Browse Topic: Polymers
What if there were a fabric that, like Superman, could take a bullet and self-heal? Such a super-dynamic, action-powered polymer might actually help protect real-life flyers in space.
This device belongs to the field of aviation materials technology and discloses a high-efficiency drilling equipment for manufacturing aviation materials, which includes a bottom plate. The top of the bottom plate is provided with a clamping structure and a positioning structure. The clamping structure includes a second moving plate, a third sliding groove, a second bi-directional screw, a fourth screw block, a clamping plate, and a rubber block. This device can hold materials through a clamping structure and effectively and quickly locate and drill holes through a positioning structure. By rotating the first threaded rod, it can drive the first screw block to move the U-shaped column. During the movement of the U-shaped column, it will drive the second threaded rod to move together. By rotating the second threaded rod, it will drive the second screw block to adjust the height of the connecting plate for drilling holes. By rotating the third threaded rod, it will drive the first moving plate to move, which will facilitate the multi-directional movement of the drill bit, improve the efficiency of drilling, avoid multiple position changes, and be beneficial for practical applications and operations.
Conveyor belt fault detection is critical for ensuring the safety and efficiency of industrial material transportation. In this study, a screen-printed flexible strain sensor based on a thermoplastic polyurethane (TPU) substrate and graphene conductive ink was fabricated. The sensor exhibited excellent flexibility, mechanical robustness, and stable electromechanical performance. Comprehensive evaluations were conducted, including microstructural analysis, strain sensitivity, hysteresis, dynamic response, and long-term cycling stability. The results demonstrated that a two-layer graphene configuration achieved an optimal balance between sensitivity and structural stability, showing high gauge factor, fast response, and reliable cyclic performance. Furthermore, the sensor was applied to conveyor belt fault monitoring. Experiments validated its ability to detect both halting faults and foreign object intrusions, with distinctive resistance signal features enabling not only fault occurrence detection but also identification of fault location, type, and severity. These findings highlight the potential of the proposed flexible sensor system as a promising solution for intelligent conveyor belt monitoring in harsh industrial environments.
This research demonstrates a facile method for fabricating an anti-icing coating through spray deposition on a metallic substrate. A dual-layer structure was designed to enhance icephobic properties: a primer layer incorporating fluorocarbon resin, butyl acetate, and rod-shaped micrometer-sized metal oxides to establish a secondary roughness morphology, followed by a topcoat composed of butyl acetate and nano-scaled superhydrophobic particles. Evaluation of the coating performance revealed a maximum water contact angle of 171.9°, indicating exceptional hydrophobicity. Furthermore, the coating exhibited notable abrasion resistance and anti-icing capabilities against overlaying ice.
Noise phenomena in automobiles caused by the stick-slip effect are increasingly among the most frequent reasons for customer complaints and therefore represent a critical vehicle quality attribute. To proactively address such issues, stick-slip testing of contacting material pairs is commonly applied during development. However, the predictive capability of current stick-slip test methods remains limited, particularly when highly flexible materials and realistic, stochastic excitation conditions are involved. The flexibility of sealing systems often allows the actual relative motion at the contact interface to be accommodated through adhesion and elastic deformation, thereby delaying or even preventing sliding. To date, this effect has not been represented by any characteristic parameter in conventional stick-slip testing. Instead, existing evaluations focus exclusively on the analysis of occurring stick-slip oscillations. For the initiation of stick-slip phenomena, however, not only the mean displacement between two stick-slip oscillations during the sliding phase is relevant, but also the relative displacement required to initiate the first slip event of the sealing contact. With the algorithm developed in this work, which reproducibly determines the distance to first slip based on changes in the friction force slope, this methodological gap is now closed. The displacement to first slip depends on numerous influencing factors, including profile geometry, normal load, sliding velocity, excitation profile, and environmental conditions, and was previously inaccessible by both experimental and numerical approaches. In particular, the onset of slip in sealing contacts can now be determined under stochastic excitation of the friction pairing, thereby closely reflecting real operating conditions. As a result, the prevention of noise phenomena can be significantly strengthened at an early stage of vehicle development.
Sometimes referred to as “solid smoke,” aerogels are the world’s lightest solid materials, composed of approximately 85 percent air by volume. Polyamide aerogels open up a whole new world of applications due to their unique properties: translucent like silica aerogels; thermoplastic; ultra-low density; superior mechanical properties; low-temperature operating range; and highly flexible (as compared to NASA Glenn’s polyimide aerogels). Polyamide aerogels are further novel because of their tunable glass transition temperatures, meaning that crystallinity, and hence strength, can be controlled via operating temperature. Addressing the key drawbacks of aerogel technology (hydroscopicity, fragility, cost), NASA Glenn’s suite of organic aerogels are cost-competitive with both existing silica aerogels and, with scale-up, high-end foamed polymer insulation.
The future of Moon exploration may be rolling around a non-descript office on the CU Boulder campus. Here, a robot about as wide as a large pizza scoots forward on three wheels. It uses an arm with a claw at one end to pick up a plastic block from the floor, then set it back down.
Researchers have developed a solar-powered reactor to break down hard-to-recycle forms of plastic waste – such as drinks bottles, nylon textiles and polyurethane foams – using acid recovered from old car batteries, and converting it into clean hydrogen fuel and valuable industrial chemicals.
This research investigates the fabrication and evaluation of Delrin (polyoxymethylene, POM) composites reinforcing 5-20 wt.% chopped ramie fiber (RF). The polymer composites were fabricated via the injection moulding technique. Glass transition temperature (Tg), thermal conductivity, Vicat softening temperature (VST), heat deflection temperature (HDT), melt flow index (MFI), and coefficient of linear thermal expansion (CLTE) were the various thermal characteristics of the sustainable composites that were systematically evaluated as per the ASTM standards. The addition of RF drastically altered the Delrin matrix's performance. Among the formulations, the composite with 15 wt.% RF had the best combination of properties: higher VST and HDT values, which provide greater dimensional stability at high temperatures; lower CLTE, resulting in less thermal expansion; comparatively better thermal conductivity; and improved heat dissipation. Eventually, there was a moderate drop in the MFI, indicating more rigid polymer chains that restrict the flowability of the composite, thereby increasing its heat-withstanding capabilities. DSC analysis revealed a slight upward shift in Tg and increased crystallinity, suggesting restricted polymer chain mobility and enhanced load transfer at 20 wt.% RF loadings, agglomeration effects, and weaker interfacial bonding with the matrix led to deterioration in properties. Aircraft cabin components like interior panels, ducting supports, and lightweight non-structural fittings requires dimensional stability, thermal resistance, and mechanical reliability under fluctuating flight conditions.
Aerospace and defense systems demand materials capable of maintaining performance under extreme environmental and operational stressors, including wide thermal cycling ranges, exposure to hydrocarbon fuels, vacuum conditions, and repeated mechanical strain. Silicone-based materials have become essential in these environments because they can retain elasticity, stability, and functionality where many traditional materials fail. Silicones are widely used as coatings, adhesives, sealants, and elastomers in aircraft and spacecraft applications. Their chemical structure enables resistance to both high and low temperatures, while also providing durability against solvents and fuels such as jet fuel. In contrast, many conventional elastomers degrade under prolonged thermal exposure or become brittle at cryogenic temperatures.
AMS6885/5 is the Material Specification (MS) which defines the requirements of a unidirectional carbon fiber tape epoxy repair prepreg capable of curing under vacuum for repair of carbon fiber reinforced epoxy structures. It also defines the requirements of an epoxy film adhesive to be applied in a co-bonding process with the prepreg for solid laminate and sandwich bonding.
We present a nonlinear topology optimization framework for designing crash--tolerant rotorcraft substructures by maximizing plastic work under prescribed crush displacement and volume constraints. The quasi-static response is modeled using a rate-independent elastoplastic formulation to capture path-dependent inelastic deformation of metallic components. A path-dependent adjoint method is developed to efficiently compute sensitivities of accumulated plastic work, revealing a mechanistic decomposition into elastic stiffness, deviatoric response, and yield surface contributions. Optimized 2D and 3D subfloor structures develop emergent plastic hinge networks and distributed deformation paths, significantly enhancing energy absorption compared to uniform designs. The results demonstrate that topology optimization can directly embed energy-dissipating mechanisms into primary rotorcraft structures, providing a practical framework for crashworthy rotorcraft and eVTOL airframe designs.
Ultrasonic welding (UW) provides a rapid and efficient method for joining composite components by inducing resin flow through thermally driven diffusion and crystallization at the bonded interface. However, in the absence of a multiphysics modeling framework or a digital twin approach, current practice still depends on extensive trial-and-error testing to determine key welding parameters such as vibration amplitude, weld time, weld pressure, hold time, and downspeed. While in-situ thermal cameras can monitor surface temperatures, the internal temperature at the bonded interface is often significantly higher, introducing the risk of thermal degradation and inconsistent bond quality. To overcome these limitations, GEM developed a high-fidelity multiphysics model to establish a quantitative relationship between process parameters and the evolving temperature field within welded thermoplastic parts. The model integrates coupled mechanical, thermal, and acoustic physics to simulate high-frequency vibrations and static pressure, capture the generation and spatial distribution of heat, and represent the temperature-dependent viscoelastic response that governs bond formation. A validation test matrix was designed by systematically varying weld time and vibration amplitude. Through-thickness temperature distributions were measured using infrared thermal imaging, enabling direct comparison with model predictions. Upon validation, the model was applied for process tailoring, allowing precise control of temperature distribution to achieve target bond strength. This integrated modeling and validation approach demonstrated substantial benefits, including reduced design iterations, accelerated process optimization, and improved quality and performance of welded composite structures.
Cold spray deposition is a kinetic-based deposition method that uses an inert gas flow to accelerate particles, where kinetic energy causes plastic deformation upon impact with a substrate, as discussed in Reference 1. Cold spray has been investigated as a method to deposit metal coatings on polymer-based composites, such as aerospace carbon-fiber-reinforced plastics (CFRP's), as discussed in Reference 2. These methods also exhibit low deposition efficiency (15-45%) as shown in Reference 3. In this work, to achieve high deposition efficiency and create an erosion-resistant coating, we use metal-polymer composite powders for cold spray, to make polymer-on-polymer bonding the dominant and effective bonding mechanism; this method lowers impact velocities relative to pure metal deposition to avoid substrate damage. The polymer can also lower the effect of material mismatch, while the nickel can help enhance the erosion performance of the final coating above that of pure polymer. This paper discusses the development of the cold spray deposition process, sample post-processing, erosion testing, and characterization of the samples. The results validate that this method successfully creates a method of depositing a coating with erosion resistance approaching that of bulk titanium without substrate damage on PEEK substrates. Further work is needed to address the issues with depositing on CF-PEEK substrates.
This paper investigates the feasibility of using flax fiber-reinforced composites in combination with additively manufactured polymer cores for helicopter rotor blades. A new rotor blade with flax composite spar and skin laminates and a 3D-printed ASA Aero core was designed to be geometrically equivalent to an existing carbon fiber/foam reference blade of the MERIT rotor test rig and manufactured using identical tooling. Material characterization included compression testing of the printed core at ambient and elevated temperatures, single-lap shear adhesion testing with epoxy laminates, and hygroscopic conditioning of core and laminate specimens. Structural testing comprised static beam bending, experimental modal analysis with axial pre-loading to approximate centrifugal stiffening, and sustained-load creep and recovery testing of the flax blade. The results show that the 3D-printed core provides sufficient compressive stiffness at curing temperature and adhesion to epoxy laminates, enabling its use as an internal consolidation tool during blade manufacturing. Compared to the carbon reference blade, the flax/3D blade exhibits reduced flapwise and lead–lag bending stiffness, altered modal behavior, and pronounced viscoelastic effects, including creep, incomplete recovery, and strong hygroscopic swelling. Component-level hygroscopic tests reveal that moisture-induced mass and thickness changes can generate sufficient internal stresses to locally initiate structural damage. Overall, the study identifies key limitations and design considerations for applying flax fiber composites in primary rotor blade structures.
A team led by Professor Yan Lu, Helmholtz-Zentrum Berlin, and Professor Arne Thomas, Technical University of Berlin, has developed a material that enhances the capacity and stability of lithium-sulfur batteries. The material is based on polymers that form a framework with open pores (known as radical-cationic covalent organic frameworks or COFs). Catalytically accelerated reactions take place in these pores, firmly trapping polysulfides, which would shorten the battery life.
Certain materials — such as quartz, some ceramics, and even bone — produce an electrical charge when they are squeezed, pressed, or vibrated. This is piezoelectricity, which comes from the Greek “piezein” meaning to press. Modern vehicles rely on piezo components in fuel injectors, parking sensors, airbag systems, and other functions.
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