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Polypropylene (PP) is a commonly used raw material for the production of 3D printing composite filament, which has many advantages, such as low density, insulation, chemical resistance, and environmental friendliness, but its mechanical strength is poor, which affects the comprehensive performance of the 3D printing PP model. In order to effectively improve the flexural strength of material-extrusion-based 3D printing (ME-3DP) PP model, this study investigated the influence of three printing parameters (infill rate, extrusion speed, platform temperature) on the flexural strength of the 3D printed PP model through the three-point support flexural test. The results show that the flexural strength of 3D printed PP model gradually increases with the increase of the infill rate, the decrease of the extrusion speed, and the increase of the platform temperature; the degree of influence of the three parameters on the flexural strength of the 3D printed PP model is as follows: infill rate ] extrusion speed ] platform temperature; the optimal combination of the printing parameters is as follows: infill rate (90%), extrusion speed (20 mm/s), and platform temperature (70°C). The flexural strength of the 3D printed PP model fabricated according to the optimal printing parameters is 41.7 MPa, which is the maximum value in the orthogonal experiment, verifying the reliability of the experiment results.

This research describes the development of a new sustainable and high-performance hybrid polymer matrix composite (HPMC) that reduces ecological impact by adding waste-based piassava fiver as a key reinforcing, sustainable, and biodegradable material. The composite contains Kevlar and waste based-piassava fibers in an epoxy matrix with nanosilicon dioxide particles (SiO2 NPs) to have the desired mechanical properties for uses in aerospace, railway cabins, structural frameworks, sports, medical equipment, and so on. Employing the hand lay-up method and compression moulding, sixlayered composites were made with different stacking sequences (A to O type) and SiO2 nanoparticle content (0, 0.5, 1, 1.5, and 2 wt.%). N-type stacking (KKPPKK) at 1.5 wt.% SiO2 NPs achieved the highest level of performance. The optimized composition produced impressive tensile strength (336 MPa), and flexural strength (381 MPa). Further, M-type composites with 1 wt.% SiO2 NPs had the highest impact strength of 263 J/m. Among all the combinations, the N-type composites absorbed less water, with 8.96% absorption, making them more useful in wet conditions. By incorporating waste-based piassava fiber and optimal nano SiO2 filler, this research creates a new way to achieve lightweight, durable, and environmentally responsible composite hybrid materials, positioning with the aims of sustainable engineering and waste valorization.

Natural rubber is a material, of vital importance, which is formed not only by the Hevea brasiliensis tree but also by various plant species (Carica papaya, Ficus carica, Taraxacum kok-saghyz, Parthenium argentatum). Amongst these, only the species Taraxacum kok-saghyz and Parthenium argentatum are explored as alternative sources of natural products. The goal of this article was to assess the screening of latex extracts, the determination of density, the determination of total solids, the determination of alkalinity, the determination of conductivity, the determination of total polyphenol content, the determination of total flavonoid content, the determination of antioxidant activity, the rubber extraction and the determination of rubber moisture. The screening result revealed the presence of proteins, amino acids, fatty acids, carboxylic acids, resins, alkaloids, phytosterols, terpenes, diterpenes, terpenoids, coumarins, polyphenols, flavonoids, saponins, steroids and the absence of catechins, glycosides, xanthoproteins, and anthocyanins. Following the determinations, the following values of the determined parameters were obtained: density 0.977 g mL−1, total solids 43.5%, alkalinity 0.53%, conductivity 210 μS cm−1, total polyphenols 349.7 μg GAE mL−1, total flavonoids 13.4 mg EC g−1, DPPH antioxidant activity 59.75%, ABTS antioxidant activity 511 μg TEmL−1, rubber mass 3.78% and rubber moisture 98.2%.

This paper proposes a new bridge reinforcement approach grounded in the technologically mature and extensively studied polymer mortar-HSSWM reinforcement technology. To verify the feasibility of this reinforcement method, this paper investigates the mechanical properties of high-strength steel wire mesh-polyurethane cement (HSSWM-PUC) composites through bond anchorage tests. The bond anchorage test of HSSWM with PUC was completed by setting wire diameter, longitudinal wire relative anchorage length, and transverse wire spacing as test variables. Some of the test results were verified by finite element analysis. The finite element model was established with the number of transverse wires, wire spacing, relative anchorage length, and wire diameter as variables. The experimental results were further studied and analyzed. The slip, ultimate load, and load-slip relationships of HSSWM and PUC under different variables were explored. Building upon this foundation, the variation rule between bond stress and slip of HSSWM-PUC composites is analyzed. Reducing the transverse wire spacing was found to increase the ability of the transverse wires to restrain the longitudinal wires. Meanwhile, with the increase of wire diameter, the bonding stress between HSSWM and PUC gradually decreases, whereas the bonding performance of PUC can be improved by appropriately reducing the ratio of adhesive powder.

This study investigates the properties and degradability of starch-based biofilms as sustainable, non-toxic, and biodegradable materials, emphasizing the effects of starch content and plasticizers on their performance. Starch biofilms are produced by casting a water solution that utilizes glycerol as a plasticizer and acetic acid as a co-plasticizer. A comprehensive analysis of the films was conducted, assessing various properties such as water absorption, swelling, water vapor transmission rate, water vapor permeability, environmental degradation, thermal decomposition, and tensile strength. The findings reveal that the addition of acetic acid significantly improves the physical properties of the starch biofilms, while the starch content predominantly influences their physical and mechanical characteristics. Notably, all film samples demonstrated excellent soil degradability, with substantial breakdown observed after just one month of burial in the soil garden. This research contributes to the field of biodegradable materials by showcasing the effectiveness of starch biofilms as an eco-friendly alternative, highlighting the role of plasticizers in enhancing their performance and confirming their environmental sustainability through rapid degradation in soil.

Phosphogypsum, as a by-product of the wet process phosphoric acid industry, is in urgent need of resource utilization due to the environmental risks caused by its massive accumulation; at the same time, the green recycling of used wind turbine blades (including glass fibers) is also a hotspot of global concern. In this study, a synergistic regenerative preparation method of environmentally friendly construction gypsum is proposed using phosphogypsum and recycled glass fibers from waste wind turbine blades as raw materials. The matrix material was prepared by mixing physically treated phosphorus building gypsum with natural building gypsum (8:2 ratio) and blended with recycled glass fibers of different lengths (0–5, 5–10, 10–15, 15–20 mm) and blending amounts (1.0%, 1.5%, 2.0%, 2.5%), and the effect on the performance of the gypsum was systematically analyzed. The results showed that the incorporation of glass fibers significantly reduced the slurry extension (maximum drop of 30 mm) and setting time (final setting time shortened by 115 s), but significantly improved the mechanical properties. The flexural strength reached 5.6 MPa when 15–20 mm glass fibers (2.0% doping) were doped, which was 51.35% higher than that of the blank control group; the compressive strength was raised to 11.3 MPa (24.17% higher) when 10–15 mm fibers (2.5% doping) were doped. The softening coefficient reached 0.67 at 15–20 mm fiber (dosing 1.5%), an enhancement of 32.37%. The microstructure shows that the glass fibers fill the pores inhibit crack extension through the bridging effect, and present a composite damage mode of fiber fracture and matrix debonding. This study provides a new way for the efficient synergistic utilization of phosphogypsum and waste wind turbine blades, with both environmental benefits and engineering application potential.

To evaluate and compare the surface roughness and optical properties in resinbased CAD/CAM materials during thermal aging. Methods: Lava Ultimate HT (3M ESPE, USA) and VITA Enamic HT (Vita Zahnfabrik, Germany) were selected for this study. Ten specimens for each group were prepared and polished. The surface roughness (Ra) and translucency (%) were measured by a 3D profilometer and spectrophotometer before and after the accelerated aging protocol (10,000 cycles, 5◦C, and 55◦C). The freeze-fracture surfaces of tested materials were observed by SEM. Results: Enamic HT had the lower surface roughness value of 82.56 ± 6.21 nm, while Ultimate HT owned the higher Ra of 125.89 ± 8.64 nm before thermal aging. Enamic HT had the lower transparency (%) of 55.02 ± 2.57, while Ultimate HT owned the higher transparency (%) of 58.89 ± 1.63 before thermal aging. Ra in tested CAD/CAM materials was greater than 0.2 μm after 10,000 thermocycles of 5/55◦C. Conclusions: The thermal aging led to a significant increase in surface roughness and a significant decrease in transparency in both CAD/CAM materials. Ultimate HT were significantly more translucent than Enamic HT before thermal aging, while Ultimate HT showed less translucent than Enamic HT after 10,000 thermocycles of 5/55◦C.

Epoxy resin (EP) can be flexibly bonded to various materials and has a wide range of applications in aerospace manufacturing. One of the most common applications is as a matrix phase in the preparation of advanced fiber composites. Therefore, it determines the mechanical properties of composites, particularly in view of the effect of differences in strength. To this end, we prepared tensile and compressive specimens of EP according to the ASTM standard and carried out quasi-static loading tests at different strain rates (0.001 to 0.1 s−1). The results show that EP has an obvious strain rate dependence, and the elastic modulus, yield strength, and plastic flow platform in tension and compression have obvious differences. Furthermore, by fitting the experimental stress-strain curves in tension, we used the power function to establish a theoretical model in terms of yield stress and elastic modulus. Subsequently, the nonlinear constitutive models in the compressive state were established based on the Sherwood-Frost model. Thus, a complete constitutive model was obtained which takes into account both tensile and compressive differences. Based on these constitutive models, the tensile and compressive mechanical behaviors obtained by parameter inversion are in good agreement with their experimental results, proving that the developed constitutive models have good theoretical prediction capability. These research results provide a reference for the practical engineering application of EP, especially for the fiber-reinforced EP composites.

Background: Neuroinflammation and oxidative stress are key features of Alzheimer’s disease (AD), offering potential targets for localized therapeutic intervention. Delivering neurotrophic factors specifically to inflamed brain regions could improve treatment efficacy while minimizing systemic exposure. Methods: We developed a reactive oxygen species (ROS)–responsive hydrogel incorporating oxidation-labile linkers to enable the on-demand release of brain-derived neurotrophic factor (BDNF). The hydrogel’s porous structure was characterized via Scanning Electron Microscopy (SEM), and drug release behavior was evaluated under oxidative and physiological conditions. Cytoprotective efficacy was tested in H2O2-treated PC12 cells. Results: The hydrogel exhibited high porosity and released BDNF rapidly in oxidative environments, with minimal release under normal conditions. It reduced intracellular ROS in stressed PC12 cells. Conclusion: This ROS-responsive hydrogel serves as a biocompatible and intelligent drug delivery system with potential for targeted oxidative stress modulation and neurotrophic support in the treatment of AD.

This paper was created within the EU Horizon project - RECICLARM - which conducted waste management research with the purpose of recycling up to 70% of Europe’s waste [1]. Our investigation focused on developing an algorithm capable of accurately classifying materials including plastic onces in categories of interest with the help of machine learning. Various types of materials and input variables have been documented and considered while prototyping and testing the intelligent classification algorithm, which resulted in a precise and efficient solution.