J. Compos. Sci., Volume 7, Issue 1 (January 2023) – 42 articles

The radiation curing paradigm of opaque WS₂ nanoparticle (NP)-based epoxy/acrylate nanocomposites was studied and found to exhibit both a reduction in viscosity and an enhanced degree of curing when incorporating WS₂ NPs. The objective of this study was to investigate the mechanical, thermal, and physical properties of a radiation-induced and cured epoxy/acrylate blend containing 0.3 to 1.0 wt.% WS₂ NPs. Experimental results indicate that the tensile toughness increased by 22% upon optimizing the NP content compared to that of WS₂-free formulations. Tensile fractured surfaces with different WS₂ NP contents were analyzed with a scanning electron microscope and an atomic force microscope and showed distinctive morphology depending on the WS₂ NP content, supporting the results of the tensile test. The energy required to break shear adhesion specimens demonstrated an increase of up to 60% compared to that of the neat resin. The glass transition temperature determined by dynamic mechanical analysis presented similar or higher values upon WS₂ NP incorporation. Furthermore, up to 80% improvement in impact strength was demonstrated when WS₂ NPs were dispersed in the epoxy/acrylate blend. It was concluded that the surface chemistry and dispersion level of the WS₂ NPs are the major variables affecting the macro properties of cationically radiation-cured resins and their adhesion properties. This study is the first to demonstrate the possibility for radiation-induced curing of opaque NPs based on WS₂ that serve as both a reinforcement nanoparticle at low concentrations and an enhancement of the degree of curing. Full article

Cationic photo-initiated and polymerized epoxies are characterized by good adhesion, high modulus, zero volatiles, low shrinkage and living polymerization characteristics. Radiation—cured acrylate resins are characterized by rapid initial curing with increased initial strength. The combination of radiation-cured acrylates and epoxies may present advantageous attributes. Thus, the system investigated is a hybrid epoxy/methyl acrylate and three different initiators for cationic polymerization of epoxies, the radical reaction of acrylates and the thermal initiator. When incorporating additives like opaque WS₂ nanoparticles (NPs), absorption of the photo radiation takes place, which may lead to low photo activity. Curing kinetics measurements revealed that the absorbing/masking effect of WS₂ was insignificant, and surprisingly, the level of curing was enhanced when the WS₂ NPs were incorporated. FTIR results demonstrated that covalent bonds were formed between the inorganic fullerenes (IF-WS₂) and the crosslinked matrix. Viscosity measurements showed a surprising reduction of five to ten times in the low-shear viscosity upon NPs incorporation compared to neat resins. It was concluded that the decrease of viscosity by the inorganic NPs, in addition to the enhanced level of conversion, has profound advantages for structural adhesives and 3D printing resins. To the best of our knowledge, this investigation is the first to report on a radiation-induced curing system containing opaque WS₂ NPs that leads to an enhanced degree of curing and reduced shear viscosity. Full article

This study aimed to evaluate and compare the microleakage of composite resin restorations under a total-etch adhesive system applied with two different techniques, with and without cure. Cavities were made on the buccal surface of twenty-six intact teeth and subsequently restored with bulk-fill flow composite resin (SDR^®® flow+) and conventional resin (Spectra™ ST HV). Two experimental groups were created, one where the total-etch adhesive (Prime & Bond Active^®) was cured and another where the adhesive was not cured before placing the flowable resin. Two control groups were also created, negative and positive. After the restorations were finished the, teeth were submerged in a solution of sodium pertechnetate (^99mTcNaO4) for 3 h to evaluate the microleakage. The results showed more infiltration of radioisotopes characterized by the highest total count values of microleakage in group 1 (cured adhesive) and in the positive control. Group 2 (noncured adhesive) and the negative control showed lower values. We therefore considered that these groups were similar since their p-value was less than 0.05, with no statistically significant difference. Group 4 showed a statistically significant increase in relation to group 3 (p = 0.027). We concluded that the method of bulk-fill composite resins with noncured adhesive agents can have a positive effect on the longevity of bond strengths, with reduced microleakage. Full article

This study aims to investigate the effect of alkaline pH on the bottom-up synthesis of nanocomposites (NCs) containing terbium sulfide nanoparticles (Tb₂S₃ NPs), where chitosan (CS) was employed as a capping agent, along with evaluation of the antibacterial activity of these NCs. The NCs were characterized using spectroscopy (FESEM-EDX, Raman, FTIR, XRD, XPS, and DLS), zeta-potential, and TGA. The results of FE-SEM, XPS, Raman, and FTIR characterization support the formation of CS-Tb₂S₃ NPs. A pH variation from 9 to 11 during composite formation was shown to affect the size and composition of NCs. The antibacterial activity of CS-Tb₂S₃ NCs was studied by coating onto commercial contact lenses, where the best loading efficiency of NCs was 48%. The NCs prepared at pH 10 (without contact lenses) had greater antibacterial activity against Staphylococcus aureus, with a zone of inhibition diameter of 7.15 mm. The coating of NCs onto commercial contact lenses was less effective for inhibition of Staphylococcus aureus, in contrast with the greater activity observed for tetracycline. CS-Tb₂S₃ NCs offer promising antimicrobial properties that can be further optimized by control of the surface loading and accessibility of Tb₂S₃ NPs through further study of the role of the chitosan capping agent, since steric effects due to CS are likely to attenuate antimicrobial activity via reduced electron transfer in such nanocomposite systems. Full article

Due to the versatility of its implementation, additive manufacturing has become the enabling technology in the research and development of innovative engineering components. However, many experimental studies have shown inconsistent results and have highlighted multiple defects in the materials’ structure thus bringing the adoption of the additive manufacturing method in practical engineering applications into question, yet limited work has been carried out in the material modelling of such cases. In order to account for the effects of the accumulated defects, a micromechanical analysis based on the representative volume element has been considered, and phase-field modelling has been adopted to model the effects of inter-fiber cracking. The 3D models of representative volume elements were developed in the Abaqus environment based on the fiber dimensions and content acquired using machine learning algorithms, while fulfilling both geometric and material periodicity. Furthermore, the periodic boundary conditions were assumed for each of the representative volume elements in transversal and in-plane shear test cases,. The analysis was conducted by adopting an open-source UMAT subroutine, where the phase-field balance equation was related to the readily available heat transfer equation from Abaqus, avoiding the necessity for a dedicated user-defined element thus enabling the adoption of the standard elements and features available in the Abaqus CAE environment. The model was tested on three representative volume element sizes and the interface properties were calibrated according to the experimentally acquired results for continuous carbon-fiber-reinforced composites subjected to transverse tensile and shear loads. This investigation confirmed the consistency between the experimental results and the numerical solutions acquired using a phase-field fracture approach for the transverse tensile and shear behavior of additively manufactured continuous-fiber-reinforced composites, while showing dependence on the representative volume element type for distinctive load cases. Full article

In the manufacturing process of innovative fiber-based composite materials, natural fibers are among the most commonly employed reinforcements. In this study, Enset/Sisal (E/S) fiber with a polyester matrix was used to develop the hybrid composites. Hand layup methods were employed for the sample preparation from untreated, 5%, and 10% alkali-treated unidirectional and woven fiber orientations having 50:50 volume ratios. The mechanical properties and water absorption of natural fiber hybrid composites were influenced by fiber treatment and orientation. In the present investigation, the result shows that treated and woven fiber orientation hybrid composites exhibit better mechanical properties than untreated and unidirectional E/S hybrid composites. The 5% NaOH-treated samples have higher tensile and flexural strength properties than the untreated and 10% alkali-treated composites, while the 5% NaOH-treated fiber composites have lower water absorption properties. The tensile and flexural strengths and impacts of 5% NaOH-treated composites were improved by 5.21%, 9.25%, and 5.98%, respectively, over untreated E/S hybrid composites. The morphological properties of the fracture surface of the composite were observed using scanning electron microscopy (SEM). Full article

The blending of polymers leads to materials with the desired combined properties. These properties can further be improved by the incorporation of compatibilizer, organoclay, or both. In the present manuscript, the effects of compatibilizer and organoclay, as well as their combined use on the rheological, thermal, and mechanical properties of styrene copolymer blends, is examined. Styrene-containing copolymers blends were prepared by melt-mixing in a twin screw extruder. The addition of SAN into ABS decreases its thermal stability, whereas it increases its tensile strength and modulus. The incorporation of organoclay in ABS/SAN blends increases their viscosity and slightly improves their thermal stability and significantly improves the tensile and storage moduli. In PC/SAN blends, the SAN copolymer increases the flow rate, as well as the tensile strength and modulus of PC, whereas it decreases the thermal stability. The addition of ABS-g-MAH compatibilizer in PC/SAN blends increases the melt viscosity and maximum decomposition rate temperature of SAN phase, while it leads to the earlier decomposition of the PC phase. The incorporation of organoclay reinforcement enhances the thermal decomposition resistance of thes SAN phase. The opposite effect was recorded for the PC phase. The addition of organoclay enhances the elastic modulus of PC/SAN hybrids. Full article

Sulfur cements have drawn significant attention as binders because sulfur is a byproduct of fossil fuel refining. Sulfur cements that can be formed by the vulcanization of elemental sulfur and plant-derived olefins such as terpenoids are particularly promising from a sustainability standpoint. A range of terpenoid–sulfur cements have shown compressional and flexural properties exceeding those of some commercial structural mineral cements. Pozzolans such as fly ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS) and abundant clay resources such as metakaolin (MK) are attractive fines for addition to binders. Herein, we report 10 composites prepared by a combination of sulfur, terpenoids (geraniol or citronellol), and these pozzolans. This study reveals the extent to which the addition of the pozzolan fines to the sulfur–terpenoid cements influences their mechanical properties and chemical resistance. The sulfur–terpenoid composites CitS and GerS were prepared by the reaction of 90 wt% sulfur and 10 wt% citronellol or geraniol oil, respectively. The density of the composites fell within the range of 1800–1900 kg/m³ and after 24 h submersion in water at room temperature, none of the materials absorbed more than 0.7 wt% water. The compressional strength of the as-prepared materials ranged from 9.1–23.2 MPa, and the percentage of compressional strength retained after acid challenge (submersion in 0.1 M H₂SO₄ for 24 h) ranged from 80–100%. Incorporating pozzolan fines into the already strong CitS (18.8 MPa) had negligible effects on its compressional strength within the statistical error of the measurement. CitS-SF and CitS-MK had slightly higher compressive strengths of 20.4 MPa and 23.2 MPa, respectively. CitS-GGBFS and CitS-FA resulted in slightly lower compressive strengths of 17.0 MPa and 15.8 MPa, respectively. In contrast, the compressional strength of initially softer GerS (11.7 MPa) benefited greatly after incorporating hard mineral fines. All GerS derivatives had higher compressive strengths than GerS, with GerS-MK having the highest compressive strength of 19.8 MPa. The compressional strengths of several of the composites compare favorably to those required by traditional mineral cements for residential building foundations (17 MPa), whereas such mineral products disintegrate upon similar acid challenge. Full article

Herein, the vacuum arc-melting process is applied to incorporate various amounts of Ti and C into SUS304 austenitic stainless steel based on the high-entropy alloy concept to obtain wear- and corrosion-resistant alloys with in situ carbide reinforcements. Five compositions containing the equivalent of 5, 10, 15, 20, and 25 volume percentages of TiC in SUS304 stainless steel, named A1, A2, A3, A4, and A5, respectively, were designed, melted, and solidified by the arc-melting method. Microstructural analyses, hardness measurements, immersion tests in four corrosive solutions, electrochemical measurements in a 3.5 wt % NaCl_(aq) solution, and tribological tests were conducted to determine the properties and explain the relevant mechanisms. A1 exhibited a eutectic structure between FCC dendrites, while A2, A3, A4, and A5 possessed proeutectic dendritic TiC, FCC dendrites enveloping the TiC dendrites, and a eutectic structure. A5 represents the optimal composition. Its hardness, wear resistance, and corrosion resistance are 2, 14, and 4 times higher than those of SUS304, respectively. Additionally, its wear resistance is 2.5 times that of high-chromium cast iron. Consequently, A5 could have a 2.5-fold longer lifetime in wear operation. Therefore, A5 could be potentially applied in corrosive and abrasive environments, such as rotary shafts, rotors, bearings, and structural parts in food, chemical, and optoelectronic industries. Full article

The split Hopkinson pressure bars (SHPB) system is the most commonly employed machine to study the dynamic characteristics of different materials under high strain rates. In this research, a numerical investigation is carried out to study different bar shapes such as square, hexagonal, and triangular cross-sections and to compare them with the standard cylindrical bars. The 3D finite element model developed for circular cross-sectional shapes was first validated with the experimental results and then compared with the other proposed shapes. In most scientific research, cylindrical cross-section bars with a square cross-section specimen are traditionally used as they have several advantages, such as in situ imaging of the side surfaces of the specimen during stress wave propagation. Moreover, the flat surfaces of the proposed shapes counter the problem of debonding strain gauges, especially at high impact pressures. Comparison of the results showed an excellent confirmation of the sample dynamic behaviour and different geometric shapes of the bar geometries, which validates the choice of the appropriate system. Full article

Lattice structure topology is a rapidly growing area of research facilitated by developments in additive manufacturing. These low-density structures are particularly promising for their medical applications. However, predicting their performance becomes a challenging factor in their use. In this article, four lattice topologies are explored for their suitability as implants for the replacement of segmental bone defects. The study introduces a unit-cell concept for designing and manufacturing four lattice structures, BCC, FCC, AUX, and ORG, using direct melt laser sintering (DMLS). The elastic modulus was assessed using an axial compression strength test and validated using linear static FEA simulation. The outcomes of the simulation revealed the disparity between the unit cell and the entire lattice in the cases of BCC, FCC, and AUX, while the unit-cell concept of the full lattice structure was successful in ORG. Measurements of energy absorption obtained from the compression testing revealed that the ORG lattice had the highest absorbed energy (350 J) compared with the others. The observed failure modes indicated a sudden collapsing pattern during the compression test in the cases of BCC and FCC designs, while our inspired ORG and AUX lattices outperformed the others in terms of their structural integrity under identical loading conditions. Full article

Shear thickening fluids (STFs) have been shown to improve the effectiveness of fabrics used in soft body armor applications. They are used to increase the puncture and ballistic impact resistance of Kevlar^® fabrics. However, the effect of using STFs with natural fabrics such as flax appears to have never been studied. Similarly, the hybridization of different fabric types impregnated with STF has also only undergone limited study. The rheology of STFs at varying concentrations of nanosilica dispersed in polyethylene glycol (PEG) was studied at different temperatures. It was found that the STFs behave as a non-Newtonian fluid in response to changes in shear rate. In this study the effectiveness on the puncture and ballistic impact resistance of impregnating flax fabric with STF at concentrations of 30%, 50%, and 70% w/w of nanosilica in PEG was investigated. The effect of hybridization of flax and Kevlar^® fabrics impregnated with STF was also investigated. The puncture resistance of both flax fabrics treated with STFs and hybrids treated with STFs was found to increase significantly and can be controlled by STF concentration. The ballistic impact resistance was also found to increase in the hybrid samples when STF concentration was at least 50%. The flax treated with STFs showed either a decrease in specific energy absorption per layer for the lower STF concentration, or a very small increase at 70% STF concentration. Full article

A formulation for the analysis of the nonlinear vibrations of Variable Stiffness (VS) plates is presented. Third-order Shear Deformation Theory (TSDT) is employed in conjunction with a mixed variational formulation. The solution is sought via Ritz approximation for the spatial dependency, while time dependency is handled via Differential Quadrature (DQ) and Harmonic Balance (HB) methods. The main advantage of the framework is the reduced computational time, which is of particular interest to explore the large design space offered by variable stiffness configurations. The results are validated against reference solutions from the literature. Exemplary parametric studies are presented to demonstrate the potential of the approach as a powerful means for exploring the nonlinear vibration response of VS plates. Full article

One of the biggest problems facing the use of carbon nanotubes in reinforced composites is agglomeration within the matrix phase. This phenomenon—caused by Van der Waals forces—leads to dispersion problems and weakens the properties of the composites. This research presents a multi-stage homogenization approach used to investigate the influence of the aspect ratio, volume fraction, and agglomeration of the nanofillers on the effective mechanical properties of a polymer biocomposite containing randomly dispersed carbon nanotubes and graphene nanoplatelets. The first stage consisted in evaluating the properties of the reinforced polymers by the CNT/GNP. The second step consisted in combining the reinforced polymers with different natural and synthetic unidirectionally oriented fibers. It was found that agglomeration has a huge influence on the mechanical properties of the composite. The novelty of this work consisted of the consideration of the parameters influencing the elastic properties using different micromechanics approaches and numerical techniques. Full article

The fouling of biomaterials (e.g., membranes) by plasma proteins has always garnered attention because it renders biomedical devices ineffective and can jeopardize the patient’s well-being. Modeling the fouling process sheds light on its mechanisms and helps improve the biocompatibility of biomaterials. Assuming proteins to be hard spheres with uniform surface properties reduces the modeling complexity, but it seriously deviates from the accurate, real perspective. One reason for the inaccuracy is that proteins’ properties tend to change as environmental factors such as pH and ionic strength are varied. This study critically reviews the pH-induced changes in protein properties, namely size, charge, conformity, hydrophobicity, and denaturation. Though these properties may be interrelated, they are addressed individually to allow for a thorough discussion. The study illustrates the necessity of incorporating the protein property changes resulting from pH alteration to better explain and model the fouling process. The discussion is focused on human serum albumin and fibrinogen. Human serum albumin is the most abundant plasma protein, while fibrinogen plays a major role in blood clotting and triggering of the thrombogenic response. Full article

Although polylactic acid (PLA) is one of the most used materials in additive manufacturing, its mechanical properties are quite limiting for its practical application, therefore, to improve these properties it is frequent to add fibers and, in this way, create a more resistant composite material. In this paper, the authors developed PLA composites reinforced with flax fibers to evaluate the improvement of tensile and flexural strength. The experimental design of experiments was based on the L18 Taguchi array where the control factors were the extruder temperature (three levels), number of strands (three levels), infill percentage of the specimens (three levels), and whether the flax fiber had surface chemical treatment. The tensile and flexural specimens were made on a 3D printing machine and was a mold was developed to fix and align the fiber strands during the printing process. The tensile and flexural experimental tests were performed in agreement with ASTM D638.14 and ISO 14125 standards, respectively. Analyzing the results, it was verified that the surface chemical treatment (NaOH) of the fiber did not show any influence in the mechanical properties of the composites; in contrast, the infill density demonstrated a huge influence for the improvement of mechanical strength. The maximum values of tensile and bending stress were 50 MPa and 73 MPa, respectively. The natural fiber reinforcement can improve the mechanical properties of the PLA composites. Full article

Hydrogels are hydrophilic, three-dimensional networks able to imprison large amounts of water and are largely used in pharmaceutical formulations. Hydrogels are frequently obtained from hydrophilic polymers, either natural, biohybrid, or synthetic. Owing to their peculiar structure, dendrimers can be considered prospective building blocks for hydrogel networks. This review gathers the use of different types of amphiphilic dendritic structures able to generate physical hydrogels alone. Such dendritic structures comprise dendrimers, Janus dendrimers, and dendrons. The first part concerns different types of positively charged phosphorus dendrimers used to generate hydrogels, which are also suitable to form fibers, and for encapsulating diverse substances, or forming complexes with genetic materials for their slow delivery. The second part concerns PAMAM dendrimers functionalized with collagen mimetics. The third part concerns amphiphilic Janus dendrimers, whereas the fourth part displays different types of amphiphilic dendrons and their use, in particular in the fields of materials and drug delivery. Full article

In this study, the oxidation stability up to 1000 °C in air of the Hf(C,N)-MoSi₂ composites was explored under non-isothermal and isothermal conditions. Composites with 1, 5, 10, and 20% volume fractions were produced by low-energy ball milling and subsequent spark plasma sintering. Differential scanning calorimetry (DSC) and thermogravimetric (TG) coupled with mass spectrometry were used to reveal the staging of the oxidation process depending on the additive content. It was found that samples containing 1 and 5 vol% MoSi₂ had the lowest weight gain and the best oxidation behavior. The results of this study were supported by microstructural and phase analyses of the samples after isothermal treatment in a furnace. The samples with the lowest molybdenum disilicide content had a dense and thin protective oxide film on the surface, consisting of hafnium orthosilicate and monoclinic HfO₂. The increase in the amount of MoSi₂ contributed to the formation of a loose and porous oxide layer due to the increase in the concentration of volatile MoO₃. However, all samples exhibited higher oxidation resistance compared to the pure Hf(C,N). Full article

Shape memory polymers (SMPs) are emerging smart materials that have the ability to change to a shape and revert to their permanent shape on application of external stimulus. SMPs can be divided into four types based on their permanent shape, elasticity origin, and temporary shape fixing mechanism: chemically cross-linked glassy thermosets, chemically cross-linked semi-crystalline, physically cross-linked glassy copolymers, and physically cross-linked block copolymers. The broad overview of recent developments on SMPs for biomedical applications proves their wide applicability in the field of general medicine, drug delivery, regenerative medicine, dentistry, neuromedicine, cancer therapy, orthopedics, and corrosion protection. Herein, a comprehensive analysis of SMPs and their composites with focus on their types, mechanism, functionality and biomedical applications is presented. Relevant biomedical technologies based on SMPs and their future advancement towards biomedical applications are also discussed. Full article

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing of as-new samples. In order to get closer to the condition on the roads, where not only new vehicles are driving, the influence of service loads on the crashworthiness has to be investigated. This paper reports on studies of PBT GF30, a polybutylene terephthalate reinforced with 30% glass fibres, in which fatigue damage was induced in the material by cyclic loading. The residual strength was then determined in a high-speed experiment and compared with the strength of virgin samples. In order to enable the usability of the findings in the simulation, a modified failure criterion was implemented that takes the previous fatigue damage into account. The prediction quality of the simulation model was compared with the experimental findings and it can be concluded that there is good agreement. Full article

The analytical or numerical determination of the stress intensity factor (SIF) in cracked bodies usually assumes the body to be isolated. However, in fibre-reinforced composites, the fibre, which is the main load-carrying component, is embedded in a matrix. To clarify the effect the embedding matrix has on the SIF of the fibre, we propose a 3D computational model of an orthotropic fibre embedded in an isotropic matrix, and compute the SIF using the J-integral method. A parametric analysis based on dimensionless variables explores the effect of the fibre–matrix stiffness ratio as well as the effect of the degree of elastic orthotropy of the fibre. The results show that the SIF is strongly influenced by both factors, and that the matrix reduces the SIF by limiting the crack opening. Full article

This work analyzes the use of sewage sludge, generated in wastewater treatment plants, as an alternative for small aggregate to be used in concrete. Concrete cylindrical specimens with height h = 20 cm and diameter D = 10 cm were prepared using different amounts of sludge in the substitution of fine aggregates. Portland cement (CP II Z 32 RS cement) was used in all concrete mixtures, and two water-cement ratios and four cement-sludge mixtures were investigated. Compressive strength, sclerometer index, ultrasonic wave transmission velocity, and water absorption capillary tests were performed. The results showed that the use of sewage sludge as a replacement for fine aggregate to produce concrete exhibited a positive effect on both its compressive strength and its capillary water absorption. The results, even preliminary ones, demonstrated that the sludge could be used as an effective replacement for fine aggregate to produce concrete. The replacement of fine aggregate with 5% sewage sludge proved to be the optimal replacement value for the type of sewage sludge investigated. Full article

Supercapacitors are one of the promising devices for the accumulation and storage of electrical energy. The purpose of this study is to develop a synthesis and modification method of carbon material to improve the electrochemical characteristics of a supercapacitor. In the proposed study, by varying the sequence and parameters of the processes of carbonization, mechanoactivation and thermochemical activation, the conditions for obtaining nanoporous carbon with a specific surface area of 2200 (±50) m²/g from walnut shells (WSs) are optimized. In addition, to increase the electrochemical efficiency of the electrode material, the resulting nanoporous carbon was modified with nickel oxide (NiO) nanoparticles by the thermochemical method. It is shown that the modification with nickel oxide nanoparticles makes it possible to increase the specific capacitance of the supercapacitor electrode by 16% compared to the original unmodified nanoporous carbon material. Full article

Cellulose-Sn(IV) (CSn) biocomposite was synthesized by cellulose and stannic chloride in ethanol medium using microwave irradiation for 2 min with 30 s of intermittent time intervals. The incorporation of Sn(IV) into the cellulose matrix was confirmed through FT-IR, XRD, TGA, SEM- EDS, and BET. The prepared composite CSn has been used for the adsorptive removal of As(III) from water. Parameters, such as initial concentration, adsorbent dose, initial As(III) concentration, and time required for the adsorption process, were optimized through the batch-adsorption process. The adsorption capacity of the CSn for As(III) adsorption was found to be 16.64 mg/g at pH 7.0. Freundlich isotherm was found to be more suitable for the adsorption process based on regression coefficient values. Pseudo-second-order kinetic model was found to be more suitable for understanding the kinetics of the adsorption of As(III). Weber–Morris model with non-zero intercept revealed that the mechanism of adsorption was not limited to the diffusion process only. The adsorption process was spontaneous and exothermic and showed a decrease in randomness. Chloride ions decreased the percentage removal of As(III) when the concentration of chloride ions was ten times that of As(III) concentration according to the results obtained through the effect of co-anions study. In this study, 5% (w/v) NaCl solution has been used for the regeneration of the material, and during up to five adsorption–desorption cycles, there was a gradual decrease in percentage removal of As(III) from 95% to 78% only, which proves the greener aspect of the CSn. The breakthrough volume of 1.25 L of 10 mg/L of As(III) in column studies revealed that the CSn could be applicable for larger sample volumes also. Full article

The properties and oxidation wear patterns in the composite nanostructured coating of Zr-ZrN-(Zr,Mo,Al)N were studied during the turning of Inconel 718 alloy at the cutting speeds of v_c = 125 and 200 m/min. The hardness of the coating, its elastic modulus, and critical fracture load during the scratch testing were determined. The study focused on the tribological properties of the Zr-ZrN-(Zr,Mo,Al)N coating at temperatures of 400–900 °C paired with an insert made of Inconel 718, which exhibited a certain advantage over the reference coatings of Zr-ZrN and Ti-TiN-(Ti,Cr,Al)N of similar thickness. The coating of Zr-ZrN-(Zr,Mo,Al)N provided for the longest tool life at the cutting speed of v_c = 125 m/min (the tool life was four times longer in comparison with that of the uncoated tool and 15% longer in comparison with that of the Ti-TiN-(Ti,Cr,Al)N-coated tool) and at the cutting speed of v_c = 200 m/min (the tool life was 2.5 times longer in comparison with that of the uncoated tool and 75% longer in comparison with that of the Ti-TiN-(Ti,Cr,Al)N-coated tool). While at the cutting speed of v_c = 125 m/min, the surface coating layers exhibit only partial oxidation of the external layers (to a depth not exceeding 250 nm), with mostly preserved cubic nitride phases, and then the cutting speed of v_c = 200 m/min leads to almost complete oxidation (to the depth of at least 500 nm), however, with a partially preserved nanolayered structure of the coating. Full article

In the present study, polyamide (PA) was successfully reinforced with cellulose nanocrystal (CNC) prepared from date palm leaves using two different techniques, electrospinning and the solution casting method, and a comparative study of these two systems was performed. The morphological, thermal, wetting, and mechanical properties of the nanocomposites were analyzed for CNC content between 0 and 5 wt%. Morphological analyses showed different roughness in the fractured surface of neat PA and its nanocomposites after the addition of CNC. The modified composite is found to have a smooth surface without cracks and showed increased roughness with greater hydrophilicity and thermal stability. The nano-indentation results showed that the highest hardness was obtained at 5% CNC loading for the solution cast composite samples, which could be related to the relatively good CNC dispersion with good filler matrix bonding as evidenced by the morphological characterization. We also observed that the electrospinning technique produced nanocomposites of better thermo-physical properties than the solution cast method. The results point to the prospect of the development of nanocomposite films using date-palm-leaf-derived CNC incorporated in PA for high-performance and advanced material applications such as membranes. Full article

This paper presents a mesoscale model to study the influence of rubber particles on the mechanical performance of crumb rubber mortar (CRM). The indirect tensile and flexural behaviors of CRM with different rubber replacement rates, shapes, and sizes were investigated. Rubber mortar is assumed to be a three-phase material composed of rubber aggregate, a mortar matrix, and an interface transition zone (ITZ). Numerical analysis showed that rubber content was the governing factor affecting the reduction rate of indirect tensile and flexural strength. The effect of the ITZ on the tensile strength of CRM was within one percent, which could be ignored. The influence of rubber particle size was investigated by analyzing CRM models containing five different rubber sizes from 0.86 mm to 7 mm. For each size, six different models with randomly distributed rubber particles were set up. CRM models presented a similar average strength even with different rubber particle sizes. However, the strength variation among the random models became higher when the rubber particle size increased. Numerical results also proved that treating rubber particles as pores in modeling led to negligible errors. Then, a prediction formula after considering the increase in air content is provided. Finally, the accuracy of numerical simulations was verified through a series of experimental studies. Full article

Developing composite materials with both thermal conductivity and microwave absorption is an effective strategy to solve the problems of heat dissipation burden and microwave radiation interference caused by the development of miniaturization and high performance of portable electronic equipment. However, these properties are not easy to simultaneously implement due to the limitation of single type fillers with a single particle size, inspiring the possibility of realizing multifunctional composites with the introduction of composite fillers. In this work, using alumina (Al₂O₃) and zinc oxide (ZnO) as head-conducting fillers, carbonyl iron (Fe(CO)₅) as microwave-absorbing fillers, silicone rubber (SR) composites (Al₂O₃/ZnO/Fe(CO)₅/SR) with enhanced microwave absorption, high thermal conductivity and good mechanical properties were successfully mass prepared. It was found that the composites can achieve a thermal conductivity of 3.61 W·m⁻¹·K⁻¹, an effective microwave absorption bandwidth of 10.86–15.47 GHz. Especially, there is an effective microwave absorption efficiency of 99% at 12.46–14.27 GHz, which can realize the integration of electromagnetic shielding and heat dissipation. The compact microstructure, formed by the overlapping of large particle size fillers and the filling of their gaps by small particle size fillers, is helpful to enhance the thermal conduction path and weaken the microwave reflection. The heat-conducting microwave-absorbing Al₂O₃/ZnO/Fe(CO)₅/SR composites also have the advantages of thermal stability, lightness and flexibility, providing a certain experimental basis for the research and development of high-performance and diversified composites. Full article

A novel ion-mediated self-assembly method was applied for integration of graphene oxide (GO), propanoic- and glutaric-substituted perylenes (glu-PDI and PA-PDI), and Zn (OAc)₂ into new hybrid materials with photocatalytic properties. The structuring of chromophores through coordination bonding on the GO surface is controlled by the chemistry of the PDI linkers. Four-substituted glu-PDI forms consolidated microporous particles, whereas di-substituted PA-PDI binds with GO into a macroporous gel-like structure. The GO/PDI controls without Zn²⁺ ions form only non-integrated dispersions. Both hybrids can initiate photodestruction of 1,5-dihydroxynaphtalene (DHN) due to the effective charge separation between the PDI components and GO by generating hydroxyl radicals determined by luminescent probing with terephthalic acid. The reduction mechanism of photodegradation was confirmed by MALDI-TOF spectroscopy. The structure of the hybrids controls the rate of photodegradation process. The glu-PDI-based photocatalyst shows a smaller rate of photoreduction of 3.3 × 10⁻² min⁻¹ than that with PA-PDA (4 × 10⁻² min⁻¹) due to diffusion limitations. Our results suggest that the ion-mediated synthesis is a useful and rational alternative for the conventional synthesis of GO-based functional hybrid materials through aromatic stacking between the graphene oxide and organic chromophores to produce new affordable and efficient photocatalysts. Full article

In this work, the physicomechanical, chemical and thermal properties of low-density polyethylene (LDPE) modified with a biocide containing metal nanoparticles: nanoAg, nanoCu, and nanoFe₂O₃ were examined. The presented studies, apart from the previously proven antimicrobial effectiveness, have shown that the application of the biocide in concentrations of 0.5% and 1% has the least influence on the remaining properties. In the remaining concentrations (2–5%), despite the lack of significant influence on the chemical structure, the biocide primarily influenced the strength properties and melt flow rate (MFR). Previous research showed almost 100% antimicrobiological properties against bacteria and fungi of samples with the addition of 4% biocide. For such samples, the presented studies showed a decrease in MFR by approx. 17%, tensile strength at break by approx. 45%, an increase in elongation at breaking by approx. 25%, a decrease in density >2%, no increase in water absorption, and no significant changes in the chemical structure and in thermal properties in relation to LDPE without biocide. Full article