J. Compos. Sci., Volume 7, Issue 3 (March 2023) – 42 articles

A contrast agent with specific characteristics is essential for high-quality magnetic resonance imaging (MRI). It plays a crucial role in enhancing the visibility of certain tissues and structures, making it imperative for diagnostic procedures. Superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as a promising alternative to traditional contrast agents for MRI due to their non-toxicity and superior magnetic properties. However, a suitable surface coating strategy is needed to produce polymer-coated SPIONs with controllable sizes in order to enhance their stability and biocompatibility. This study presents a novel one-pot synthesis method for the production of highly stable polyvinylpyrrolidone (PVP)-coated SPIONs. By systematically manipulating the physicochemical properties of SPIONs, the effect of different molecular weights of PVP was studied. The results showed that SPIONs coated with PVP with molecular wight 40,000 g/mol (40 K) exhibited a high magnetization (Ms = 48.4 emu/g), an average size distribution (11.61 nm), and excellent stability. The relaxivity of coated and uncoated SPIONs was investigated using MRI images. The results revealed that the (r₂/r₁) ratio of PVP40K-SPIONs was 72.55, compared to 55.72 for the bare SPIONs, making them a highly promising T₂-contrast agent for future development of MRI applications. This study opens new avenues for the development of biocompatible and stable SPIONs for improved medical diagnostic and imaging. Full article

A great challenge hindering the use of cellulose nanofibers (CNF) as a reinforcing filler in bio-based polymeric matrices are their poor chemical compatibility. This is because of the inherent hydrophilic nature of CNF and the hydrophobic nature of the polymeric matrix. In this study, cellulose laminates were prepared by using CNF as a filler and cellulose acetate butyrate (CAB) as the polymer matrix. To improve the compatibility between CAB and CNF, the residual hydroxyl groups of CAB and the hydroxyl groups on the surface of CNF were cross-linked with bio-derived polyisocyanurate D376N (STABiO™). The composite material was obtained in one step by sandwiching a CNF sheet (10 wt%) coated with a cross-linking agent between CAB films (90 wt%) using hot pressing. When 14.3 wt% of the cross-linking agent to the total weight of CNF and CAB was added, the tensile strength and flexural strength were improved by 72.4% and 16.3%, respectively, compared with neat CAB. It was concluded that this increase in strength is a result of both: cross-linking between the CNF sheets as well as the cross-linking occurring at the CNF/CAB interface. Full article

Most metropolitan areas in the world are facing major solid-waste-disposal problems. The solid-waste problem is considered one of the major environmental problems that countries and environmental organizations are paying increasing attention to at present, not only due to its negative effects on public health and the environment, but also due to the dangers it may cause to the nearby residential communities. One of the visible solutions is to reuse solid waste as a partial replacement of concrete constituents. In this investigation, fine aggregate was replaced with crumb rubber at four different volumetric percentages, ranging from 5 to 20% with a 5% step size. A novel treatment technique based on a combination of chemical and thermal treatments of a crumb rubber surface was adopted. A superplasticizer was added to improve both the workability and the strength of the concrete mixtures. The mixtures were assessed in fresh and hardened phases and compared with a control mix. In the fresh phase, the mixtures were evaluated regarding workability and wet density; and in the hardened phase, compressive strength after 180 days, tensile and flexural strength after 90 days, dry density, and absorption were investigated. Additionally, the mixes were assessed using non-destructive tests, namely, the ultrasonic pulse velocity test, rebound hammer test, and core test. The results showed that the addition of rubber particles to concrete decreased the compressive strength, tensile strength, and flexural strength in comparison with control concrete. An empirical equation based on combined analysis with R² = 0.95 was derived. At the age of 180 days, the compressive strength of rubberized concrete varied from 34 to 42 MPa. From a structural point of view, its strength is regarded as acceptable. Full article

Cement-retained implant restorations still represents a widely used prosthetic solution today, considering the simple execution, the possibility of correcting the implant axis according to the dental axis and an extremely satisfactory aesthetic. The objective of the study is to evaluate whether resin-based cements are actually more aggressive towards the peri-implant tissue compared to zinc oxide cements. In the present study 18 patients (8 males and 10 females) were examined with a split-mouth design. The follow-up period for patients after delivery of the cement-retained single crown is a maximum of 48 months. A total of 36 implants were inserted and monitored during this period. Clinical and radiographic tests were carried out on all 36 implants, with constant re-evaluation, as well as the occurrence of some prosthetic or biological problems that brought the patient back to visit. The results for both cements were in line with the indications of the respective manufacturers. During the observational period, no implant failed, with a survival rate of 100% on these 36 implants. In conclusion, it is possible to establish that the number of decementations of the cement-retained crowns cemented with Temp Bond non-eugenol was higher, but not statistically significant. In contrast, the biological complications per implant and the MBL were significantly higher in the cement-retained crowns cemented with Implacem. Full article

Proper and innovative waste management methods still pose a major concern in our present world. Continuous accumulation of biowaste from bio-processing industries, household, organic residues and so on makes the environment polluted and endangers the health of man and other animals. The common waste management methods which include direct dumping into water bodies, open-air combustion, and as land fillers are obsolete and are the major causes of environmental pollution. Conversion of biowastes into valuable materials aids proper waste management, and helps to attain a cleaner environment, in addition to the fact that wastes are turned into wealth. Biowastes are rich in carbon and can serve as excellent precursors for the synthesis of important carbon materials such as activated carbon, graphene, carbon nanotubes etc. Three important methods of converting biowastes into carbon materials are discussed in this review. The electrochemical, adsorption, and electrocatalytic properties of the materials and the applications in electrochemical energy storage devices are also discussed in brief. This review focuses on the synthesis of carbon materials from biowaste residues and their use in developing electrode materials for batteries and supercapacitors. Future perspectives on the need to exploit greener technology for the conversion of biowastes into important carbon materials should be considered. Full article

Active packaging films based on chitosan/gelatin were prepared using a solution casting method by adding various essential oils (lime, tea tree, rosemary, and thyme essential oils), and their effects were compared. The fabricated films were characterized and various physical properties as well as the antioxidant performance of the films were studied. Adding essential oils to the polysaccharide/protein biopolymer mixtures resulted in compatible films with high transparency (>90% transparency). The mechanical strength and stiffness of the chitosan/gelatin films were improved by about 30% in the presence of essential oil, but the flexibility slightly decreased, and the stiffness improved. On the other hand, the water vapor barrier properties, thermal stability, and hydrophobicity of the essential oil-containing films were not significantly changed. Adding various essential oils significantly enhanced the antioxidant activity of chitosan/gelatin-based films. Therefore, bio-based functional films with added essential oils can be applied in active packaging applications. Full article

Composite sandwich structures are well-suited for applications requiring high bending strength, flexural rigidity, crashworthiness, and light weight. However, skin–core debonding and core failure remain a barrier to optimal structural performance when polymeric foams are used as core materials. Suppressing or compartmentalising these failure modes can enhance the structural integrity of sandwich structures. In this paper, the flexural response of a sandwich structure was improved by adding carbon fibre-reinforced plastic in the form of through-thickness ribs during the manufacturing process. The effect of the position of the ribs was investigated using a quasi-static three-point bend test. A camera was used to capture failure events, while the digital image correlation technique provided the full-strain field at different stages of loading. Improved flexural performance was obtained when a reinforcement was placed on either side of the loading roller. With this configuration, skin–core debonding was restricted to a confined portion of the panel, resulting in a more localised and stable fracture process, which involved enhanced foam crushing and hardening. A simple FEA approach has been adopted in this paper and has proven to be an effective approach for capturing the details of the failure process, including the debonding in the composite foam structures, without the need for complex and computationally expensive interface modelling. Full article

This paper presents the development of composite silicate mass compositions based on man-made waste for the production of autoclave hardening products, as well as the results of physico-chemical studies of hydration products of silicate materials. The possibility, expediency and efficiency of using multi-tonnage technogenic waste of Kazakhstan in the industry of composite building materials is shown. Based on the results of the conducted research, the composition of a composite silicate mass based on burnt carbonate-barium tailings (8–12%), electrothermophosphoric slags (82–90%) or sand and dust from cement kiln electrofilters (2–5%) for the production of autoclave hardening products was developed. It was found that the cementing substance in composite silicate materials is represented by CSH(B) calcium silicate hydrates, tobermorite and serpentine. The simultaneous presence of fibrous and crystalline calcium and magnesium silicate hydrates in hydration products leads to the creation of composite products with a maximum strength of 41–49 MPa. Full article

Titanium silicon carbide (Ti₃SiC₂) is a novel composite material that has found a multitude of uses in the aerodynamics, automobile, and marine industries due to its excellent properties such as high strength and modulus, high thermal and electrical conductivity, high melting point, excellent corrosion resistance, and high-temperature oxidation resistance. These properties are strongly associated with physical properties and microstructural features. Due to difficulties in the synthesis of this material, there have been very few investigations on the relationship between microstructure and physical characteristics of titanium silicon carbide composites processed through powder metallurgical process. However, the importance of thermal conductivity and electrical conductivity of titanium silicon carbide composites in various potential applications has led to keen attention from several researchers. Hence, in this paper, optimization, and prediction of process input parameters during processing under vacuum sintering for achieving maximum electrical and thermal conductivity of Ti-6Al-4V-SiC(15 Wt.%) has been presented. Using Taguchi’s L₉ Orthogonal Array, it has been observed that aging temperature (1150 °C), aging time (four hours), heating rate (25 °C/min), and cooling rate (5 °C/min) result in optimum input parameters for achieving the highest electrical conductivity values during the processing of Ti-6Al-4V-SiCp composites. Further, for maximum thermal conductivity values during the processing of Ti-6Al-4V-SiCp composites, aging temperature (1150 °C), aging time (four hours), heating rate (5 °C/min), and cooling rate (5 °C/min) are preferred. A second-order response surface model generated can be effectively used for predicting the electrical conductivity and thermal conductivity during the processing of Ti-6Al-4V-SiCp composites with an accuracy of 99.28% (electrical conductivity) and 99.14% (thermal conductivity). By comparing the experimental results along with the results of the mathematical model and the BPANN model results for nine trials, it was observed that the estimated value is accurate for all tests with an error of 0.39% (electrical conductivity) and 0.48% (thermal conductivity). Further, from X-ray diffraction studies and microstructural analysis, it has been observed that aging at 1150 °C for four hours resulted in the formation of a ternary carbide phase of titanium silicon carbide (Ti₃SiC₂), which resulted in maximum electrical conductivity (4,260,000 Ω⁻¹ m⁻¹) and thermal conductivity (36.42 W/m·K) of the Ti-6Al-4V-SiC (15 Wt.%) composite specimen. Full article

Despite significant advancements in bio-based natural-fiber-reinforced composites, the recyclability/reprocessing of thermoset composites remains a persistent challenge that needs to be addressed. In the present study, an effort is made to provide a justification for the recyclability/reprocessing assessment of sandwich composite panels made with ‘recyclate’ (i.e., recycled flax/bio-based epoxy composite) cores and (flax/bio-based epoxy) skins produced by liquid composite molding. Resin transfer molding and vacuum-assisted resin infusion processes were used to investigate the influence of production processes on mechanical properties. Two different recyclate sizes—4 mm and 10 mm—were used to fabricate sandwich composite panels to study the effect of size on the mechanical properties of the panels. This study aims to compare the qualities of sandwich panels to those of virgin composite panels in terms of their physical (density) and mechanical properties (tensile and flexural). Additionally, the recyclate packing was verified by employing digital microscopy. The results illustrated that the sandwich panels made with the 4 mm recyclates exhibited better mechanical properties compared to those made with the 10 mm recyclates. In comparison with virgin composite panels, the sandwich composite panels made of flax fiber and (flax/epoxy) recyclate exhibited significantly higher flexural moduli, which was attributed to their moments of inertia. This article emphasizes recycling/reprocessing and demonstrates an effective closed-loop approach. Thus, by preserving the structural integrity of recyclates, sandwich panels could be advantageous for semi-structural applications. Full article

The aviation industry is facing the challenge of reducing fossil fuels and emissions. Fuel efficiency is improved by making efficient powerplant systems and lighter aircraft. Modern passenger aircraft utilize polymeric and polymeric composite materials to achieve lighter structures without compromising strength. The European Union already has legislation to prevent landfilling and to increase the use of recyclable materials in the automotive industry. While older-generation aircraft, made mainly from metallic materials, are easily dismantled and recycled into other uses, such a process does not yet exist for aircraft made from composite materials. In the coming years, the industry will have to answer the question of how retired polymeric composite aircraft structures are to be recycled. One solution to increase the life cycle of polymeric and polymeric composite parts would be closed-loop recycling. In this paper, a perspective of the closed-loop recycling of polymeric aircraft parts is discussed. The technical aspects of recyclability and the different business models for the remanufacture of a finger pinch shroud certified for use in Airbus A350-900 passenger aircraft are investigated. The results show that closed-loop recycling is possible for polymeric aircraft parts. Future studies could include studying an LCA between virgin and recycled materials for a certain part. Full article

Natural fiber (NF) is one of the many resources that nature has provided. NFs decompose quickly and are biodegradable, renewable, and cost-effective. It may be scavenged from a variety of plant and animal sources. They are employed as reinforcing materials in polymers for NF composite development. Because of its environmental friendliness and long-term survivability, NF is growing in appeal among academics and researchers for usage in polymer composites. This study aims to offer a thorough evaluation of the most suitable and widely utilized natural fiber-reinforced polymer composites (NFPCs), along with their manufacture, processing, and applications. It also defines several external treatments of NF and their influence on the characteristics of NFPCs. The characteristics of NFPCs are affected by fiber supply, fiber type, and fiber structure. Numerous physical and chemical treatments were tested to see how they affected the thermal and strength properties of natural fiber-reinforced thermoplastic and thermosetting composites. Several polymer composite fabrication techniques were also studied. NFPCs have several disadvantages, notably low fire protection, poor strength properties, and greater moisture absorption, which have prevented their application. It is shown how NFPCs are employed in a variety of industries, particularly automotive and research industries. The review discovered that intentionally changing the regular fiber enhanced the thermochemical and physico-mechanical properties of the NFPCs by means of improving the grip between the fiber surface and the polymer framework. This study aims to provide important and fundamental facts on NF and their composites, which will aid in new investigations, the creation of a creative framework for polymer composite types, and the achievement of Sustainable Development Goals. Full article

The environmental impact of CO₂ emissions is widely acknowledged, making the development of alternative propulsion systems a priority. Hydrogen is a potential candidate to replace fossil fuels for transport applications, with three technologies considered for the onboard storage of hydrogen: storage in the form of a compressed gas, storage as a cryogenic liquid, and storage as a solid. These technologies are now competing to meet the requirements of vehicle manufacturers; each has its own unique challenges that must be understood to direct future research and development efforts. This paper reviews technological developments for Hydrogen Storage Vessel (HSV) designs, including their technical performance, manufacturing costs, safety, and environmental impact. More specifically, an up-to-date review of fiber-reinforced polymer composite HSVs was explored, including the end-of-life recycling options. A review of current numerical models for HSVs was conducted, including the use of artificial intelligence techniques to assess the performance of composite HSVs, leading to more sophisticated designs for achieving a more sustainable future. Full article

Bio-aggregate composites (BACs) are typically formed by binding plant origin aggregates using organic or inorganic binders. Composite boards are being manufactured from hemp shives and Portland cement or lime and such material is associated with the so-called “hempcrete”. To reach a low greenhouse gas emission rate, alternative binders must be considered. Gypsum binder releases a seven times lower amount of CO₂ during production compared with Portland cement, while waste gypsum can be even more efficient. In this research, gypsum-based BACs were elaborated and tested. Phosphogypsum was evaluated as an alternative binder. The objective of the research was to evaluate the fire resistance of gypsum- and phosphogypsum-binder-based BAC. In this study, the amount of binder was varied and BACs with a density from 200 to 400 kg/m³ were tested. For the first time, commercial gypsum- and phosphogypsum-based hemp shive BAC fire performance was evaluated using a cone calorimeter. Results indicate that the role of gypsum content has a significant effect on the fire resistance. Time on ignition increased from 14 to 19 s and the heat release rate peak was reduced by 57%. Phosphogypsum binder, compared with commercial gypsum, showed a slight improvement of fire resistance as impurities with high water attraction are in the structure of PG. Full article

Polymer nanocomposites have attracted global attention as a metal replacement for electrical and electronic applications. Graphene nanoplatelets (GNPs) are widely used as a nanoreinforcement to enhance the functional and structural properties of thermoset and thermoplastic polymers. In the present study, ABS nanocomposites were prepared by reinforcing 3–15 wt.% GNPs in steps of 3 wt.%. The neat ABS and ABS+GNP nanocomposite specimens for the mechanical test were prepared using injection molding, followed by extrusion, as per American Society for Testing and Materials (ASTM) standards. It was found that the modulus of ABS improved due to the reinforcement of GNPs. Additionally, we noticed higher thermal stability of nanocomposites due to the faster heat-conducting path developed in the nanocomposites by the presence of GNPs. However, observed agglomeration of GNPs at higher concentrations and poor wetting with ABS led to the deterioration of the mechanical properties of the nanocomposites. Moreover, 350 µm thick nanocomposite films were manufactured by compression molding, followed by the extrusion method, and we investigated their electrical conductivity, magnetic permeability, permittivity, and electromagnetic-wave-shielding effectiveness. The developed nanocomposites showed improved conductivity and effective electromagnetic wave shielding by absorption. The 15 wt.% GNP-reinforced ABS composite film showed a maximum shielding effectiveness of 30 dB in the X-band. Full article

Polymer parts often replace traditional metallic parts in load-bearing applications due to their high strength-to-weight ratio, with thermoplastics at the forefront. Conventional manufacturing processes rely on using fasteners or adhesives to hold composite assemblies together, but thermoplastics can be welded together. Ultrasonic welding is widely used but becomes challenging for complex geometries, and new parameters need to be developed for different polymers and specimen geometries. In this work, we developed a closed-loop welding machine that employs the recent discovery of radio-frequency (RF) heating of carbonaceous materials. The machine is successfully able to weld polylactic acid (PLA) coupons with graphitic RF susceptors at the bondline in less than 2 min and using less than 50 W of input RF power. We found that a higher areal density of the graphitic paint lowers the mechanical properties of the weld because the carbonaceous materials hinder polymer chain diffusion. A significant change was not observed in weld properties for welding pressure ranges between 0 and 0.3 MPa. However, increasing out-of-plane welding displacement increased the modulus and strength of the weld. This work provides an interesting new automated system for welding polymer composites using RF fields, with potential applications in various manufacturing industries. Full article

The present study assessed the potential of engaging response surface analysis in the experimental design, modeling, and optimization of the strength performance of aluminum-7075 green composite. The design of the experiment was carried out via the Box–Behnken method and the independent variables are rice husk ash (RHA) at 3–12 wt.%, glass powder (GP) at 2–10 wt.%, and stirring temperature (ST) at 600–800 °C. Responses examined are yield, ultimate tensile, flexural, and impact strengths, as well as microhardness and compressive strength. ANOVA analysis revealed that the input factors had consequential contributions to each response, eventually presenting regression models statistically fit to represent the experimental data, further affirmed by the diagnostic plots. The result of the optimization envisaged an optimal combination at 7.2% RHA, 6.2 GP, and 695 °C with a desirability of 0.910. A comparison between the predicted values for the responses and the values of the validation experiment revealed an error of <5% for each response. Consequently, the models are certified adequate for response predictions at 95% confidence, and the optimum combination is adequate for the design of the composite. Full article

This ‘opinion’ article has been undertaken to provide a plausible answer to the question of why nanocomposites that are reinforced by acicular nanoparticles such as carbon nanotubes (CNTs) do not exhibit the anticipated physical properties—particularly, why the glass transition temperature in some compositions exhibits huge decreases, contrary to expectations. It is claimed that this behavior is typical of fully exfoliated, uniformly dispersed nanocomposites, whose structure is that of molecular composites or solid solutions, and which abide by colligative rules. Full article

The plywood industry’s sustainability, performance, and production costs depend on wood adhesives and the hot pressing technique. In this investigation, a cold-setting plywood adhesive based on polyvinyl alcohol (P), tannin (T), and hexamine (H) was produced. The physical and mechanical properties of plywood were examined at different formulations such as tannin concentration (10% and 20%), hexamine content (5%, 10%, and 15%), and cold-pressing time (3, 6, 12, and 24 h). This study showed that high tannin and hexamine content also increased the solids content, but decreased the average viscosity of the adhesive. Markedly, the cohesion strength of PTH-based adhesives increased from 5.57 Pa at 1/s to 1411.6 Pa at 400/s shear rate, regardless of the adhesive formulation. The shear modulus subsequently decreased as a function of the shear rate and increased with a higher tannin and hexamine content. This study revealed that the higher tannin and hexamine content and longer cold-pressing times could produce plywood with the tested adhesive that met the Japanese standard strength requirements. A combination of PTH-based adhesive prepared with formula 2 and 24 h cold-pressing resulted in the highest TSS value of 1.42 MPa, MOR values of 88.7 MPa, MOE values of 14,025.6 MPa, and wood failure of 47.2%. This study showed the possibility of fabricating eco-friendly plywood panels bonded with PTH-based adhesive using the cold-pressing process as an alternative to conventional plywood. Full article

Additive manufacturing (AM) opens new possibilities of obtaining ceramic green parts with a tailored complex design at low cost. Meeting the requirements of highly demanding industries (aeronautical and biomedical, for example) is still challenging, even for machining. Hybrid machines can solve this problem by combining the advantages of both additive and subtractive processes. However, little information is currently available to determine the milling parameters of additively fabricated ceramic green parts. This article proposes a systematic approach to experimentally determine the cutting parameters of green AM zirconia parts. Three tools, one dedicated to thermoplastics, one to composites, and a universal tool, were tested. The tool–material couple standard (NF E 66-520-5) was followed. The lower cost and repeatable generation of smooth surfaces (Ra < 1.6 µm) without material pull-out were the main goals of the study. The universal tool showed few repeatable working points without material pull-out, while the two other tools gave satisfying results. The thermoplastic tool ensured repeatable results of Ra < 0.8 µm at a four times lower cost than the composite tool. Moreover, it exhibited a larger chip thickness range (from 0.003 mm to 0.036 mm). Nevertheless, it generated an uncut zone that must be considered when planning the milling operations. Full article

Plastic is being used increasingly in daily life. Most of it is not recyclable, and the remaining plastic cannot be used or decomposed. This causes increased plastic waste, contributing to global warming due to thermal recycling. The major objective of this research was to utilise the maximum plastic waste possible to manufacture bricks that compete with the properties of conventional bricks without affecting the environment and the ecological balance. A balanced mixture of high-density polyethylene (HDPE), quartz sand, and some additive materials, such as bitumen, was used to produce these bricks. Various tests were performed to assess the bricks’ quality, such as compression, water absorption, and efflorescence tests. These bricks had a compression strength of 37.5 MPa, which is exceptionally strong compared to conventional bricks. The efflorescence and water absorption tests showed that the bricks were nearly devoid of alkalis and absorbed almost no water. The obtained bricks were light in weight and cost-effective compared to conventional bricks. Full article

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride with varying thicknesses and non-woven fibers are then combined by bonding to study the sound insulation characteristics of a two-layer composite structure. A sound insulation prediction model is established using the multi-parameter nonlinear regression method. An optimal cost mathematical model is established based on experimental and mathematical methods that can quickly determine the optimal cost scheme for different designs with the same effect. Full article

Surgical simulations require fast and accurate simulation of biological materials. In general, linear analysis is faster but less accurate, whereas nonlinear analysis is more accurate but slower. In this work, a kidney is simulated by using both linear analysis and nonlinear analysis, the results are compared, and the errors quantified. The software package ANSYS is used for the purpose. This work presents detailed results and comparison of linear and nonlinear analysis in the context of simulation of a human kidney, which is not easily found in the literature. The results reinforce the idea that linear analysis is a useful tool for simulating biological materials when solution time is as much important as the accuracy of solutions. Full article

Graphene is a unique nanocarbon nanostructure, which has been frequently used to form nanocomposites. Green-synthesized graphene has been focused due to environmentally friendly requirements in recent technological sectors. A very important application of green-synthesized graphene-based nanocomposite has been observed in energy storage devices. This state-of-the-art review highlights design, features, and advanced functions of polymer/green-synthesized graphene nanocomposites and their utility in supercapacitor components. Green graphene-derived nanocomposites brought about numerous revolutions in high-performance supercapacitors. The structural diversity of conjugated polymer and green graphene-based nanocomposites has facilitated the charge transportation/storage capacity, specific capacitance, capacitance retention, cyclability, and durability of supercapacitor electrodes. Moreover, the green method, graphene functionality, dispersion, and matrix–nanofiller interactions have affected supercapacitance properties and performance. Future research on innovative polymer and green graphene-derived nanocomposites may overcome design/performance-related challenging factors for technical usages. Full article

The world is suffering from heavy pollution because of synthetic petrochemical plastic used in our daily activities. A possible solution is the use of bioplastic synthesized from natural renewable resources. The present work investigates the development and characterization of polymer bioplastic using ginger tea and green tea to decrease the adverse effect of petrochemical plastic waste for versatile applications. Two kinds of bioplastic samples were produced with two types of tea, ginger tea and green tea, using glycerol, vinegar, starch, and water. SEM (scanning electron microscopy), FTIR (Fourier transformed infrared spectroscopy), mechanical (tensile), TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), and time tests of bioplastic degradation analysis were carried out to evaluate the morphological, mechanical, and thermal behaviors of the synthesized tea bioplastics. The research result showed ginger tea bioplastic had a maximum tensile strength of 2.9 MPa and a minimum elongation of 7.46 mm. More than 78% of degradation occurred in ginger bioplastic within 30 days. Compatible thermal and morphological characteristics are also observed in the prepared bioplastic samples. Full article

The adaptation of a sealer along with the periphery of the dentinal tubules of the root canal is studied. Various techniques have been used for the application of these sealers onto the canal wall for better adaptation but have not been compared to date. The purpose of the study was to comparatively evaluate the sealing ability of a bioceramic sealer with AH plus sealer with root canal dentin using three different techniques for the application of sealer. One hundred twenty extracted maxillary and mandibular anterior teeth were collected, disinfected, and decoronated at the cemento-enamel junction to maintain a standard working length for all samples. The establishment of the working length (40.10) and instrumentation was performed using a rotary instrument, along with a standard irrigation regimen. The teeth were then divided into two main groups according to the sealer used, i.e., Group A (AH Plus) and Group B (iRoot SP). These two main groups were categorized into three sub-groups depending on the technique of sealer placement, i.e., Subgroup 1 (master cone gutta-percha), Subgroup 2 (bidirectional spiral), and Subgroup 3 (passive ultrasonic activation). Out of the 20 samples, 15 samples were randomly allocated for the assessment of sealing ability using the routine dye extraction method, and to verify the results of the dye extraction method, a more advanced evaluation method, i.e., SEM evaluation, was utilized further. To this end, five random samples from each subgroup were allocated for SEM analysis. The obtained scores were then statistically analyzed using an ANOVA test and Post Hoc Tukey’s test. In the current study, statistical significance was seen among the three main groups and six subgroups with p-values < 0.005. Subgroup B3 performed significantly better than the other subgroups in both the dye extraction method as well as in SEM analysis. The highest microleakage was shown by subgroup A1; it also exhibited poor penetration of sealer in SEM evaluation. The bioceramic sealer (iRoot SP), when applied using passive ultrasonic activation, showed the best results in both the dye extraction method and the SEM evaluation. Full article

The invention of an easy synthetic approach for extremely impactful nanomaterials (NMs) is one of the crucial research areas in modern science and engineering. In the present work, we describe a cost-effective, simple, rapid and environmentally gracious biogenic fabrication of nickel/nickel oxide nanoparticles (Ni/NiO NPs) using Gymnema sylvestre as a natural fuel. The textural characteristics of as-prepared Ni/NiO NPs were explored using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), field-emission scanning electron microscope (FESEM), energy dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HRTEM). XRD affirmed the crystalline nature and phase formation of Ni/NiO NPs. The FTIR spectrum ascertains the formation of Ni/NiO NPs, and the band gap of 4.29 eV is revealed from DRS studies. Ni/NiO NPs display an intense emission peak at 576.2 nm in their PL spectrum. The fabrication of pseudo-spherical Ni/NiO NPs was displayed by FESEM and HRTEM images. The particle size obtained from HRTEM was 21 nm, which resembles the median crystallite size ascertained from the XRD data. Additionally, the plausible mechanism for Ni/NiO NPs formation is illustrated. Moreover, as-synthesized Ni/NiO NPs displayed considerable antifungal potential against Candida albicans and Aspergillus niger. Results revealed that the Gymnema sylvestre leaves extract can synthesize Ni/NiO NPs with appealing biological effectiveness for application in the nanomedicine sector. Full article

The development of scaffolds for tissue-engineered growth of the anterior cruciate ligament (ACL) is a promising approach to overcome the limitations of current solutions. This work proposes novel biodegradable and biocompatible scaffolds matching the mechanical characteristics of the native human ligament. Poly(L-lactic acid) (PLA) scaffolds reinforced with graphite nano-platelets (PLA+EG) as received, chemically functionalized (PLA+f-EG), or functionalized and decorated with silver nanoparticles [PLA+((f-EG)+Ag)], were fabricated by conventional braiding and using 3D-printing technology. The dimensions of both braided and 3D-printed scaffolds were finely controlled. The results showed that the scaffolds exhibited high porosity (>60%), pore interconnectivity, and pore size suitable for ligament tissue ingrowth, with no relevant differences between PLA and composite scaffolds. The wet state dynamic mechanical analysis at 37 °C revealed an increase in the storage modulus of the composite constructs, compared to neat PLA scaffolds. Either braided or 3D-printed scaffolds presented storage modulus values similar to those found in soft tissues. The tailorable design of the braided structures, as well as the reproducibility, the high speed, and the simplicity of 3D-printing allowed to obtain two different scaffolds suitable for ligament tissue engineering. Full article

Polymers have been proven to be an interesting class of adsorbents applied in water treatment. Biopolymers are of special interest due to their unique properties such as biocompatibility, biodegradability, and reusability. This work reports a composite formed by a chitosan biopolymer and activated charcoal using sodium citrate as a crosslinking agent. The chitosan–citrate-activated charcoal composite (CCA) was characterized using FT–IR, SEM, EDAX, XRD, TGA–DTA and BET surface area analysis. The material was found to be microporous in nature with a surface area of 165.83 m²/g that led to high adsorption capacities toward both the targeted pollutants. In an aqueous phase, the dye adsorption studies were carried out with reactive orange 16 (R-16) dye, while in a gaseous phase, CO₂ adsorption capacity was evaluated. Under optimum solution conditions, maximum R-16 dye removal capacity was found to be 34.62 mg g⁻¹, while in the gas phase the CO₂ adsorption capacity was found to be 13.15 cm³g⁻¹. Intrinsic microporosity of CCA resulted in an enhanced capture capacity for R-16 dye and carbon dioxide in the respective phases. Material sustainability studies were carried out to evaluate various sustainability parameters. Full article

This cutting-edge review highlights the fundamentals, design, and manufacturing strategies used for sandwich composites. Sandwich composite structures have the advantages of light weight, high strength, impact resistance, stability, and other superior features for advanced applications. In this regard, different core materials have been used in the sandwich composite structures, such as cellular polymer foam, metallic foam, honeycomb, balsa, tubular, and other core geometries. Among these, honeycomb sandwich composite materials have been effectively applied in space engineering, marine engineering, and construction applications. The foremost manufacturing techniques used for sandwiched composite structures include hand lay-up, press method, prepreg method, vacuum bagging/autoclave, vacuum assisted resin infusion, resin transfer molding, compression molding, pultrusion, three-dimensional (3D) printing, four-dimensional (4D) printing, etc. In advanced composite manufacturing, autoclave processes have been the method of choice for the aerospace industry due to less delamination between plies and easy control of thickness dimensions. Moreover, machining processes used for sandwich composites are discussed in this article. In addition to aerospace, the high-performance significance of sandwiched composite structures is covered mainly in relation to automobile engineering and energy absorption applications. The structure-, fabrication-, and application-related challenges and probable future research directions are also discussed in this article. Full article