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This study involves the preparation of hybrid bio-composites using the hand lay-up method, with epoxy resin serving as the matrix and natural fibers as the reinforcement. The primary objective was to conduct a mechanical and tribological analysis of jute–coir and banana–coir hybrid composites, as well as neat coir bio-composites. The results indicated that the jute–coir hybrid composite exhibited the lowest water absorption (7.6%) and thickness swelling (6.8%) when compared to the banana–coir and neat coir bio-composites. Moreover, the jute–coir composites demonstrated superior hardness and strength, with a higher hardness (78HRB) and tensile strength (120MPa) compared to other bio-composites. Furthermore, sliding and erosion wear tests demonstrated that the jute–coir bio-composite displayed excellent resistance to abrasion and erosion under various wear conditions. As a result, the jute–coir composite, with its reduced thickness swelling and water absorption and favorable mechanical and tribological properties, holds potential for application in diverse areas such as railway coach interiors, aircraft industries for interior components, as well as everyday items like plates and spoons.

Single crystals of Na_0.495CoO₂ were obtained through a flux method followed by de-intercalation of sodium. The resistivity (ρ) and thermal stability were studied for the de-intercalated samples exposed to humid air. It was found that the de-intercalated Na_0.495CoO₂ crystal is vulnerable to water in the air, and a hydration process in which H₂O molecules fill oxygen vacancies in CoO₂ layers instead of being intercalated between CoO₂ layers is suggested to be responsible for the remarkable change in resistivity induced by water absorption. The Na_0.495CoO₂ sample shows a weak localization of carriers just below 200 K and Co³⁺–Co⁴⁺ charge ordering at about 40 K, lower than the corresponding charge ordering transition temperature reported in Na_0.5CoO₂. The lower charge ordering transition temperature might be caused by the slight deviation of Na content (x) from 0.5.

The compressive properties of a biodegradable plastic were measured over a wide range of strain rates from 10⁻⁵ to 10⁴s⁻¹, using a universal testing machine and a split Hopkinson pressure bar method. The yield stress of the biodegradable plastic increased with increasing strain rate and decreased with temperature and water absorption. Empirical equations for the yield stresses were derived for the strain rates from 10⁻⁵ to 10³s⁻¹ and from 10³ to 10⁴s⁻¹, respectively.

This study analyzed the relationship between the defect area identified through a C-scan and the void volume in CF-PEKK composite materials through the water absorption behavior to predict the void volume. The water absorption content varies with the defect area; however, the defect area identified through a C-scan and the water absorption content did not show a proportional relationship. This is because voids are distributed in the through-thickness. The results indicated that the absorption behavior could be used to predict the void volume. Irreversible absorption was found to be independent of the void volume. Further, no matrix degradation was seen with water immersion at $70^{\circ }$C; however, some local swelling was seen.

This research aims to study the effects of water pH and immersion time on water absorption and mechanical properties of carbon fiber-reinforced bioplastic composites. The composite samples were exposed to three different water conditions of normal water, distilled water and saltwater. The composites were immersed for a maximum of 40 days. After immersing for 40 days, the highest moisture absorption was found for the composites immersed in distilled water. Young’s modulus and tensile strength decreased with increasing the immersion time for the composite immersed in normal water. Moreover, the effect of the moisture absorption on the mechanical properties and the fracture surface was discussed by the glass transition temperature’s thermal behavior.

The internal defects formed during infrared (IR) heating of carbon fiber-polyetherketoneketone thermoplastic composites at different temperatures and dwell times were analyzed based on the water absorption characteristics. IR heating generates internal defects such as voids, which affect the water absorption behavior of the composites; lesser voids were generated under higher heating temperatures and longer dwell times. A void formation mechanism consisting of growth, transfer, and removal of voids was proposed based on the difference in the standard deviation of the water absorption content. The reduction in the water absorption content of the composite after reforming confirmed the recovery of voids. All the specimens, except those heated at 420${}^{\circ }$C for 5 min or more, showed good recovery.

Although there is much discussion on the evaluation of the dissemination ability of sci-tech periodicals, there is no perfect evaluation method system in the existing studies, and especially the evaluation model is not operable. This paper converts the qualitative evaluation of the dissemination ability into a multi-criteria decision-making problem, and proposes a research method of sci-tech periodicals dissemination ability based on hesitant fuzzy linguistic. Firstly, this paper systematically combs the research progress of the evaluation of dissemination ability of sci-tech periodicals and multi-criteria decision-making under uncertainty. Then, a multi-criteria decision-making method based on hesitant fuzzy linguistic correlation is proposed, which fully considers the preferences of decision makers and effectively integrates the incomplete compensation hypothesis. Finally, the periodical topic planning, knowledge popularization recognition, publishing market operation ability and supporting discipline construction are selected as empirical conditions to verify the applicability and effectiveness of the model. At the same time, in order to make the empirical results more objective and scientific, the density clustering results of the questionnaire are used instead of the decision-maker membership score in the evaluation of dissemination ability. Theoretical analysis and empirical results show that the method proposed in this paper can be effectively applied to the evaluation of the dissemination ability of sci-tech periodicals.

Expanded flyash clay aggregate (EFCA) is a promising sustainable alternative to coarse aggregate in concrete. Concrete specimens with conventional natural aggregate and EFCA as coarse aggregates were prepared separately and exposed to elevated temperatures of range 200°C, 400°C, 600°C and 800°C, observed for surface changes like change in color and formation of visual cracks, tested for loss in mass, strength and water absorption, analyzed by XRD for mineralogical changes through variation in chemical composition. Specimens when exposed up to 400°C has not shown any notable changes in the above property, beyond which strength of both specimens started to decrease gradually, at higher temperature EFCA mix showed loss in mass of 4.5% compared with normal concrete, visual observation of specimen surface showed EFCA specimens sustained cracks till 600°C. EFCA mix also showed a constant rate of water absorption. Concrete with EFCA showed consistently higher compressive strength at higher temperature up to 400°C and found satisfactory in all aspects tested made EFCA as coarse aggregate in concrete as a sustainable alternative to natural aggregates.

In recent years, the use of natural fibers has increased in manya applications, particularly in automotive industry, owing to their lightweight, high specific strength, recyclability, and ecological properties. This study aims to investigate the influence of copper filler on fiber-coated hybrid composite through mechanical and machining (CNC milling) characterization. Initially, the copper filler was characterized using the energy dispersive X-ray (EDX), particle size analysis (scanning electron microscope), and component analysis (X-ray diffraction (XRD)). Four coated natural fiber/wire mesh hybrid composite designs were developed and identified as hemp/mesh/ramie composite [HMR (1-4)]. In this work, 16 experiments were designed by central composite design (CCD) using Design Expert 13, considering the spindle speed, feed rate, and composite type as input parameters. The results indicate that copper filler particle proportion influenced the tensile strength and impact resistance of the HMR hybrid composite (16% & 15.42%). A fiber coating with a higher infill percentage reduces water absorption. The responses were estimated based on the resultant force and surface roughness, which were influenced by the weight percentage of the filler. In all the spindle speeds, the resultant forces are increased with raise in feed rates (120–600 mm/min).

A series of acrylic-based superabsorbent resins were synthesized by inverse suspension polymerization, using potassium persulfate as the initiator, N, N′-methylene bisacrylamide (BIS) and divinylbenzene (DVB) as the multiple crosslinking agents. The morphology of the resulting superabsorbent resins revealed by SEM demonstrated that a hard shell layer was indeed formed due to surface crosslinking. The swelling and deswelling properties, and the mechanical strength of superabsorbents were investigated. The results indicated that the adding time of DVB and the amount of DVB participated in the crosslinking show a significant influence on the properties of superabsorbents. When DVB was added in polymerization later, the amount of DVB participated in reaction decreases and the surface crosslinked shell becomes thinner. It is suitable for DVB to be introduced in the later stage of the polymerization process, because the absorption rate of resin is efficiently improved in conjunction with higher water absorption. Furthermore, it was found that the mechanical strength of swollen superabsorbent with surface crosslinking was indeed enhanced in comparison with that of the conventional one.

This study analyzed the relationship between the defect area identified through a C-scan and the void volume in CF-PEKK composite materials through the water absorption behavior to predict the void volume. The water absorption content varies with the defect area; however, the defect area identified through a C-scan and the water absorption content did not show a proportional relationship. This is because voids are distributed in the through-thickness. The results indicated that the absorption behavior could be used to predict the void volume. Irreversible absorption was found to be independent of the void volume. Further, no matrix degradation was seen with water immersion at 70^°C; however, some local swelling was seen.

This research aims to study the effects of water pH and immersion time on water absorption and mechanical properties of carbon fiber-reinforced bioplastic composites. The composite samples were exposed to three different water conditions of normal water, distilled water and saltwater. The composites were immersed for a maximum of 40 days. After immersing for 40 days, the highest moisture absorption was found for the composites immersed in distilled water. Young’s modulus and tensile strength decreased with increasing the immersion time for the composite immersed in normal water. Moreover, the effect of the moisture absorption on the mechanical properties and the fracture surface was discussed by the glass transition temperature’s thermal behavior.