Service Life Of Materials Research Articles

Polyurethane combining preeminent toughness, puncture-resistance, and self-healing capabilities by multiple repair options based on dual dynamic covalent bonds

The development of self-healing materials has enabled the production of more reliable and intelligent materials. However, resolving the conflict between mechanical strength and self-healing efficiency as well as limited repair options of the self-healing materials is still the most pressing scientific challenge. In this study, a self-healing polyurethane with multiple repair methods is prepared by introducing disulfide bonds into thermo-reversible imine bonds-based polyurethane. The resultant polyurethane exhibits impressive comprehensive mechanical properties and preeminent repair capabilities. More importantly, damages can be repaired through various routes such as room temperature, moderate temperature, hair dryer blowing, and ethylenediamine assistance treatments. The superior mechanical properties, repetitive self-healing performance, and multiple options for repair is attributed to the cooperation of thermally reversible imine and disulfide exchanges, thermal motion of molecular chains, and dissociation/regeneration of hydrogen bonds. So this research provides numerous ideal options for repairing cracks and other damages in materials used in construction industry under different usage environments. Consequently, high-quality repairs, improved efficiency, and extended service life of construction engineering materials can be ensured.

A self-healing sustainable halloysite nanocomposite polyurethane coating with ultrastrong mechanical properties based on reversible intermolecular interactions

Endowing sustainable polyurethane (PU) materials with ultrastrong mechanical properties and highly efficient self-healing performancesimultaneously is extremely challenging and of great significance to dramatically extend the service life of metal materials. In this work, 4,4′-dithiodianiline (DTDA) and bio-based 2,5-Tetrahydrofurandimethanol (THFDM) were used as chain extenders to introduce hierarchical hydrogen bonds and aromatic disulfide bonds into the PU matrix, after which rich interfacial hydrogen bonds were obtained by incorporating environment-friendly polydopamine-modified halloysite nanotube (PDA@HNT) into the PU matrix. The developing PU nanocomposite exhibits record toughness (774.4 MJ m−3), outstanding tensile strength (68.3 MPa), and exceptional elongation at break (2882.7 %), as well as distinguished self-healing performance (85.4 % at 35 °C for 24 h; 95.9 % at 80 °C for 15 min). Thanks to the shielding effect of PDA@HNT fillers, the PU nanocomposite also possesses good corrosion resistance proved by its high impedance value at 0.01 Hz of 2.23 × 108 Ω cm2 after immersing in 3.5 wt% NaCl solution for 30 days. This work provides constructive guidance to create an ultra-robust self-healing sustainable PU nanocomposite with long-term corrosion resistance.

Pre-study of the evaluation of ecological sessile succession and their relationship with bacteria on concrete artificial reef material

Artificial reefs are human-made structures built for promoting marine life. Long-term monitoring and research regarding the use of artificial reefs in terms of ecological and economic perspective is essential. In this study, the ecological succession and their relationship with bacteria on concrete artificial reef material was investigated. Heybeliada artificial reef site was selected as sampling area. After three years period, the visual examination of ecological succession and sessile marine bacteria count were performed on the concrete artificial reef material. All the results showed that the strength of the artificial reef material is also affected by the biofilm layer and the creatures in the microecosystem. Therefore, monitoring studies should be carried out to determine the service life of artificial reef materials as well as to reveal the existence of the ecosystem formed and developing in these areas qualitatively and quantitatively.

Investigation of the interfacial bonding of new and old pavement materials for pothole applications: Bonding materials optimization, mechanical properties and structural performance

Under the combined effects of heavy traffic loading and extreme environmental conditions, the failure issues of repaired potholes caused by insufficient interfacial bonding strength between the new and old pavement materials occur frequently, which severely impairs the durability of the repaired structure. This study aims to improve the interfacial bonding strength between the new and old pavement materials and prolong the service life of repair pothole materials. Firstly, the mechanical analysis was carried out using finite element simulation, and a technical measure was proposed to ensure improved interfacial bonding strength between new and old pavement materials. Secondly, emulsified asphalt (EA), light asphalt (LA), waterborne epoxy resin-modified emulsified asphalt (WER-EA) and silicone penetrant (SP) were selected to investigate the paving workability, viscosity changing and curing times of bonding materials at different temperatures. On this basis, the interlaminar shear and pull-out tests were performed under different paving mass, temperatures and humidity conditions, and the shear and pull-out strengths of four bonding materials were compared to optimize the type and paving mass of interface bonding material. The results show that an increase in bonding coefficient (BC) significantly reduces the values of pressure stress (σy) and pressure strain (εy), even the bucking depth of the pothole sides, thus decreasing the risk of pothole repair failure. Under normal or low-temperature conditions and field construction, SP has exceptional paving workability, and its shear and pull-out strengths are much higher than other bonding materials, with an optimum paving mass rate being 0.3 kg/m2 ∼ 0.4 kg/m2. The research results are of great significance in improving the pothole repairing level, standardizing the repair process and extending the service life of pavements.

Effect of microtexture morphology on the tribological properties of PI/EP-PTFE-WS2 coating under starved oil and dry sliding wear

The limited wear resistance of aluminum alloys constrained their applications and longevity. Surface microtexture combined with polymer coating technology can prolong the service life of aluminum alloy materials under extreme conditions of aerospace. A370 aluminum specimens were textured with three types of microtexture surfaces including circular pits, rectangular grooves and cross grids. A PI/EP-PTFE/WS2 coating was designed and prepared on the surfaces of these textures by liquid spraying to improve the tribological properties of A370 aluminum under starved oil and dry sliding wear. The influences of different micro-texture morphology on the tribological performances of these coatings were experimented. The results indicated that the surface qualities of the micro-textures are improved by coating deposition on their surfaces. The friction coefficients of the coated surfaces on all micro-texture are effectively reduced under the relatively stable wear stage compared to the sample without micro-texture coating. The coating on the pitted texture exhibits superior performance in friction tests, reducing average coefficients and wear rate by 13.58% and 35.34% in dry sliding wear, and by 16.18% and 83.98% under the starved oil lubrication compared to the non-textured substrate, respectively. This is followed by the coating on cross-mesh texture and the rectangular groove texture. The reason is that the pitted texture facilitates the local stress release of coating during the process of coating deposition due to its smaller spacing between pits and higher density of pits per unit area. The bearing capacity of the pitted texture is highest and its deformation is the lowest. The wear debris created in the friction process is more easily accumulated in the pit units, which results in a reduction in wear.

Vibration Response of Thermoplastic Veil Interleaved Carbon Fiber Reinforced Epoxy Composites

Plate composite structures are used in many sectors today. Therefore, the demand for these structures is increasing. Especially in the field of aerospace, layered composite structures attract more attention. These wide range of applications affect composite materials in various aspects such as dynamic and mechanical in terms of working environments. Time-dependent variable stresses, vibrations and fatigue that occur in structures subjected to dynamic loads adversely affect both the internal and external structure of composite materials. This situation reduces the safe service life of composite materials. It is an important problem to eliminate or minimize the parameters that negatively affect the economic service life of fiber reinforced layered composite structures. In order to overcome these problems, it is aimed to create new composite structures by adding two different thermoplastic veil layers between fiber fabrics, which are widely used on an industrial basis. In this study, carbon fiber was used as the fiber fabric and Polyamide (PA) and Polyether ether ketone (PEEK) veils were used as the thermoplastic veil layers. The productions were made by Vacuum Assisted Resin Transfer Molding (VARTM) method and dynamic (natural frequency and damping ratio) tests were performed according to the relevant ASTM standards. With the experimental results obtained, the dynamic properties of thermoplastic veil-layered carbon fiber/epoxy composites were comparatively investigated to determine the effect of both veil layers and different fiber contents.

Self‐healing waterborne fluorinated polyurethane‐acrylate based on photoreversible reaction and hydrogen bonds

AbstractThe development of self‐healing materials is an effective strategy to improve the service life of polymer materials. In this study, self‐healing waterborne fluorinated polyurethane‐acrylate (WFPUA) containing UV‐responsive coumarin groups was prepared by Pickering emulsion polymerization using modified cellulose nanocrystal as a stabilizer. The effect of double bond‐terminated waterborne polyurethane content on emulsion polymerization and latex film properties was mainly studied. Due to the dynamic reversibility of the coumarin groups and the synergistic effect of hydrogen bonds, the optimized sample (WFPUA‐30) had excellent mechanical properties and self‐healing properties. The tensile strength was 5.24 MPa and the elongation at break was 267%. The self‐healing efficiency of tensile strength and elongation at break after 6 h of repair was 86.52% and 93.20%, respectively. In addition, due to the presence of fluorine‐containing groups, the water and oil contact angles of the latex film could reach 101.7° and 82.1°, respectively. This work broadens the way for the manufacture of self‐healing and multifunctional waterborne polyurethane‐acrylates. © 2024 Society of Industrial Chemistry.

Evaluating the impact of material service life on embodied energy of residential villas in the United Arab Emirates

PurposeRecently, there has been a shift toward the embodied energy assessment of buildings. However, the impact of material service life on the life-cycle embodied energy has received little attention. We aimed to address this knowledge gap, particularly in the context of the UAE and investigated the embodied energy associated with the use of concrete and other materials commonly used in residential buildings in the hot desert climate of the UAE.Design/methodology/approachUsing input–output based hybrid analysis, we quantified the life-cycle embodied energy of a villa in the UAE with over 50 years of building life using the average, minimum, and maximum material service life values. Mathematical calculations were performed using MS Excel, and a detailed bill of quantities with >170 building materials and components of the villa were used for investigation.FindingsFor the base case, the initial embodied energy was 57% (7390.5 GJ), whereas the recurrent embodied energy was 43% (5,690 GJ) of the life-cycle embodied energy based on average material service life values. The proportion of the recurrent embodied energy with minimum material service life values was increased to 68% of the life-cycle embodied energy, while it dropped to 15% with maximum material service life values.Originality/valueThe findings provide new data to guide building construction in the UAE and show that recurrent embodied energy contributes significantly to life-cycle energy demand. Further, the study of material service life variations provides deeper insights into future building material specifications and management considerations for building maintenance.

Nano-friction behavior and deformation study of hydroxyapatite in ultra-precision polishing process.

In order to study the effect of ultra-precision machining on the surface quality of hydroxyapatite semiconductor materials as well as the material removal mechanism of hydroxyapatite, the mechanical polishing behaviors of hydroxyapatite at different polishing depths were studied by molecular dynamics method. The results show that the subsurface damage of hydroxyapatite increases with increasing polishing depth. The polishing temperature and the polishing force showed a positive correlation with the polishing depth, and the variation of the polishing force was related to the accumulation-release effect of the potential energy of hydroxyapatite material. In addition, the variation of stresses in hydroxyapatite during polishing is mainly influenced by the thermal softening effect. With a smaller polishing depth, the hydroxyapatite semiconductor material has fewer structural defects, fewer atoms undergoing phase transitions, lower surface roughness, and better surface quality. Therefore, to ensure the long-lasting service life of hydroxyapatite semiconductor materials, a small polishing depth should be used in ultra-precision machining. Additionally, this study also provides a theoretical reference for future research on the mechanical properties of hydroxyapatite-based composites. A Large-Scale Atomic/Molecular Parallel Simulator (LAMMPS) was utilized to perform molecular dynamics simulations. The output was visualized and analyzed by the Open Visualization Tools (OVITO) software. The intermolecular interactions were described by the polymer consistent force-field and the 12/6 Lennard-Jones potential functions. The workpiece was polished under a micro-canonical ensemble with the temperature settled at 300 K. Periodic boundary conditions were adopted and the velocity-Verlet algorithm was used to integrate the atomic motion with a timestep of 0.1 femtoseconds (fs).

The Role of Big Data in Circular Supply Chain Practices and Corporate Sustainability Performance

The green industry is a national priority target, with one of the indicators being the application of a circular economy. The application of a circular economy to the entire supply chain process is an effort to extend the service life of materials so that sustainability arises. The application of circular supply chains needs to be supported by digital technology to improve processes. This study aims to analyze the effect of circular supply chain practices on corporate sustainability performance and the moderating effect of Big Data. The hypothesis testing using SEM analysis tools. The number of samples used was 140, who are currently working or have worked in companies that have implemented a circular economy. [KM1] The results of the study show that Circular Supply Chain Practices do not influence on Corporate Sustainability Performance, so the moderating effect of Big Data is not supported. Therefore, managerial parties need to implement a circular supply chain in the company's business processes. Managers need to provide technical training related to designing environmentally friendly products and educational strategies to customers regarding the application of a circular economy. Nonetheless, this study also has limitations, in that it consists of only one variable, Circular Supply Chain practices, which affect Corporate Sustainability Performance. Thus, the next researcher should add other variables that can affect Corporate Sustainability Performance, such as the purchasing realized absorptive capacity variable. [KM1]Refer in research method section for my comment.

Recyclable flexible materials with MOF-derived nanospheres for electromagnetic wave absorption

Self−healing and recyclable characteristics were beneficial for wave−absorbing materials to extend the service life, reduce the cost, stability and electromagnetic pollution in the practical application. The flexible composites with recyclable and electromagnetic wave (EMW) absorption were fabricated by employing MOF derived carbon nanoparticles (ZnCoNC) and polymers with dynamic boron ester bonds. The benzene structure of eugenol derived polybenzoxazine structure can stick on the surface of the MOF−derived nanoparticles by π−π interaction, which benefits the recyclable and mechanical properties. With the synergistic effect of dynamic boron ester bond and π−π interaction, the tensile strength of composites with 15 wt% ZnCoNC reached 7.88 MPa after 3 times recycling, it remained 88 % compared to origin composites. The minimum RL obtained is −36.6 dB at a thickness of 2 mm, it can approximately maintain the same effect in EMW absorption performance after recycling. This work was expected to broaden the EMW absorption application field and extend the service life of materials.

Bio-based conductive polyurethane composites derived from renewable castor oil with enhanced self-healing ability for flexible supercapacitors

To alleviate the pressure on the petrochemical industry and address environmental concerns, the utilization of polyurethane (PU) derived from castor oil (CO) (as an ester polyol replacement of petrochemical-based materials) has garnered significant attention in recent decades. Extending the service life of materials requires imparting self-healing properties to vegetable oil-based polymers, an aspect that has received limited attention in current studies. However, low self-healing efficiency still poses a significant challenge, and non-conductivity also remains an obstacle in current research, crucial for their application in electronic devices. In this work, we present the first series of electrically self-healing biopolymer composites constructed by incorporating carbon nanotube (CNT) networks into crosslinked castor oil-based polyurethane (BPU) through a simple curing process. These materials address the challenges mentioned above and exhibit improved mechanical, electrical, and self-healing capabilities compared to other bio-based self-healing materials. The resulting BPU/CNT composite demonstrated exceptional repeated self-healing capacity, restoring both mechanical properties and electrical performance even after experiencing severe mechanical damage. Notably, this composite served as a conductive substrate in flexible solid-state supercapacitor (FSSC) devices. Consequently, the FSSC derived from the composite conductive substrate achieved an impressive 92.4 % self-healing efficiency even after undergoing 7 cutting/healing cycles. The device remained virtually unchanged even after being bent at a 180° angle with a bending radius of 1.6 mm, indicating excellent repeatability and durability. The exceptional self-healing ability, with ∼98 % electrical recovery at 100 °C for 70 s and 93 % at 80 °C after 6 min, of these composites was attributed to the synergistic interactions of the dynamic exchange reactions of disulfide bonds and dense hydrogen bonds within the BPU matrix, which provide a reversible dynamic polymer network. The healing efficiency of these dynamic bonds was evaluated by adjusting the composition ratio of the long linear chain of pTHF in hybrid polyols of the crosslinked polymer network. Overall, this work highlights a series of green, simple, and highly efficient self-healing polymer composites derived from renewable castor oil, and it establishes an essential framework for future sustainable polymer composite design.

Aging and life control of cross-linked polyethylene as cable insulation material

Cross-linked polyethylene (XLPE) has been widely used in the field of power cables due to its excellent mechanical properties and insulating properties. However, during the manufacturing of high voltage cables, XLPE will inevitably be affected by electrical aging, thermal aging and electro-thermal combined aging, which makes the resistance and life of the material decline. Therefore, it is necessary to enhance the aging resistance of XLPE without affecting its mechanical properties and insulating properties, so as to extend its service life. In this work, the structural characteristics and cross-linking mechanism of XLPE are introduced, the aging process and influencing mechanism are systematically analyzed, and the life decay problems of XLPE due to aging are explored by using methods such as the temperature Arrhenius equation and the inverse power law of voltage. The improvement strategies such as grafting, blending, and nanoparticle modification can be used to enhance the thermal stability, antioxidant properties, and thermal aging resistance of XLPE, thereby extending its service life. Finally, the strategies of adjusting and controlling the service life of XLPE cable insulation materials in the future are discussed, which provide theoretical guidance for further improving long-term stable operation of XLPE cable insulation materials.

Effects of forming techniques on residual stresses in stiffening ribs of sandwich panels

This study investigates residual stresses in stiffening ribs of composite materials formed by stamping in a punch-die system. Using two-dimensional X-ray diffraction (XRD), we measured residual stresses on both the anterior and posterior sides. Three LITECOR® composite types, with core thicknesses of 0.8, 1.25, and 1.6 mm, were examined. Results indicate that as core thickness increases, residual stress values decrease on both sides. Notably, anterior side stresses on the y-axis are relatively higher (1027–1199 MPa) compared to the x-axis, exceeding posterior side values (998–1083 MPa) at 0.8 mm core thickness. Moreover, the study compares these values with Single Point Incremental Forming (SPIF) and finds that SPIF generally yields lower stress values for all core thicknesses. These findings suggest that SPIF is favourable for achieving minimal residual stress in LITECOR® composites. Addressing residual stresses is crucial for enhancing structural integrity and extending the service life of sandwich panels and composite materials.

Reuse of wood biomass ash to improve thermal behavior of gypsum plasters

Huge amounts of waste are generated each year in the world. In addition, the construction sector is one of the larger producers of residues and a huge energy consumer. Thus, architects, engineers and other actors of the building sector should give solutions in order to reduce that problem. In that sense, the idea of finding solutions for the end of the service life of materials, in order to promote circularity, has been studied by several researchers. In this study, biomass wood ash has been used as aggregate for the generation of new eco-efficient gypsum plasters, for its application in new buildings and rehabilitation works. In order to conduct an exhaustive characterization of the new composites, an experimental campaign of the plasters has been conducted: dry bulk density and thermal conductivity of the plasters have been measured. The results showed that it was possible to add up to 25% of wood ash without modifying the water/gypsum ratios. Moreover, thermal conductivity of the plasters has improved up to18% when the ash was added to the mixture. Finally, the effects of using the new gypsum composites in the thermal envelope of buildings was analyzed by its usage in a rehabilitation case study simulation.

Slippery Porous-Liquid-Infused Porous Surface (SPIPS) with On-Demand Responsive Switching between "Defensive" and "Offensive" Antifouling Modes.

Slippery liquid-infused porous surfaces (SLIPS) have received widespread attention in the antifouling field. However, the reduction in antifouling performance caused by lubricant loss limits their application in marine antifouling. Herein, inspired by the skin of a poison dart frog which contains venom glands and mucus, a porous liquid (PL) based on ZIF-8 is prepared as a lubricant and injected into a silicone polyurethane (SPU) matrix to construct a new type of SLIPS for marine antifouling applications: the slippery porous-liquid-infused porous surface (SPIPS). The SPIPS consists of a responsive antifoulant-releasing switch between "defensive" and "offensive" antifouling modes to intelligently enhance the antifouling effect after lubricant loss. The SPIPS can adjust antifouling performance to meet the antifouling requirements under different light conditions. The wastage of antifoulants is reduced, thereby effectively maintaining the durability and service life of SLIPS materials. The SPIPS exhibits efficient lubricant self-replenishment, self-cleaning, anti-protein, anti-bacterial, anti-algal, and self-healing (97.48%) properties. Furthermore, it shows satisfactory 360-day antifouling performance in actual marine fields during boom seasons, demonstrating the longest antifouling lifespan in the field tests of reported SLIPS coatings. Hence, the SPIPS can effectively promote the development of SLIPS for neritic antifouling.

Self-healing polyurethane elastomer with ultra-high mechanical strength and enhanced thermal mechanical properties

Polyurethane (PU) materials are widely used due to their excellent comprehensive properties including high strength, good wear resistance and weather resistance. To further improve the service life and safety of polyurethane materials, self-healing polyurethane materials have been developed. However, self-healing polyurethane generally suffers from low mechanical strength and poor thermal mechanical properties. Here, we have constructed a strong dual network by introducing benzene-1,4-diboronic acid (PDBA) into poly(urethane-urea) (PUU). On one hand, PDBA can form coordination bonds with nitrogen atoms in PUU, leading to the formation of a dual network consisting of boron-nitrogen coordination and hydrogen bonding. This dual network imparts PUU with a maximum tensile strength of 84.2 MPa. On the other hand, boron-nitrogen coordination is more stable than hydrogen bonding at high temperature, thereby significantly enhancing the thermal mechanical properties of PUU (the mechanical strength of PUU-PDBA-50 % and PUU-PDBA-100 % increased by 1.8 times and 2.4 times, respectively, compared to PUU at 100 °C). Meanwhile, the dynamic nature of the dual network endows the material with self-healing ability.

Low-Hysteresis and High-Toughness Hydrogels Regulated by Porous Cationic Polymers: the Effect of Counteranions.

Service life and range of polymer materials is heavily reliant on their elasticity and mechanical stability under long-term loading. Slippage of chain segments under load leads to significant hysteresis of the hydrogels, limiting its repeatability and mechanical stability. Achieving the desired elasticity exceeding that of rubber is a great challenge for hydrogels, particularly when subjected to large deformations. Here, low-hysteresis and high-toughness hydrogels were developed through controllable interactions of porous cationic polymers (PCPs) with adjustable counteranions, including reversible bonding of PCP frameworks/polymer segments (polyacrylamide, PAAm) and counteranions/PAAm. This strategy reduces chain segment slippage under load, endowing the PCP-based hydrogels (PCP-gels) with good elasticity under large deformations (7 % hysteresis at a strain ratio of 40). Furthermore, due to the enlarged chain segments entanglement by PCP, the PCP-gels exhibit large strain (13000 %), significantly enhanced toughness (68 MJ m-3 ), high fracture energy (43.1 kJ m-2 ), and fatigue resistance. The unique properties of these elastic PCP-gels have promising applications in the field of flexible sensors.

Room-temperature self-healing polyurethane elastomers with high strength and superior self-healing efficiency based on aromatic disulfide-induced

Polymers are inevitably subject to mechanical damages during molding, processing, and application. Self-healing of internal and surface damage in polymers can be achieved by endowing the materials with room-temperature self-healing functions. This improvement significantly eliminates safety risks caused by material damage, enhances the safety, stability, and service life of polymer materials, facilitates the realization of sustainable resource development, and aligns with the concept of "low carbon". Room-temperature self-healing materials mainly rely on motility of molecular chain segments and dynamical equilibration of forces acting within the system. However, there have been few reports of polyurethane elastomers with high strength and high self-healing efficiency. In this paper, PUIPBD polyurethane elastomers were prepared by the chemical reacting of polytetrahydrofurandiol PTMEG-2000, isophorone diisocyanate IPDI, 1,4-butanediol (BDO) with 4,4′-dihydroxydiphenyl disulfide (DHDDS) as monomers. It was found that the self-healing efficiency of the synthesized polyurethane elastomer series was very high after 48 h of self-healing at 25 °C, all of which exceeded 79 %, and the tensile strength, elongation and fracture toughness of best performing elastomer PU90/10 could reach 89.8 %, 99.9 %, and 95.6 %, respectively after 48 h of self-heal at room temperature, showing good simultaneous room temperature self-healing efficiency.

Macrokinetics of the deterioration of cement-based grouting material for predicting its service life under acid rain attack

Cement-based grouting material is widely used to reinforce the unsafe rock and control seepage of rock-carved relics although it is considered inappropriate in protection of ancient sites. As this approach is irreversible, a longer service life is desirable for the grouting material and methods to predict the service life are needed. Here we propose a universal formula based on the dissolved amount of calcium ion to predict the deterioration rate of cement-based grout caused by acid deposition in the laboratory. The experimental results showed that the dissolved amount of calcium ion had a linear relationship with lnT and the pH value, with better accuracy when the pH value was greater than 3.0. This work maybe could provide a facile and quantitative method to help us predict the service life of cement-based grouting material under acid rain attack outdoors.