Search Results (349)

Vehicle crash boxes are elements that protect the integrity of vehicles and ensure the safety of occupants in potential vehicle accidents. These crash boxes are mounted on the chassis of vehicles. In this study, composite crash boxes fabricated from aluminum, which is known for its lightweight properties, as well as denim and ultra-high-molecular-weight polyethylene, both of which are widely available on the market, were investigated experimentally. Composite crash boxes composed of an epoxy resin matrix reinforced with denim fabric (DenimFRP) and ultra-high-molecular-weight polyethylene (UHMWPEFRP) fibers, as well as aluminum (Al), were produced. The crash boxes were manufactured using a vacuum infusion method. This combination was produced by wrapping these fibers around an aluminum core. The energy absorption values, peak force values, and specific energy absorption values of the manufactured crash boxes were obtained through quasi-static compression tests and then compared. The best energy absorption value was achieved with the Al+denimFRP composite crash box manufactured by wrapping denim around aluminum at a workload of 1645.22 J, and its specific energy absorption value was also calculated as 15.52 J/g. The difference between the highest and lowest energy absorption was determined to be 244.61%. The highest peak strength value was obtained with the Al+denim+UHMWPEFRP sample, which contained a combination of aluminum on the inside, denim fabric in the middle, and UHMWPE fabric on the outside. Among the individually produced samples, the Al+denimFRP composite crash box manufactured with denim fiber exhibited higher results compared with the UHMWPEFRP composite box manufactured with ultra-high-molecular-weight polyethylene. Full article

To address the difficulty in controlling the filtration performance of water-based drilling fluids under high-temperature and high-salinity conditions during the drilling of deep and ultra-deep wells, a salt-responsive micro-crosslinked polymer gel filtration loss reducer, designated LZX, was developed. The synthesis employed 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N,N-dimethylacrylamide (DMAA), dimethyldiallylammonium chloride (DMDAAC), and a betaine monomer containing an unsaturated double bond as monomers, with polyethylene glycol diacrylate (PEGDA) introduced as a crosslinker. Experimental results showed that the product structure matched the design expectations, and the thermal decomposition temperature of the main molecular chain exceeded 290 °C, indicating good thermal stability. At 220 °C under saturated salt conditions, a dosage of 2.5 wt% LZX maintained the API filtration loss at 5.8 mL and the HPHT filtration loss at 28.6 mL. Comparative experiments at different temperatures demonstrated that LZX exhibited superior filtration control performance compared to the commercial high-temperature filtration reducer Driscal Temp and Driscal D. The micro-crosslinked structure of LZX enhanced the rigidity of the molecular chains, raising the upper limit of its thermal resistance. Rheological and viscosity-average molecular weight measurements revealed that LZX exhibited typical antipolyelectrolyte behavior in high-salinity environments—the molecular chains tended to extend and the filtration reduction capability was accordingly maintained—preliminarily achieving a functional transition from passive salt tolerance to active salt responsiveness. LZX is expected to support the construction of high-performance water-based drilling fluids with high temperature and high salt resistance for future deep-earth drilling. Full article

Ultra-High Molecular Weight Polyethylene (UHMWPE), the standard base material in ski manufacturing, offers excellent gliding performance but exhibits limited mechanical and scratch resistance on hard and icy snow conditions. In this work, stainless steel is proposed as a mechanically robust alternative, and its inherently higher friction against snow is addressed through surface engineering. The snow friction behavior of 301H stainless steel surfaces decorated with fishbone-like microstructures combined with Laser-Induced Periodic Surface Structures (LIPSSs) was investigated using a custom-built snow tribometer. Several pattern designs, with different pitch distances and depths, were engraved using femtosecond laser pulse irradiation. We conducted morphological, physical, and chemical investigations through microscopy, static contact angle measurements, and X-ray Photoelectron Spectroscopy analyses. Results indicate that the gliding performance is not directly related to the modifications in surface chemistry and wetting behavior of the samples but is affected by the geometry and orientation with respect to the sliding direction of the specific micro- and nano-features. Overall, we achieved friction coefficient values comparable to those found in UHMWPE with a fast and economically sustainable single-step laser-texturing process. This approach allows the industrial up-scaling of the fishbone-texture design to real-size alpine ski prototypes. Full article

Five modifications of polytetrafluoroethylene (PTFE) are considered as a modern alternative to PTFE as sliding layers of bridge bearing parts. Radiation-modified PTFE without additives and with nano-additives as well as composites based on PTFE with bronze inclusions and nanomodified carbon fiber fillers were investigated. Ultra-high-molecular-weight polyethylene (UHMWPE) and classic pure PTFE were considered as control samples. The thermomechanical properties of the materials were studied within the framework of dynamic mechanical analysis in the operating temperature range of bridge structures [−40; +80] °C. The exit zones from the linear theory of viscoelasticity were established for all the materials considered. Temperature dependencies of the storage modulus and the loss modulus were determined. Thermoviscoelastic models of material behavior were constructed using a numerical identification procedure, experimental data, and simulation models. The thermomechanics of materials during the deformation of the spherical support part of the bridge were analyzed. Temperature dependencies of the parameters of the contact stress-strain state were determined with an average coefficient of determination R² = 0.97 and an average error size RMSE = 0.092. Full article

The Successive Self-Nucleation and Annealing (SSA) technique is a thermal fractionation method that involves subjecting a polymer sample to sequential self-nucleation and annealing steps at progressively decreasing temperatures, using differential scanning calorimetry (DSC). Since its introduction in the late 1990s, SSA has been widely applied to study the molecular structure of polymers with structural irregularities, including highly branched or crosslinked polyethylenes and random copolymers. However, the use of SSA for medical-grade ultra-high-molecular-weight polyethylene (UHMWPE), a highly linear homopolymer with minimal defects, has not yet been explored. This study aims to evaluate both its applicability to biomedical UHMWPE and its ability to reveal morphological differences among commercially available formulations. Several biomedical UHMWPE formulations, including conventional, highly cross-linked, and α-tocopherol-stabilized materials, were characterized by micro-FTIR, gel fraction and cross-link density measurements and subsequently subjected to SSA thermal fractionation. The results show that ram extrusion induces entanglements that act as interruptions in the otherwise linear chain structure, thereby enabling thermal fractionation: more than 80% of the crystalline fraction of ram-extruded UHMWPE is composed of three crystal populations melting at approximately 135, 132, and 126 °C, accompanied by four additional minor fractions at progressively lower melting temperatures. Gamma irradiation followed by thermal treatments significantly modifies the fractionation behavior, leading to the formation of an additional population of high-melting crystallites as evidenced by an increase in the number of melting peaks from 7 to 8. Oxidative degradation of highly crosslinked and annealed UHMWPE increases crystallinity by approximately 11% relative to its unoxidized counterpart but reduces the ability of the material to undergo thermal fractionation, decreasing the number of melting peaks. In contrast, the addition of low concentrations of α-tocopherol does not significantly influence the fractionation behavior. These findings demonstrate that thermal fractionation of medical-grade UHMWPE is feasible and that SSA is an effective tool for detecting morphological differences among formulations. Full article

Ultra-high molecular weight polyethylene (UHMWPE) fibers have recently emerged as a promising reinforcement material in fiber-reinforced concrete (FRC). To investigate the synergistic effects and reinforcing mechanisms of fibers with different elastic moduli within the concrete matrix, a series of hybrid fiber-reinforced concrete (HFRC) specimens were prepared by incorporating 0.25 vol%, 0.5 vol%, and 0.75 vol% carbon fibers (CFs) or polypropylene (PP) fibers into concrete containing 1 vol% UHMWPE fibers. The mechanical performance of the prepared composites was systematically evaluated through compressive, splitting tensile, flexural, and drop-weight impact tests. The experimental results indicate that concrete reinforced solely with UHMWPE fibers exhibits higher compressive strength but lower tensile strength, flexural strength, ductility, and impact toughness than the hybrid fiber systems. For both UHMWPE-CF and UHMWPE-PP hybrid concretes, the initial cracking impact resistance and failure impact resistance increased progressively with increasing CF or PP content. At equivalent fiber volume fractions, UHMWPE-PP hybrid concrete demonstrated superior resistance to initial cracking, whereas UHMWPE-CF hybrid concrete exhibited better post-failure impact resistance. Furthermore, fractal theory was employed to quantitatively characterize the impact damage behavior of HFRC specimens. The impact damage evolution equation is established by using the two-parameter Weibull distribution model. The findings provide theoretical and experimental support for the design and optimization of hybrid fiber-reinforced concrete subjected to impact loading. Full article

Herein, we describe a versatile synthetic strategy for constructing Prussian Blue (PB)-coated polymeric nanocapsules (PB@nanocapsules) with tunable sizes and controlled PB loading. A soft template was first formed from a miniemulsion composed of water/chloroform/hexadecane (94.55:5:0.2, w/w/w), using P4VP₈₂-b-PDMAA₁₈₀ as a stabilizer and varying amounts of P4VP homopolymer as a hydrophobe and additional reactive site provider. Crosslinked nanocapsules were obtained by adding 1,2-bis-(2-iodoethoxy)ethane (BIEE) as a crosslinker. The resulting nanocapsules exhibited average hydrodynamic diameters ranging from approximately 282 nm (without P4VP homopolymer) down to 58 nm (with 0.01 g P4VP homopolymer), as determined by DLS and TEM. Subsequently, sequential coordination with sodium pentacyanoammine -ferroate(II) hydrate (Na₃ [Fe(CN)₅NH₃]), followed by the addition of FeCl₃, yielded a uniform PB coating, as confirmed by the appearance of a characteristic absorption peak at 780 nm in the UV–Vis spectra and a CN stretching shift from 2060 to 2070 cm⁻¹ in FT-IR. TEM and HAADF-STEM with EDX mapping revealed the homogeneous distribution of Fe across the nanocapsule shells. The PB loading could be further controlled by varying the Fe³⁺ addition (5.0 × 10⁻³–4.5 × 10⁻² mmol), with higher loading improving thermal stability. This rational design provides a robust and generalizable platform for engineering polymer–inorganic hybrid nanostructures with tailored functionalities. Full article

Background/Objective: Traditional hip implant evaluations often overlook patient-specific dynamic loadings. This study investigates the performance of novel collared hip implant designs under walking conditions, focusing on geometric profiles and two common stem materials: Ti-6Al-4V and CoCr alloy. Methods: Patient-specific dynamic forces were applied using commercial finite element analysis, adhering to ISO and ASTM standards. Four cross-sectional profiles—circular, elliptical, oval, and trapezoidal—were initially evaluated for induced stresses and displacements. Subsequently, wear characteristics at implant junctions were analyzed, comparing CoCr (MC 1) and Ti-6Al-4V (MC 2) stems. The study also assessed the impact of using Ultra-High Molecular Weight Polyethylene (UHMWPE) acetabular cups. Results: The elliptical (CS 2) cross-sectional profile demonstrated superior performance. Junction analysis revealed that the CoCr stem (MC 1) exhibited a stem-to-head sliding distance four times higher and contact pressure 5.5 times higher than the Ti-6Al-4V stem (MC 2). Specifically, MC 1 showed 82% higher contact pressure and 89% greater sliding distance at the stem–head junction compared to MC 2. Additionally, utilizing UHMWPE cups effectively eliminated squeaking sounds attributed to CoCr cups due to superior wear resistance. Conclusions: The combination of an elliptical (CS 2) cross-sectional profile with a Ti-6Al-4V stem and UHMWPE acetabular cup offers optimal performance. This configuration significantly reduces wear and contact pressure, suggesting enhanced functionality and durability for hip implants under dynamic loading conditions. Full article

Resin and interlayer properties play significant roles in the resistance to impact of fibre-reinforced polymer composites (FRPCs). To investigate the contribution of each factor within the coupled variables to the impact resistance ability of FRPCs, in this work, waterborne polyurethane (WPU) with different tensile elastic modulus, tear strength and bonding strength was obtained. To systematically evaluate the impact resistance and failure mechanisms of the composite materials under varying external loads, impact resistance tests, numerical simulations, and relative weight analysis were conducted. The relative weight analysis results quantified the individual contributions of these three factors to the overall energy absorption capacity across diverse loading conditions. The results indicated that with the increasing rate of the external loading, the resin modulus consistently contributed more significantly to energy absorption than tear strength of resin and interlayer strength, reaching up to 44.3%. In ballistic penetration tests, with the increase in resin modulus, the ballistic performance of PE/WPU laminates demonstrated an S-shaped downward trend. Composites prepared with more rigid matrix could lead to unsatisfactory interlayer damage. A more robust structure could result in fibre pull-out and breakage to a greater extent at the point of forced impact while less in the secondary affected area, presenting comparatively lower impact resistant performance. Full article

A 10-year-old castrated male Chihuahua weighing 3.06 kg was presented with a chronic, progressively worsening cough of five months’ duration. Diagnostic imaging, including thoracic radiography and computed tomography, identified a well-defined cranial mediastinal mass consistent with a thymic tumor. Surgical excision was performed via median sternotomy with complete thymectomy. Following tumor removal, sternal closure was achieved using a non-absorbable ultra-high-molecular-weight polyethylene (UHMWPE) suture material (FiberWire^®, Arthrex, Naples, FL, USA). Histopathological examination confirmed the diagnosis of an epithelial-predominant thymoma with narrow but complete surgical margins. Postoperative recovery was uneventful, and the dog was discharged three days after surgery. Clinical signs, including coughing, progressively improved during follow-up. Radiographic evaluation performed up to postoperative day 57 demonstrated stable sternal alignment without evidence of dehiscence, implant-related complications, or disease recurrence. This report describes the first clinical case of FiberWire use for median sternotomy closure following thymectomy in a dog. The favorable clinical and radiographic outcomes observed during postoperative follow-up suggest that FiberWire may represent a viable alternative to traditional stainless-steel wire for sternal fixation in canine thoracic surgery. Full article

This study investigates the mechanical performance and blast resistance of high-performance aramid, carbon, and ultra-high molecular weight polyethylene (UHMWPE) fiber fabrics, responding to the need for lightweight and flexible materials in anti-explosion containers for aviation and critical infrastructure. The experimental methodology integrated quasi-static and dynamic tensile tests to characterize the strain-rate effect, followed by near-field air blast tests on both single-material and hybrid multi-ply fabric specimens to analyze their dynamic response, failure modes, and overpressure attenuation. Key findings revealed that carbon fabric exhibited high stiffness but was strain-rate insensitive and susceptible to brittle perforation failure, whereas aramid and UHMWPE fabrics demonstrated strain-rate sensitivity, with UHMWPE showing superior ductility and energy absorption. The hybrid multi-ply configuration (A-C-U sequence) achieved the least amount of failure, effectively utilizing the wave impedance of aramid fabric for initial shock reflection, high stiffness of carbon fabric for stress homogenization, and plasticity of UHMWPE fabric for energy dissipation. Additionally, all fabrics attenuated peak overpressure by over 80%, with enhancement observed for increased thickness. The study concludes that the strategic layering of different fabrics creates a synergistic effect, mitigating the weaknesses of individual fabrics and establishing an effective design paradigm for advanced blast-resistant structures, further enhancing the protective performance. Full article

This study systematically investigates a novel two-step approach to enhance the tribological performance of ultra-high molecular weight polyethylene (UHMWPE) by combining biaxial stretching with a subsequent hot pressing treatment. The significance of this work lies in developing a continuous, high-efficiency process that allows for decoupled control of bulk mechanical properties and surface tribological characteristics. The material’s evolution was comprehensively characterized using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), tensile testing, and a Taber Abraser. Results show that biaxial stretching significantly enhanced the film’s bulk mechanical strength and thermal stability, creating a wider processing window for subsequent surface treatment. A subsequent hot pressing step was then applied to refine the surface characteristics, yielding an optimal wear rate of 0.002 g/1000 cycles and a kinetic coefficient of friction (µk) of 0.106. Achieving such a concurrent optimization of high wear resistance and low friction is crucial in materials processing. The study demonstrates that the synergistic effect of biaxial orientation and hot pressing-induced crystal perfection provides a powerful and previously unreported pathway to achieving a superior balance of low wear and low friction in UHMWPE. Full article

Infiltrative lipomas involving the upper cervical spine present a significant surgical challenge, as the extensive muscular resection required for tumor control often leads to severe structural instability. This report describes the surgical treatment of an infiltrative lipoma that extensively invaded the cervical area in a 9-year-old dog. Following wide surgical debulking, a dual-plane stabilization strategy was employed. Ventral stabilization was attempted using standard C1–C2 transarticular screw fixation, while a modified dorsal stabilization technique anchored the occipital protuberance to the C2 spinous process using an ultra-high molecular weight polyethylene (UHMWPE) suture construct, combined with nuchal ligament reconstruction. Follow-up at 78 days revealed failure of the ventral implants, characterized by immediate improper positioning of the right screw and subsequent migration of the left screw. Despite these complications and confirmed tumor recurrence, the patient maintained normal neurological function and clinical cervical stability. This clinical course was suggestive of fibrous or early osseous union at the atlantoaxial joint. These findings suggest that the modified dorsal stabilization technique provided critical biomechanical support, effectively compensating for the compromised ventral fixation, and may represent a potential surgical option for managing extensive occipito-cervical instability in dogs. Full article

This study investigates the influence of cooling rates on the structural evolution and mechanical properties of ultra-high-molecular-weight polyethylene/high-density polyethylene fibers by systematically varying cooling media from ambient air (f1) to room-temperature water (f5). A significant structural inversion was observed between the as-spun and drawn fiber stages: while slow cooling (f1) promotes thermodynamic crystallization to form large, stable grains and maximum initial crystallinity (54%), rapid quenching (f5) effectively “freezes” the molecular chains in a low-crystallinity, highly orientable precursor state by suppressing thermal relaxation. During subsequent hot-drawing, the quenched samples (f5) exhibited a superior response to tensile stress, achieving the highest maximum draw ratio due to reduced crystalline obstacles and enhanced chain mobility. This enables efficient stress-induced crystallization, leading to near-perfect crystal orientation (f_c > 0.95) and a dense microfibrillar framework. Consequently, the fiber performance trends reversed, with f5 achieving peak tensile strength (1.33 GPa) and modulus, whereas f1 remained limited by its rigid thermal history. These findings highlight that rapid quenching is essential for developing high-performance fibers by preserving a precursor structure that maximizes the potential of stress-induced crystallization. Full article

Total knee arthroplasty (TKA) is one of the most frequently performed surgical procedures for patients with advanced knee joint disease, which is intended to relieve pain and restore normal joint function. A critical component of the TKA system is the ultra-high-molecular-weight polyethylene knee liner, which acts as the bearing surface between the metallic components. Despite continuous improvements in material processing and implant design, these liners remain vulnerable to several damage mechanisms such as wear, fatigue, delamination, oxidative degradation, pitting, embedded debris, overload, creep, edge damage, backside wear, and fracture. This study introduces a new quadrant-based characterization system to evaluate retrieved knee liners through non-destructive methods. The liners, collected from revision surgeries, were divided into nine anatomical zones labelled Q1 to Q9 to systematically identify and map surface damage. Damage density was determined manually as well as by using computational image analysis through MATLAB R2024a and Python 3.13. The computational methods demonstrated greater accuracy and reproducibility, showing a strong correlation with manual evaluation, with p equalling 0.41 for Python and p equalling 1.00 for MATLAB. The proposed quadrant-based system, together with computational validation, offers a more reliable framework in studying wear and damage patterns in retrieved implants. This approach contributes to an enhanced understanding of how different damage modes interact and offers useful guidance for enhancing implant design, material durability, and clinical outcome improvement in total knee arthroplasty. Full article