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The dynamic response and damage fracture of brittle materials under explosive cutting have always been important research issues in the fields of military, aerospace, and other engineering fields. In this paper, a linear shaped charge cutting model for explosive cutting of brittle materials is proposed. This model suggests that explosive cutting is caused by the combined effects of jet penetration, spallation, and impact fracture. Theoretical calculation models for jet penetration, spallation, and impact fracture were constructed, and the concept of impact strength was introduced to establish dynamic mechanical performance parameters for brittle materials. A calculation program for explosive cutting of brittle materials was developed using the Python language, which can calculate the jet penetration depth, spallation thickness, and impact fracture thickness by inputting parameters such as the size and mechanical properties of the linear shaped charge and target plate, and determine whether the target plate can be successfully cut. Subsequently, a series of explosion cutting experiments and numerical simulations for brittle target plates were conducted to verify the accuracy of the calculation program. The results indicate a high degree of consistency between simulation, experimentation, and program calculation results. This work can provide guidance and promotion for the design and application of explosive energy harvesting cutters. [ABSTRACT FROM AUTHOR]

The best known solutions for k-message broadcast in dynamic networks of size n require Ω (nk) rounds. In this article, we see if these bounds can be improved by smoothed analysis. To do so, we study perhaps the most natural randomized algorithm for disseminating tokens in this setting: at every timestep, choose a token to broadcast randomly from the set of tokens you know. We show that with even a small amount of smoothing (i.e., one random edge added per round), this natural strategy solves k-message broadcast in \(\tilde{O}(n+k^3)\) rounds, with high probability, beating the best known bounds for \(k=o(\sqrt {n})\) and matching the Ω (n+k) lower bound for static networks for k=O(n1/3) (ignoring logarithmic factors). In fact, the main result we show is even stronger and more general: Given ℓ-smoothing (i.e., ℓ random edges added per round), this simple strategy terminates in \(O(kn^{2/3}\log ^{1/3}(n)\ell ^{-1/3})\) rounds. We then prove this analysis close to tight with an almost-matching lower bound. To better understand the impact of smoothing on information spreading, we next turn our attention to static networks, proving a tight bound of \(\tilde{O}(k\sqrt {n})\) rounds to solve k-message broadcast, which is better than what our strategy can achieve in the dynamic setting. This confirms the intuition that although smoothed analysis reduces the difficulties induced by changing graph structures, it does not eliminate them altogether. Finally, we apply tools developed to support our smoothed analysis to prove an optimal result for k-message broadcast in so-called well-mixed networks in the absence of smoothing. By comparing this result to an existing lower bound for well-mixed networks, we establish a formal separation between oblivious and strongly adaptive adversaries with respect to well-mixed token spreading, partially resolving an open question on the impact of adversary strength on the k-message broadcast problem. [ABSTRACT FROM AUTHOR]

This study examines how the strength of social ties between focal and peer fundraisers interacts with the network structure generated by these social ties to determine crowdfunding performance. With relationship intensity and preference similarity between focal and peer fundraisers as the two dimensions of tie strength, our study discloses how the benefits and costs associated with these tie strength dimensions are affected by network closure, the degree to which peer fundraisers are connected to each other. Our estimation results indicate that (1) relationship intensity and preference similarity exhibit inverted U-shaped relationships with crowdfunding performance, and (2) network closure attenuates the effectiveness of tie strength dimensions. Together, our study findings reveal an important interplay between indirect and direct social ties. In essence, social ties among peer fundraisers facilitate a group identity that reduces the returns of time and resources a fundraiser spends on strengthening ties with these peer fundraisers. [ABSTRACT FROM AUTHOR]

This study delves into the influence of inherent minerals within coal gangue (CG) on the preparation and performance of coal gangue /polyethylene (CG/PE) composites, focusing on the role of SiO2 in interfacial compatibility. A systematic examination unveils the consequences of varying SiO2 content on physical, mechanical, thermal, and microstructural attributes of the composites. SiO2 incorporation significantly improves physical properties, boosting density and hardness but impacting tensile strength negatively. It enhances bending strength and modulus while diminishing tensile strength. Judicious SiO2 addition enhances thermal stability, but excess SiO2 may compromise thermal decomposition. Microstructural analysis, including SEM and FTIR, elucidates SiO2‐PE interactions, primarily through physical entanglement. SiO2 introduction promotes more ordered PE molecular chain arrangements, elevating composite crystallinity. In summary, this study provides in‐depth insights into SiO2's mechanistic impact on CG/PE composite properties, laying a robust foundation for designing environmentally friendly composites. These findings hold promise for advancing sustainable materials science and engineering. Future research may explore SiO2 optimization for specific applications and synergistic effects with other fillers in composites. Highlights: SiO2 greatly improves the properties of CG/PE composites with detailed exploration.Reveals the specific SiO2‐PE interaction mechanism for a better comprehension.Performs structural analysis via XRD with valuable findings presented.Promotes pioneering advancements in eco‐friendly materials with broad significance. [ABSTRACT FROM AUTHOR]

This research proposes a novel sustainable composite using basalt (B), hemp (H) and polyurethane rubber (Pu) reinforced in nano clay functionalised epoxy matrix for sacrificial structural applications prone to low‐velocity impact (LVI). To this end, symmetric and asymmetric laminates such as HHHH, BBBB, BHHB, BHPuHB, BBPuHH and BPuBPuHPuH are fabricated using compression molding techniques and subjected to LVI at three different impact energies of 19.66, 39.39, and 59.05 J. The hemp fibers were treated with NaOH solution before fabrication. Material characterization such as X‐ray diffraction, Raman spectroscopy and morphological studies has been carried out. The impact and post‐impact properties of the proposed composites are experimentally evaluated and validated with the finite element (FE) results. The effect on the residual tensile strength degradation of laminates at different interlayers and energy levels is also investigated using the Caprino analytical model. The barely visible impact damages (BVID) are investigated through non‐destructive dye‐penetration tests, which facilitate easy identification of the prominent LVI damages like "Plateau" and "Cliff‐drop" impressions. Based on the impact energy absorption and residual tensile strength, proposed laminates followed BHPuHB > BBBB > BHHB > HHHH. The experimentation suggests that Polyurethane core laminates support maximum impact energy absorption by favoring a structural change in interlayers. Also, the residual tensile strength decreases as impact velocity increases. Highlights: Low‐velocity impact behavior of sustainable composites is experimented.Basalt, hemp and polyurethane rubber are reinforced in nano clay epoxy matrix.A FE framework to validate the experimentation is proposed.Dye penetrant NDT is adopted to investigate the damages.Morphological studies are conducted to understand LVI responses. [ABSTRACT FROM AUTHOR]

This study focused on the preparation of bamboo flour/Poly (butylene adipate‐co‐terephthalate) (PBAT) composites with high bamboo flour content and high mechanical strength using polyurethane prepolymer as chemical–physical compatibilizer via in‐situ reaction. Additionally, this work explored the effects of different bamboo flour contents and different types of polyurethane prepolymers on the mechanical properties, morphology, thermodynamics, water absorption, and surface wettability of the bamboo flour/PBAT composites. The results showed that PBA‐based polyurethane prepolymer (PBAPU) was an effective compatibilizer, promoting the interfacial adhesion between bamboo flour and PBAT. The strength at break, elongation at break, and impact strength of composites with 50% bamboo flour content reached 19.56 MPa, 25.53%, and 12.8 KJ/m2. With the increase of bamboo flour content, the strength of composites was still higher. The addition of PBAPU enhanced the thermal stability, mechanical properties, water resistance, and hydroscopicity of the bamboo flour/PBAT composites. Furthermore, the compatibilization of PBA‐based polyurethane prepolymer on composites was better than that of PCL‐based polyurethane prepolymer. Overall, we provided an effective strategy for preparing renewable, green, and practical high‐bamboo flour composites. Highlights: This work successfully prepared bamboo flour/PBAT composites with high bamboo content using an in‐situ melt blending reaction.A new interface structure of physical PBA‐PBA interaction between the PBAPU layer and PBAT matrix improved the compatibilization of the composites.PBAPU as a compatibilizer effectively improved the interface compatibility, thermal stability, and water resistance of Bamboo flour/PBAT blends.Bamboo flour/PBAT composites with high bamboo flour content have excellent mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, Washingtonia fibres (AW) and Kenaf fibres (KF) were utilized as environmentally friendly fillers to improve the quality of the resin matrix. The mechanical, morphological, and physical properties of the WA/KF biocomposites were assessed throughout this research. The mechanical tests (tensile strength and moduli, elongation at break, flexural strength along with moduli, and the impact properties) were carried out. The hybrid biocomposites (3AW/7KF) exhibited the highest tensile strength (16.05 MPa) and modulus (4.6 GPa) among pure and other hybrid biocomposites. The impact strength and resistance of hybrid biocomposites (1AW/1KF and 7AW/3KF) showed the highest impact strength (1694 J/m2) while the 3AW/7KF hybrid biocomposite, the impact strength value was 1630 J/m2 (17.2 J/m). SEM images indicated good distribution and bonding of hybrid biocomposites. The investigation using morphological tests (Scanning Electron Microscopy (SEM)) displays the longitudinal roughness on the surface, which acts as a very significant function in the adhesion between the AW/KF fibres and the resin. Furthermore, the results of SEM confirm better bonding in the biocomposites, fibre fracture, pull-out, fibre shearing, and tearing in the pure and hybrid composites. From the water absorption test, it was observed that, when increasing the immersion time of biocomposites, the WA percentage of KF biocomposite significantly increased (37%) compared to other biocomposites. However, the hybrid and pure biocomposites exhibited more resistance to increase the WA percentage after increasing the immersion times, compared to other biocomposites. Furthermore, the thickness swelling (TS) of hybrid biocomposites increased compared to pure biocomposites. The biocomposite sample (3AW/7KF) was thicker on the 7th day exhibiting the greatest increases in thickness swelling (4.98%) while the hybrid biocomposite exhibited greater WA value compared to other correspondence samples. Finally, the KF and AW hybrid blends can be appropriate for several applications, for example, textiles, machinery part production industries, medicine, and automobiles, and construction, specifically buildings, bridges, and structures such as boat hulls, swimming pool panels, racing car bodies, shower stalls, bathtubs, storage tanks. Overall, the findings exhibit that the hybridisation of natural fibres (KF/AW) is a sustainable approach for obtaining biocomposites with advanced mechanical and thermal performance. Hence, they could be used in numerous specific applications, including automobile panels, structural products, sporting goods and furniture tools. [ABSTRACT FROM AUTHOR]

Wood modification processes based on citric acid in combination with various copolymers have gained in importance in recent years. These processes also include modification with citric acid (CA) and sorbitol, a sugar alcohol, which is currently in the industrial realisation phase in Germany (SorCA) and Norway (CIOL). The modification of wood with sorbitol and citric acid (SorCA) can significantly improve the dimensional stability and durability of the wood. It is hypothesised that the addition of a copolymer may improve the fixation of the chemicals within as well as the flexibility of the modified wood matrix. In this study, the macroscopic changes, the fixation of the chemicals and the impact bending properties of wood modified with CA and SorCA are compared. Both modifications cause a permanent increase in mass (WPG) and volume (CWB). The fixation of the chemicals was comparable for both modifications; at high chemical concentrations, the SorCA polyester fixed slightly better within the wood matrix. Both modifications led to embrittlement of the wood, measured by a decrease in the impact bending strength (IBS). This embrittlement was clearly concentration-dependent and slightly more pronounced for the modification with CA. [ABSTRACT FROM AUTHOR]

The effect of resin modification through the incorporation of the biomass waste in the form of seashell powder on the mechanical properties of basalt fiber–reinforced epoxy/seashell composites is examined through experimental investigations. The resin modification is done through the addition of seashell powder in 5, 10, 15, and 20 wt.%. The modified resin is then reinforced with basalt fiber mat and the required laminate is obtained through compression molding technique. The specimens required for various mechanical tests, such as flexural, tensile, inter laminar shear (ILSS), and the impact strengths, are cut from the laminate as per the standard ASTM dimensions. The mechanical test results indicate that through the addition of the seashell filler additional toughening mechanisms are introduced which improves the strength of the composite laminate. The improvement in the flexural modulus value for all the laminates made from modified resin indicates the ability of the laminate to deflect the applied load effectively and efficiently. The optimum wt.% addition of seashell filler into the resin is found to be 5% for flexural, ILSS, and impact strength while for tensile strength it was observed to be 10%. The addition of higher wt.% loading of seashell filler into the resin has rendered the resin too thick and viscous with minimum flowability. Thus, there is a reduced wettability of the modified resin with the basalt fibers due to which the strength of the laminates reduces. The SEM analysis indicates widespread delamination for higher wt.% addition of the seashell filler into the resin. [ABSTRACT FROM AUTHOR]

In this study, we compare synergistic performance of two different nanofillers, namely halloysite nanotubes (HNT) clay and multiwalled carbon nanotubes (MWCNT), in conjunction with a fixed concentration (0.125 phr) of semi‐anthracite coal‐derived graphene oxide (AC‐GO) on mechanical properties improvement of EGFPs (E‐glass fiber‐based epoxy resin composites). The dispersion of AC‐GO with HNT clay (GO‐H) and AC‐GO with MWCNT (GO‐C) within epoxy matrix was achieved using sonication and homogenization. Further mixture was incorporated into mats of E‐glass fiber employing "vacuum‐assisted resin infusion molding" (VARIM). Significant enhancements (18.3% flexural strength, 14.6% tensile strength, and a slight increase of impact strength (1.8%)) were observed in EGFPs reinforced with GO‐H at 0.50 phr loading of HNT, with an AC‐GO concentration maintained at 0.125 phr. Correspondingly, optimal values for GO‐C reinforced EGFPs at 0.25 phr were 40.3%, 18.7%, and a 10.5% decrease in impact strength, respectively. Analytical techniques such as XRD, FESEM, EDX mapping, and FTIR reveal presence of relatively abundant functionalities and strong interfacial adhesion in GO‐H as well as GO‐C. The cost of HNT clay is approximately 15 times cheaper than industrial‐grade MWCNTs, therefore, these results underscore potential of GO‐H as a very economical nano‐reinforcement alternative to GO‐C for polymer nanocomposites. Highlights: 0.50 phr HAGRP improves 18.3% flexural, 14.6% tensile, 1.8% impact strengths.Beyond 0.50 phr HAGRP and 0.25 phr CAGRP, mechanical properties decreased.0.25 phr CAGRP improves 40.3% flexural, and18.7% tensile strengths.FESEM, FTIR reveal strong interfacial adhesion between nanofillers and epoxy.GO‐H has proven to be an inexpensive reinforcement for polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Inorganic fillers like hexagonal boron nitride (h‐BN) have the potential to enhance the thermal conductivity of polymer mixtures. However, it has been restricted due to poor dispersion of particles in polymer matrices by melt mixing process. The addition of inorganic powders into sticky prepolymer is expected to alleviate the aggregation of powders. In this paper, h‐BN/polymethyl methacrylate (PMMA) composites were prepared by in situ polymerization of methyl methacrylate (MMA) with 5 and 20 μm of h‐BN particle as fillers respectively, for even distribution of fillers with in composites. The structures and properties of composites were characterized by FT‐IR, DSC, TGA, SEM, laser thermal conductivity meter and universal electronic tester. By SEM, it can be seen that a highly uniform dispersion of h‐BN in PMMA. When the mass fraction of h‐BN is 20 wt%, the thermal conductivity of the composites is increased by 107% for 5 μm h‐BN and 189% for 20 μm h‐BN, respectively. With the mass constituting of 5 wt% h‐BN, majority of mechanical characteristics of the composite, such as tensile strength, tensile modulus, along with impact strength, are enhanced, alongside a decrease in bending strength. This work would provide a filling strategy of h‐BN into the polymer matrices to achieve uniform dispersion, and enhance both the thermoconductivity and mechanical strength of thermoplastic composites. Highlights: A technique for creating h‐BN/PMMA composites using in suit redox polymerization.Ehancing the thermal conductivity of these composites is achievable through the even distribution of h‐BN flakes within the PMMA matrix.It provides a reference for the design of future h‐BN/PMMA composites with favorable the thermal conductivity which achieves a good balance between performance and cost. [ABSTRACT FROM AUTHOR]

Highlights The widespread use of thermoset composites has raised significant environmental and economic concerns due to their non‐recyclable nature. This study addresses these issues by developing vitrimers and their composites featuring dynamic imine bonds synthesized from vanillin, 3,3′‐dimethyl‐4,4′‐diaminodicyclohexylmethane, and epoxy. To enhance toughness and bio‐content in the vitrimer and its composites, a green reactive monomer, epoxy methyl ricinoleate (EMR), was synthesized via the transesterification of epoxidized castor oil (ECO) and incorporated as the reactive diluent. The effect of EMR on bio‐resin mechanical, thermo‐mechanical, and relaxation times (τ) of the vitrimer was examined. The inclusion of EMR reduced the relaxation time, indicating improved dynamic bond exchange efficiency. EMR incorporation decreased the relaxation time, suggesting enhanced efficiency in the interchange of dynamic bonds. In addition, the incorporation of 20% EMR increased the impact strength of the epoxy vitrimer by 37.8%. The study also details the manufacturing and characterization of greener composites made with these vitrimers and flax fabric, which were evaluated for various mechanical and thermo‐mechanical properties. Morphological analysis using a scanning electron microscope revealed good interfacial adhesion between the fiber and matrix. Furthermore, the flax fiber vitrimer‐based composite demonstrated effective chemical recyclability. The results indicate that these composites possess mechanical and thermal‐mechanical properties well‐suited for lightweight engineering applications. Recyclable vitrimers were developed from vanillin and epoxy. Toughness and bio‐content were enhanced by adding EMR. Relaxation time was reduced by EMR, improving bond exchange efficiency. Epoxy vitrimer impact strength was increased by 37.8% with 20% EMR. Green composites with vitrimers and flax fabric were manufactured. [ABSTRACT FROM AUTHOR]

The widespread use of traditional petroleum‐based plastics is causing significant environmental pollution for example microplastics issues, due to its non‐biodegradability. Poly (lactic acid) (PLA) as a representative biodegradable polymer is a promising candidate to replace petroleum‐based plastics in some fields of disposable packaging materials and tableware. In this work, in order to improve the poor crystallization, mechanical and heat resistance performances of PLA, styrene–acrylonitrile‐glycidyl methacrylate (SAG) as a chain extender and octamethylenedicarboxylic dibenzoylhydrazide (ST‐NAB3) as a heterogeneous nucleating agent (HNA) were added simultaneously into PLA matrix. The chain‐extended PLA (CPLA) with branch structures had smaller crystal sizes and higher crystal density, compared with those of pure PLA. In addition, thanks to the nucleation effect of ST‐NAB3 and the development of "shish‐kebab", this tendency became more pronounced in CPLA/HNA systems. It was worth mentioning that, CPLA with the ST‐NAB3 content of 1 wt% (CPLA‐1) possessed the highest crystallinity of 43.6%. Meanwhile, CPLA‐1 had the best impact strength and heat deformation temperature of 38.9 kJ/m2 and 91.3°C respectively, which had increased by 11.3 kJ/m2 and 32.4°C contrast to pure PLA. On the whole, this study proposed a simple and effective method, which provided a new possibility for PLA modification research. [ABSTRACT FROM AUTHOR]

A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the "specific work of fracture" (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer "in situ" (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation. [ABSTRACT FROM AUTHOR]

While zirconia implants exhibit osseointegration comparable to that of titanium, concerns arise regarding low-temperature degradation and its potential impact on fracture strength. This study investigated the phase transformation and fracture characteristics of zirconia dental implants after aging through chewing simulation and subsequent static loading. The experimental setup involved 48 one-piece monobloc zirconia implants with diameters of 3.0 mm and 3.7 mm that had straight or angled abutments, with crown restorations, which were divided into six groups based on intraoral regions. The specimens underwent chewing simulation equal to five years of oral service, which was followed by static loading. Statistical analyses were performed for the data obtained from the tests. After dynamic and static loadings, the fractured samples were investigated by Raman spectroscopy to analyze the phase composition and micro-CT to evaluate fracture surfaces and volume changes. According to the results, narrow-diameter zirconia implants have low mechanical durability. The fracture levels, fracture patterns, total porosity, and implant fracture volume values varied according to the implant diameter and phase transformation grade. It was concluded that phase transformation initially guides the propagation of microcracks in zirconia implants, enhancing fracture toughness up to a specific threshold; however, beyond that point, it leads to destructive consequences. [ABSTRACT FROM AUTHOR]

Biochar is a well‐known sustainable and effective additive used in mortar/concrete to improve its mechanical properties. However, its potential to improve the impact resistance of concrete is still unexplored. This paper investigates biochar's effectiveness in improving the strength and impact performance of alkali‐activated slag concrete (AASC). Five AASC samples with 0%, 2%, 4%, 6%, and 8% rice husk biochar (RB) were employed in an experimental program. The strength and the impact resistance were tested, and the latter was assessed over a drop‐weight test conforming to the ACI Committee 544 guidelines. The crack propagation of the impact‐tested samples was examined using micro‐CT images. The results showed that adding RB up to 6% improved, notably the 28‐day compressive strength of AASC. At 6% RB, the strength enhancement was 44.6%, whereas no additional gain was observed at the 8% RB blend. More importantly, except for the 8% RB sample, the impact resistance was considerably augmented with the RB level increment. The increment in the impact number at the first crack and the failure in the 6% RB sample were as high as 185% and 180%, respectively. The reduction in the solution/binder ratio of the mix with the addition of biochar and the internal curing effect of biochar were deemed to be responsible for these improvements. However, possibly due to biochar's brittle characteristics, the increase in RB dosage from 6% to 8% reduced the impact resistance drastically. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical properties of the ultra‐high molecular weight polyethylene (UHMWPE) fiber‐reinforced high‐density polyethylene (HDPE) composite, carbon nanotube (CNT) was grafted on the UHMWPE fiber. The UHMWPE fiber/HDPE composite was prepared by injection molding process, and the effects of CNT contents on the mechanical properties of composite materials were studied. The results show that the mass fraction of CNT will significantly affect the mechanical properties of the composite. When the CNT content is 4 wt%, the tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength of the UHMWPE fiber/treated CNT/HDPE composite increased compared to the UHMWPE fiber/CNT/HDPE composite and UHMWPE fiber/HDPE composite. When the CNT content is 4 wt%, the above‐mentioned performance is the best. Pull‐out and fracture, bridging effect, and crack deflection effect are the main mechanisms of CNTs in UHMWPE fiber/HDPE composites. This study provides new insights into the interface design of UHMWPE fiber/HDPE composites and paves the way for their further development. [ABSTRACT FROM AUTHOR]

The current study attempts to explore the crystallographic, rheological and, dynamic mechanical properties of the submicron‐treated cenosphere (t‐ CSF) particles and sisal fiber (SF) reinforced Styrene‐(Ethylene‐Butylene)‐Styrene (SEBS) toughened PP hybrid composites. Moreover, the composites reinforced with 25 wt.% of SF and 5 wt.% of CSF (Treated 6 wt.% cetrimonium bromide (CTAB)) demonstrated the most significant storage modulus (E′), loss modulus (E"), and lowest damping (tan δ) factor throughout the temperature range. Likewise, X‐ray diffraction techniques were used to assess the samples' crystallographic properties. The composites reported an enhanced β phase (responsible for high impact strength and reduced α phase of the base matrix compared to pristine PP. Likewise, all the composites' rheological properties showed an improved complex viscosity (η*) compared to the BM but lower than that of the pristine PP. Overall processing parameters of the BM and composites were improved due to the decrement in the η* of all the composites. The rheological properties confirmed the easy processing of the fabricated composites due to the improved flowability. The storage (G′) and loss (G") modulus of all the composites were desirably higher than that of the BM. [ABSTRACT FROM AUTHOR]

The present study investigates the reactions of polystyrene and epoxy/polystyrene powder composites, exploring different weight percentages (8%, 12%, and 16%) of polystyrene during decomposition under highly elevated temperatures within a nitrogen atmosphere. The findings reveal that polystyrene content significantly influences the thermal behavior of pure epoxy, with a higher polystyrene content correlating with the increased thermal stability of the composites. This study observed a three-stage mass loss process by examining the reaction kinetics of thermal decomposition using the Coats-Redfern approach. Initially, weight reduction occurs due to moisture and volatile elimination, followed by a smooth mass loss phase attributed to weaker polymer chain linkages and, ultimately, char formation. Chemical kinetic parameters, such as activation energy and frequency factor, were successfully determined using the Coats-Redfern approach, with a first-order reaction observed across all data points, demonstrating a high R-square mean value of 99.8%. Differential scanning calorimetry (DSC) and thermal gravitational analysis (TGA) analyses revealed an increase in glass temperature from 86.95 to 92.85 °C and an elevation in activation energy from 75.38 to 92.85 kJ/mol with increasing polystyrene content (0–16 wt%). Furthermore, the study investigated the influence of thermodynamic parameters. In terms of mechanical properties, increasing polystyrene content reduced impact strength (from 8.5 to 4.23 Kj/m²). In contrast, hardness increased from 77.5 for pure epoxy to 80.4 at 12 wt% polystyrene content in the composite. These findings underscore the importance of thermal stability results in developing a comprehensive understanding of thermal decomposition processes, informing future research endeavors and industrial applications. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to investigate the relationship between microstructure and mechanical performance of polylactic acid when mixed with styrene-ethylene butylene-styrene copolymer and also graphene nanoplatelets. For this purpose, a series of neat polymer blends were first prepared with varying mixing ratios through a one-step melt mixing technique. Subsequently, the effect of various loadings of graphene nanoplatelets on the best mixing ratio (optimal composition) of the binary blend was investigated. To understand the different performances of various nanocomposites, the correlation of mechanical, rheological, and microstructural properties was thoroughly investigated using X-ray diffraction, scanning electron microscopy, linear viscoelastic behavior, tensile testing, and impact strength analyses. Furthermore, the influence of the mixing sequence of nanocomposites preparation on the microstructure and mechanical performance of nanocomposites was studied. Results demonstrated that the incorporation of graphene nanoplatelets as well as mixing sequence has a substantial effect on the final properties of prepared nanocomposites which was deeply discussed. [ABSTRACT FROM AUTHOR]

Reducing the dependence of epoxy resin preparation on petroleum resources and developing thermosetting epoxy resins with excellent comprehensive performance are important directions for the current development of epoxy resins. This article uses biomass resource magnolol as the main raw material to prepare magnolol epoxy monomer (DGEM). Then, using 4,4-diaminodiphenylmethane (DDM) as the curing agent, the DGEM and bisphenol A epoxy resin (E44) were blended and cured. The results showed a dual modification effect of DGEM on the toughening and strengthening of E44 epoxy resin. When the mass ratio of DGEM to E44 is 30:70, the bending strength of the cured blended resin is 18.7% higher than that of the E44 system, and the tensile strength is 57.7% higher. When the mass ratio of DGEM to E44 is 5:95, the cured blended resin exhibits the optimal impact strength (5.10 kJ/mol), which is 22.9% higher than the pure E44 system. However, the addition of DGEM reduced the glass transition temperature and crosslinking degree of the blended resin system. The addition of DGEM improves the heat resistance and flame retardancy of the blended resin. When the mass ratio of DGEM: E44 was 50:50, the vertical combustion reached UL-94 V-0 level. [ABSTRACT FROM AUTHOR]

This paper presents a numerical parametric study to examine the structural response of drilled shaft footings (pile caps) presenting different design characteristics, which have not been studied in depth in previous experimental studies. The numerical analyses were conducted with nonlinear finite element models representing typical designs and details of actual footings. The modeling scheme was validated using experimental data from large-scale drilled shaft footings. Key parameters of the numerical study included footing geometric properties, concrete strength, and reinforcement ratios. The results of the parametric studies were examined to identify key behavioral and design aspects to be considered when using 3D strut-and-tie models for the design of drilled shaft footings. The analysis results show that influences associated with footing and column aspect ratios were essentially negligible. However, it was estimated that an increase of the angle of inclination between the compression strut and the vertical axis led to significant reductions in footing stiffness and load capacity. The effect of shaft diameter was also examined in light of lateral concrete confining effects, and it was found that larger shaft diameters provide increased footing capacities. Analyses performed to estimate the influence of concrete compressive strength showed that splitting of the strut controlled the concrete-governed failure mechanism of footings. Finally, the models developed with different amounts of reinforcement revealed that increasing bottom mat reinforcement leads to increased ultimate loads; however, the rate of strength increase decreases with increasing reinforcement ratio. Providing a minimal amount of top mat and side face reinforcement was estimated to impact the structural responses of the footings positively; however, increasing the ratios of the top mat and side face reinforcing bars beyond this minimum did not significantly impact footing strength. [ABSTRACT FROM AUTHOR]

Microbially induced carbonate precipitation (MICP) represents a technique for biocementation, altering the hydraulic and mechanical properties of porous materials using bacterial and cementation solutions. The efficacy of MICP depends on various biochemical and environmental elements, requiring careful consideration to achieve optimal designs for specific purposes. This study evaluates the efficiency of different MICP protocols under varying environmental conditions, employing two bacterial strains: S. pasteurii and S. aquimarina, to optimize soil strength enhancement. In addition, microscale properties of carbonate crystals were investigated and their effects on soil strength enhancement were analyzed. Results demonstrate that among the factors investigated, bacterial strain and concentration of cementation solution significantly influence the biochemical aspect, while temperature predominantly affects the environmental aspect. During the MICP treatment process, the efficiency of chemical conversion through S. pasteurii varied between approximately 80% and 40%, while for S. aquimarina, it was only around 20%. Consequently, the CaCO3 content resulting from MICP treatment using S. pasteurii was significantly higher, ranging between 5% and 7%, compared to that achieved with S. aquimarina, which was about 0.5% to 1.5%. The concentration of the cementation solution also plays a pivotal role, with an optimized value of 0.5 M being critical for achieving maximum efficiency and CaCO3 content. The ideal temperature span for MICP operation falls between 20°C and 35°C, with salinity and oxygen levels exerting minor impact. Furthermore, although salinity influences the characteristics of formed carbonate crystals, its effect on unconfined compressive strength (UCS) values of MICP-treated soil remains marginal. Samples subjected to a one-phase treatment, adjusted to pH values between 6.0 and 7.5, exhibit roughly half the UCS strength compared to the two-phase treatment. These findings hold promising potential for MICP applications in both terrestrial and marine environments for strength enhancement. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, the surface morphology of the parts was improved by the in‐mold decoration and microcellular foaming injection molding (MIM‐IMD), and the mechanical properties of the parts were improved by inorganic particles modification. The effects of different inorganic particles (CaCO3, MMT, Talc) on the rheological behavior, crystallization properties, cell structure, surface quality, and mechanical properties of the MIM‐IMD composites were analyzed through experimental research and comprehensive macro and micro characterization. It was found that the foamed composite added with MMT had the highest surface quality, the best cell structure, the minimum average cell diameter of 78.4 μm and the maximum cell density of 3.09 × 106 cells/cm3. Talc improved the crystallinity of polypropylene (PP) matrix, and the resulting mechanical properties were the most significant improvement. Tensile, flexural, and impact strength were increased by 20.3%, 11.6%, and 45.2%, respectively. Highlights: The MIM‐IMD process was used to improve the surface quality of the samples.The enhancement of different inorganic particles on the properties were compared.The properties were evaluated by macro‐ and micro‐characterization.Inorganic particles can significantly improve the cell structure.Inorganic particles can greatly improve mechanical properties. [ABSTRACT FROM AUTHOR]

Poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is well‐known to be miscible with polystyrene, but immiscible with styrene copolymers containing polar groups. Certain nitrated‐PPOs (NPPOs) were found to be miscible with copolymers of styrene/acrylonitrile (SANs), copolymers of styrene/maleic anhydride (SMAs), a terpolymer of α‐methylstyrene/styrene/acrylonitrile (α‐MS/S/AN), and a copolymer of o‐ and p‐chlorostyrene (PCS). Also, certain simultaneously nitrated‐ and chlorinated‐PPOs (NCPPOs) were found to be miscible with SANs, SMAs and PCS whereas immiscible with the α‐MS/S/AN. The miscibility was indicated by the presence of a single composition‐dependent glass‐transition temperature for a given blend across the entire range of blend compositions tested. The miscibility of the aforementioned NPPOs and NCPPOs blends with SAN1 and SMA1 is attributed to hydrogen bonding of hydroxy groups of NPPOs and NCPPOs with nitrile groups and carbonyl groups, respectively, based on the literature information. The hydroxy groups were generated during nitration and simultaneous nitration/chlorination of PPO as a result of nucleophilic chain scission. Miscible blends of ‐NPPO/SAN and ‐NPPO/SMA with ABS1 showed a substantially better balance of the following properties than a comparable immiscible‐NPPO/SAN blend and a ‐PPO/SAN blend with ABS1: notched Izod impact strength, tensile properties, heat distortion temperature and gasoline stress‐crack resistance. Highlights: Nitration and simultaneous nitration/chlorination of PPO generated hydroxyl end groups.Certain NPPOs and NCPPOs were miscible with SANs, SMAs and PCS.Miscibility indicated by a single composition dependent Tg for a given blend.Miscibility attributed to hydrogen bonding of respective functional groups.Impact‐modified miscible‐NPPO/SAN blends and ‐NPPO/SMA blends with ABS1 as impact modifier had good key properties. [ABSTRACT FROM AUTHOR]

The increasing application of additively manufactured (AM) materials in engineering and biomedical fields highlights the necessity of understanding their mechanical behavior, particularly with complex lattice structures. Polylactic acid (PLA), a popular biopolymer in additive manufacturing, exhibits mechanical characteristics highly dependent on its structural design. This research investigates the quasi‐static puncture failure analysis and mechanical characteristics of additively manufactured (AM) polylactic acid (PLA) materials with various lattice structures. The mechanical behavior, including tensile strength, flexural properties, interlaminar shear strength (ILSS), Izod impact resistance, and quasi‐static punch shear strength (QS‐PSS), was investigated following the respective ASTM protocols. Results indicate a 6% increase in tensile strength, to ca. 28 MPa, for the triangular PLA lattice structure compared with plain lattice structures. In the flexural test, the hexagonal structure showed a 13% increase in bending strength, to ca. 45 MPa, compared with the plain structure. Additionally, the hexagonal PLA lattice structure exhibited a 24% increase in shear strength, to approximately 8 MPa, over the plain lattice structure in the interlaminar shear strength analysis. In the Izod impact analysis, the plain lattice structure demonstrated a 17% increase in impact strength, to ca. 278 J/m, compared with the circular structure. A stainless‐steel hemispherical indenter was employed to investigate the quasi‐static punch shear behavior (QS‐PSS) of different lattice structures. The triangular structure displayed increased total energy absorption capacity and specific energy absorption of ca. 19 J and 0.529 J/g, respectively, compared with other lattice structures. These results are important for the creation of additively manufactured PLA lattice structures, improving the puncture resistance of advanced composites. Highlights: Polylactic acid (PLA) lattice structures were fabricated.Plain, circular, triangular, and hexagonal lattice structures were investigated.Lattice structures were used as reinforcements.The triangular structure demonstrated improved strength.The triangular structure reduced crack formation and propagation. [ABSTRACT FROM AUTHOR]

The shear‐thickening gel (STG) is introduced as a toughening agent into the epoxy resin (EP) to improve the toughness and impact resistance of the EP without significantly increasing its viscosity. By utilizing the unique BO dynamic bonds present in STG, the EP/STG composite exhibits remarkable toughness at low strain rates due to the gradual disentanglement of molecular chains. Conversely, at high strain rates, the disentanglement of molecular chains is hindered, resulting in a pronounced impact hardening effect and overall superior impact resistance. Our findings reveal that when STG is added at a concentration of 15%, the EP/STG composite material attains its peak mechanical performance. Specifically, it demonstrates a tensile strength of 31.8 MPa and a modulus of elasticity of 550.6 MPa. Furthermore, compared to pure EP, the EP/STG composite experiences an increase in elongation at break and impact strength by 40% and 8.1%, respectively. Additionally, the introduction of hydroxyl and B atoms in STG promotes the ring‐opening reaction of epoxy groups during the curing process of the EP, thus accelerating the curing reaction rate. These insights provide a solid theoretical foundation for optimizing the performance of EPs in engineering applications. Highlights: The STG was actively utilized to enhance the toughness of EP.The modified EP system exhibits significant improvements in toughness and impact resistance without a notable increase in viscosity.The promotional effect of STG on the curing of EP systems was revealed through curing kinetics analysis and rheological analysis. [ABSTRACT FROM AUTHOR]

In this study, resveratrol was substituted for phenol in different molar ratios (4%, 8%, 12%, 16% and 20%) with lignin, phenol and formaldehyde as raw materials, and a new resveratrol modified lignin-based phenolic resin (R-LPF) with high glass transition temperature (Tg) and improved mechanical properties was synthesized. The curing behaviors of phenolic resin (PF), lignin phenolic resin (LPF) and R-LPF were investigated. The thermal mechanical properties, thermal stability, comprehensive mechanical properties, frictional properties and morphology were systematically tested and analyzed. The results show that the highest Tg of the modified R-LPF reaches 346.2 °C. The Ts reaches 231.5 °C, and the residual carbon rate reaches 66.2% at 800 °C. For 12% substitution ratio, the maximum tensile strength, bending strength and impact strength are respective 28.72 ± 1.10 MPa, 57.58 ± 1.95 MPa and 3.14 ± 0.19 KJ/m2. Compared with PF and LPF, the tensile strength of R-LPF is increased by 21.5% and 40.4%, and the bending strength is increased by 6.5% and 30.4%, while the impact strength is increased by 38.9% and 58.6%, respectively. The wear resistance is also significantly improved. The modified R-LPF structure has good rigidity, high crosslinking density, excellent mechanical and thermal properties, and it makes up for the defects of system performance decline caused by the introduction of lignin and provides a direction for the development of green high-performance phenolic resin. [ABSTRACT FROM AUTHOR]

Poly(butylene succinate) (PBS) was melt-blended with paramylon based mixed ester, paramylon propionate hexanoate (PaPrHe) and characterized for its morphology, thermal and mechanical properties. The PBS/PaPrHe blends were found to be immiscible throughout the loading range of PaPrHe (10–90 wt%), with individual glass transition peaks. Due to the immiscibility, there was phase separation observed in the bulk, evident by sea-island morphology. However, further observation of the micro-structure revealed that, in low PaPrHe loading (10–30 wt%), there was a micron to sub-micron order distribution of PBS particles and partially miscible PBS/PaPrHe phase. On increasing the PaPrHe to 50 wt% and beyond, the sub-micron scale domains fused to form a co-continuous morphology. As a result, the impact strength of PBS increased from 6.6 to 16.4 kJ/m2 in the 50/50 blend. Under tensile loading, the strength at break and elongation decreased after the introduction of less-flexible PaPrHe particles in the blend. This could be countered by uniaxially stretching the blended films with 10–30 wt% PaPrHe, after which the tensile strength increased by up to 380% (from 33–52 MPa to 165–200 MPa) compared to the unstretched films, attributable to the increased degree of orientation of the molecular chains. In terms of thermal processability, all the blend ratios had high thermal degradation temperature (>350 °C), higher than the melt-flow temperature (124–133 °C) providing a wide processing window. Overall, PBS/PaPrHe blend is a novel bio-based blend with properties suitable for packaging, mulching, and related applications. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This experiment was conducted to demonstrate that the use of the injection molding method of samples with different PBT/PA6 and PP blend ratios clearly shows the effect of the PP ratio on the mechanical properties of the blend to study and use the results for application in the manufacture of recycled plastic materials. PP/PBT/PA6 blends were mixed in the ratios of 100/0/0, 90/5/5, 80/10/10, 70/15/15 and 0/50/50. The tensile strength increased gradually, reaching the highest value in the 90PP/5PBT/5PA6 sample of 31.97 MPa, an increase of 18% compared to the 50PBT/50PA6 sample (27.1 MPa). The impact strength increased gradually from 2.83 kJ/m2 in the 70PP/15PBT/15PA6 sample to 3.55 kJ/m2 in the 90PP/5PBT/5PA6 sample, which was 5% higher than that of the sample without PP − 50PBT/50PA6. However, the flexural strength gradually decreases when adding PP to the blend, from 43.79 MPa in the sample without PP − 50PBT/50PA6 to 41.40 MPa at 80PP/10PBT/10PA6. The 50PBT/50PA6 sample had the highest stress value of 43.79 MPa. The hardness decreased gradually with increasing PP content; the value achieved at the 50PBT/50PA6 mixture was 80.2 MPa; however, at the 90PP/5PBT/5PA6 sample, the Shore D hardness achieved was 72.2 MPa. Therefore, increasing the PP content in the mixture will improve the tensile strength and impact strength but reduce the flexural strength and hardness of the sample. Our research results show that the 90PP/5PBT/5PA6 mixture has mechanical properties equivalent to PP plastic. Thus, instead of using 100% traditional PP plastic, the 90PP/5PBT/5PA6 mixture can be used, and PBT/PA6 material can be obtained from waste from producing toothbrush bristles, partly solving the plastic waste problem. [ABSTRACT FROM AUTHOR]

This manuscript presents a comprehensive investigation into the tensile strength and flexural behavior of steel fiber‐reinforced concrete (SFRC), utilizing a robust dataset comprising 457 meticulously selected data points, including 54 instances of self‐tested experimental data. The study establishes an empirical relationship governing the tensile strength of steel fiber concrete (SFC) based on the fiber reinforcement index (FRI) and the grade of concrete. The experimental study has extended its scope by testing an additional 27 full‐scale SFRC beams (rectangular cross‐sectioned) under monotonic loading to quantify the impact of tensile strength on the overall structural performance. The beam specimens feature continuous longitudinal and transverse reinforcement throughout their span, with steel fibers strategically positioned below the neutral axis. The steel fiber content was systematically varied from 0% to 2% in intervals of 0.25%. This work introduces modifications to the design of SFRC flexural members, emphasizing the consideration of tensile contribution below the neutral axis. The study integrates both experimental and analytical methodologies, providing diverse insights into the flexural behavior of SFRC beams. The proposed design methodology considers the tensile strength contribution from SFC, effectively predicting flexural capacity, particularly in scenarios involving higher volume fractions. Its applicability extends to structural design, offering insights into evaluating structural capacity for both newly designed and existing structures. [ABSTRACT FROM AUTHOR]

PLA was melt-blended with a chain extender (CEAX8840) and a nucleating agent (ST-NAB3) by using a torque rheometer, and the microstructure, crystallization behavior, mechanical properties, and heat resistance of the modified PLA were characterized by suing scanning electron microscope, hot-plate polarizing microscope, differential scanning calorimeter, thermal deformation meter, universal testing machine, and impact tester. The results indicated that the modified PLA obtained the smallest crystal size at CEAX8840 and ST-NAB3 contents of 6 and 1 wt%, respectively; however, its crystal density was the highest. Moreover, the crystallization temperature and crystallinity degree of the modified PLA were increased to 123. 9 °C and 44. 9 %, respectively. In addition, its impact strength and thermal deformation temperature were increased to 64. 7 kJ/m² and 84. 9 °C, respectively. [ABSTRACT FROM AUTHOR]

Hydroxy-functionalized polyacrylate rubber particles (ACR-OH) were synthesized with micrcrcrosslinked poly-butyl acrylate (PBA) as a rubber core and methyl methacrylate-hydroxyethyl acrylate copolymer (HEA) as a shell through seed emulsion polymerization. ACR-OH was mixed with triglycidyl isocyanurate (TGIC) and then added into polybutylene terylene phthalate (PBT). Owing to the reactions occurring between the hydroxyl groups on the surface of ACR particles and epoxy groups in TGIC and between the epoxy groups in TGIC and hydroxyl end-group of PBT in the melt blending process, the modified PBT (PBT/TGIC/ACR-OH) gained the good compatibility between ACR and PBT. The effect of the addition of ACR-OH and TGIC on the impact strength and tensile strength of the modified PBT were investigated. The results indicated that the addition of ACR-OH effectively improved the toughness of PBT due to good compatibility. When the addition amounts of ACR-OH and TGIC were 20 and 2 phr, respectively, the impact strength of the modified PBT reached 20. 45 kJ/m², which was 8. 4 times as high as that of pure PBT (2. 43 kJ/m²). Moreover, with the help of multi-functional TGIC, the modified PBT exhibited both good toughness and good strength at addition amounts of ACR-OH and TGIC of 8 and 2 phr, respectively. Its impact strength and tensile strength reached 10. 87 kJ/m² and 42. 1 MPa, respectively. [ABSTRACT FROM AUTHOR]

AbstractA non-traditional friction stir welding (FSW) is used to joint the materials that are challenging to join together by utilizing the fusion welding processes. This study investigated the influence of the welding speed ratio (υ) to rotating speed (ꞷ) on the weld quality and found the relationship between mechanical qualities and welding peak temperature. With increase in (ꞷ/υ), there was a corresponding rise in peak temperature, leading to the expansion of both the nugget zone (NZ) and the softened region within the joint. As (ꞷ/υ) increased because of the increased heat, as a result in the joint hardness decreased. The joint ultimate tensile strength (UTS) increased with increasing (ꞷ/υ), then decreased, with the maximum value reaching 84.75% of the base material at a (ꞷ/υ) of 9.6. As a result of the low (ꞷ/υ), a flexural crack formed. In comparison to the base material, the thermos mechanically affected zone (TMAZ) and the nugget zone (NZ) showed greater impact strength. The impact strengths first increased and subsequently dropped with an increase in (ꞷ/υ). The tensile specimens’ fracture surfaces showed dimples, signifying a ductile mode of fracture. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to explore the impact of COVID-19 on strength performance in highly trained athletes. Method: A force plate was employed to measure squat jump height (SJH), counter-movement jump height (CMJH), and drop jump reactive strength index (DJRSI) in 27 highly trained athletes before infection, and at one week, two weeks, and four weeks post-recovery. Additionally, an Isometric Mid-thigh Pull (IMTP) test was conducted to record maximum isometric strength (MIS) and the rate of force development of the initial phase (RFD 0–50; RFD 0–100). Repeated measures analysis of variance was utilized to compare variations in these indicators across different time points. Results: One week post-recovery, SJH (-7.71%, P = 0.005), CMJH (-9.08%, P < 0.001), DJRSI (-28.88%, P < 0.001), MIS (-18.95%, P < 0.001), RFD 0–50 (-64.98%, P < 0.001), and RFD 0–100 (-53.65%, P < 0.001) were significantly lower than pre-infection levels. Four weeks post-recovery, SJH (-2.08%, P = 0.236), CMJH (-3.28%, P = 0.277), and MIS (-3.32%, P = 0.174) did not differ significantly from pre-infection levels. However, DJRSI (-11.24%, P = 0.013), RFD 0–50 (-31.37%, P = 0.002), and RFD 0–100 (-18.99%, P = 0.001) remained significantly lower than pre-infection levels. Conclusion: After COVID-19, highly trained athletes exhibited a significant reduction in maximum strength, explosive strength, reactive strength, and initial phase force generation capability. By four weeks post-recovery, their maximum and explosive strength had returned to near pre-infection levels, yet their reactive strength and initial phase force generation capability remained significantly impaired. [ABSTRACT FROM AUTHOR]

This study focuses on the experimental investigation of the mechanical properties of PBT/PC blends with varying compositions. The studied mechanical properties include tensile strength, elongation, tensile modulus, impact strength, and Shore hardness of PBT/PC blends with different PC contents. PBT, characterized by its semi‐crystalline and tough nature, contrasts with PC, known for its impact resistance and hardness. Achieving an optimal blend composition proves to be crucial for attaining the best combination of these properties. The tensile strength of the PBT/PC 30/70 blend increased by approximately 24%, with Shore hardness also experienced a 12% enhancement compared to pure PBT. This improvement is attributed to the presence of PC segments in the blend structure. Conversely, an increase in PC content led to the elongation and impact strength of the blends peaking in the PBT/PC 70/30 blend. Notably, the impact strength of the PBT/PC blend with 30% PC increased by about three times compared to PBT and 18% more than pure PC. Scanning Electron Microscopy (SEM) analysis revealed that PBT and PC segments disperse at lower PC content, while at higher content, phase separation becomes prominent. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicates direct transesterification between PBT and PC, resulting in the formation of a long‐chain blend structure with random copolymer blocks. The transesterification mechanism is also supported by Differential Scanning Calorimetry (DSC) results, wherein a reduction in the crystallization temperature (Tc) and an increase in the glass transition temperature (Tg) is observed. The study concludes that the volume of these segments and their bonding play a decisive role in determining the mechanical properties. The bonding mechanism elucidated through FTIR and SEM provides valuable insights into the fabrication and property engineering of PBT/PC blends. [ABSTRACT FROM AUTHOR]

The integration of compatibilisers with thermoplastics has revolutionised the field of polymer composites, enhancing their mechanical, thermal, and rheological properties. This study investigates the synergistic effects of incorporating SEBS-g-MAH on the mechanical, thermal, and rheological properties of polycarbonate/acrylonitrile-butadiene-styrene/graphene oxide (PC/ABS/GO) (PAGO) and the properties of polycarbonate/acrylonitrile-butadiene-styrene/graphene oxide (PC/ABS/rGO) (PArGO) composites through the melt blending method. The synergistic effects on thermal stability and processability were analysed by using thermogravimetry (TGA), melt flow index (MFI), and Fourier-transform infrared spectroscopy (FTIR). The addition of SEBS-g-MAH improved the elongation at break (EB) of PAGO and PArGO up to 33% and 73%, respectively, compared to the uncompatibilised composites. The impact strength of PAGO was synergistically enhanced by 75% with the incorporation of 5 phr SEBS-g-MAH. A thermal analysis revealed that SEBS-g-MAH improved the thermal stability of the composites, with an increase in the degradation temperature (T80%) of up to 17% for PAGO at 1 phr SEBS-g-MAH loading. The compatibilising effect of SEBS-g-MAH was confirmed by FTIR analysis, which indicated interactions between the maleic anhydride groups and the PC/ABS matrix and GO/rGO fillers. The rheological measurements showed that the incorporation of SEBS-g-MAH enhanced the melt flowability (MFI) of the composites, with a maximum increase of 38% observed for PC/ABS. These results demonstrate the potential of SEBS-g-MAH as a compatibiliser for improving the unnotched impact strength (mechanical), thermal, and rheological properties of PC/ABS/GO and PC/ABS/rGO composites, achieving a synergistic effect. [ABSTRACT FROM AUTHOR]

The widespread use of poly(lactic acid) (PLA) from packaging to engineering applications seems to follow the current global trend. The development of high-performance PLA-based blends has led to the commercial introduction of various PLA-based resins with excellent thermomechanical properties. The reason for this is the progress in the field of major PLA limitations such as low thermal resistance and poor impact strength. The main purpose of using biobased polymers in polymer blends is to increase the share of renewable raw materials in the final product rather than its possible biodegradation. However, in the case of engineering applications, the focus is on achieving the required properties rather than maximizing the percentage of biopolymer. The presented review article discusses the current strategies to optimize the balance of the key features such as stiffness, toughness, and heat resistance of PLA-based blends. Improving of these properties requires molecular structural changes, which together with morphology, crystallinity, and the influence of the processing conditions are the main subjects of this article. The latest research in this field clearly indicates the high potential of using PLA-based materials in highly demanding applications. In the case of impact strength modification, it is possible to obtain values close to 800 J/m, which is a value comparable to polycarbonate. Significant improvement can also be confirmed for thermal resistance results, where heat deflection temperatures for selected types of PLA blends can reach even 130 °C after modification. The modification strategies discussed in this article confirm that a properly conducted process of selecting the blend components and the conditions of the processing technique allows for revealing the potential of PLA as an engineering plastic. [ABSTRACT FROM AUTHOR]

Withania somnifera, commonly known as ashwagandha, has gained popularity in recent years among individuals interested in healthy lifestyles, natural medicine, and sports. This review aims to summarize the current knowledge regarding the effects of ashwagandha supplementation on various aspects of physical performance, particularly in the context of resistance training. Studies have shown that ashwagandha can positively impact muscle strength, with significant increase of muscle force and power output. Additionally, it has demonstrated potential in modulating body composition, with reduction of body fat percentage noted in certain populations. However, results of studies on ashwagandha's effect on muscle size remain inconclusive and may depend on various factors such as training status and individual responses. In terms of endurance, ashwagandha supplementation has been associated with improvement in maximal oxygen uptake, indicating enhanced aerobic capacity and delayed exhaustion during endurance activities. Furthermore, ashwagandha was shown to aid muscle recovery by reducing exercise-induced muscle damage and inflammatory response, potentially accelerating the muscle regeneration process. Ashwagandha may also influence hormone levels, such as testosterone and cortisol, with potential implications for muscle growth and recovery. However, further research is needed to fully understand the mechanisms underlying these effects. Overall, ashwagandha supplementation appears to hold promise for enhancing physical performance and overall well-being. Further research is needed to elucidate optimal dosages, long-term safety, and potential interactions with other supplements or medications. [ABSTRACT FROM AUTHOR]

This study fabricates multiscale glass fiber/epoxy composites by incorporating graphene nanoparticles (GNPs) and zinc oxide nanoparticles (ZnO NPs) to investigate the influences of NPs on the mechanical properties of composites. The composites are manufactured using the compression molding technique with different GNP contents (i.e., 0, 0.5, 1, and 1.5 wt.%), whereas the contents of glass fibers and ZnO NPs remained the same at 40 and 4 wt.%, respectively. Their mechanical properties, chemical compositions, and fracture morphologies are then evaluated. It is found that the mechanical properties of composites improve significantly at a lower content (i.e., 0.5 wt.%) of GNPs and tend to decrease at higher contents (i.e., 1 and 1.5 wt.%). The composite is composed of 0.5 wt.% GNPs exhibit maximum tensile modulus and strength of 6.74 GPa and 230.25 MPa, and flexural modulus and strength of 16.43 GPa and 831.79 MPa, respectively, impact strength of 47.25 kJ m−2, and maximum hardness (97.96 Shore D), among all nanocomposites. Moreover, fracture morphologies reveal that composite failure is predominately caused by fiber breakage, fiber‐matrix debonding, voids, and GNP agglomeration. The outcomes of this study provide some insights to promote the application of manufactured multiscale composites in the aerospace, automotive, and marine industries. [ABSTRACT FROM AUTHOR]

In this study, the challenges of brittleness and flammability in Polyamide 6/glass fiber (PA6/GF) composites, which are crucial for heat‐resistant and stress‐bearing structural parts, are addressed. Polyphosphazene (PZ) elastomers, known for their exceptional flame‐retardant properties, are introduced to enhance the robustness and safety of these composites. Specifically, poly(diaryloxy)phosphazene (PDAP) and poly(difluoroalkoxy)phosphazene (PDFP) are utilized, both contributing to the improved toughness and flame resistance of the PA6/GF composites. Experimental results show that PDAP mainly played the role of solid‐phase flame retardant, while PDFP mainly acted the role of gas‐phase flame retardant. For PA/PZs composites without adding GF, PDFP plays a more efficient flame retardant effect than PDAP. By introducing 15 Vol% of PDFP, the limiting oxygen index (LOI) of the composite reached 26.1%, while the notched impact strength increased by 297%. For PA/PZs/GF composites, PDAP plays a better flame retardant role than PDFP. Under the action of 30 vol% GF and 15 vol% PDAP, the LOI of PA6/PDAP/GF composite reached 26.8%, and the notch impact strength improved to 18.7 kJ/m2, which is 165% higher than that of PA6/GF, and the UL‐94 test reaches V‐0 level. The findings of the study highlight the potential of PDAP and PDFP to act as dual‐function modifiers. These modifiers can considerably ameliorate both the impact resistance and flame retardancy of PA6 and PA6/GF composites. Such dual enhancement surpasses the typical trade‐offs seen in conventional composites, indicating a constructive direction for future material innovation. Highlights: Polyphosphazenes simultaneously enhance PA6's toughness & flame resistance.Distinct flame retardant mechanisms found in PDAP and PDFP.GF presence alters PDAP and PDFP's flame retardant efficacy.PDAP shows superior flame resistance in GF‐reinforced PA6 composites.Without GF, PDFP outperforms PDAP in enhancing flame retardancy. [ABSTRACT FROM AUTHOR]

We herein report the enhancement of thermal, electrical, electromagnetic interference (EMI) shielding, and mechanical performance of polyethylene (PE) nanocomposites by the introduction of non‐covalently modified multi‐walled carbon nanotube (MWCNT) and ethylene‐glycidyl methacrylate (EGMA) copolymer. For this purpose, benzylacetic acid‐functionalized MWCNT (BA‐M) is prepared by ball milling, and it is melt‐mixed with EGMA to prepare a masterbatch. The masterbatch is then melt‐compounded with neat PE to manufacture a series of PE/EGMA/BA‐M nanocomposites with 0.5–5 wt% MWCNTs. Electron microscopic and spectroscopic analyses confirm the successful fabrication of non‐covalently functionalized BA‐M, the uniform dispersity of MWCNTs in the PE matrix, and the chemical reactions between the carboxylic acid groups of BA‐M and the epoxy group of EGMA in the nanocomposites. Scanning calorimetric data reveals that BA‐M acts as an efficient nucleating agent for the crystallization of PE. The excellent dispersity and robust interfacial bonding of BA‐M in the PE matrix result in improved electrical and EMI shielding properties in PE/EGMA/BA‐M nanocomposites. Furthermore, the tensile strength, initial modulus, and impact strength of the nanocomposites gradually rise as the BA‐M content increases. Thus, the PE/EGMA/BA‐M nanocomposite containing 5 wt% MWCNT achieves excellent performance of EMI shielding effectiveness of ~14.7 dB/mm, tensile strength of ~34.5 MPa, initial modulus of ~295.7 MPa, and impact strength of ~539.9 J/m, which represent enhancements of ~265%, ~40%, ~82%, and ~452%, respectively, compared to pristine PE. Highlights: Non‐covalently modified MWCNT (BA‐M) was prepared by facile ball milling.PE nanocomposites with BA‐M and EGMA were prepared by masterbatch melt‐mixing.Excellent dispersity and interfacial bonding of MWCNT in the PE matrix were attained.Tensile strength and initial modulus of the nanocomposites were highly improved.EMI shielding effectiveness of the nanocomposite with 5 wt% MWCNT was ~14.7 dB/mm. [ABSTRACT FROM AUTHOR]

This study aimed to explore the application of a mechanochemical method for effectively integrating polyimide nanofibers, which are widely recognized for their outstanding thermal and mechanical properties, into an epoxy resin matrix. The researchers observed an 87.5% reduction in the diameter of polyimide nanofibers after mechanical treatment. The dispersion, compatibility, and interface between the nanofibers and epoxy matrix were analyzed using molecular dynamics simulations and scanning electron microscopy. The addition of polyimide nanofibers significantly increased the binding energy of the composite, resulting in a 52.8% improvement. Moreover, compared to pure epoxy resin, the inclusion of modified polyimide nanofibers led to a 21.9% increase in tensile strength and an 18.8% increase in impact strength. The PI/epoxy composite also exhibited a 15.6% increase in tensile strength and a 16.4% increase in impact strength. Additionally, electrochemical corrosion analysis showed that the PI/epoxy composite had excellent corrosion resistance. In conclusion, due to the exceptional mechanical properties and strong interfacial adhesion of polyimide nanofibers, the PI/epoxy resin composite demonstrated significant overall performance improvement compared to pure epoxy resin. Highlights: Mechanochemical method to disperse polyimide fiber, shorter and finer fibers were obtainedImprove performance by adding small amountsMicroscopic analysis of composites by Materials Studio, PIENFs efficiently improved the interaction on the phase interfaceExperiments have verified that PIENFs could make the mechanical properties and corrosion resistance [ABSTRACT FROM AUTHOR]