Increase In Modulus Research Articles

Numerical Simulation Study on Vibration Characteristics and Influencing Factors of Coal Containing Geological Structure

Accurately determining the natural frequency of coal-containing geological structures is crucial for preventing mine dynamic disasters and utilizing vibration waves to break coal and enhance its permeability. Based on the modal theory of rock, vibration models of coal-containing geological structures, including layering and fractures are established. By analysis, the undamped vibration equation and its characteristic equation for both the layered coal system and the fractured coal system are derived. Subsequently, the Lanczos method is employed to solve the system’s vibration modes using ABAQUS. The effects of the layering position, layering thickness, layering physical properties, crack width, and crack length on the natural frequency and vibration response of coal-containing geological structures are investigated. The results indicate that when a single influencing factor is altered, the displacement response distribution of the coal body vibration system with geological structures remains essentially the same, and these single influencing factors have a minimal impact on the vibration displacement of the coal-containing geological structure. The natural frequency of the system decreases exponentially as the distance between the layering and the geometric center of the coal system with geological structures increases. The presence of layering in the coal system with geological structures significantly reduces the system’s natural frequency. The natural frequency of the coal system with geological structures increases in a power function manner as the layering elastic modulus increases. Conversely, the natural frequency decreases with an increase in crack length. When the change ranges of crack width and bedding thickness are the same, the natural frequency of the fractured coal body system exhibits more significant changes. The natural frequency of the coal system with geological structures initially decreases and then increases as bedding thickness and crack width increase. The trend in the natural frequency changes and the position of the extreme point are related to the ratio of the elastic modulus and density of the geological structure.

Effects of waste oyster shell replacing fine aggregate on the dynamic mechanical characteristics of concrete

Waste oyster shells (WOS) have the potential to serve as a construction material, offering a sustainable alternative to traditional fine aggregates in the production of WOS concrete. This can play a critical role in reducing environmental issues resulting from the overexploitation of river sand and the haphazard disposal of WOS. Although existing research has predominantly focused on understanding the static mechanical characteristics of concrete when WOS is employed, the dynamic mechanical properties have still received less attention. To understand the impact of WOS as a substitute for fine aggregates on the dynamic mechanical properties of concrete, a series of tests employing Split Hopkinson Pressure Bar (SHPB) were carried out. The findings demonstrate that the peak stress and elastic modulus increase as the WOS substitution ratio (Sr) increases from 0 to 20% but exhibit an exponential decline as Sr increases from 20 to 100%. This response can be explained by the joint effects of the pore-filling effect caused by WOS sand and the increasing air content caused by WOS sand. As Sr increases from 0 to 20%, the pore-filling mechanism becomes predominant as the water absorption rate decreases slightly from 4.31 to 3.83%. However, for Sr increasing from 20 to 100%, the negative influence of the air content becomes the primary contributing factor, where the water absorption rate increases from 3.83 to 14.68%. Furthermore, under the same impact pressure, the concrete with Sr = 20% absorbed the most energy, providing the best dynamic mechanical performance. These findings highlight the potential use of WOS in concrete for improving its dynamic characteristics, promoting both sustainable construction and enhancing the material properties in impact-resistant structures.

Effect of fiber content on flexural properties of jute fiber reinforced perlite/gypsum composite core-based sandwich structures

In this work, two types of sandwich structures were fabricated to develop sustainable building materials using renewable and waste resources. The chopped jute fiber reinforced perlite-filled gypsum composite was used as the core and the brown paper and the woven jute fiber reinforced epoxy composite (JFRC) were used as skins to manufacture the sandwiches. The effect of jute fiber content (10 g - 20 g) in the core on the flexural properties was studied. The flexural test was conducted to determine the flexural strength, modulus, energy absorption, and the load-bearing capacity of brown paper skin-based sandwiches (BPSS) and JFRC skin-based sandwiches (JFSS). The results of this study show that the flexural properties of both BPSSs and JFSSs are improved significantly with increasing jute fiber content up to 17.5 g indicating the optimum fiber content. The flexural strength and modulus of BPSS at 17.5 g jute fiber content are respectively 8.44 % and 30.16 % greater than those at 10 g jute fiber content. On the other hand, the JFSSs show 30.24 % and 60.36 % increase in flexural strength and modulus respectively at 17.5 g jute fiber content compared to those at 10 g fiber content. The flexural energy absorptions of BPSS and JFSS are also increased by 45.40 % and 22.90 % respectively when jute fiber content in the core is increased from 10 g to 17.5 g. The specific load-bearing capacity of JFSSs is 130.38 % - 216.56 % greater than BPSSs depending on the fiber content in the core.

Effect of clays incorporation on properties of thermoplastic starch/clay composite bio-based polymer blends

In this study, thermoplastic starch (TPS) biofilms were developed using starch isolated from the seeds of Melicoccus bijugatus (huaya) and reinforced with bentonite clays at concentrations of 1%, 3%, and 5% by weight. Novelty of this research lies in utilizing a non-conventional starch source and enhancing properties of TPS through clay reinforcement. FTIR analysis verified bentonite’s nature of clays, while SEM analysis provided insights into morphology and agglomeration behavior. Key findings include a notable increase in biofilm thickness and elastic modulus with higher clay content. Specifically, tensile strength of biofilms improved from 2.5 MPa for pure TPS to 5.0 MPa with 5% clay reinforcement. The elastic modulus increased from 25 MPa (TPS) to 60 MPa (5% clay). Thermal stability also showed enhancement, with initial degradation temperature increasing from 110 °C for pure TPS to 130 °C for TPS with 5% clay. Water vapor permeability (WVP) tests demonstrated a decrease in WVP values from 4.11 × 10−10 g m−1 s−1 Pa−1 for pure TPS to 2.09 × 10−10 g m−1 s−1·Pa−1 for TPS with 5% clay, indicating a significant barrier effect due to clay dispersion. These results suggest that biofilms based on huaya starch and reinforced with bentonite clay have considerable potential for sustainable food packaging applications, offering enhanced mechanical and barrier properties.

Lateral kinematic properties of offshore pipe piles embedded in saturated soil considering soil plug effect

AbstractThis study establishes a theoretical framework for analyzing the lateral oscillation of marine pipe piles. The additional mass model is introduced herein to consider the inertial fluctuation effect of the soil plug. Analytical mathematical methods are used to determine the complex impedance variation of the pile over a range of frequency effects. An investigation is performed to determine how the presence of soil plugs changes the lateral complex stiffness and natural frequency of pipe piles. Additionally, comparisons of the applicability of the plane strain model and continuous medium model have been conducted to enable the easy use of the theoretical model. The main conclusions can be drawn as (1) if the fluctuation inertia effect of the soil plug is not taken into consideration, the dynamic active length and the dynamic stiffness of the pipe pile will be underestimated; (2) for the soft soil, the plane strain model may give rise to substantial calculation errors attributed to them regardless of the vertical continuity of the soil, nevertheless, the calculation error decreases rapidly with the increase of soil shear modulus and vibration frequency.

Behavior of self-sensing masonry structures exposed to high temperatures and rehydration

High temperatures can compromise the structural integrity of structural masonry. Therefore, assessing the post-fire mechanical behavior is crucial for selecting suitable rehabilitation methods. Recent research has proposed the application of self-sensing cementitious composites for monitoring strains, stresses, and damage of structural masonry in room temperature. No previous research has been found on the self-sensing performance of fire-damaged masonry prisms exposed to elevated temperatures, with or without subsequent rehydration. Masonry prisms with integrated self-sensing joints and blocks were produced and exposed to different maximum temperature levels, followed or not by rehydration. Then, experimental tests for determination of compressive strength, modulus of elasticity, gauge factor (GF) and damage-detection performance were carried out. The exposure to 300 ºC caused a 7.4 % decrease in compressive strength and a 44.5 % reduction in elastic modulus. Rehydration methods had negligible effects in this case. After 600 ºC, substantial reductions of 42.2 % in compressive strength and 81.5 % in elastic modulus occurred. In this case, rehydration led to a 15.9 % increase in compressive strength and a 117.4 % increase in elastic modulus. Regardless of the exposure temperature, the predominant rupture mode initiated by vertical cracks originating at the block-mortar interfaces. After 300 ºC, slight GF increases occurred due to the thermal decomposition of hydrates of the cementitious matrix, while exposure to 600 ºC resulted in high GF increases due to partial oxidation of nanomaterials and substantial microcracking propagation. Post-fire curing improved the GF by sealing microcracks with nonconductive rehydration products and enhancing tunneling conduction mechanisms. The self-sensing prisms also demonstrated the ability for real-time damage detection and quantification, providing valuable predictive insights into the propagation of damage.

Mechanical and Thermal Properties of Epoxy Resin upon Addition of Low-Viscosity Modifier.

Thermoset-based polymer composites containing functional fillers are promising materials for a variety of applications, such as in the aerospace and medical fields. However, the resin viscosity is often unsuitably high and thus impedes a successful filler dispersion in the matrix. This challenge can be overcome by incorporating suitable low-viscosity modifiers into the prepolymer. While modifiers can aptly influence the prepolymer rheology, they can also affect the prepolymer curing behavior and the mechanical and thermal properties of the resulting matrix material. Therefore, this study investigates the effects that a commercial-grade low-viscosity additive (butyl glycidyl ether) has on a common epoxy polymer system (diglycidyl ether of bisphenol-A epoxy with a methylene dianiline curative). The weight percentage of the modifier inside the epoxy was varied from 0 to 20%. The rheological properties and cure kinetics of the resulting materials were investigated. The prepolymer viscosity decreased by 97% with 20 wt% modifier content at room temperature. Upon curing, 20 wt% modifier addition reduced the exothermic peak temperature by 12% and prolonged the time to reach the peak by 60%. For cured material samples, physical and thermo-mechanical properties were characterized. A moderate reduction in glass transition temperature and an increase in elastic modulus was observed with 20 wt% modifier content (in the order of 10%). Based on these findings, the selected material system is seen as an expedient base for material design due to the ease of processing and material availability. The present study thus provides guidance to researchers developing polymer composites requiring reduced prepolymer viscosity for successful functional filler addition.

Microstructural and rheological influence of different strategies to mitigate oil migration in chocolate pralines during storage in limiting conditions

Chocolate pralines are metastable systems in which oil migration, particularly at high storage temperatures, represents the main contributor to quality loss. In this study, two strategies were compared to retard this migration respect to a control sample (C); the use of a barrier consisting of cocoa butter high-melting (CB) and the use of an oleogel realized with beeswax and sunflower oil (CA). Samples were stored in thermal abuse conditions (28 °C) and subjected to: microstructural, rheological and ability to retain oil in the filling analysis and colorimetric evaluation. Microstructure highlighted the highest percentages of oil in CA samples filling during storage, respect to C and CB, as confirmed by oil release. According to fundamental rheological analysis, C and CB showed the highest filling yield stress values respect to CA, which showed a linear and homogenous trend. Dynamic rheological analysis underlined the presence of an increase in the elastic modulus during storage, suggesting matrix aggregation and gummy filling cream, which was lowest for CA, supporting the positive effect exhibited by this barrier. For empirical-imitative analysis, CA showed a more spreadable and creamy filling. Results revealed the ability of beeswax oleogels to improve quality attributes of pralines during storage, also at higher temperatures.

Effect of hyaluronic acid-based viscosupplementation on cartilage material properties

Viscosupplementation by intra-articular injections of hyaluronic acid (HA) is used to treat symptomatic osteoarthritis. Exogenous HA remains in the joint cavity for a short period of time (days) while claimed pain relief period lasts over months. There is a clear lack of understanding of viscosupplementation mechanism of action. Here, we hypothesize that HA penetrates the cartilage and contributes to the restoration of its mechanical quality.Confocal microscopy and bio-indentation were used to confirm HA penetration into cartilage and modulation of cartilage quality. Bio-indentation was performed on rat distal femurs incubated overnight in HA solutions, using phosphate buffered saline (PBS) as control. For this proof-of-concept evaluation, measurements of elastic modulus (MPa) and of maximal force (µN) were recorded before and immediately after exposure with HA, as well as after an additional washout with PBS. Cartilage thickness at the site of indentation was evaluated by contrast enhanced computed tomography with an ionic contrast agent. Indentation depths were located in the upper part of hyaline cartilage. Ostenil®, commercial product containing 1 % HA, induced a decrease in indentation depth in the range of forces influencing the whole cartilage thickness, together with an increase of the elastic modulus. Then, bio-indentation and size distribution of HA chains via SEC-SLS were assessed for a range of commercially available products. The results showed higher modulation of cartilage quality in the presence of 0.25–1 MDa HA chains.The present in vitro study suggests that HA modulates cartilage quality and might thus explain the long-term beneficial effect of viscosupplementation.

Design and additive manufacturing of novel hybrid lattice metamaterial for enhanced energy absorption and structural stability

In this work, a novel dual-phase metamaterial, named as “hybrid lattice metamaterial (HLM),” are designed and fabricated by combining reentrant and sea-urchin (SU) based surface-lattice (SL) structure with polyamide12 (PA12) material via material extrusion (MEX) process. Four different designs with varying reentrant truss thicknesses of 0.8 mm (H1), 1.0 mm (H2), 1.2 mm (H3), and 1.5 mm (H4) have been modified to assemble seamlessly with the empty spaces within the SL structure. Quasistatic compression tests were conducted to evaluate the deformation modes and compression characteristics. The findings from quasistatic experiments were subsequently validated using numerical simulations. The H4 metamaterial exhibited superior structural properties, with 42 % increase in stiffness and 35 % enhancement in specific energy absorption compared to only SL structure. Additionally, dynamic sinusoidal compression tests were conducted to evaluate the dynamic elastic ratio (DER), hysteresis work and viscoelastic properties using the tan δ. The H4 metamaterial outperformed the SL in all dynamic properties, with a 50 % increase in elastic modulus and 36 % increase in hysteresis work. This study shows metamaterial properties can be tailored for specific requirements. SL structure facilitate elastic recovery, while H4 metamaterials offer superior energy absorption and stability, making it well-suited for protective equipment and impact-resistant components.

4D printed Electroactive carbon fiber and carbon nanotube synergistically reinforced composites for supporting personalized insole

Smart footwear plays a vital role in walk correction, with mechanical behavior and shape memory effect (SME) being essential aspects. To create personalized smart insoles, we developed a novel blend of polylactic acid (PLA), thermoplastic polyurethane (TPU), and carbon nanotubes (CNT) via melting-extrusion for a continuous-fiber 3D printer. Diverse insole support unit-cell structures (triangular, rhombus, grid) were fabricated with PLA/TPU/CNT filaments, incorporating continuous carbon fibers (CFs) in the front, middle, and back parts of a particular orthopedic insole. The compressive strength and modulus of samples unexpectedly decreased upon CNT incorporation. However, CNT in the TPU phase improved the shape memory performance, shortening the recovery time by 58 %. CF-reinforced composites exhibited excellent mechanical properties and SME; the front triangular structure showed a 13.4 times increase in compressive strength and a 22.6 times increase in modulus compared to free-fiber composites. The printed samples demonstrated remarkable electro-induced shape memory properties due to the dual conductive network formed by CF and CNT. Our PLA/TPU/CNT/CF (nano-) composite is well-suited for personalized shape-memory insole applications, offering enhanced mechanical performance and electro-induced shape-memory capabilities.

Identification of Effects of Parylene-C Coating on Electrospun Fibers

As various healthcare technologies such as regenerative medicine, precision medicine, and alternative approaches to animal testing develop, the interest in the use and application of nano- and microfibers is steadily increasing. In this study, the effect of parylene-C coating on electrospun fibers was investigated, and a pattern coating method was developed to expand the potential utilization of parylene-C-coated electrospun fibers. An SEM analysis demonstrated that parylene-C was successfully deposited on the electrospun fibers without any failure such as pinholes or air bubbles. Biocompatibility was investigated through cell tests, which indicated that the coated fibers were non-toxic and supported cell growth well. Tensile tests demonstrated a significant increase in the elastic modulus of the parylene-C-coated fibers, with it nearly quadrupling compared to the original PCL fibers, and the fracture strength almost doubled. At the same time, hydrophobicity was well maintained without any statistically significant changes. In particular, a non-adhesive magnet–metal masking was proposed in order to selectively coat the electrospun fibers with parylene-C with a specific pattern. Furthermore, it was presented that the magnet–metal mask-based coating electrospun nanofibers with parylene-C could be used in the fabrication of hybrid fibers composed of different diameters and materials.

Influence of nanofiller surface treatment on mechanical properties of pyrolyzed ceramic nanocomposites

The brittleness and limited plastic deformation of ceramics restrict their applications. In this work, the effects of pristine (CNTP), functionalized (CNTOH, CNTCOOH) and silanized MWCNTs on the mechanical properties of Silicon Carbide obtained by pyrolyzing polycarbosilane SMP-10 were studied. Functionalization with 3-glycidoxypropyltrimethoxy was analyzed through dispersion stability, zeta potential, and EDS analyses, revealing increased silicon content and colloidal stability in silanized MWCNTs. However, silanized MWCNTs led to reduced mechanical properties in composites, while untreated MWCNTs (CNTP, CNTOH, CNTCOOH), showed a substantial increase in modulus by 74.2 %, 86.9 %, and 30.5 %, respectively. The observed enhancement in mechanical properties exceeded the outcomes predicted by the rule of mixtures, suggesting notable morphological changes induced by MWCNTs. Potential underlying factors including toughening mechanisms and changes in porosity were evaluated and discussed in depth. Composites with untreated MWCNTs showed nearly a two-fold increase in fracture toughness. This work shows a streamlined approach for the development of ceramic nanocomposites (CNCs), achieving significant improvement in mechanical properties through pyrolysis, surpassing traditional methods reliant on densification processes. These findings demonstrate the substantial potential of CNCs, enhancing their suitability for advanced engineering applications.

Investigation of mechanical properties of compatibilized polyvinyl chloride/polylactic acid nanocomposites

AbstractPolymer alloying is particularly important due to the possibility of choosing a wide range of materials and the ability to design a product with desired properties. In case of incompatibility between the components, the resulting alloy cannot meet the set of desired properties and shows poor performance. In this research, alloys of polyvinyl chloride and polylactic acid were prepared in an internal mixer and nanoclay and maleic anhydride‐grafted styrene‐ethylene/butylene‐styrene (SEBS‐g‐MAH) compatibilizer were used to improve the properties. In order to investigate the morphology and phase distribution of polylactic acid, scanning electron microscope images were taken. Tensile and dynamic mechanical thermal analysis tests were performed to evaluate the properties of the samples. The scanning electron microscope test images show the improvement of system uniformity by adding compatibilizer to the alloy. Adding nanoclay to the alloy increased the storage modulus and uniformity of the system. An increase in glass transition temperature and storage modulus was observed in the samples containing compatibilizer, and the uniformity of the system was also improved. The tensile test results showed that by adding nanoclay up to 3 % by weight, the tensile strength and Young′s modulus increase. Addition of compatibilizer up to 5 % by weight increased the physical and mechanical properties.

Corrosion resistance of polymer-modified hardened cement paste and phosphoric acid-activated metakaolin geopolymer in carbonic acid solution

Corrosion resistance of hardened Portland cement paste (HCP), polymer-modified hardened cement paste (PHCP) and phosphoric acid-activated metakaolin (PMK) geopolymers in carbonic acid solution was comparatively evaluated by multiple techniques of thermogravimetry (TG), energy dispersive spectrometer (EDS), fourier transform infrared spectrometer (FTIR), inductively coupled plasma optical spectrometer (ICP), microindentation and compressive tests. The incorporated polymer kinetically slows down the corrosion process of Portland cement paste as the carbonation depth of PHCP is lower than those of HCP characterized by all techniques. Meanwhile, the addition of polymer slightly hinders leaching of substances from HCP by blocking the pores. Despite the increase of elastic modulus, decreases of compressive strength of both HCP and PHCP samples caused by carbonation are observed probably due to the generation of microcracks and uneven brittleness across the section. PHCP presents less mechanical loss after carbonation treatment than HCP. PMK geopolymer samples soaked in deionized water and carbonic acid solution have comparatively identical results of TG, EDS, FTIR and mechanical measurements, indicating that the PMK geopolymer is highly resistant to carbonic acid, thanks to its inherent acidic nature. In addition, the leaching amount of PMK geopolymer in carbonic acid solution is also much less than the HCP and PHCP.

A Mathematical Model for Postimplant Collagen Remodeling in an Autologous Engineered Pulmonary Arterial Conduit.

This study was undertaken to develop a mathematical model of the long-term in vivo remodeling processes in postimplanted pulmonary artery (PA) conduits. Experimental results from two extant ovine in vivo studies, wherein polyglycolic-acid (PGA)/poly-L-lactic acid tubular conduits were constructed, cell seeded, incubated for 4 weeks, and then implanted in mature sheep to obtain the remodeling data for up to two years. Explanted conduit analysis included detailed novel structural and mechanical studies. Results in both studies indicated that the in vivo conduits remained dimensionally stable up to 80 weeks, so that the conduits maintained a constant in vivo stress and deformation state. In contrast, continued remodeling of the constituent collagen fiber network as evidenced by an increase in effective tissue uniaxial tangent modulus, which then stabilized by one year postimplant. A mesostructural constitute model was then applied to extant planar biaxial mechanical data and revealed several interesting features, including an initial pronounced increase in effective collagen fiber modulus, paralleled by a simultaneous shift toward longer, more uniformly length-distributed collagen fibers. Thus, while the conduit remained dimensionally stable, its internal collagen fibrous structure and resultant mechanical behaviors underwent continued remodeling that stabilized by one year. A time-evolving structural mixture-based mathematical model specialized for this unique form of tissue remodeling was developed, with a focus on time-evolving collagen fiber stiffness as the driver for tissue-level remodeling. The remodeling model was able to fully reproduce (1) the observed tissue-level increases in stiffness by time-evolving simultaneous increases in collagen fiber modulus and lengths, (2) maintenance of the constant collagen fiber angular dispersion, and (3) stabilization of the remodeling processes at one year. Collagen fiber remodeling geometry was directly verified experimentally by histological analysis of the time-evolving collagen fiber crimp, which matches model predictions very closely. Interestingly, the remodeling model indicated that the basis for tissue homeostasis was maintenance of the collagen fiber ensemble stress for all orientations, and not individual collagen fiber stresses. Unlike other growth and remodeling models that traditionally treat changes in the external boundary conditions (e.g., changes in blood pressure) as the primary input stimuli, the driver herein is changes to the internal constituent collagen fiber themselves due to cellular mediated cross-linking.

Self-adhesive fiberboards fabricated from waste bamboo powder through biological pretreatment

Using renewable and sustainable agricultural and forestry wastes to produce bio-based materials is an effective approach for significantly reducing the environmental pollution caused by petroleum-based materials such as plastics and chemical fibers. This research aims to develop a cleaning process for large-scale production of high-performance green bio-based materials without the use of any chemical binders. The mechanical properties of self-adhesive fiberboards are improved through pretreatment with white rot fungi. By pretreating bamboo powder with biological factors like sugars and laccase produced by white rot fungi under high temperature and pressure, lignin-active molecules are formed on the surface. These active molecules can reconstruct chemical bonds between multi-fiber materials, thereby exhibiting biological adhesion. The reconfiguration of lignin molecules on the material's surface also helps prevent rapid water penetration. After biological pretreatment, the surface of bamboo powder forms a concave-convex structure, effectively increasing the area of biological adhesion during hot-pressing conditions. Compared to regular bamboo powder control samples, bio-pretreated fiberboards showed an increase in modulus of rupture (MOR) by 83.33 % and modulus of elasticity (MOE) by 100.79 %. In contrast to traditional fossil-based adhesive synthetic materials, the findings of this study circumvent the emission of harmful volatiles from chemical adhesives while effectively substituting petroleum-based synthetic materials that necessitate diverse chemical additives, which are in alignment with the principles of environmental protection and sustainable development.

Topological Rearrangement-Induced Mesoscale Phase Redistribution to Enhance the Fatigue Resistance of Polymer Blends.

Maintaining a high modulus to simultaneously withstand deformation and increase fatigue resistance to restrict crack propagation in a material presents a significant challenge. In this work, a straightforward strategy was developed to address this issue in polymers. A dynamic network was incorporated into a permanent one prior to the formation of the latter, and two incompatible polymer networks were created to prevent common phase separation. The mechanical and fatigue resistance properties were substantially enhanced by the exact modulation of the soft and hard phase distribution by precise control over the densities of dynamic and permanent networks as well as the number of reprocessing steps. The experimental results demonstrated a nearly 9-fold increase in the fatigue life of polyurethane compared with traditional design methods and a 2.5 times increase in modulus. This strategy shows potential for the design of fatigue-resistant thermosetting and thermoplastic materials. The results offer new insight into the development of durable, high-performance materials that are reprocessable and compatible.

Effect of ionic liquid [emim][OAc] on the set recovery behavior of densified wood

Wood modification techniques, like densification, can improve the mechanical performance of low-density and undervalued wood species, rendering them suitable for high-value engineering applications. Nevertheless, densified wood (DW) commonly manifests a set recovery (SR) phenomenon when exposed to water, negating the enhancements achieved through densification. Our method addresses the SR issue and the non-recyclability associated with conventionally produced DW using chemical techniques in wood densification. To mitigate SR in DW, an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate was impregnated as a cellulose plasticizing agent prior to wood densification. This method facilitated permanent deformation within the cellulose network, resulting in negligible SR. Moreover, the DW treated with IL (DW_1w) demonstrated an increase in both modulus of rupture and modulus of elasticity after water washing and subsequent redrying, in comparison to the untreated control (UC). Notably, spectroscopic (FTIR) analyses indicated that the chemical structure of DW_1w remained akin to that of UC. Additionally, the IL leached out during the DW-water washing step can be recovered. This research contributes to advancing sustainable alternatives to less ecologically friendly (chemical) pretreatment methods to reduce SR related issues in DW.

Elastic and strength properties of MXene/CNT reinforced epoxy/glass fibre based nanocomposites: Experimental and analytical study

In the current work, the strength and elastic properties of MXene/CNT reinforced epoxy/glass fibre based nanocomposites were investigated using experimental and analytical approach. To achieve this, the Halpin-Tsai model and Chamis model was employed to evaluate the mechanical properties of two -phase (MXene-CNT)/Epoxy composite and three-phase (MXene-CNT)/Epoxy/Glass fibre composite. The accuracy of the analytical model was verified by comparing the results with the experimental data. To study the strength properties of the composites in detail, experimental tensile and flexural tests were carried out. Finally, a parametric study was performed to investigate the influence of weight fractions and aspect ratios on the elastic properties of MXene/CNT reinforced composites. It was observed that the MXene/CNT reinforced glass/epoxy based composite exhibited higher load bearing capacity as compared to neat glass/epoxy composite for all the performed mechanical tests. The tensile, shear and flexural modulus of MXene/CNT reinforced laminated composite were found to be 17.2%, 15.6%, and 16.2%, higher in comparison to the neat glass/epoxy laminated composite. The addition of nano-fillers exerted positive impact on the elastic properties of both the two-phase and three-phase nanocomposites and the properties kept on improving with weight fraction of the nano-fillers. Regarding the impact of aspect ratio on elastic modulus, however, conflicting findings were noted. Increase in the aspect ratio, on one hand, resulted in an increase in the longitudinal elastic modulus; on the other hand, it resulted in a monotonous reduction in the shear modulus.