Search Results (106)

This work presents a comparative study of micro- and nano-scale fillers in liquid composite molding processes, focusing on how particle size and morphology affect resin rheology, flow behavior, and filler filtration within fiber preforms. Glass microspheres and organo-modified montmorillonite were dispersed in epoxy resin and injected through glass-mat preforms at different fiber volume fractions (ranging from 0.27 to 0.47). Our study integrates rheological characterization, in situ flow-front tracking, unsaturated permeability analysis, thermogravimetric quantification of retained particles, and microstructural observations by SEM. Despite their smaller loading, nanoclay suspensions showed a markedly higher viscosity increase than microsphere systems, yet their permeability remained nearly unchanged. In contrast, microsphere-filled resins exhibited strong filtration at the flow inlet, density-driven settling near the lower tool face, and significant permeability loss. The results demonstrate that nano-fillers, although more viscous, maintain homogeneous distribution and flow continuity, whereas micro-fillers promote cake formation and local compaction. This controlled side-by-side comparison clarifies how filler size and shape govern filtration mechanisms in liquid composite molding (LCM), providing design guidelines for processing filled resin systems without compromising part quality. Full article

(1) Background: Starch-based breads can closely mimic wheat bread in texture and appearance; however, their nutritional value must be improved while maintaining their inherent bread-like characteristics. The objective of this study was to incorporate whole-grain pearl millet flour (PMF) into a starch-based bread formulation to enhance its dietary fiber and protein content. (2) Methods: The PMF was obtained using a combination of laboratory rollers and hammer mills, as well as appropriate sieves to obtain a particle size ≤ 250 µm. The incorporation of PMF affected the properties of the base flour (BF), dough, and gluten-free bread (GFB). (3) Results: In the BF, setback viscosity was significantly reduced from 6379 to 1354 mPa·s. Similarly, in the freshly kneaded dough, both the elastic and viscous moduli decreased, from 168.3 to 17.8 kPa and from 36.3 to 4.3 kPa, respectively. During fermentation, dough-specific volume increased from 0.76 to 1.73 cm³/g. In the GFB, the moisture content decreased from 47.9 to 42.2%, bread specific volume varied from 2.13 to 2.68 cm³/g, and crumb hardness increased from 12.8 to 25.3 N. PMF incorporation segmented bread consumers into two preference-based clusters, characterized by lower (1) and higher (2) PMF levels. (4) Conclusions: Incorporating 30% PMF increased the fiber and protein contents of the starch-based bread by 4.9% and 2.2%, respectively, without compromising specific volume (2.56 g/cm³) or overall acceptance, which remained comparable to that of a commercial gluten-free bread (7.30 and 6.32 for clusters (1) and (2), respectively). Full article

The solubility and rheological properties of high-molecular-weight xanthan gum (XG) are crucial to its functional performance and determine its applications. Ultrasound modifies these properties mainly by altering acoustic propagation in viscous systems, which depends strongly on concentration and frequency mode. In this work, the propagation behavior of three frequency modes (33 kHz mono-frequency, 20–40 kHz dual-frequency, and 20–50–68 kHz triple-frequency) of arc-shaped flat-plate ultrasound was systematically investigated in XG solutions, as well as their effects on solubility and rheological properties. Results showed that multi-frequency ultrasound generated stronger and more uniform acoustic fields, maintaining higher space peak temporal peak acoustic intensity (I_SPTP) over a wide concentration range, which was superior to the significant attenuation observed in mono-frequency mode above 10.0 g·L⁻¹. Ultrasonic treatment effectively increased solubility from 62.0 to 63.5% (untreated) to a maximum of 85.6% in the 20–40 kHz group. In terms of rheology, ultrasound reduced viscosity and altered viscoelastic behavior by disrupting the molecular network, with multi-frequency modes showing greater effects at higher concentrations. Surface tension decreased to a minimum of 58.4 mN·m⁻¹ under mono-frequency treatment. Frequency sweep and creep recovery tests indicated enhanced chain mobility and improved structural recovery after ultrasound. Microstructure analysis confirmed fiber fragmentation and the formation of a microporous structure, especially under multi-frequency modes. Overall, the key mechanism lies in the ability of multi-frequency ultrasound to maintain effective acoustic propagation in viscous media, thereby enhancing solubility and modulating rheological behavior. Full article

To address the issue of sound absorption valleys in open-cell aluminum foam and enhance mid-to-high frequency (800–6300 Hz) performance, we developed a novel pore-penetrating 316L stainless steel fiber–aluminum foam (PPFCAF) composite using an infiltration method. The formation mechanism of the pore-penetrating fibers, the resultant pore-structure, and the accompanying sound absorption properties were investigated systematically. The PPFCAF was fabricated using 316L stainless steel fiber–NaCl composites created by an evaporation crystallization process, which ensured the full embedding of fibers within the pore-forming agent, resulting in a three-dimensional fiber-pore interpenetrating network after infiltration and desalination. Experimental results demonstrate that the PPFCAF with a porosity of 82.8% and a main pore size of 0.5 mm achieves a sound absorption valley value of 0.861. An average sound absorption coefficient is 0.880 in the target frequency range, representing significant improvements of 9.8% and 9.9%, respectively, higher than that of the conventional infiltration aluminum foam (CIAF). Acoustic impedance reveal that the incorporated fibers improve the impedance matching between the composite material and air, thereby reducing sound reflection. Finite element simulations further elucidate the underlying mechanisms: the pore-penetrating fibers influence the paths followed by air particles and the internal surface area, thereby increasing the interaction between sound waves and the solid framework. A reduction in the main pore size intensifies the interaction between sound waves and pore walls, resulting in a lower overall reflection coefficient and a decreased reflected sound pressure amplitude (0.502 Pa). In terms of energy dissipation, the combined effects of the fibers and refinement increase the specific surface area, thereby strengthening viscous effects (instantaneous sound velocity up to 46.1 m/s) and thermal effects (temperature field increases to 0.735 K). This synergy leads to a notable rise in the total plane wave power dissipation density, reaching 0.0609 W/m³. Our work provides an effective strategy for designing high-performance composite metal foams for noise control applications. Full article

Graphene oxide (GO) has been successfully used as a filler to modify various properties of polymers and fiber-reinforced composites. The resulting properties depend on the filler content and on the distribution of GO in the polymer matrix. In this work, for the first time, we introduced GO into the highly viscous DEN-438 epoxy novolac resin and investigated rheological properties of the resulting compositions. In particular, we studied the functions of complex viscosity, storage and loss moduli, and mechanical loss tangent on temperature and GO content. The unusual behavior of the newly prepared formulations compared to typical GO/epoxy mixtures was discovered. At low GO content, introduction of GO led not to an increase, but to a decrease in the resin viscosity, with the minimum registered at 0.29 wt.% GO. After this threshold value, viscosity increased with GO content, which we explained by formation of the liquid crystalline structure. At higher GO concentrations, the formulations changed their state from solid-like at rest to liquid-like under load, with the properties being highly desired for film binders. The discovered properties of the GO/novolac epoxy resin formulations suggest their potential use as the new generation of film binders for Resin Film Infusion technology. Full article

This study investigates the synergistic effect of phenolic resin impregnation on the mechanical and adhesive properties of hydrothermally treated bamboo composites further reinforced with a silica nanoparticle sol–gel catalyzed by Fe₃O₄ (SiO₂/Fe₃O₄). The hydrothermal pre-treatment was found to enhance cellulose crystallinity, as confirmed through XRD analysis. Dynamic mechanical analysis (DMA) and nanoindentation tests revealed that the hybrid treatment significantly influences the viscoelastic response. Composites treated only with hot water and resin (GB-W) exhibited superior short-term creep resistance and higher elasticity, attributed to their optimized crystalline structure. In contrast, the silica-reinforced composites (GB-M) demonstrated the most viscous behavior and lowest stress relaxation, making them most effective at minimizing elastic springback. Nanoindentation further showed that GB-W had the highest nano-adherence at the fiber cell wall level. FTIR analysis indicated a stronger interaction between the phenolic resin and the hydroxyl groups of the bamboo matrix in GB-0 and GB-W compared to GB-M, where the silica layer potentially altered this interface. Microscopy confirmed a resin penetration depth of at least 1 mm, primarily into porous tissues. The results demonstrate that while silica reinforcement enhances relaxation properties, the hydrothermal pre-treatment combined with phenolic resin creates a more favorable interface, leading to better overall creep resistance and adherence. Full article

High-performance spun bionanocomposite fibers, composed of high-molecular-weight chitosan (HMW), low-molecular-weight chitosan “oligomers” (LMW), and cellulose nanofibers (CNFs), were successfully fabricated via gel spinning of viscous aqueous chitosan (CHI) based formulations into a NaOH coagulation bath. The X-ray diffraction (XRD) analysis revealed that the incorporation of cellulose nanofibers contributed to enhance crystallinity of chitosan in spun fibers. The spinning process, which comprised sequential acidic solubilization, basic neutralization, stretching, and drying steps, produced chitosan/CNF composite fibers with high crystallinity, further enhanced by the incorporation of low molecular weight chitosan. The cellulose nanofibers seem to promote CHI crystallization, by acting as nucleation sites for the nucleation and growth of chitosan crystals, with those latter of LMW further enhancing crystallization and orientation due to higher mobility of shorter polymer chains. Two-dimensional XRD patterns demonstrated the preferential alignment of both CNFs and chitosan crystals along the fiber axis. Increasing the proportion of short-chain chitosan led to a reduction of the viscosity of collodion, facilitating the spinning of solutions with higher polymer concentrations. The X-ray diffraction (XRD) analysis revealed that the addition of low-molecular-weight chitosan (LMW), with an intermediate molecular weight Mw of ~4.4 × 10⁴ g/mol, produced the most significant improvements in the crystallinity index (CrI) and orientation. This structural enhancement corresponded to superior mechanical properties like Young’s modulus, yield stress σ_y, and stress-at-break σ_b of the processed composite fibers. By incorporating that intermediate molecular weight chitosan, a Young’s modulus as high as 20 GPa was achieved for the spun composite fibers, which was twice higher than the modulus of around 10 GPa obtained by adding the lowest molecular weight chitosan of Mw ~ 2.9 × 10⁴ g/mol in the composite, and largely above the modulus of around 5 GPa obtained for fiber just spun with chitosan without incorporation of cellulose nanofibers. Full article

Concrete materials undergo a series of physical and chemical changes under high temperature, leading to the degradation of mechanical properties. This study investigates basalt fiber-reinforced concrete (BFRC) through high-temperature testing using the split Hopkinson pressure bar (SHPB) apparatus. Impact compression tests were conducted on specimens after exposure to elevated temperatures to analyze the effects of varying fiber content, temperature levels, and impact rates on the mechanical behaviors of BFRC. Based on fractional calculus theory, a dynamic constitutive equation was established to characterize the viscoelastic properties and high-temperature damage of BFRC. The results indicate that the dynamic compressive strength of BFRC decreases significantly with increasing temperature but increases gradually with higher impact rates, demonstrating fiber-toughening effects, thermal degradation effects, and strain rate strengthening effects. The proposed constitutive model aligns well with the experimental data, effectively capturing the dynamic mechanical behaviors of BFRC after high-temperature exposure, including its transitional mechanical characteristics across elastic, viscoelastic, and viscous states. The viscoelastic behaviors of BFRC are fundamentally attributed to the synergistic response of its multi-phase composite system across different scales. Basalt fibers enhance the material’s elastic properties by improving the stress transfer mechanism, while high-temperature exposure amplifies its viscous characteristics through microstructural deterioration, chemical transformations, and associated thermal damage. Full article

This study examines the rheology and fiber formation of poly(2,5(6)-benzimidazole) (ABPBI) solutions in polyphosphoric acid (PPA) at 12.5 wt%. These solutions exhibit typical features of associative polymer systems, such as pronounced shear thinning and high elasticity. The activation energy of the viscous flow increases with the polymer concentration, reaching 29 kJ/mol at 12.5 wt%, but remains significantly lower than in phosphoric acid solutions. This indicates more efficient solvation and chain mobility in PPA. A comparison with two superbasic solvent systems further highlights the critical role of the solvent nature in flow mechanisms and associative interactions. Model coagulation experiments revealed how the non-solvent composition controls the fiber morphology and solidification. Under optimized conditions, homogeneous monolithic fibers with good mechanical performance were obtained. These findings provide new insight into the physicochemical principles of ABPBI fiber formation and establish PPA as a promising solvent for producing high-performance fibers. Full article

This study presents a high-performance external strengthening strategy for reinforced concrete (RC) beam–column joints, integrating near-surface mounted (NSM) Carbon Fiber Reinforced Polymer (C-FRP) ropes with externally bonded C-FRP sheets. The X-shaped ropes, anchored diagonally on both principal joint faces and complemented by vertical ropes at column corners, provide enhanced core confinement and shear reinforcement. C-FRP sheets applied to the beam’s plastic hinge region further increase flexural strength and delay localized failure. Three full-scale, shear-deficient RC joints were subjected to cyclic lateral loading. The unstrengthened specimen (JB0V) exhibited rapid stiffness deterioration, premature joint shear cracking, and unstable hysteretic behavior. In contrast, the specimen strengthened solely with X-shaped C-FRP ropes (JB0VF2X2c) displayed a markedly slower rate of stiffness degradation, delayed crack development, and improved energy dissipation stability. The fully retrofitted specimen (JB0VF2X2c + C-FRP) demonstrated the most pronounced gains, with peak load capacity increased by 65%, equivalent viscous damping enhanced by 55%, and joint shear deformations reduced by more than 40%. Even at 4% drift, it retained over 90% of its peak strength, while localizing damage away from the joint core—a performance unattainable by the unstrengthened configuration. These results clearly establish that the combined C-FRP rope–sheet system transforms the seismic response of deficient RC joints, offering a lightweight, non-invasive, and rapidly deployable retrofit solution. By simultaneously boosting shear resistance, ductility, and energy dissipation while controlling damage localization, the technique provides a robust pathway to extend service life and significantly enhance post-earthquake functionality in critical structural connections. Full article

Meat analog manufacturing via high-moisture extrusion technology is a complex process wherein the properties of protein materials constitute a critical determining factor. In this study, we enhanced the fiber structure properties of high-moisture extruded peanut protein-based meat analogs by incorporating different starches (cassava starch, acetyl distarch phosphate [ADSP], and hydroxypropyl starch) to address challenges in water retention, emulsification, and digestibility. The impact of the starch content (0, 3, 6, 9, 12%) was assessed using low-field nuclear magnetic resonance, ultraviolet/fluorescence spectroscopy, differential scanning calorimetry, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, and functional tests. Compared with controls without starch, adding 6% ADSP significantly improved the water retention by forming a dense, charged network, reducing T_2b (0.37 ms) and T₂₂ (175.30 ms). ADSP (12%) enhanced the emulsification (activity index 10.28 m²/g, stability index 75%); the cassava starch (12%) increased the in vitro protein digestibility to 83% due to amylopectin degradation. Hydroxypropyl starch (6%) elevated the thermal stability (peak temperature 125.71 °C) by forming a viscous protective matrix (p < 0.05). Ultraviolet and fluorescence spectra indicated protein–starch interactions, with ADSP inducing the most pronounced conformational changes. This study demonstrated that the starch type and concentration critically modulate protein–starch interactions, offering guidance for enhancing the quality of meat analogs. Full article

Cardiovascular disease (CVD) remains the leading cause of death worldwide, with elevated low-density lipoprotein cholesterol (LDL-C) as a major risk factor. Beyond medications, dietary interventions and functional foods offer significant cholesterol-lowering potential. This article provides a comprehensive review of functional foods and nutraceutical ingredients that help to reduce cholesterol levels and introduces the novel Cholesterol-Lowering Capacity Index (CLCI), designed to quantify and communicate the efficacy of such foods. In doing so, it summarizes key functional components, including plant sterols/stanols, viscous fibers, soy protein, red yeast rice, berberine, polyphenols (e.g., bergamot extract, garlic), and others, highlighting their mechanisms of action and the typical LDL-C reductions observed in clinical studies. Strategies for the design of next-generation cholesterol-lowering foods are discussed, such as combining multiple bioactives for synergistic effects, personalized nutrition approaches, and novel food processing techniques to enhance bioavailability. Building on these strategies, the CLCI is then proposed as a practical scoring system, analogous to the glycemic index for blood sugar, that integrates the evidence-based potency of ingredients, effective dosing, and synergistic interactions into a single metric. A methodology for the calculation of the CLCI is presented, alongside potential applications in food labeling, clinical guidance, and dietary planning. Full article

To investigate the settling behavior and drag characteristics of particles in fiber-containing non-Newtonian fluids, a series of systematic single-particle settling experiments were conducted. Power-law and Herschel–Bulkley fluids were prepared as base media, into which polyester fibers of various concentrations and lengths were introduced. The effects of fiber structural parameters on fluid rheology and terminal settling velocity were thoroughly evaluated. First, the rheological changes induced by fiber addition were quantitatively analyzed, revealing a nonlinear increase in both viscosity and yield stress with increasing fiber concentration and length. Subsequently, the total drag force was decomposed into viscous and fiber-induced components, and a predictive model for the fiber-induced drag coefficient was developed based on fiber structural parameters. A power-law fitting approach was employed to characterize the nonlinear relationship between the fiber drag coefficient and the particle Reynolds number. Furthermore, a parametric coupling strategy was employed, in which fiber concentration and length were embedded into the model coefficients to construct a unified and continuous predictive model for the total drag coefficient. Experimental validation demonstrated that the mean relative errors (MREs) of the proposed model were within 5.17% for power-law fluids and 9.95% for Herschel–Bulkley fluids, indicating strong predictive accuracy and applicability. The findings of this study provide a robust theoretical and experimental basis for optimizing fiber-enhanced cutting transport systems and modeling particle transportation under complex drilling conditions. Full article

The work presented here describes an approach that separates the viscous stress from the quasi-static counterpart for polycarbonate (PC) and its short glass fiber composite (GF-PC), with the aim to characterize the influence of short glass fiber on the viscous behavior of PC as the matrix of GF-PC. A multi-relaxation (MR) test was used for the mechanical testing and a three-branch spring–dashpot model for the data analysis, using a genetic algorithm to establish 100 sets of fitting parameter values that enabled the three-branch model to regenerate the measured stress decay during relaxation. Using the spring modulus $\left(K_{v,s}\right)$ of the short-term branch in the three-branch model, two groups for these fitting parameter values were established as a function of specimen displacement (named stroke) of GF-PC, one of which shows a trend that is similar to the trend of the corresponding fitting parameters for the pure PC, and thus is believed to reflect the influence of glass fiber on the PC matrix of GF-PC. The study concludes that the short glass fiber increases the short-term viscous stress, but its role on the long-term viscous stress is marginal. Full article

To investigate the motion patterns of flexible fibers inside a sewage pump and their impact on internal flow characteristics, visualization experiments were conducted to compare the pump flow when transporting water—0.3% CMC solution and 0.3% CMC solution containing flexible fibers under different operating conditions. The results showed that changes in the rheological properties of the 0.3% CMC solution primarily affected fluid viscous dissipation. Under the same rotational speed, the flow rate increased by only 2.4%, but power consumption decreased by 9.1%, resulting in a 6.4% improvement in efficiency. The curvature and distribution of fibers within the impeller flow channel remained stable. Their impact on the flow was characterized by an overall reduction in velocity within the impeller region, with the peak velocity decreasing by up to 26.3%. The primary cause of pump failure due to fibers was their tendency to repeatedly accumulate and detach at the tongue, leading to blockages. Fiber length had a more significant impact on the blockage rate than mass concentration. Full article