffer jumps. The strong and weak governing formulations are then derived for multi-coated fibrous composites containing
general imperfect interfaces in arbitrary shapes, and a computational approach is further developed with the aid of the extended finite element method (XFEM) combined with the level set method (LSM) to properly reconstruct the interfacial discontinuities induced by
these thin transition layers. Hereafter, a benchmark problem involving a simplified general interfacial relation is designated, analytically solved, and applied to test the validity and robustness of the elaborated computational approach. Both the convergence analysis and
physical evaluations highlight that the elaborated computational approach can robustly predict the physical quantities within both the primary and secondary fields, and accurately reproduce the interfacial discontinuities across each general imperfect interfaces.
Eventually, the influence of thin transition layers are discussed in detail, and a few remarks are concluded.

ABSTRACT Foaming prepolymer compositions were synthesized on the basis of 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) esterified with ethanol, 4,4′‐methylenedianiline (MDA), and various amounts of single‐walled carbon nanotubes (SWCNT). These prepolymers modified with nanotubes were used as foaming binding agents to obtain new polyimide composite materials (foam composites) reinforced with carbon‐containing polyimide fibers Arimid. The results of comparative studies of thermal and mechanical properties of the obtained nano‐modified foam composites are presented. The investigated samples demonstrated high thermal stability (the onset of mass loss was observed at 546°C–555°C) and low density (0.23–0.24 kg/m 3 ); the values of flexural modulus of elasticity varied from 147 to 260 kPa, the longitudinal and transverse compression moduli were equal to 35–70 and 5–7 MPa, respectively. It was shown that the prepared foam composites were fire resistant. The samples retained their characteristics at −50°C without any increase in brittleness or deterioration of their mechanical properties, which makes them suitable for use in building structures operated in northern regions.

This paper continues the analysis from Parts I and II, which addressed two-dimensional dispersed random composites. This part extends previous analytical studies by incorporating machine learning (ML) methods to quantitatively classify microstructures. The methodology relies on decomposing the expressions for the effective tensors into geometrical and physical parts, represented by structural sums and component-specific physical constants. The study concerns a two-phase composite with non-overlapping circular inclusions embedded in an isotropic elastic matrix. The random distribution of inclusions ensures macroscopic isotropy of the composite. A key outcome is the explicit demonstration of how the effective tensor depends on the geometric probabilistic distributions of inclusions and the computational protocols employed in their realization. These steps constitute the strategy for studying elastic fibrous composites, classifying them by macroscopic properties, and describing an analytical algorithm to derive expressions for computing the effective constants. The decomposition theorem and the construction of feature vectors consisting of structural sums are used as inputs to the ML analysis. As a result, we develop a computationally effective strategy to classify dispersed random composites indistinguishable by simple observations.

This study explores the process of cutting fibrous polymer composite materials. The main reason for limiting the use of polymer composites is the deterioration of their performance properties after mechanical processing because of destruction of the surface layer. It is high time substantiated recommendations for the mechanical processing of fibrous polymer composites (FPCs) are provided. This could reduce the depth of destruction of an FPC surface layer to 20–50 μm and expand the area of functional application of these materials. An experimental study on the influence of cutting modes and geometric parameters of the cutting part of the tools on the technological components of the cutting force has been conducted, which made it possible to establish that the greatest influence on the cutting force when processing fibrous composites is exerted by the values of the geometric characteristics of the tool. Reducing the energy consumption for cutting to the level of 1.5 kN∙m/s helps minimize the influence of mechanical, thermal, and chemical factors on the destruction of the composite. FPCs have high elastic properties, which determines the features in the cutting process. As this leads to increased values of cutting forces on the rear surface, it is recommended to carry out processing by a sharpened tool at large values of the front γ and rear α angles of the blade. Determining the cutting force makes it possible to correctly assign the geometric parameters of the tool and estimate the processing error. The specified machining modes make it possible to reduce the depth of the defective layer by 10 times (RZ ≤ 20 mm, KB ≤ 5%, N ≤ 1012 spin/gr, M ≤ 50 μm) and increase the stability of the cutting tool by two times. The results could make it possible to improve the process of shaping articles from polymeric materials during production

The novel fibrous composites of Al61Cu27Fe12 alloy with a single-crystalline matrix and quasi-crystal phase fraction obtained in situ by directional solidification by the Bridgman method were studied to characterize the voids and their role in composites cracking. The voids were analyzed using light-optical and scanning electron microscopy to study their nature before and after uniaxial tensile tests. Tension tests were performed on plate-like samples up to rupture. The tensile fracture surfaces were also observed and analyzed. The single-crystallinity and crystalographic parameters of composites were studied using the X-ray Laue diffraction method. It was stated that such new type of composite is characterized by a relatively high void content with a ratio of approximately 2.6%. The composite’s cracking is initiated at voids and progress through the voids and stair steps in the matrix and the reinforcing fibers.

Abstract The widespread impacts of industrial air pollutants address the urgent need for advanced filtration technologies mitigating various environmental pollutants. This study conducted comparative investigations of zinc oxide (ZnO) and zeolitic imidazolate framework-8 (ZIF-8) treated fibrous composites with subsequent corona charging, to apply as a dual-function air filter that is simultaneously protective against particulate and gaseous matters. While both ZnO and ZIF-8 presented charge-trapping capability, the uniform coating of ZIF-8 nanocrystals on the fibrous material, rather than uneven coating of ZnO aggregates, produced higher charging capacity, leading to a superior electrostatic filtration efficiency. On the other hand, agglomerates of ZnO crystals in the fibrous web advantageously affected the mechanical filtration efficiency, especially in the layered structure. Concerning the SO2 gas adsorption capacity, the inherent pore characteristic of ZIF-8 allowed a superior gas removal performance. The SO2 adsorption was hardly influenced by the post-corona charging process, either for ZnO or ZIF-8 treated composites. This study highlights the advantages of ZIF-8 integration in fibrous composites for the advanced design of dual filters, where ZIF-8 integration not only gives high gas removal performance but also significantly enhances charge trapping ability and the associated electrostatic filtration performance.

Abstract Human hair is a fibrous protein composite, for which the thermal and mechanical properties change in specific ways with acidic and alkaline pH levels. To study these effects, DSC (wet) is a practical method for pH-equilibrated and unrinsed samples. When samples are exposed to deionised water in the DSC-pan, a secondary process of ion partitioning occurs. Based on the Freundlich sorption isotherms for H+ as well as OH− -ions for hair, we found the effect to be small and constant. Furthermore, the isotherms provided estimates for the ion contents in hair, allowing us to study changes of the DSC-parameters based on ion content rather than pH. These changes are discussed with regard to the impacts of ion contents on the α-helic fraction of the IFs (denaturation enthalpy: ΔH D) and on the matrix (denaturation temperature: T D). T D increases linearly with H+ -content by ≈8 °C down to ≈pH2 (≈ 800 μM g−1 H+). However, for alkaline, pH changes are more complex. We observe two non-linear regions with OH− -content and a discontinuous change around pH12. These observations are discussed on the basis of cross-link reformation in the matrix through lanthionine formation. The helical fraction in the IFs is found to be very stable against H+- as well as OH− -contents up to ≈1500 μM g−1. Any signs of helix denaturation for higher contents for both ions are attributed to the destabilisation of the apolar interactions, which stabilise helical dimers.

Abstract Arthropod cuticle is a widespread biological composite with a broad range of mechanical anisotropy, which arises from a fiber-layered architecture. While the cuticle commonly exhibits helicoidal chitin-protein fiber architecture, specific structural parameters, such as rotation angle, lamella thickness, and sublayer number, differ across taxa and anatomical regions. These variations are thought to reflect adaptations to specialized mechanical functions. However, linking these structural features to mechanical behavior remains experimentally challenging. Therefore, we present here a general numerical model that studies the anisotropic mechanical behavior of layered fibrous materials typical of arthropod cuticle. The model reproduces the three-dimensional helicoidal arrangement of chitin fibers and their interactions using a simplified phenomenological approach based on movable cellular automata. Without tuning to specific experimental parameters, the model captures key features, such as anisotropic deformation under directional indentation and energy dissipation patterns. The simulated anisotropy index falls within the experimentally observed range for natural cuticles, supporting the idea that architecture alone can strongly influence mechanical response. Our literature-based analysis highlights a consistent trend observed in the numerical model: increased matrix stiffness/sclerotization is often associated with reduced anisotropy, likely due to more isotropic mechanical reinforcement. This study provides a general modeling framework for understanding structure-property relationships in fibrous biological composites.

Fabrication and evaluation of fibrous gelatin/PVA scaffolds incorporated with TiO₂-NPs for wound healing applications.

Novel Zn(II)-Based Metal–Organic Frameworks@Polyacrylonitrile Fibrous Composites: Fabrication, Characterization, and Selective Anionic Dyes Sorption Properties

Semi-synthetic fibrous fibrin composites promote 3D microvascular assembly, survival, and host integration of endothelial cells without mesenchymal cell support.

Abstract Carbon fiber and other fibrous composites are widely used in structural components for wind turbines and aircraft. These applications not only require high strength and low weight but also tailored electrical properties. Designing new composites that can resist lightning strikes or be used in bioelectronics relies on accurately predicting their electrical conductivities. Yet most models of conductivity in these composites lack a geometrically meaningful basis, particularly if applied far from the percolation threshold which often occurs in the earliest 1% of the composite design space. An electrical model that is grounded in real fiber geometries and arrangements is derived. New equations are obtained, combining materials science and network physics, that accurately predict individual fiber overlap, neighbor distributions, and percolation thresholds in systems of overlapping shapes. Combining these equations with the new electrical model of a “foamy cluster”, yielded excellent predictions of conductivity in many different types of fibrous composites.

Composites from fiber materials (fibrous composites) continue to be researched and developed to become alternative materials to replace metal materials, this is due to the nature of composite materials that are strong and have a lighter mass compared to metal. This study aims to make fiber composites from palm fiber and coconut fiber with epoxy resin binders. In this study, a mixture of palm fiber, coconut fiber and epoxy resin was carried out with a ratio of 20%: 30%: 50%, 25%: 25%: 50%, and 30%: 20%: 50%. The highest bending strength test results occurred in specimen 3 with a mixture of 50% bamboo fiber: 50% polyester resin has a tensile strength value of 18.93 MPa with an impact price of 0.387 Joule / mm2 This is because the variation of the mixture of palm fiber fibers is getting bigger and the smaller the coconut fiber with epoxy resin will affect the elastic strain of the fiber core (cellulose), cellulose from larger palm fibers can increase the bending strength value and impact price, so it can be seen from the impact test results (charpy) where in specimen 3 (30%: 20%: 50%) has the highest bending strength and impact value and vice versa if the mixture of coconut fiber is more then it will decrease the impact price. The type of fracture in specimen 1 is a brittle fracture form and specimen 2, specimen 3 is a brittle fibrous fracture form

Local field statistics in linear elastic unidirectional fibrous composites

The challenge of water shutoff in carbonate reservoirs is complicated by the presence of fractures, which cannot be effectively blocked using conventional hydrogel screens designed for granular reservoirs. To reliably seal fractures, fibrous and dispersed fillers are added to hydrogels. These fillers must exhibit affinity for the matrix to ensure the composites can effectively isolate water. Given the wide variability in fracture apertures, it is evident that water shutoff composites should incorporate fibers and dispersed fillers of varying geometric sizes. This study presents a range of hydrogel composites reinforced with mono-, bi-, and tri-component fibers, as well as dispersed fillers, designed for water shutoff in fractured carbonate reservoirs with varying fracture apertures. Oscillation test results demonstrated a twofold increase in the elastic modulus (40-45 Pa) for compositions with various fillers compared to the base composition (23 Pa). Filtration studies revealed the effectiveness of the optimized compositions under different fracture apertures. Specifically, even at a fracture aperture of 650 μm, the residual resistance factor (RRF) reached 82.3 and 9.76 at water flow rates of 0.1 cm3/min and 0.5 cm3/min, respectively. The conducted rheological and filtration tests, along with field trials, confirmed the validity of the selected approach.