Search

Zinc (Zn) alloys have demonstrated significant potential in healing critical-sized bone defects. However, the clinical application of Zn alloys implants is still hindered by challenges including excessive release of zinc ions (Zn2+), particularly in the early stage of implantation, and absence of bio-functions related to complex bone repair processes. Herein, a biodegradable aliphatic polycarbonate drug-eluting coating was fabricated on zinc-lithium (Zn–Li) alloys to inhibit Zn2+ release and enhance the osteogenesis, angiogenesis, and bacteriostasis of Zn alloys. Specifically, the photo-curable aliphatic polycarbonates were co-assembled with simvastatin and deposited onto Zn alloys to produce a drug-loaded coating, which was crosslinked by subsequent UV light irradiation. During the 60 days long-term immersion test, the coating showed distinguished stable drug release and Zn2+ release inhibition properties. Benefiting from the regulated release of Zn2+ and simvastatin, the coating facilitated the adhesion, proliferation, and differentiation of MC3T3-E1 cells, as well as the migration and tube formation of EA.hy926 cells. Astonishingly, the coating also showed remarkable antibacterial properties against both S. aureus and E. coli. The in vivo rabbit critical-size femur bone defects model demonstrated that the drug-eluting coating could efficiently promote new bone formation and the expression of platelet endothelial cell adhesion molecule-1 (CD31) and osteocalcin (OCN). The enhancement of osteogenesis, angiogenesis, and bacteriostasis is achieved by precisely controlling of the released Zn2+ at an appropriate level, as well as the stable release profile of simvastatin. This tailored aliphatic polycarbonate drug-eluting coating provides significant potential for clinical applications of Zn alloys implants.

This article presents experimental research conducted on polycarbonate sheets deformed via single-point incremental forming (SPIF). Building upon established frameworks from previous studies, the analysis focuses on evaluating the formability and failure modes, particularly necking and fracture, of polymeric sheets in both conventional and incremental forming processes. The experimental design encompasses an investigation of spindle speed and step down process parameters, utilizing both oil and water as lubricants, to comprehensively assess their effects. The findings provide insights into how these parameters influence formability and affect the failure mode. When using oil as a lubricant, three distinct failure modes were observed during deformation: fracture, twisting, and crazing. An increased twisting was associated with higher step down values, whereas elevated spindle speeds contributed to increase crazing. Additionally, these tests revealed a “post-crazing” failure mode following deformation. Conversely, when water was used as a lubricant, only fracture and twisting were observed in the SPIF specimens. This work introduces, for the first time ever, a complete investigation of these failure modes through scanning electron microscopy analysis of the failure surface. This analysis scrutinizes surface features and interprets them, thus providing a valuable tool for failure analysis.

Abstract Interfacial bond formation during sputter deposition of metal‐oxide thin films onto polycarbonate (PC) is investigated by ab initio molecular dynamics simulations and X‐ray photoelectron spectroscopy (XPS) analysis of PC|X interfaces (X = Al2O3, TiO2, TiAlO2). Generally, the predicted bond formation is consistent with the experimental data. For all three interfaces, the majority of bonds identified by XPS are (C─O)─metal bonds, whereas C─metal bonds are the minority. Compared to the PC|Al2O3 interface, the PC|TiO2 and PC|TiAlO2 interfaces exhibit a reduction in the measured interfacial bond density by 75 and ∼65%, respectively. Multiplying the predicted bond strength with the corresponding experimentally determined interfacial bond density shows that Al2O3 exhibits the strongest interface with PC, while TiO2 and TiAlO2 exhibit ∼70 and ∼60% weaker interfaces, respectively. This can be understood by considering the complex interplay between the metal‐oxide composition, the bond strength, and the population of bonds formed across the interface.

Abstract India’s cement industry is the second largest in the world, generating 6.9% of the global cement output. Polycarbonate waste ash is a major problem in India and around the globe. Approximately 370,000 tons of scientific waste are generated annually from fitness care facilities in India. Polycarbonate waste helps reduce the environmental burden associated with disposal and decreases the need for new raw materials. The primary variable in this study is the quantity of polycarbonate waste ash (5, 10, 15, 20 and 25% of the weight of cement), partial replacement of cement, water-cement ratio and aggregates. The mechanical properties, such as compressive strength, split tensile strength and flexural test results, of the mixtures with the polycarbonate waste ash were superior at 7, 14 and 28 days compared to those of the control mix. The water absorption rate is less than that of standard concrete. Compared with those of conventional concrete, polycarbonate waste concrete mixtures undergo minimal weight loss under acid curing conditions. Polycarbonate waste is utilized in the construction industry to reduce pollution and improve the economy. This study further simulated the strength characteristics of concrete made with waste polycarbonate ash using least absolute shrinkage and selection operator regression and decision trees. Cement, polycarbonate waste, slump, water absorption, and the ratio of water to cement were the main components that were considered input variables. The suggested decision tree model was successful with unparalleled predictive accuracy across important metrics. Its outstanding predictive ability for split tensile strength (R2 = 0.879403), flexural strength (R2 = 0.91197), and compressive strength (R2 = 0.853683) confirmed that this method was the preferred choice for these strength predictions.

Mechanical behavior of press-induced deformation of polycarbonate at intermediate strain rates was studied by finite element method. Based on DSGZ constitutive model, polycarbonate cylindrical uniaxial compression finite element simulation was carried out. Effectiveness of the model for prediction of compressive mechanical response was verified by contrast of simulated and experimental results, calculation of prediction accuracy of model, and analyzation of multi-physics distribution in material after compressive deformation. Mechanical evolution rule of polycarbonate plates was obtained by simulation of the solid-state deformation in lateral restricted mode. The results show that simulated stress-strain curves is in good agreement with that acquired from experiment in the process of uniaxial compressive deformation, and stress-strain relationship in compressive elastic-plastic deformation can accurately predicted by DSGZ model relatively. The overall deformation of material was uniform, and the sensitivity of stress response to temperature is higher than that of strain rate in cylindrical uniaxial compressive deformation and press-induced deformed simulation. Mechanical behavior of press-induced deformation of polycarbonate was reflected by simulated results, which can be an important basis for engineering realization of press-induced deformation of polycarbonate, and provide strong support for material strengthening and its application in aircraft cockpit transparencies.

The study of the physical and mechanical properties of polycarbonate under various temperature conditions, taking into account its widespread use as a base material of monolithic polycarbonate systems in various climatic regions, will ensure a high degree of reliability of structures during operation in a wide temperature range. The authors of the article conducted a series of tensile tests of monolithic polycarbonate in the temperature range from -60 to +80 °C. The influence of temperature on the following characteristics of monolithic polycarbonate was evaluated: elongation at break, tensile yield strength, tensile stress at break, strains at the end of the elastic stage of the material. As a result of the conducted experimental studies, the relationship between the strength properties of monolithic polycarbonate and the operating temperature was revealed. The values of elongation at break at temperatures exceeding 15 °C for various samples generally correspond to the values obtained during tests conducted under standard conditions.

In this study, the investigation of damage caused by a spherical steel projectile on the polycarbonate (PC) panels has been undertaken both numerically and experimentally. The material properties are obtained from both static and dynamic tests. High-velocity impact experiments are performed using a pressure-based projectile launching system. The effect of panel curvatures and impact locations on the deformation are investigated experimentally. The impact locations are selected as both at the plate center and near the edge of the plate. A validation study is performed by analyzing the impact response of a PC plate as previously presented in the literature and subsequently comparing it with the results obtained. An analysis of the impact behavior of PC panels is carried out through numerical simulations using finite element program (LS-DYNA). The effect of boundary conditions on the impact response is also investigated numerically. Plastic strains, von Mises stresses, dent depth, and energy absorption arc obtained. It is indicated by the results that the deformation behavior of PC panels exhibits a strain rate dependence. Additionally, the deformation behavior is influenced by panel curvatures and boundary conditions, emphasizing the necessity to consider these factors in the design of structures, such as canopies made of PC panels. Highlights * Provides a comprehensive understanding of polycarbonate behavior. * Emphasizes the influence of impact locations and panel curvatures. * Dent depth and stress rise with panel curvature, crucial for design considerations. * Emphasizes the significance of strain rate and boundary condition in design. KEYWORDS curvature effect, penetration, polycarbonate panel, projectile impact, strain rate, 1 | INTRODUCTION Engineering thermoplastics demonstrate a blend of superior thermal, mechanical, electrical, and chemical characteristics in contrast to basic material resins. These versatile plastics can be fashioned into components [...]