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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]

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Heat-resistant semi-aromatic poly (decamethylene terephthalamide) acid (PA10T) and a series of poly (decamethylene terephthalamide/decamethylene furanamide) (PA10T/10F) with a high content of bio-based carbon were synthesized by a cost-effective high-pressure solution polycondensation method. The chemical structures of the obtained samples were evaluated by Fourier infrared spectroscopy (FT-IR). Moreover, the effect of the addition of copolymer 2,5-furandicarboxylic acid (FDCA) and the copolymerization ratios of FDCA for PA10T on thermal performances, crystallization behaviors, and mechanical properties of PA10T and PA10T/10F were studied in detail. In addition, the results of DSC indicate that the melting points of PA10T/10F copolyamides can be adjusted appropriately by varying the feed ratios of FDCA, suggesting the improvement of processabilities. Besides, with increasing the copolymerization ratios of FDCA, the sizes of spherulites decreased gradually analyzed by POM. Furthermore, the results of XRD showed that the PA10T homopolymer and PA10T/10F copolyamides possess similar shapes around 2θ = 21°. In addition, compared with pure PA10T, the tensile strength, breaking elongation, bending strength, bending modulus, and izod impact strength all increased obviously when the feed ratio of FDCA and terephthalic acid (PTA) was 5:95. Therefore, the crystallization behaviors, processing performances, and mechanical characteristics of PA10T can be improved significantly by introducing FDCA, to improve the bio-based carbon content of PA10T and meet the increasing demand for environmentally friendly materials all over the world. [ABSTRACT FROM AUTHOR]

Optimizing the impact properties of polymer composites is essential in aircraft industries. Hybridization of fibres is one of the efficient methods to enhance the impact properties of polymer composites. Dispersion of nanoparticles into epoxy resin improves the toughness of composites. This study examines the low-velocity impact (LVI) behaviour of hybrid epoxy-based carbon/glass fibre-reinforced laminates. Initially, the epoxy resin was modified with 0, 0.5, 1, 1.5, and 2 wt% of nanoclay and TiO2 nanoparticles using mechanical stirring followed by an ultrasonication method. To investigate the influence of stacking sequences, laminates were fabricated with (90 G/0 G/90 C)S, (90 G/0 C/90 G)S, and (90 C/0 G/90 G)S. The samples used for this study are six-ply symmetric laminates. Laminates were impacted with different impact energies between 30 and 80 J with an impact velocity of 7 m/s to generate damages. The residual strength of damaged specimens is determined using compression after the impact test. The order of stacking, fibre orientation, and the presence of nanoparticles all have a significant impact on the residual strength of laminates. By using C-scan images, layer-wise damage mechanisms were identified. The specimen with (90 C/0 G/90 G)S sequence has very high damage resistance compared to other laminates. [ABSTRACT FROM AUTHOR]

Automotive bumper beams play a very crucial role in absorbing impact energy during crash collisions and reducing damage from the front or rear ends of the vehicle during low or high-velocity impact. This paper discusses the impact of different energy-absorbing materials introduced between the fascia and the metallic beam. A novel recipe, with combinations ranging from 0% to 50% and 20% to 80% of Polypropylene (PP) with Ethylene vinyl acetate (EVA) and Polypropylene (PP) with Ethylene propylene diene monomer (EPDM), was prepared by weight and comparative study based on their impact strengths was done both experimentally and numerically. The mechanical properties of the polymer blends have been determined under tensile, compressive, and impact testing. Results obtained from numerical simulation analysis lie in reasonable agreement with the experimental findings. The tensile and compression test results show that polymer blend PP/EPDM-50/50 is the best selection as an energy absorber due to its ductility and toughness properties which is evident from experimental testing. The introduction of this blend in front of the metallic strip (bumper beam) has significantly supported the improvement in the energy-absorbing capacity and impact strength. [ABSTRACT FROM AUTHOR]

Al7075 is employed as the matrix material and sugarcane bagasse ash (SBA) is a reinforcing material in this work, which is targeted at creating lightweight metal matrix composites (MMCs) at a reasonable cost. Hybridized improved composite castings have been produced and industrial as per ASTM standards with changing wt.% of 0%, 4%, 8%, 12%, and 16% wt.%, correspondingly, after mechanical testing for the evaluation of their strength. It is tested for hardness, tensile, impact, and flexural strength. Composites with hybrid enhanced metal matrix have greater tensile, hardness, and flexural strengths than single-reinforced MMCs. The composite's tensile and flexural strengths were boosted by a 12 wt.% increase in bagasse ash, which resulted in maximum values of 96.42% tensile and 23.58% flexural strength, respectively. As the bagasse weight percentage grew over 12%, these values fell, although Bagasse ash AA7075's impact and ductility improved slightly. [ABSTRACT FROM AUTHOR]

Extensive research efforts have been focused on customizing the microstructure, macrostructure, and phase composition of calcium phosphate for enhanced biocompatibility and bioactivity in scaffolds for bone substitutes. Despite significant progress, achieving precise phase composition and microstructure remains a challenge, primarily due to the necessity of scaffold sintering. This study addresses the challenges in developing customized patient‐specific bone substitutes by proposing a sequential approach that reduces processing steps while providing control over the phase and morphology of the scaffolds' structure. The methodology utilizes freeze‐casting and sintering for highly porous the scaffolds' preparation, followed by hydrothermal treatment to modify the microstructure. The introduction of CaCO3 induces a phase transformation of tricalcium phosphate, increasing the hydroxyapatite content, while the overall macrostructure retains the characteristics of freeze‐casting. The surface morphology undergoes a transition from equiaxial grains to whiskers‐like structures and hexagonal rods, impacting compressive strength. Following hydrothermal treatment, the formation of whiskers‐like hydroxyapatite grains leads to a notable strength increase from 2.8 to 5.7 MPa. Remarkably, the scaffolds undergo nearly complete phase transformation, shifting from 100% tricalcium phosphate to 99% hydroxyapatite, all while conserving the macrostructure. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polyethylene (UHMWPE) is utilised for several purposes, including as a biomedical material for artificial joint replacement. This study looks at the effects of adding nanosized hydroxyapatite (HAP), nanosized titanium dioxide (TiO2), carbon fibre (CF), and Kevlar fibre (KF) to bone plate fixation in the femur bone prosthesis. Because of the ease with which they could be processed, their low cost, remarkable mechanical properties, good cell interaction, different amounts of n-HAP and n-TiO2 (1.5, 2.5, 3.5, and 4.5 wt%), and a fixed amount of CF and KF (5 wt%) were dispersed in UHMWPE-based biocomposites. The UHMWPE/n-HAP and UHMWPE/n-TiO2 particulate biocomposites were prepared by using the dispersing technique followed by hot pressing moulding, then mechanical testing was performed, including flexural, maximum shear stress, and impact tests. Scanning electron microscopy (SEM) is used to observe reinforcement and matrix fractures. Biocomposites with n-HA/Carbon fibre hybrid biocomposites showed better results concerning specific mechanical strength, as well as flexural strength, max. shear and impact energy. The composites show an increase in flexural strength, flexural modulus, impact strength, and max. shear stress by 44%, 32.49%, 120.7%, and 182.6% respectively concerning neat UHMWPE. This review focuses on the benefits of UHMWPE particulate biocomposites in a variety of weight proportions and hybrid biocomposites, which have not yet been tested as a superior alternative for the creation of bone plate fixation. [ABSTRACT FROM AUTHOR]

This study aims at determining the optimal material and process parameters that will maximize the quality characteristics of miscanthus fiber-reinforced polypropylene (MFRPP) composite. Taguchi L16 was utilized in the design of experiment and larger-the-better signal-to-noise ratio was used in the analysis of the impact strength of MFRPP. Optimal combination of material and process parameters and the main effects were determined, and the significant variables were identified using analysis of variance. Artificial neural network (ANN) and extreme learning machine (ELM) were utilized on the Taguchi experimental data and used in the prediction of the impact strength of MFRPP. The results showed the optimum impact strength occurred at 25 wt% miscanthus fiber loading. The results of the predictions made revealed that both ANN and ELM are very efficient in predicting the impact strength of MFRPP as shown by the relative errors when compared with the experimental data. Both the performance metrics assessments and the quality of prediction show that ELM is a better machine learning technique than ANN. The high impact strength of MFRPP composite is a confirmation that MFRPP is a very useful material for industrial applications. [ABSTRACT FROM AUTHOR]

This study aims to investigate the recycling of end‐of‐life computer plastics, focusing on polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) copolymer, which constitute a significant portion of collected computers. Through differential scanning calorimetry and infrared spectroscopy analyses, the properties of raw PC, ABS and poly(methyl methacrylate) (PMMA) were evaluated. Various blends of PC and ABS were prepared, incorporating different percentages of recycled PMMA as a cost‐effective coupling agent. These blends were processed through melt compounding using a contra‐rotating twin‐screw extruder and subsequently shaped by injection molding. An experimental mixture design was applied to evaluate the mechanical and physical properties of the composite materials, including melt flow index, hardness, flexural strain at break and Charpy impact strength. The results of the desirability analysis indicated that the optimal blend for achieving a balance between mechanical and physical properties consists of a high PC content (approximately 80% or more), a low ABS content (less than 20%) and less than 5% recycled PMMA. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study focuses on achieving enhanced mechanical properties of the welded joints, which is critical for the applications of mild steel (MS) plates in various industries. In this regard, a systematic approach is used to adjust welding parameters such as welding current and workpiece thickness in shielded metal arc welding (SMAW), with the objective of identifying the optimal combination that maximizes weld quality. The experiments were planned with the help of Taguchi's L9 orthogonal array method in order to reduce experimental cost and time. The weld quality is optimized by determining the signal-to-noise ratios of weld penetration, tensile strength, impact strength, and microhardness for each experimental sample. As a result, 110 A welding current is obtained as the optimal SMAW parameter for a 5 mm thick MS IS 2062 Grade B plate. This optimized result has also achieved 394.78 N/mm2 tensile strength and 53 J of impact resistance for the respective specimen. Besides, research not only enhances understanding of the SMAW process but also offers practical implications for industries requiring high-performance welded joints in MS structures. Additionally, this study can assist upcoming researchers in optimizing any existing welding procedures. [ABSTRACT FROM AUTHOR]

This research explores the scope of natural fibers for prosthetic socket application. A variety of conditions including maladies, accidents, and genetic disorders, necessitate the adoption of prosthetic organs. The human body undergoes significant physiological changes over time due to factors such as growth, weight fluctuations, and the periodic replacement and adjustment of appendages. In this study, biocomposite materials are fabricated using vacuum bag technology, with sisal fibers reinforced in vinyl ester at five different weight percentages: 0%, 5%, 10%, 15%, and 20%. Mechanical characteristics are determined through destructive testing, including flexural, tensile, impact strength, and hardness measurements according to ASTM standards. Scanning electron microscopy (SEM) analysis is employed to assess factrography and bonding properties. Results indicate that the biocomposite with 15% sisal reinforcement exhibited superior tensile and impact resistance compared to other compositions and matrices. However, at the expense of impact strength, the 20% sisal-reinforced vinyl ester increased hardness and flexural strength by 47% and 27%, respectively. This research aims to expand natural fibers and their utility in biomaterial applications, outlining points for elaboration and enhancement in this field, along with addressing associated challenges. [ABSTRACT FROM AUTHOR]

SUMMARY Cotton stands as a pillar in the textile industry due to its superior natural fibers. Lignin, a complex polymer synthesized from phenylalanine and deposited in mature cotton fibers, is believed to be essential for fiber quality, although the precise effects remain largely unclear. In this study, we characterized two ubiquitously expressed cinnamyl alcohol dehydrogenases (CAD), GhCAD37A and GhCAD37D (GhCAD37A/D), in Gossypium hirsutum. GhCAD37A/D possess CAD enzymatic activities, to catalyze the generation of monolignol products during lignin biosynthesis. Analysis of transgenic cotton knockout and overexpressing plants revealed that GhCAD37A/D are important regulators of fiber quality, positively impacting breaking strength but negatively affecting fiber length and elongation percentage by modulating lignin biosynthesis in fiber cells. Moreover, GhCAD37A/D are shown to modulate anther vitality and affect stem lodging trait in cotton by influencing lignin biosynthesis in the vascular bundles of anther and stem, respectively. Additionally, our study revealed that Ghcad37A/D knockout plants displayed red stem xylem, likely due to the overaccumulation of aldehyde intermediates in the phenylpropanoid metabolism pathway, as indicated by metabolomics analysis. Thus, our work illustrates that GhCAD37A/D are two important enzymes of lignin biosynthesis in different cotton organs, influencing fiber quality, anther vitality, and stem lodging. [ABSTRACT FROM AUTHOR]

Highlights Hybrid fiber‐reinforced composites uniquely address the performance limitations of carbon fiber‐reinforced polymers (CFRPs). In this study, continuously wrapping large tow CF (48 K) with low‐cost nylon was proposed to create nylon‐CF core‐spun yarns (NCCYs). Unidirectional nylon‐CF/epoxy composites (NCFECs) were successfully fabricated using NCCYs as hybrid fiber reinforcement. The nylon wrapping on the CF significantly enhanced the energy absorption and dispersion of the CFRPs, thereby improving the impact strength. The measured impact strength of the NCFECs was 108.7 kJ/m2, which was 70.4% greater than that of the corresponding CF/epoxy composite (63.8 kJ/m2) with the same CF content. Additionally, NCCYs exhibited an excellent interfacial shear strength of 35.3 MPa, representing a 73.9% increase compared to that of the large tow CF (20.3 MPa). This study developed NCFECs using a simple and low‐cost process to produce advanced composites, providing an innovative manufacturing strategy for CFRPs with high impact resistance. The NCCYs are prepared by using the wrapping technology. The structure of the wrapped yarns endows the NCCYs with high interfacial shear. The nylon fiber layer gives NCFECs higher impact strength. [ABSTRACT FROM AUTHOR]

Highlights This study investigates the effect of atmospheric plasma activation (APA) treatment on the thermomechanical performance of adhesively bonded skins of composite sandwich panels. The investigations show that APA treatment enhances surface wettability through the water contact angle measurements, and adhesion between the skin and honeycomb core of the panels under mechanical tests. Specifically, APA treatment results in an 11% increase in flatwise tensile strength and a 12% enhancement in the impact strength of the sandwich laminates. Flatwise tensile tests reveal superior tensile strength and toughness in APA‐treated specimens, with fracture patterns suggesting more robust adhesion. Charpy impact test results confirm increased energy absorption, reflecting better mechanical resilience. Scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) techniques are utilized to validate these findings. Overall, APA treatment proves to be an effective technique for enhancing the performance of composite sandwich panels, offering improved adhesion, strength, and impact resistance. This approach holds significant promise for advancing high‐performance composite materials in various engineering applications. APA treatment enhances wettability and adhesion in sandwich panels. Improved adhesive distribution between skin‐core after sandwich manufacturing. 11% increase in tensile strength and 12% in impact strength with APA. Better toughness and energy absorption via SEM and DMA support in APA. [ABSTRACT FROM AUTHOR]

The use of waste‐based bio‐fillers in composite manufacturing has increased in recent years due to their sustainable and biodegradable characteristics. The current study fabricates jute/banana (JB) fiber‐reinforced epoxy composites incorporating waste‐derived eggshell (ES) bio‐filler and investigates the effect of ES bio‐filler on the mechanical, morphological, and water absorption properties of the composites. JB fibers (1:1) and varying ES filler contents (5, 10, 15, and 20 wt%) were used to manufacture the composites using the hand lay‐up technique. Their tensile, flexural, and impact properties, microstructure, chemical compositions, and water absorption are then examined. It is found that the composite composed of 15 wt% ES exhibits better tensile and flexural properties with a tensile modulus and strength of 4.42 GPa and 95.27 MPa, and a flexural modulus and strength of 3.96 GPa and 117.47 MPa, respectively, whereas the composite filled with 5 wt% ES shows a maximum impact strength of 46.83 kJ/m2 and drops with increasing bio‐fillers. Scanning electron microscopy reveals that composite failures occur due to jute and banana fiber fractures, filler–fiber‐matrix debonding, fiber pullout, and ES filler agglomeration. Moreover, water absorption reduces as the ES content rises, and the 20 wt% ES filler‐based composite shows a minimum water absorption of 7.67% after 240 h. This study provides some insights to promote the usage of ES bio‐filler in natural fiber composites to improve their mechanical and water absorption properties and their potential applications in the internal structures of automobiles, aircraft, and construction. [ABSTRACT FROM AUTHOR]

Highlights The performance of carbon fiber‐reinforced thermoplastic composites (CFRTP) has been restricted by the performance of the interface. In general, the interfacial properties of CFRTP are determined by both the surface properties of the carbon fiber (CF) reinforcement and the infiltration properties of the thermoplastic matrices, which possess high melt viscosity and seem difficult to sufficiently infiltrate the fiber reinforcement. As a result, the melt flow characteristics of different matrices significantly influence the interfacial melt penetration and mechanical properties of CFRTP. In this paper, in order to explore the influence of melt flow characteristics of various thermoplastic resins toward CFRTP interfacial behaviors, high‐polarity polyamide (PA) and low‐polarity polypropylene (PP) resins are selected as representative resin matrices among commonly used resin systems. Specifically, the polarity differences and interface‐forming mechanisms of CFRTP are first established. Following a systematical discourse on the latest research progress of interfacial modifications in PP/PA‐based CFRTP are described, centering on the effects of various modification methods on improving the interlaminar/interfacial strength, toughness, impact strength, and bending strength of the composites. In addition, this paper also classifies the interfacial mechanisms of CFRTP in terms of interface bonding, interface strengthening, and interface failure. Finally, the shortcomings and future research directions are pointed out to achieve effective interfacial construction and innovative modification of CFRTP. An introduction of resin polarity differences of CFRTP is established. An introduction of interface‐forming mechanisms of CFRTP is established. State‐of‐art characterization techniques of CFRPs interface are provided. Effect of melt flow property on the interfacial behavior of CFRTP was explored. The interfacial mechanisms are systematically analyzed. [ABSTRACT FROM AUTHOR]

This work examines the effects of varying weight percentages (0.1, 0.3, and 0.5 wt%) of pristine and functionalized graphene (–COOH, –OH, and –NH2) on the compression and impact strength of carbon fiber-reinforced polymer (CFRP) composite laminates. The laminates were fabricated in two different stacking sequences of carbon fiber in composite laminates, i.e., 0/90° and 0/90/ ± 45° by hand layup technique. Experimental results showed that the inclusion of graphene in epoxy matrix enhances the compressive strength and impact characteristics, namely impact force, displacement, energy profile, and damage behavior of CFRP laminates. Moreover, the orientation of carbon fiber layers in laminates affects the internal damage behavior of specimens and the delamination between fiber layers. The maximum improvements of 38.65 and 76.82% are noticed in the compressive strengths of 0/90° and 0/90/ ± 45° stacked laminates with the reinforcement of 0.1 wt% of pristine and 0.3 wt% of –COOH functionalized graphene to epoxy, respectively. In summary, the test results have shown that using graphene as a reinforcing filler can significantly improve the impact performance of CFRP composites. [ABSTRACT FROM AUTHOR]

Highly cross‐linked thermosets possess superior mechanical properties and have found broad applications in engineering. However, due to the dense cross‐links, it is extremely challenging to recycle highly cross‐linked thermosets, causing serious environmental and sustainable concerns. Herein, a mechanochemical recycling strategy is proposed for highly cross‐linked thermosets via the synergy of mechanics and chemistry, which is economic‐friendly and pollution‐free. To demonstrate the strategy, diverse metal‐complex catalysts are employed to recycle highly cross‐linked epoxy incorporated with switchable covalent bonds at certain pressure, temperature, and time. The effect of each catalyst on the efficiency of recycling is evaluated, which follows a descending order: Zr4+ > Mn3+ > Co3+ > Fe3+ > Co2+ > Zn2+ > OTi4+ > Ni2+. The results show that the mechanical properties, such as Young's modulus, ultimate strength, peak strain, impact strength, flexural modulus and strength, as well as thermal stability of the recycled samples are almost identical to those of as‐synthesized ones. The effectiveness of the method is further confirmed via micromorphology. [ABSTRACT FROM AUTHOR]

Highlights This study is an attempt to develop high‐quality hybrid composites via functionalization (for homogeneous distribution) of the graphene nanoplatelets (FGNP) and then doping to carbon fiber reinforced especial aviation epoxy matrix (Araldite LY5052) via vacuum bagging molding (VBM). The utilized materials were characterized by UV–Vis spectroscopy, tensile, impact, hardness tests, and fracture mode analysis using a scanning electron microscope (SEM). The results revealed a 92% (502.5 MPa) and 85% (490 MPa) improvement in tensile strength values by doping the 1 and 1.5 wt% FGNPs, respectively. There was an improvement in impact strength with the addition of FGNP; a 28% (3.23 J/mm2) increase was achieved in the nanocomposite with 1 wt% FGNP added, and there was a decrease again in the nanocomposite with 1.5 wt% FGNP added. However, it was still 12% (2.83 J/mm2) better than the neat composite. In addition, the results of examining the fractured surface structures of the impact and tensile test specimens were compatible with these results. It reveals a significant separation of fiber‐matrix bonds with 1.5 wt% FGNP contribution. While tensile and impact strengths peak at 1 wt% FGNP value and decrease afterward, hardness values increase in parallel with the increase in FGNPs. Composites were developed by functionalized graphene nanoplatelets (FGNP). The fiber‐matrix interface was strengthened with FGNP interphase. A 92% tensile strength increase was achieved with 1 wt% FGNP additives. 28% in impact strength and 55% in hardness increase by 1 wt% FGNP. The morphology confirmed that the FGNP interphase filled the interface. [ABSTRACT FROM AUTHOR]

The main challenge of fused deposition modeling (FDM) is the limited variety of commercially available semicrystalline polymer materials. Isotactic polypropylene (iPP), with a fast crystallization rate and high crystallinity, tends to undergo extensive volumetric shrinkage during the FDM process, further inducing severe deformation and poor dimensional accuracy in 3D‐printed parts. This study aims to develop desirable iPP‐based materials for the FDM technique through physically blending iPP and thermoplastic polyester elastomer (TPEE). TPEE retards the nonisothermal crystallization ability of iPP, as indicated by the significant decrease in crystallinity (Xc) from 47.7% for neat iPP to 28.5% for the iPP blend at a weight ratio of 30/70. The suppressed crystallization behavior accounts for a drastic decrease in the warpage degree of the 3D‐printed parts. The greater the content of TPEE is, the lower warpage the 3D‐printed parts have. Additionally, the presence of TPEE slightly influences the shear viscosity of iPP. As a result, iPP blends exhibit excellent extrudability during a typical FDM process. TPEE also enhances the impact strength of 3D‐printed parts by 168% compared to that of injection‐molded iPP. Taken together, the iPP blends developed in this work are promising FDM feedstock materials with good dimensional accuracy and excellent impact strength. [ABSTRACT FROM AUTHOR]

The dimensional accuracy of injection molded parts plays an increasingly significant role in the plastics processing industry, as is the utilization of recycled raw materials. To obtain the desired dimensions and properties of injection moldings, various material modification methods are used simultaneously. The conducted research aimed to assess the impact of hybrid modification of non-nucleated heterogeneously isotactic polypropylene using recovered phosphogypsum and a chemical blowing agent on the shrinkage value and mechanical properties of injection molded parts. Additionally, changes in dimensions and properties of composites with solid and porous structures that occur within 1000 hours of their removal from the injection mold were determined. The research showed that the filler used acts as a nucleating agent causing an increase in the shrinkage of the parts, up to 10 wt%. Similar changes were observed in the case of tensile strength. The increase in the value of this parameter at the lowest phosphogypsum contents used was most likely the result of changes in the crystalline structure of polypropylene. Changes in the mechanical properties of the molded parts that occurred during conditioning are correlated with shrinkage changes that occur from the moment the molded parts are removed from the injection mold. Young's modulus and tensile strength increased linearly for both solid and porous moldings. However, the rate of stiffness increases as a function of shrinkage changes with the filler content. Nevertheless, the opposite tendency was observed in the case of changes in impact strength, the values of which decreased as a function of shrinkage to the greatest extent in the case of unfilled polypropylene. [ABSTRACT FROM AUTHOR]

Highlights To improve the thermal conductivity and mechanical properties of graphene‐acrylonitrile butadiene‐styrene plastic (ABS) composite, sub‐phosphite‐based ionic liquid (IL) was synthesized, and its structure was characterized by FTIR, NMR, and mass spectrometry. IL was as a modifier, and graphite powder (G powder) was modified by the ball milling method to obtain functional graphene thermal conductive filler (G‐IL). The structure and morphology of G‐IL were characterized by FTIR, X‐ray photoelectron spectroscopy (XPS), XRD, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results of the Molau test showed that the presence of IL improved the interfacial interaction of G‐IL and ABS, enhanced the dispersion of G‐IL in the ABS matrix, made G‐IL contact with each other, and it was easier to establish a thermal conduction network and promote phonon transfer. The thermal conductivity of 9 wt% G‐IL/ABS composite was 0.392 W·m−1·k−1, which was 96% and 14% higher than that of pure ABS and G/ABS composite, respectively. The tensile strength and bending modulus of 9 wt% G‐IL/ABS composite were 44.89 and 2124.37 MPa, which were 13% and 11% higher than those of pure ABS, respectively. The impact strength of 9 wt% G‐IL/ABS composite was 34.17 kJ/m2. It was 18% and 7% higher than that of pure ABS and 9 wt% G‐IL/ABS, respectively. Phosphorus imidazole ionic liquids were prepared. Graphene was modified by ionic liquids through non‐covalent. Enhanced mechanical properties and thermal conductivity of G‐IL/ABS composites. [ABSTRACT FROM AUTHOR]

The preparation of wood‐plastic composites (WPCs) with high filling fibers and excellent physical properties remained a great challenge. This study used Camellia oleifera shell (COS, agroforestry product waste) as raw material, and prepared 60 wt% COS/high‐density polyethylene (HDPE) WPCs using profile extrusion method through pretreating fibers including hot water, hot steam, alkali, acid, extraction, and fine fiber screening. After pretreatments, the relative contents of cellulose and lignin increased, the relative contents of hemicellulose and extract decreased significantly, and the length‐diameter ratio was improved. The flexural strength, tensile strength and impact strength of hot water and steam heat treated composites reached 31.4, 17.1 MPa and 6.9 kJ/m2, 31.8, 16.8 MPa and 6.7 kJ/m2, respectively. Compared with untreated 28.8, 14.7 MPa and 5.5 kJ/m2, the advantages were more obvious. Alkali treatment and acid treatment improved the thermal stability and residue rate of the material. Extraction treatment and alkali treatment significantly reduced the processing torque force, which was conducive to processing, while acid treatment was the opposite. The highest water absorption and thickness expansion rate were 13.75% and 3.60% respectively at 7 days after alkali treatment, which were considerably higher than 5.60% and 0.78% without treatment, while other pretreatments improved the dimensional stability of the material. Highlights: High filling Camellia oleifera shell waste/HDPE composites were prepared.Physical and chemical pretreatments improved interfacial adhesion of the composites.Heat treatments significantly improved mechanical performance of the composites. [ABSTRACT FROM AUTHOR]

This paper focuses on the mechanical response and viscoelastic properties of double‐blade composite stiffened structure (DCSS) under low‐velocity impact (LVI). Firstly, the impact resistance and viscoelastic behavior of the DCSS are revealed by LVI testing at four different locations using the same initial velocity. Next, the damage morphologies at the impact locations are observed with ultrasonic A‐ and C‐scan equipment and optical microscopy. At last, the DCSS containing impact damage is implemented for axial compression and the strain values of the DCSS surface are obtained using a strain testing system to reveal its residual properties and buckling behavior. The results show that there are significant differences in the impact damage modes at the four different locations. The maximum impact resistance is observed at location D, while location A has the opposite. The DCSS has a certain viscoelastic behavior at LVI and conforms to an exponential decay model. Moreover, position B presents interface debonding damage due to stiffness discontinuities at the flange and skin bonding and severely weakens the load carrying performance of the DCSS. Highlights: The impact resistance of different positions is analyzed by LVI experimental results.Viscoelastic properties exist at different impact locations and obey the exponential decay model.Impact damage alters the buckling load and residual strength of the DCSS.The damage mechanism of the triangular zone is revealed by damage morphology. [ABSTRACT FROM AUTHOR]

The high‐strength and lightweight carbon fiber‐reinforced composites are widely used in various industries. Fused Filament Fabrication (FFF), the most cost‐effective Additive Manufacturing (AM) technology, has gained significant application advantages in the industry. The objective of this study is to improve the toughness of the carbon fiber‐reinforced polyamide composites used for FFF. In this work, HDPE was selected to reduce the hygroscopicity of PA6 while lowering the cost, carbon fiber was introduced to reinforce the PA6/HDPE blend. The elastomer POE‐g‐MAH was applied to increase the toughness of the composites as well as to improve the compatibility of the incompatible system of PA6/HDPE. Mechanical tests and micromorphology observation were carried on the FFF printed samples. The test results show that when 20 phr POE‐g‐MAH was added, optimum mechanical properties were obtained for the composites with about 18.9 wt% carbon fiber content. The tensile strength reached 94.1 MPa, and the notched impact strength reached 21.0 kJ/m2, which were 180.8% and 610.7% higher than that of the neat PA6, respectively. It is applicable for various applications that require high‐impact strength, including automotive parts and some machine components. Highlights: The PA‐2CF‐C20 composite exhibits high strength and high toughness, the tensile strength reaches 94.1 MPa and the notched impact strength reaches 21.0 kJ/m2.Successfully prepared cost‐effective and high‐performance filament for FFF 3D printers. [ABSTRACT FROM AUTHOR]

Highlights Biodegradable biobased polymers are a promising solution to reduce the dependence on conventional plastics and minimize their environmental impact. This work evaluated the recycling capacity of a biodegradable polymer (MaterBi) and its composite with agave fibers. The materials were reprocessed by several cycles using compression molding. Service life simulation was performed using accelerated weathering. Samples from each reprocessing cycle were characterized in terms of melt flow index (MFI), color, porosity, water absorption, compostability, and mechanical and thermal properties. The MFI of MaterBi increased with each cycle, going from 3.5 to 95 g/10 min for the first to sixth cycles and from 2 to 117 g/10 min for the first and fourth cycles for the biocomposite. Reprocessing produced chain scission and modified the thermal and mechanical properties. MaterBi exhibited competitive mechanical properties compared to conventional polymers, even after four reprocessing cycles (tensile, flexural, and impact strengths of 27, 55 MPa, and 30 J/m). Besides potential cost reductions, the agave fiber addition positively affected the tensile and flexural modulus, which remained after the fourth cycle in 1100 and 2300 MPa. The results confirmed that MaterBi and its biocomposites can be recycled for several cycles, extending their useful life before final biodegradation. MaterBi (MB) and its agave fiber biocomposites are suitable for reprocessing. MB tensile and flexural properties remained stable after four reprocessing cycles. Agave fibers make MB more prone to weathering, impacting its properties. MB and its biocomposites degrade in water and compost conditions. [ABSTRACT FROM AUTHOR]

PurposeDesign/methodology/approachFindingsResearch ImplicationsPractical ImplicationsOriginalityThe factors that drive user value co-creation behavior are unique to China due to the country’s unique economic, political and cultural influences. However, few scholars have paid attention to the driving factors of user value co-creation behavior in the Chinese context. In this study, the authors deepen their understanding of the drivers of user value co-creation behavior by exploring the impact of relationship strength, a variable with Chinese characteristics, on value creation behavior.The article takes the relationship strength of online fitness users as the research object from the user’s perspective, uses literature and questionnaires to establish a model of the influence mechanism of online fitness users’ relationship strength on value co-creation behavior, use AMOS to test the model empirically based on the data of 471 senior Chinese online fitness users.The findings confirm that all dimensions of relationship strength, except duration, have a significant positive impact on value experience. Each dimension of relationship strength has a significant positive impact on demand satisfaction. Value experience and demand satisfaction have a significant direct positive impact on value co-creation behavior.This study introduced the variable relationship between strength, explore the user relationship strength with Chinese characteristics variables influence on value creating behavior, follow the “stimulus → psychological perception → value co-creation behavior” logic, build the user relationship strength of value creating action mechanism model, and carries on the empirical test, it broadens the research perspective of driving users to produce value co-creation behavior.The results of this study show that managers need to enhance the relationship strength of users in online fitness communities, especially to improve users’ perception of reciprocity, and to focus on users’ needs and experiences to achieve value co-creation.This study makes two main contributions. It examines the impact of online fitness user relationship strength on value co-creation behavior in the Chinese context, enriching the research on the drivers of value co-creation behavior. Additionally, this study reveals the influence mechanisms of online fitness user relationship strength on value co-creation behavior and provides theoretical guidance for online fitness company to drive users to generate value co-creation behavior. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced biocomposites offer sustainable alternatives to conventional plastics. This study investigates the development of biocomposites using coconut spathe fiber, a renewable byproduct, reinforced with corn starch and poly(vinyl alcohol). The composites demonstrated significant mechanical properties, including a tensile strength of 46.8 MPa, flexural strength of 42.1 MPa, and an impact strength of 11.2 kJ m−2. Water absorption was limited to 33.6% after 24 hours, indicating hydrolytic stability. Biodegradation tests confirmed the complete breakdown of the material in composting conditions. These findings highlight the potential of coconut spathe-based biocomposites for applications in the automotive and packaging industries, addressing the need for sustainable and biodegradable materials in place of non-degradable thermoplastics. [ABSTRACT FROM AUTHOR]

Poly(lactide)/poly(butylene adipate‐co‐terephthalate) (PLA/PBAT) blends containing different amounts of polyethylene wax (PEW) were fabricated via melt‐blending, and the effects of PEW on the interfacial morphological evolution and properties of the PLA/PBAT blends were investigated. Scanning electron microscopy (SEM) micrographs show that the compatibility between PLA and PBAT is obviously improved by addition of low contents of PEW. Differential scanning calorimeter (DSC) results indicate that PEW can simultaneously enhance the crystallization ability of PLA and PBAT. Rheological behavior of the blends indicates that PEW has a significant plasticizing effect and can promote the mobility of polymer chains in the blends. More importantly, it is revealed that PEW can effectively improve the mechanical and barrier properties of the blends. Even with a PEW content of only 1 wt%, the elongation at break and notched impact strength of the blend reach 344.1% and 12.55 kJ/m2, respectively, which are 54% and 140% higher than the blend without PEW. Meanwhile, the water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) of the films containing 1 wt% PEW are decreased from 87.34 to 67.40 g m−2·24 h−1 and from 118.26 to 80.94 cm3 m−2·24 h−1, respectively, which are 22.8% and 31.5% lower than those of the PLA/PBAT film. [ABSTRACT FROM AUTHOR]

Polybutadiene grafted methyl methacrylate copolymer (PBL‐g‐MMA, MB) with core‐shell structure was prepared by emulsion polymerization. Without adding compatibilizers, PC/ABS composites were blended with polycarbonate (PC) and SAN. The effects of methacrylate butadiene (MB) on mechanical properties, flow properties, and thermal properties of PC/ABS composites were investigated. The results show that the addition of MB has obvious toughening effect on PC/ABS, effectively improving the mechanical properties and melt flow rate (MFR) of PC/ABS composites, and hence significantly improving the processability of PC/ABS composites. When the amount of MB is 12 phr, the notched impact strength of PC/ABS blend can reach up to 430 J/m. This is several times more than pure PC resin. The scanning electron microscope (SEM) analysis results show that the compatibility of PC/ABS and the impact strength of PC/ABS blend are improved with the increase of MB dosage. With the increase of MB content, the softening temperature of Vicat first decreased and then increased. It increased with the increase of PC content. [ABSTRACT FROM AUTHOR]

For decades, solid solution strengthening with up to 9 wt.% Ni has been the only successful strategy to obtain high strength and high impact toughness in bcc‐structured (ferritic or tempered martensitic) cryogenic steels. Until now coherent nano‐precipitates, an effective strengthening agent at room temperature, cannot be used to improve properties at cryogenic temperatures. Here, a new type of Mo‐rich nano‐B2 precipitates formed in a 6.5 wt.% Ni steel upon doping with 0.2 wt.% of Mo is reported. These precipitates are not only fully coherent with the matrix but are also shearable at 77 K. A high precipitate number density in excess of 2 × 1024 m−3 has been achieved by an industrially feasible process optimization, which brings both the cryogenic strength and impact toughness of the steel to the same levels as those of 9Ni steels. The Mo‐rich B2 precipitation strengthening, therefore, opens a new avenue for the design and development of low‐cost high‐performance cryogenic steels. [ABSTRACT FROM AUTHOR]

Finding appropriate measures to drive industrial agglomeration is particularly urgent for Africa, which has been facing a decline in industrial production activities. Therefore, this study contributed by developing a multi-level spatial analysis framework that explored the global driving mechanisms and local heterogeneity of industrial agglomeration in Africa through various critical factors. The findings are as follows: (1) From 2009 to 2019, the industry in Africa has always been highly concentrated in a few countries, but the degree of agglomeration has been declining, with some countries in the East and West African regions showing a significant increase in the level of industrial agglomeration and a high potential for development. (2) Industrial agglomeration in African countries was driven by several factors, of which GDP per capita, highway network density, and electricity supply were the strongest and most consistent drivers. The impact strength of factors varied considerably across regions. (3) The drivers didn’t act independently and directly on the dependent variable, but were the product of synergy after the interaction between the two factors. Synergies between access to electricity and GDP per capita and other factors dominated the pattern of industrial agglomeration in Africa. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of polyether block amide (PEBA) thermoplastic elastomeric nanofibers in reducing low-velocity impact damage across three carbon fiber composite lay-up configurations: a cross-ply [0°/90°]2s (CP) and a quasi-isotropic [0°/45°/90°/−45°]s (QI) lay-up utilizing unidirectional plies, and a stacked woven [(0°,90°)]4s (W) lay-up using twill woven fabric plies. The flexural strength and interlaminar shear strength of the composites remained unaffected by the addition of nanofibers: around 750 MPa and 63 MPa for CP, 550 MPa and 58 MPa for QI, and 650 MPa and 50 MPa for W, respectively. The incorporation of nanofibers in the interlaminar regions resulted in a substantial reduction in projected damage area, ranging from 30% to 50% reduction over an impact energy range of 5–20 J. Microscopic analysis showed that especially the delamination damage decreased in toughened composites, while intralaminar damage remained similar for the cross-ply and quasi-isotropic lay-ups and decreased only in the woven lay-up. This agrees with the broad body of research that shows that interleaved nanofibers result in a higher delamination resistance due to toughening mechanisms related to nanofiber bridging of cracks. Despite their ability to mitigate delamination during impact, nanofibers showed limited positive effects on Compression After Impact (CAI) strength in quasi-isotropic and cross-ply composites. Interestingly, only the woven fabric composites demonstrated improved CAI strength, with a 12% improvement on average over the impact energy range, attributed to a reduction in both interlaminar and intralaminar damage. This study indicates the critical role of fiber integrity over delamination size in determining CAI performance, suggesting that the delaminations are not sufficiently large to induce buckling of sub-layers, thereby minimizing the effect of nanofiber toughening on the CAI strength. [ABSTRACT FROM AUTHOR]

This paper presents the obtaining and characterization of blends based on high-density polyethylene (HDPE) and plasticized starch. In addition to plasticized starch (28.8% w/w), the compositions made also contained other ingredients, such as polyethylene-graft-maleic anhydride as a compatibilizer, ethylene propylene terpolymer elastomer, cross-linking agents, and nanoclay. Plasticized starch contains 68.6% w/w potato starch, 29.4% w/w glycerin, and 2% w/w anhydrous citric acid. Blends based on HDPE and plasticized starch were made in a Brabender Plasti-Corder internal mixer at 160 °C, and plates for testing were obtained using the compression method. Thermal analyses indicate an increase in the crystallization degree of the HDPE after the addition of plasticized starch. SEM micrographs indicate that blends are compatibilized, with the plasticized starch being well dispersed as droplets in the HDPE matrix. Samples show high hardness values (62–65° ShD), good tensile strength values (14.88–17.02 N/mm2), and Charpy impact strength values (1.08–2.27 kJ/m2 on notched samples, and 7.96–20.29 kJ/m2 on unnotched samples). After 72 h of water immersion at room temperature, mixtures containing a compatibilizer had a mass variation below 1% and water absorption values below 1.7%. Upon increasing the water immersion temperature to 80 °C, the sample without the compatibilizer showed a mass reduction of −2.23%, indicating the dissolution of the plasticized starch in the water. The samples containing the compatibilizer had a mass variation of max 8.33% and a water absorption of max 5.02%. After toluene immersion for 72 h at room temperature, mass variation was below 8%. [ABSTRACT FROM AUTHOR]

This study investigates the crystallization, microstructure, and performance of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) thin films processed through blown film extrusion and biaxial orientation (BO) at various blend ratios. Succinic anhydride (SA) was used to enhance interfacial adhesion in PLA-rich blends, while blends near 50/50 formed co-continuous phases without SA. Biaxial stretching and annealing, adjusted according to the crystallization behavior of PLA and PBS, significantly influenced crystallinity, crystallite size, and molecular orientation. Biaxial stretching induced crystallization and ordered chain alignment, particularly at the cold crystallization temperature (Tcc), leading to a 70–80-fold increase in impact resistance compared to blown films. Annealing further enhanced crystallinity, especially at the Tcc of PLA, resulting in larger crystallite sizes. BO films demonstrated reduced thermal shrinkage due to improved PLA crystalline structure, whereas PLA-rich blown films showed higher shrinkage due to PLA's lower thermal resistance. The SA-miscibilized phase reduced oxygen transmission in blown films, while BO films exhibited higher permeability due to anisotropic crystal orientation. However, the annealing of BO films, especially at high temperature (Tcc of PLA), further lowered oxygen permeability by promoting the crystallization of both PLA and PBS phases. Overall, the combination of SA compatibilization, biaxial stretching, and annealing resulted in substantial improvements in mechanical strength, dimensional stability, and oxygen barrier properties, highlighting the potential of these films for packaging applications. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) methods are increasingly being adopted as an alternative for mass production. In particular, Fused Deposition Modeling (FDM) technology is leading the way in this field. However, the adhesion of the layers in products produced using FDM technology is an important issue. These products are particularly vulnerable to forces acting parallel to the layers and especially to impact strength. Most products used in the industry have complex geometries and thin walls. Therefore, solid infill is often required in production, and this production must take place in the ZX orientation. This study aims to optimize the impact strength against loads acting parallel to the layers (ZX orientation) of PA6, one of the most widely used materials in the industry. This orientation is critical in terms of mechanical properties, and the mechanical characteristics are significantly lower compared to other orientations. In this study, filaments containing pure PA6 with 15% short carbon fiber and 30% glass fiber were utilized. Additionally, the printing temperature, layer thickness and heat treatment duration were used as independent variables. An L9 orthogonal array was employed for experimental design and then each experiment was repeated three times to conduct impact strength tests. Characterization, Taguchi optimization, and factor analyses were performed, followed by fracture surface characterization by SEM. As a result, the highest impact strength was achieved with pure PA6 at 8.9 kJ/m2, followed by PA6 GF30 at 8.1 kJ/m2, and the lowest impact strength was obtained with PA6 CF15 at 6.258 kJ/m2. Compared to the literature and manufacturer datasheets, it was concluded that the impact strength values had significantly increased and the chosen experimental factors and their levels, particularly nozzle temperature, were effective. [ABSTRACT FROM AUTHOR]

This study investigated the closed-loop recycling of 3D-printed wood fiber (WF)-filled polylactic acid (PLA) composites via fused filament fabrication (FFF). The WF–PLA composites (WPCs) were extruded into WPC filaments (WPCfs) to produce FFF-printed WPC parts (WPCps). The printed WPCps were reprocessed three times via extrusion and 3D-printing processes. The tensile properties and impact strengths of the WPCfs and WPCps were determined. To further investigate the impact of closed-loop recycling on the surface morphology, crystallinity, and molecular weight of WPCfs, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively, were used. After closed-loop recycling, the surface morphology of the WPCfs became smoother, and a decrease in the pore sizes was observed; however, the tensile properties (tensile strength and elongation at break) deteriorated. With increasing numbers of recycling iterations, the molecular weight of the PLA matrix decreased, while an increase in crystallinity was observed due to the recrystallization of the low-molecular-weight PLA molecules after recycling. According to the SEM images of the recycled WPCps, their layer heights were inconsistent, and the layers were rough and discontinuous. Additionally, the color difference (ΔE*) of the recycled WPCps significantly increased. Compared with those of the WPCps after recycling them only once, the tensile strength, elongation at break, and impact strength of the WPCps noticeably decreased after recycling them twice. Considering the changes in various properties of the WPCfs and WPCps, the FFF-printed WPC parts can be reprocessed only once through 3D printing. [ABSTRACT FROM AUTHOR]

This study investigates the shear bond strength between four widely used façade stones—travertine, granite, marble, and crystalline marble—and concrete substrates, with a particular focus on the role of polypropylene fibers in adhesive mortars. The research evaluates the effects of curing duration, fiber dosage, and mechanical anchorage on bond strength. Results demonstrate that Z-type anchorage provided the highest bond strength, followed by butterfly-type and wire tie systems. Extended curing had a significant impact on bond strength for specimens without anchorage, particularly for travertine. The incorporation of polypropylene fibers at 0.2% volume in adhesive mortar yielded the strongest bond, although lower and higher dosages also positively impacted the bonding. Furthermore, the study introduces a novel fuzzy logic model using the Dombi family of t-norms, which outperformed linear regression in predicting bond strength, achieving an R2 of up to 0.9584. This research emphasizes the importance of optimizing fiber dosage in adhesive mortars. It proposes an advanced predictive model that could enhance the design and safety of stone-clad façades, offering valuable insights for future applications in construction materials. [ABSTRACT FROM AUTHOR]

Additive manufacturing offers great potential for various industrial solutions; in particular, the binder jetting method enables the production of components from various materials, including sand molds for casting. This work presents the results of an extensive set of experiments aimed at enhancing the structural strengthening of 3D-printed sand molds. Structural strengthening was achieved by impregnating the sand-printed structures with two polymer materials: epoxy resin and silicone varnish. Impregnation was performed with variable parameters, such as temperature, pressure, and time. Structural strengthening using polymers was investigated by analyzing the flexural strength and impact resistance of the impregnated products and comparing these obtained values with the reference material in terms of impregnation parameters and the polymer used. Microstructural observations and an analysis of the pore filling were also performed. This approach allowed for a full assessment of the influence of processing parameters and the type of polymer used for impregnation on the properties of sand-printed structures, which allowed for identifying the most optimal method to be used to strengthen the sand molds for casting the components for electrical devices. As a direct proof of concept, it was shown that impregnation with polymeric materials could effectively strengthen the sand mold, increasing its flexural strength and impact resistance by over 20 times and 5 times, respectively. A full-scale mold was printed using binder jetting, impregnated with epoxy resin at 65 °C, and used to successfully fabricate a fully functional electrification device. [ABSTRACT FROM AUTHOR]

In research aimed at improving the brittleness of WER (waterborne epoxy)-modified emulsified asphalt, commonly encountered issues are that the low-temperature performance of this type of asphalt becomes insufficient and the long curing time leads to low early strength. Matrix-emulsified asphalt was modified with WPU (waterborne polyurethane), WER, and DMP-30 (accelerator). Firstly, the performance changes of modified emulsified asphalt at different single-factor dosages were explored through conventional performance tests and assessments of its adhesion, tensile properties, and curing time. Secondly, based on a response surface methodology test design, the material composition of the composite-modified emulsified asphalt was optimized, and its rheological properties were analyzed by a DSR test and a force–ductility test. Finally, the modification mechanism was explored by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that WER can improve the adhesion strength of modified emulsified asphalt and greatly reduce elongation at break. WPU can effectively improve the elongation at break of composite-modified emulsified asphalt, but it has a negative impact on adhesion strength. DMP-30 mainly affects the curing time of modified emulsified asphalt; EPD (composite modification) can effectively improve the high-temperature rutting resistance of matrix-emulsified asphalt, and its low-temperature performance is significantly improved compared with WER-modified emulsified asphalt. The EPD modification process mainly consists of physical blending. In the case of increasing the curing rate, it is recommended that the contents of WER and WPU be lower than 10% and 6%, respectively, to achieve excellent comprehensive performance of the composite modification. [ABSTRACT FROM AUTHOR]

This work aims to assess the possibility of using packaging industry waste to modify polypropylene products (PPs). The products were made in the form of extruded foil and injected samples. The products were produced using regranulate made of polypropylene cast foil. Maleic anhydride-modified polypropylene (MAPP) and polyolefin elastomer (POE) with a glycidyl ester functional group were used to modify the polypropylene. The samples were produced based on 50% foil waste reground and 50% pure PP. The rheological properties of the blends were assessed using the melt mass flow rate (MFR) technique; thermal properties using the differential scanning calorimetry method (DSC). The products manufactured using the injection molding method were subjected to an analysis of mechanical properties, such as tensile strength and impact strength. Also, in the case of film samples, tensile strength was assessed. Color-change assessments with CIE L*a*b* were carried out for all materials. Injection-molded products based on recycled metallized cast foil showed favorable mechanical properties such as tensile strength (1 MAPP = 26.7 MPa; 2 MAPP = 27.1 MPa), which was higher than the original material (cPP = 20.7 MPa). Also, for the films produced from regrind, the tensile strength was at a level similar (1 MAPP = 24.6 MPa; 2 MAPP/POE = 25.1 MPa) to the films extruded from virgin materials (cPP = 24.9 MPa). The introduction of a POE additive to the blends resulted in increased impact strength (1 MAPP/POE = 31 kJ/mol; 2MAPP/POE = 18 kJ/mol; 3 MAPP/POE = 11 kJ/mol) in relation to unmodified samples (cPP = 7 kJ/mol). The introduction of a POE additive to the tested mixtures improved the impact strength of the injected products by almost 4 times for sample 1 MAPP/POE and 2.5 times for sample 2 MAPP/POE in comparison to virgin cPP. These studies confirmed that foil waste can be successfully used to modify polypropylene products shaped both in the injection and extrusion processes. [ABSTRACT FROM AUTHOR]

Environmental problems, such as plastic pollution and global warming, are motivating researchers worldwide to seek sustainable biodegradable polymers that would replace the nonbiodegradable ones. Polylactic acid (PLA) has emerged as one of the most promising alternatives due to its superior mechanical and thermal qualities compared to other types of biopolymers. However, PLA has some inherent deficiencies such as its brittleness and rigidity, which limit its further use. This study investigates the toughening effect of different amounts of polybutylene adipate terephthalate (PBAT) on PLA, and the compatibilization effect of ADR, a chain extender, on the PLA/PBAT blends. The results indicate that PBAT can significantly enhance the flexibility and toughness of PLA. PLA and PBAT can react with ADR to form PLA-g-PBAT copolymers thereby increasing the compatibility of these two polymers. The tensile strength, elongation at break and impact strength of the PLA/PBAT/ADR blends are all increased due to the increased compatibility. The chain extension reaction can promote the formation of a better crystalline structure in the PLA/PBAT blends, which leads to the increase of the Tm of PLA. Besides, the hydrophilicity of PLA can be adjusted by blending with PBAT, and the hydrophilicity of the blends with blend ratios of 75:25, 50:50 and 25:75 can also be enhanced after the addition of ADR. [ABSTRACT FROM AUTHOR]

The all-CFRP sandwich structure with ultralight honeycomb is designed and manufactured by stretching process. Two scenarios, including global and local impact, are considered to reveal the characteristics of impact resistance. The effects of different impact energies and core densities on energy absorption and failure mechanism are thoroughly discussed. Meanwhile, the post-impact residual compressive strength is carried out to evaluate the influence of impact on structural strength and stability. The results show that under the global impact, the impact resistance is related to core density, and the energy absorption is mainly from honeycomb core. While under the local impact, as the impact energy increases, the failure mechanism of the structure changes from core crushing to penetration. The research provides a guidance for low-velocity impact performance and structural optimization design of sandwich structures. [ABSTRACT FROM AUTHOR]

Introduction: In this study, the effects of adding titanium dioxide nanotubes (TiO2) to 3D‐printed denture base resin on the mechanical and physical properties of denture bases were examined for the first time. Methods: The specimens were digitally created using 3D builder software from Microsoft Corporation through computer‐aided design. In accordance with the test specifications for transverse strength, impact strength, hardness, surface roughness, and color stability, specimens were designed and printed with certain dimensions following relevant standards. TiO2 nanotubes (diameter: 15–30 nm and length: 2–3 μm) were added to the 3D‐printed denture base resin (DentaBase, Asiga, Australia) at 1.0% and 1.5% by weight. Flexural strength, impact strength (Charpy impact), hardness, surface roughness, and color stability were evaluated, and the collected data were analyzed with ANOVA followed by Tukey's post hoc test (α = 0.05). Field emission scanning electron microscopy (FESEM) and energy dispersive x‐ray spectroscopy (EDX) mapping were used to evaluate the dispersion of the nanotubes. Results: Compared with those of the control group (0.0 wt.% TiO2 nanotubes), the average flexural, impact, and hardness values of the 1.0 and 1.5 wt.% TiO2 nanotube reinforcement groups increased significantly. Both nanocomposite groups showed significant color changes compared to that of the pure resin, and there was a considerable reduction in the surface roughness of the nanocomposites compared to that of the control group. Conclusion: Adding TiO2 nanotubes to 3D‐printed denture base materials at 1.0 and 1.5 wt.% could enhance the mechanical and physical properties of the material, leading to better clinical performance. Clinical Significance: In terms of clinical applications, 3D‐printed denture base material has been shown to be a viable substitute for traditional heat‐cured materials. By combining this with nanotechnology, existing dentures could be significantly enhanced, promoting extended service life and patient satisfaction while addressing the shortcomings of the current standard materials. [ABSTRACT FROM AUTHOR]

In this paper, a novel ultrasonic cavitation (USC)-assisted low-speed WEDM (WEDM-LS) process is proposed to address the issue of low machining efficiency and the recast layer when cutting thick nickel-titanium shape memory alloy (NiTi SMA) workpiece. Based on the Rayleigh-Plesset model, the machining mechanism of USC-assisted WEDM-LS is explored. Firstly, considering the influence of WEDM on vapor volume fraction (VVF) in the flow field, the impact strength of microjet, which is caused by collapsing near-wall acoustic bubbles on the workpiece surface, is studied. In addition, the influence of a single bubble collapse microjet impacting on the workpiece surface and recast layer is simulated and analyzed based on water hammer effect. The results demonstrated that the microjet is useful for removing workpiece material. The verification experiment results showed that, compared to traditional WEDM-LS, the material removal rate (MRR) of USC-assisted WEDM-LS increases by 31.65%, the thickness of the recast layer reduces by 20.39%, and the degree of burn surface is effectively reduced. These machining characteristics indicate that the surface integrity of the workpiece is improved greatly. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study on the effect of two local Libyan grasses, Stipa tenacissima (locally known as Halfa) and Retama raetam (locally known as R'tem) on the mechanical properties of styrene-butadiene rubber composites (SBR). For this purpose, the effect of filler type and content (10, 20, 30 and 40 wt%) on the mechanical properties of the composites including stress at break, elongation at break, impact strength and microhardness were evaluated. The stress at break of SBR increased only with the addition of 20 wt% and 30 wt% of Halfa. The highest value of stress at break was obtained by composites made with 20 wt% Halfa content. The elongation at break was significantly decreased with the addition of Halfa and R'tem. Generally, the elongation at break of the composites made with R'tem was slightly higher than that of composites made with Halfa. On the other hand, the addition of Halfa resulted in composites with relatively higher impact properties. The impact strength of these composites was increased with increasing the Halfa content up to 30 wt% after which it was decreased noticeably. However, the impact strength of composites made with R'tem did not follow a clear path with increasing R'tem content. Furthermore, the incorporation of Halfa and R'tem resulted in a significant increase in the hardness properties of the composites. R'tem showed to produce composites with higher hardness compared to those made with Halfa. Composites made with Halfa possess better toughness and ductility to a certain degree in comparison to composites made with R'tem. Although, Halfa appears to be relatively better than R'tem in reinforcing SBR, both fillers appeared to be good candidate filler to produce low cost and density polymer composites with acceptable mechanical properties. [ABSTRACT FROM AUTHOR]

Solid waste recycling is an economically sound strategy for preserving the environment, safeguarding natural resources, and diminishing the reliance on raw material consumption. Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials. This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-highperformance geopolymer concrete (UHPGC). In total, 18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder, ranging from 10% to 40%. Similarly, for each of the mixtures above, steel fibre was added at a dosage of 1.5% to address the inherent brittleness of UHPGC. The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders. The specimens were subjected to drop-weight impact testing, wherein an examination was carried out to evaluate various parameters, including flowability, density at fresh and hardened state, compressive strength, impact numbers indicative of cracking and failure occurrences, ductility index, and analysis of failure modes. Additionally, the variations in the impact test outcomes were analyzed using the Weibull distribution, and the findings corresponding to survival probability were offered. Furthermore, the microstructure of UHPGC was scrutinized through scanning electron microscopy. Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume, with reductions ranging from 18.63% to 34.31%. Similarly, failure impact number values decreased from 8.26% to 28.46% across glass powder contents. The maximum compressive and impact strength was recorded in UHPGC, comprising 10% silica fume with fibres. [ABSTRACT FROM AUTHOR]