Search Results (6,358)

Laser local forming is an effective method for reshaping optical glass, yet the deformation of the material during the cooling phase remains poorly understood. This study investigates the dynamic evolution of the molten pool, specifically focusing on the transition from an initial convex shape to a final “M-shaped” profile. A combined approach using thermal-fluid simulation and high-speed imaging experiments was employed to track the surface changes throughout the heating and cooling cycles. The results show that while the surface bulges outward during laser irradiation, the material redistributes after the laser is switched off due to non-uniform cooling and volumetric shrinkage. The specific roles of viscosity and surface tension in driving this reverse flow were identified. Furthermore, the study established a quantitative model linking laser parameters to the final surface dimensions, providing a reliable tool for predicting and controlling the precision of glass forming. Full article

Crushing is a critical step in the efficient utilization of quasi-brittle materials such as ores and solid wastes. During this process, materials undergo fracture, and the product particles are ejected, carrying significant kinetic energy. This study investigates typical quasi-brittle materials—concrete and quartz glass—by conducting impact crushing tests using a drop-weight apparatus under varying contact modes and input energy levels. High-speed camera was employed to capture the fracture patterns of the materials and the trajectories of the ejected particles, enabling the calculation of kinetic energy during crushing. The results indicate that under point contact loading, both kinetic energy and its proportion increase significantly with rising input energy. In contrast, under surface contact loading, the kinetic energy and its proportion exhibit minimal change as input energy increases. The average ejection velocity of particles from quartz glass specimens during crushing was 6.28 m/s, which is 2.21 times that of concrete specimens. Moreover, the average proportion of kinetic energy in quartz glass crushing was 5.049%, approximately 14.43 times greater than that in concrete. Enhancing material toughness and adopting surface contact loading help reduce both the kinetic energy and its proportion during crushing. This research contributes to minimizing kinetic energy loss and improving the efficiency of energy utilization in crushing processes. Full article

This study systematically examines the fluidity, setting time, mechanical properties, and microstructural evolution of metakaolin-based geopolymer grouting materials with a relatively high water-to-solid (W/S) ratio window. A four-factor, three-level orthogonal experimental design was employed to identify the dominant factors and main effect trends of W/S ratio, alkali dosage, water glass modulus (Ms, molar ratio of SiO₂ to Na₂O in alkali solution), and steel slag content on the material’s performance. The results indicated that the W/S ratio predominantly governed fluidity, while the alkali content was the primary controlling factor for setting time and early-age strength. An intermediate range of water glass modulus with a value of 1.6 provided balanced performance. The incorporation of steel slag with a range of 10–20% showed an age-dependent contribution: it not only tended to improve the rheology of the paste but also the later-age strength. XRD, FTIR, and SEM/EDS results suggested that the hardened binders were dominated by amorphous products, where alumimosilicate gel (N-A-S-H) and Ca-containing gel (C-S-H/C-A-S-H) may coexist depending on calcium availability and activator chemistry. The proposed parameter ranges are valid within the studied design space and provide guidance for the mix design of high-W/S geopolymer grout. Full article

Recently, with concern for the environment and the request for sustainable materials, more researchers and manufacturers have focused on the substitute solution of synthetic fiber reinforcement composites in industry applications. Green hybrid composites with natural components can present excellent sustainability, possess superior mechanical behavior, and reduce hazards. Hybridization technology allows new materials to inherit their raw materials’ characteristics and generate new properties. The current study designed novel double-walled shell structures (DS1R4L, DS2R8L, and DS5R12L), containing two thin walls and different numbers of ring and longitudinal stiffeners, as unmanned maritime vehicle (UMV) components. A normal single-walled cylindrical shell was used as a control. These models will be made of hybrid kenaf/flax/glass-fiber-reinforced composites, GKFKG and GFKFG, created in the ANSYS Workbench. The mechanical responses (deformation, stress, and strain characteristics) of models were examined under three loading conditions (end force, end torque, and hydrostatic pressure) to evaluate the influence of both material change and structural configuration. Compared to the single-walled structure, the double-walled configurations display minimized deflection and torsional angle. Moreover, GKFKG-made structures are better than GFKFG-made ones. The research contributes positively to advancing the application of hybrid kenaf/flax/glass-fiber-reinforced composites in UMV structures and promotes the development of green sustainable materials. Full article

The increasing demand for sustainable polymer composites has driven the development of hybrid laminates that combine natural, recycled, and synthetic reinforcements while maintaining adequate mechanical performance. However, the combined influence of stacking sequence and mineral filler addition on the mechanical behavior of such sustainable hybrid systems remains insufficiently understood. In this study, sustainable hybrid laminated composites based on epoxy reinforced with glass fiber (G), bamboo fiber (B), and flex banner (F) were fabricated with varying stacking sequences and calcium carbonate (CaCO₃) filler contents (0 and 1 wt.%). A total of nine laminate configurations were produced and evaluated through flexural and impact testing. The results demonstrate that mechanical performance is strongly governed by laminate architecture and filler addition. The bamboo-dominant G/B/B/B/G laminate containing 1 wt.% CaCO₃ exhibited the highest flexural strength (191 MPa) and impact resistance (0.766 J/mm²), indicating a synergistic effect between reinforcement arrangement and CaCO₃-induced matrix strengthening. In contrast, the lowest performance was observed for the G/F/B/F/G configuration without filler. Overall, all hybrid composites outperformed neat epoxy, highlighting the potential of bamboo–flex banner hybrid laminates with CaCO₃ filler for sustainable composite applications requiring balanced mechanical properties. This work aligns with SDG 12 by promoting resource-efficient circular-economy practices through the utilization of flex banner material and natural fibers as reinforcements in epoxy-based hybrid composites. Full article

This paper assesses the use of ‘plastic age’ and ‘glass age’ terms, using a bibliometric approach to identify their proponents, purposes, and connections to debates in Anthropocene and heritage studies. This study explores how glass and plastic have been portrayed as age-defining materials and how this concept relates with what is expected to be preserved for future generations. Are these materials so ubiquitous that they become invisible? If visible, are they considered waste or heritage? Both materials appear in the Anthropocene discussion as stratigraphic indicators. The term ‘glass age’ is related with the marketing of glass (not only new glass formulations and new products, but also as an alternative to other more polluting materials), and the term ‘plastic age’ appears to be related to the multitude of plastics in our everyday lives and all the problems associated with their disposal. Although there are few examples of bibliometric research on glass and plastic as heritage, there is currently great investment in the study of glass and plastic from the perspective of conservation viability; this perspective needs to be promoted so that these materials can be included in heritage policies and museum collections as a reflection of today’s society. Full article

The viscoelastic properties of ultraviolet radiation-curable polymer coatings of optical fibers were studied experimentally and numerically. The test setup was completed, and a series of natural experiments were conducted for an extended temperature range from −110 °C to +120 °C using a dynamic mechanical analyzer (DMA). Discrete dependencies of the complex modulus on temperature and frequency of kinematic loading were obtained. The problem of multiparametric optimization was solved. Defining relations were obtained for protective coating polymers, making it possible to describe the thermomechanical behavior of the glass-forming materials under consideration in a wide temperature range, including relaxation transition. The optimal solution was found for 18 series terms at the selected reference temperature T_r = −70 °C, C₁ = 20.036, and C₂ = 32.666 for the DeSolite 3471-1-152A material. The optimal solution was found for 60 series terms at the selected reference temperature T_r = 0 °C, C₁ = 40,242.2827, and C₂ = 267,448.888 for the DeSolite DS-2015 material. The models were verified according to the data of creep experiments. The capabilities of the viscoelastic model were demonstrated by the example of a numerical experiment on free thermal heating/cooling of a Panda-type optical fiber. Full article

This review provides a comprehensive overview of dental materials that promote tissue healing while exhibiting antimicrobial properties. The focus is on materials that are biocompatible, bioactive, and non-toxic to host cells, with demonstrated bacteriostatic and bactericidal activities. Current advances in natural bactericides, antimicrobial polymers, and bioactive glass/polymer composites are summarized, along with techniques employed for surface modification and the coating of dental implants. Three major categories of antimicrobial coatings were identified: antibacterial phytochemicals, synthetic antimicrobial agents (including polymers and antibiotics), and metallic nanoparticles. Bioactive coatings were further examined to identify potential antimicrobial strategies within these materials, and existing research gaps were highlighted. A systematic literature search was conducted in PubMed, Scopus, and Web of Science for articles published between January 2010 and June 2025. Overall, this review underscores the growing potential of multifunctional dental materials that integrate bioactivity with antimicrobial performance, offering promising directions for the development of next-generation restorative and implant materials. Full article

Compared to reinforcing concrete with steel bars, rebars—made of fiber-reinforced plastic—have a high potential for resource savings in the construction industry due to their corrosion resistance. For the large-volume market of reinforcement elements, efficient manufacturing processes must be developed to ensure the best possible bond behavior between concrete and rebar. In contrast to established FRP-rebars made with thermosetting materials, the use of a thermoplastic matrix enables surface profiling without severing the edge fibers as well as subsequent bending of the bar. The rebars to be produced in this study are based on the process of reactive thermoplastic pultrusion of continuously glass fiber reinforced aPA6. Their surface must enable a mechanical interlocking between the reinforcement bar and concrete. Concepts for a profiling device have been methodically developed and evaluated. The resulting concept of a double wheel embossing unit with a variable infeed and an infrared preheating section is built as a prototype, implemented in a pultrusion line, and further optimized. For a comprehensive understanding of the embossing process, reinforcement bars are manufactured, characterized, and evaluated under parameter variation according to a statistical experimental plan. The present study demonstrates the relationship between the infeed, preheating temperature, and haul-off speed with respect to the embossing depth, which is equivalent to the rib height. No degradation of the Young’s modulus was observed as a result of the profiling process. Full article

The development of photonic-integrated circuits (PICs) for data communication, sensing, and quantum computing is hindered by the high complexity and cost of traditional fabrication methods, which rely on expensive equipment, limiting accessibility for research and prototyping. This study introduces a Direct Laser Writing (DLW) system designed as a low-cost alternative, utilizing an XY platform for precise substrate movement and an optical system comprising a collimator and lens to focus the laser beam. Operating on a single layer, the system employs SU-8 photoresist to fabricate polymer-based structures on substrates such as ITO-covered glass. Preparation involves thorough cleaning, spin coating with photoresist, and pre- and post-baking to ensure material stability. This approach reduces dependence on costly infrastructure, making it suitable for academic settings and enabling rapid prototyping. A user interface and custom slicer process standard .dxf files into executable commands, enhancing operational flexibility. Experimental results demonstrate a resolution of 10 µm, with successful patterning of structures, including diffraction grids, waveguides, and multimode interference devices. This system aims to transform PIC prototype fabrication into a cost-effective, accessible process. Full article

This study focuses on the development of sustainable construction materials via geopolymers synthesized from metakaolin and slag, aiming to identify environmentally friendly alternatives for construction material systems. A metakaolin–slag geopolymer mortar (MK–slag) was prepared using metakaolin and slag as fully solid waste raw materials, with sodium silicate solution and sodium hydroxide acting as composite activators. Initially, single-factor experiments were conducted to determine the optimal ranges for metakaolin–slag content, water/binder ratio, and water glass modulus. Subsequently, response surface methodology was employed to develop regression equations that analyze the main and interaction effects of these variables on the 7-day and 28-day compressive strength and water absorption of the mortar. The optimal mix ratio was then identified. The microstructure and formation mechanisms of MK–slag mortar were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). The results indicate that all factors follow quadratic polynomial relationships with the response variables, showing a regression coefficient (R²) greater than 0.98, indicating an excellent model fit and prediction accuracy. According to model predictions, the optimal mix parameters under multi-objective optimization were found to be a metakaolin-to-slag ratio of 45%: 55%, a water/binder ratio of 0.45, and a water glass modulus of 1.3. After 28 days of curing, the primary hydration products were gel-like substances such as N-A-S-H and C-A-S-H. These gels interweave and overlap to form a high-density, structurally robust binary solid waste geopolymer mortar. This approach expands the application of solid waste materials, such as metakaolin and slag, while enhancing the recycling and utilization efficiency of these waste products. Full article

Transparent polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET) are widely used as glass alternatives in algal bioreactors, where optical clarity and mechanical stability are crucial. However, their long-term use is limited by surface degradation processes. Photodegradation, hydrolysis, and biofilm accumulation can reduce light transmission in the 400–700 nm range essential for photosynthesis. This study examined the aging of PMMA, PC, and PET under bioreactor conditions. Samples were exposed for 70 days to illumination, culture medium, and aquatic environments. Changes in their optical transmittance, surface roughness, and wettability were analyzed. All polymers exhibited measurable surface degradation, characterized by an average 15% loss in transparency, significant increases in surface roughness, and reduced contact angles. PMMA demonstrated the highest optical stability, maintaining strong transmission in key blue and red spectral regions, while PET performed the worst, showing low initial clarity and the steepest decline. The most severe surface degradation occurred in areas exposed to the receding liquid interface, highlighting the need for targeted cleaning and/or a reduction in the size of the liquid–vapor transition zone. Overall, the results identify PMMA and recycled PMMA (PMMA_R) as durable, cost-effective materials for transparent bioreactor walls. Full article

In recent years, new methods to reuse, repurpose, recycle, and recover decommissioned wind turbine blades (dWTBs) have actively been developed in the wind industry. In this study, the authors address the scientific challenge of repurposing decommissioned wind turbine blades for earthwork applications, particularly as part of retaining structures. A gravity retaining structure made entirely from recycled materials is introduced, consisting of glass fibre-reinforced polymer (GFRP) composite modular units derived from dWTBs. To improve the structure’s sustainability, a mixture of typical sand and lightweight waste materials is considered for filling and backfilling of the GFRP units. In particular, two waste materials are examined—a polymer foil derived from recycled laminated glass and tyre-derived aggregate (TDA) in the form of rubber powder—which are incorporated into the sand matrix in typical dry mass proportions ranging from 2% to 32% and 5% to 20%, respectively, reflecting practical ranges considered in geotechnical backfill applications. The research involved material testing of all recyclates and their mixtures with standard sand, as well as two-dimensional finite-element (2D FE) analysis of a retaining structure using the determined material properties. To facilitate the real-world implementation of this novel technology, a structure was designed to account for ground conditions at a specific site to protect against an existing landslide. In summary, this study presents the concept of a sustainable retaining structure along with results from material tests and an initial design for implementation, supported by FE analysis of overall stability. Full article

This paper analyzes the impact of COVID-19 on the supply chain and production, investigating countermeasures for industrial recovery. In particular, the study examines how COVID-19 has affected the raw material supply chain, production, and outages on a real case study, that is, Turkey’s Glass-Reinforced Plastic (GRP) pipe industry. Using two- and three-way analysis of variance (ANOVA), significant negative impacts on the raw material supply chain are identified with 95% confidence. To enhance decision-making, the fuzzy q-rung orthopair set (FQROPS) and entropy-based multi-criteria decision-making (MCDM) methods are integrated in the baseline method. Specifically, ANOVA-identified factors, such as cost, supply continuity, production capacity, and risk level, are used as criteria in the MCDM analysis. Entropy determined criteria weights and FQROPS evaluate alternatives based on their proximity to the ideal solution. Findings show that significant disruptions occurred due to the pandemic. In addition, the MCDM analysis reveals that pre-pandemic conditions for key materials, such as fiberglass and resin, were significantly more favorable in terms of cost, supply continuity, production capacity, and risk levels. This integrated approach provides strategic insights for managing supply chains and production in the GRP pipe industry during and after pandemic events. Full article

The emulsification of a molten fusible metal alloy in a liquid epoxy matrix with its subsequent curing is a novel way to create a highly concentrated phase-change material. However, numerous challenges have arisen. The high interfacial tension between the molten metal and epoxy resin and the difference in their viscosities hinder the stretching and breaking of metal droplets during stirring. Further, the high density of metal droplets and lack of suitable surfactants lead to their rapid coalescence and sedimentation in the non-cross-linked resin. Finally, the high differences in the thermal expansion coefficients of the metal alloy and cross-linked epoxy polymer may cause cracking of the resulting phase-change material. This work overcomes the above problems by using nanosilica-induced physical gelation to thicken the epoxy medium containing Wood’s metal, stabilize their interfacial boundary, and immobilize the molten metal droplets through the creation of a gel-like network with a yield stress. In turn, the yield stress and the subsequent low-temperature curing with diethylenetriamine prevent delamination and cracking, while the transformation of the epoxy resin as a physical gel into a cross-linked polymer gel ensures form stability. The stabilization mechanism is shown to combine Pickering-like interfacial anchoring of hydrophilic silica at the metal/epoxy boundary with bulk gelation of the epoxy phase, enabling high metal loadings. As a result, epoxy shape-stable phase-change materials containing up to 80 wt% of Wood’s metal were produced. Wood’s metal forms fine dispersed droplets in epoxy medium with an average size of 2–5 µm, which can store thermal energy with an efficiency of up to 120.8 J/cm³. Wood’s metal plasticizes the epoxy matrix and decreases its glass transition temperature because of interactions with the epoxy resin and its hardener. However, the reinforcing effect of the metal particles compensates for this adverse effect, increasing Young’s modulus of the cured phase-change system up to 825 MPa. These form-stable, high-energy-density composites are promising for thermal energy storage in building envelopes, radiation-protective shielding, or industrial heat management systems where leakage-free operation and mechanical integrity are critical. Full article