Effect of Plasma Treatment on the Impact Behavior of Epoxy/Basalt Fiber-Reinforced Composites: A Preliminary Study

Enhancing the Cooling Efficiency of Aluminum-Filled Epoxy Resin Rapid Tool by Changing Inner Surface Roughness of Cooling Channels

In low-pressure wax injection molding, cooling time refers to the period during which the molten plastic inside the mold solidifies and cools down to a temperature where it can be safely ejected without deformation. However, cooling efficiency for the mass production of injection-molded wax patterns is crucial. This work aims to investigate the impact of varying surface roughness on the inner walls of the cooling channel on the cooling efficiency of an aluminum-filled epoxy resin rapid tool. It was found that the cooling time for the injection-molded products can be determined by the surface roughness according to the proposed prediction equation. Employing fiber laser processing on high-speed steel rods allows for the creation of microstructures with different surface roughness levels. Results demonstrate a clear link between the surface roughness of cooling channel walls and cooling time for molded wax patterns. Employing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm for low-pressure wax injection molding can save time, with a cooling efficiency improvement of approximately 34%. Utilizing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm on the inner walls of the cooling channel can save the cooling time by up to approximately 60%. These findings underscore the significant role of cooling channel surface roughness in optimizing injection molding processes for enhanced efficiency.

Enhancing Sustainability: Jute Fiber-Reinforced Bio-Based Sandwich Composites for Use in Battery Boxes

The rising industrial demand for environmentally friendly and sustainable materials has shifted the attention from synthetic to natural fibers. Natural fibers provide advantages like affordability, lightweight nature, and renewability. Jute fibers' substantial production potential and cost-efficiency have propelled current research in this field. In this study, the mechanical behavior (tensile, flexural, and interlaminar shear properties) of plasma-treated jute composite laminates and the flexural behavior of jute fabric-reinforced sandwich composites were investigated. Non-woven mat fiber (MFC), jute fiber (JFC), dried jute fiber (DJFC), and plasma-treated jute fiber (TJFC) composite laminates, as well as sandwich composites consisting of jute fabric bio-based unsaturated polyester (UPE) composite as facing material and polyethylene terephthalate (PET70 and PET100) and polyvinyl chloride (PVC) as core materials were fabricated to compare their functional properties. Plasma treatment of jute composite laminate had a positive effect on some of the mechanical properties, which led to an improvement in Young's modulus (7.17 GPa) and tensile strength (53.61 MPa) of 14% and 8.5%, respectively, as well as, in flexural strength (93.71 MPa) and flexural modulus (5.20 GPa) of 24% and 35%, respectively, compared to those of JFC. In addition, the results demonstrated that the flexural properties of jute sandwich composites can be significantly enhanced by incorporating PET100 foams as core materials.

A Numerical Study on the Influence of Strain Rate in Finite-Discrete Element Simulation of the Perforation Behaviour of Woven Composites

Predicting the perforation limit of composite laminates is an important design aspect and is a complex task due to the multi-mode failure mechanism and complex material constitutive behaviour required. This requires high-fidelity numerical models for a better understanding of the physics of the perforation event. This work presents a numerical study on the perforation behaviour of a satin-weave S2-glass/epoxy composite subjected to low-velocity impact. A novel strain-rate-dependent finite-discrete element model (FDEM) is presented and validated by comparison with experimental data for impacts at several energies higher and lower than their perforation limit. The strain rate sensitivity was included in the model by developing a novel user-defined material model, which had a rate-dependent bilinear traction separation cohesive behaviour, implemented using a VUSDFLD subroutine in Abaqus/Explicit. The capability of the model in predicting the perforation limit of the composite was investigated by developing rate-sensitive and insensitive models. The results showed that taking the strain rate into account leads to more accurate predictions of the perforation limit and damage morphology of the laminate subjected to impacts at different energies. The experimental penetration threshold of 89 J was estimated as 79 J by the strain-rate-sensitive models, which was more accurate compared to 52 J predicted by the strain-rate-insensitive model. Additionally, the coupling between interlaminar and intralaminar failure modes in the models led to a more accurate prediction of the delamination area when considering the rate sensitivity.

Effect of Water-Resistant Properties of Kraft Paper (KP) Using Sulfur Hexafluoride (SF6) Plasma Coating

Sulfur hexafluoride (SF₆) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF₆ plasma from 20–300 mTorr of pressure at powers from 25–75 Watts and treatment times from 1–30 min at 13.56 MHz. The prepared papers were characterized by contact angle measurement and water absorption. The selected optimum condition for the plasma-treated KP was 200 mTorr at 50 Watts for 5 min. Advancement with the change in treatment times (3, 5, and 7 min) on the physical and mechanical properties, water resistance, and morphology of KP with SF₆ plasma at 200 mTorr and 50 Watts was evaluated. The changes in the chemical compositions of the plasma-treated papers were analyzed with an XPS analysis. The treatment times of 0, 3, 5, and 7 min revealed fluorine/carbon (F/C) atomic concentration percentages at 0.00/72.70, 40.48/40.97, 40.18/37.95, and 45.72/39.48, respectively. The XPS spectra showed three newly raised peaks at 289.7~289.8, 291.5~291.7, and 293.4~293.6 eV in the 3, 5, and 7 min plasma-treated KPs belonging to the CF, CF₂, and CF₃ moieties. The 5 min plasma-treated paper promoted a better interaction between the SF₆ plasma and the paper yielded by the F atoms. As the treatment time for the treated KPs increased, the contact angle, water absorption time, and Cobb test values increased. However, the thickness and tensile strength did not show remarkable changes. The SEM images revealed that, as the treatment time increased, the surface roughness of the plasma-treated KPs also increased, leading to improved water resistance properties. Overall, the SF₆ plasma treatment modified the surface at the nano-layer range, creating super-hydrophobicity surfaces.

Factors Affecting Mechanical Properties of Reinforced Bioplastics: A Review

The short life cycle and recalcitrant nature of petroleum-based plastics have been associated with plastic waste accumulation due to their composition rather than worldwide overproduction. The drive to replace single-use products has sparked a considerable amount of research work to discover sustainable options for petroleum-based plastics. Bioplastics open up a new horizon in plastics manufacturing operations and industrial sectors because of their low environmental impact, superior biodegradability, and contribution to sustainable goals. Their mechanical properties regarding tensile, flexural, hardness, and impact strength vary substantially. Various attempts have been made to augment their mechanical characteristics and capacities by incorporating reinforcement materials, such as inorganic and lignocellulosic fibres. This review summarizes the research on the properties of bioplastics modified by fibre reinforcement, with a focus on mechanical performance. The mechanical properties of reinforced bioplastics are significantly driven by parameters such as filler type, filler percentage, and aspect ratio. Fibre treatment aims to promote fibre–matrix adhesion by changing their physical, chemical, thermal, and mechanical properties. A general overview of how different filler treatments affect the mechanical properties of the composite is also presented. Lastly, the application of natural fibre-reinforced bioplastics in the automobile, construction, and packaging industries is discussed.

Effects of Different Mold Materials and Coolant Media on the Cooling Performance of Epoxy-Based Injection Molds

Metal additive manufacturing techniques are frequently applied to the manufacturing of injection molds with a conformal cooling channel (CCC) in order to shorten the cooling time in the injection molding process. Reducing the cooling time in the cooling stage is essential to reducing the energy consumption in mass production. However, the distinct disadvantages include higher manufacturing costs and longer processing time in the fabrication of injection mold with CCC. Rapid tooling technology (RTT) is a widely utilized technology to shorten mold development time in the mold industry. In principle, the cooling time of injection molded products is affected by both injection mold material and coolant medium. However, little work has been carried out to investigate the effects of different mold materials and coolant media on the cooling performance of epoxy-based injection molds quantitatively. In this study, the effects of four different coolant media on the cooling performance of ten sets of injection molds fabricated with different mixtures were investigated experimentally. It was found that cooling water with ultrafine bubble is the best cooling medium based on the cooling efficiency of the injection molded parts (since the cooling efficiency is increased further by about 12.4% compared to the conventional cooling water). Mold material has a greater influence on the cooling efficiency than the cooling medium, since cooling time range of different mold materials is 99 s while the cooling time range for different cooling media is 92 s. Based on the total production cost of injection mold and cooling efficiency, the epoxy resin filled with 41 vol.% aluminum powder is the optimal formula for making an injection mold since saving in the total production cost about 24% is obtained compared to injection mold made with commercially available materials.

Dynamic Mechanical Properties and Thermal Properties of Longitudinal Basalt/Woven Glass Fiber Reinforced Unsaturated Polyester Hybrid Composites

This study investigates the mechanical, thermal, and chemical properties of basalt/woven glass fiber reinforced polymer (BGRP) hybrid polyester composites. The Fourier transform infrared spectroscopy (FTIR) was used to explore the chemical aspect, whereas the dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA) were performed to determine the mechanical and thermal properties. The dynamic mechanical properties were evaluated in terms of the storage modulus, loss modulus, and damping factor. The FTIR results showed that incorporating single and hybrid fibers in the matrix did not change the chemical properties. The DMA findings revealed that the B7.5/G22.5 composite with 7.5 wt% of basalt fiber (B) and 22.5 wt% of glass fiber (G) exhibited the highest elastic and viscous properties, as it exhibited the higher storage modulus (8.04 × 10⁹ MPa) and loss modulus (1.32 × 10⁹ MPa) compared to the other samples. All the reinforced composites had better damping behavior than the neat matrix, but no further enhancement was obtained upon hybridization. The analysis also revealed that the B22.5/G7.5 composite with 22.5 wt% of basalt fiber and 7.5 wt% of glass fiber had the highest T_g at 70.80 °C, and increased by 15 °C compared to the neat matrix. TMA data suggested that the reinforced composites had relatively low dimensional stabilities than the neat matrix, particularly between 50 to 80 °C. Overall, the hybridization of basalt and glass fibers in unsaturated polyester formed composites with higher mechanical and thermal properties than single reinforced composites.

Characterization of the Static, Creep, and Fatigue Tensile Behavior of Basalt Fiber/Polypropylene Composite Rods for Passive Concrete Reinforcement

Fiber-reinforced polymer (FRP) composites are becoming more frequently adopted as so-called “corrosion-resistant” concrete reinforcement materials due to their excellent mechanical properties and formability. However, their long-term reliability must be thoroughly investigated in order to understand failure mechanisms and to develop service life models. This study is on the mechanical properties of a prototype basalt fiber-reinforced polypropylene (BFPP) rod under quasi-static and sustained loading. Static strength and modulus at elevated temperatures do not decrease significantly, but the variability in strength increases with temperature, as shown by a Weibull analysis. Creep behavior is typical of unidirectional FRP, where the creep rupture strength follows a power law. Fatigue at various stress ratios R reveals the sensitivity of composite strength to the matrix damage, which increases at lower values of R (i.e., higher stress amplitudes). These results are discussed in the context of service life and concrete structure design guidelines.

Impact Strength of Hybrid Epoxy–Basalt Composites Modified with Mineral and Natural Fillers

The aim of this study was to evaluate the influence of mineral and natural additives (2.5; 5; 10 wt.%) on the impact strength of epoxy–basalt composites. Three types of filler were used to modify the epoxy matrix: basalt powder (BP), basalt microfiber (BF) and sunflower husk ash (SA). The impact strength and the maximum force were determined for the materials. The results of the conducted research confirm that the addition of a powder fillers to the epoxy matrix of basalt fiber reinforced composites is an effective method of improving their impact characteristic. The introduction of fillers to epoxy resin allowed to improve the impact properties of all tested groups of laminates. Moreover, in all cases, the introduction of the filler increased the maximum force needed to damage the composite sample and their hardness. For the modified materials, an increase in impact strength was recorded, respectively: by 44% for composites with BP, by 7.5% for composites with BF and by 2.5% for composites with SA.

Tuning the Surface Wettability of Cyclic Olefin Copolymer by Plasma Treatment and Graphene Oxide Deposition and Reduction

Selective altering of surface wettability in microfluidic channels provides a suitable platform for a large range of processes, such as the phase separation of multiphase systems, synthesis of reaction controlled, nanoliter sized droplet reactors, and catalyst impregnation. Herein we study the feasibility to tune the wettability of a flexible cyclic olefin copolymer (COC). Two methods were considered for enhancing the surface hydrophilicity. The first is argon/oxygen plasma treatment, where the effect of treatment duration on water contact angle and COC surface morphology and chemistry were investigated, and the second is coating COC with GO dispersions of different concentrations. For enhancing the hydrophobicity of GO-coated COC surfaces, three reduction methods were considered: chemical reduction by Hydroiodic acid (HI), thermal reduction, and photo reduction by exposure of GO-coated COC to UV light. The results show that as the GO concentration and plasma treatment duration increased, a significant decrease in contact angle was observed, which confirmed the ability to enhance the wettability of the COC surface. The increase in hydrophilicity during plasma treatment was associated with the increase in surface roughness on the treated surfaces, while the increase during GO coating was associated with introducing oxygen-containing groups on the GO-coated COC surfaces. The results also show that the different reduction methods considered can increase the contact angle and improve the hydrophobicity of a GO-coated COC surface. It was found that the significant improvement in hydrophobicity was related to the reduction of oxygen-containing groups on the GO-coated COC modified surface.

Investigation of Mechanical Properties for Basalt Fiber/Epoxy Resin Composites Modified with La

As an efficient reinforcing material in resin matric composites, the application of basalt fibers (BFs) in composites is limited by the poor interfacial adhesion between BFs and the resin matrix. In this study, to obtain the basalt fibers/epoxy resin composites with enhanced mechanical properties, the modification solution containing different concentrations of Lanthanum ions (La3+) was synthesized to modify the BFs surfaces to enhance the poor interfacial adhesion between BFs and the matrix. The morphology, the chemical structure and the chemical composition of the modified BFs surface were observed and detected by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The results show that, after BFs were soaked in the modification solution, the more active groups (C=O, –OH, C–O, etc.) were introduced to the BFs surfaces and effectively enhanced the bond strength between BFs and the resin matrix. The obtained mechanical performances of prepared basalt fibers/epoxy resin composites showed that the tensile strength, bending strength and interlaminar shear strength (ILSS) were improved with the modified BFs, and reached to 458.7, 556.7 and 16.77 Mpa with the 0.5 wt.% La. Finally, the enhancement mechanism of the modification solution containing La element is analyzed.