Aging Resistance Research Articles

Laboratory Evaluation of Short- and Long-Term Aging Resistance of Rejuvenated RAP Mixtures

Laboratory Evaluation of Short- and Long-Term Aging Resistance of Rejuvenated RAP Mixtures

Confined‐Synthesis of Ceria in Tubular Nanoclays for UV Protection and Anti‐Biofilm Application

AbstractUV radiation is the main cause of skin aging and cancers. Commercial sunscreens suffer from low efficacy and poor safety, while ceria nanocrystals are promising inorganic UV filters. Herein, the lumen of natural halloysite clay nanotubes (HNTs) is employed for the confined growth of ceria nanocrystals, which can effectively tailor the particle size, morphology, distribution, and oxygen vacancies of the ceria. The ceria in HNTs lumen exhibits increased UV protection and catalytic activity, while the outer surfaces of HNTs can be retained for additional modification. Ceria‐loaded HNTs (named CeOx@HNTs) can act as oil–water interfacial stabilizers to develop skin‐friendly Pickering emulsion sunscreens. Attributed to the Pickering emulsion interfacial catalytic effect of CeOx@HNTs, the UV absorption performance of the sunscreens is enhanced by 3.1 times after emulsification, achieving a sun protection factor of 58.5. In vitro and in vivo studies confirm the effectiveness of the prepared sunscreen in mitigating DNA damage, apoptosis, and malignant transformation. In addition, the sunscreen inhibits biofilm formation by disturbing membrane homeostasis through oxidative stress. This work develops a confined‐growth method of rare earth oxides within tubular nanoclays, which shows promising applications in many fields, such as aging resistance, photoluminescence, and chemical catalysis.

Evaluation of diffuse reflectance spectroscopy for predicting age, species, and cuticular resistance of Anopheles gambiae s.l under laboratory conditions

Mid-infrared spectroscopy (MIRS) combined with machine learning analysis has shown potential for quick and efficient identification of mosquito species and age groups. However, current technology to collect spectra is destructive to the sample and does not allow targeting specific tissues of the mosquito, limiting the identification of other important biological traits such as insecticide resistance. Here, we assessed the use of a non-destructive approach of MIRS for vector surveillance, micro diffuse reflectance spectroscopy (µDRIFT) using mosquito legs to identify species, age and cuticular insecticide resistance within the Anopheles gambiae s.l. complex. These mosquitoes are the major vectors of malaria in Africa and the focus on surveillance in malaria control programs. Legs required significantly less scanning time and showed more spectral consistence compared to other mosquito tissues. Machine learning models were able to identify An. gambiae and An. coluzzii with an accuracy of 0.73, two ages groups (3 and 10 days old) with 0.77 accuracy and we obtained accuracy of 0.75 when identifying cuticular insecticide resistance. Our results highlight the potential of different mosquito tissues and µDRIFT as tools for biological trait identification on mosquitoes that transmit malaria. These results can guide new ways of identifying mosquito traits which can help the creation of innovative surveillance programs by adapting new technology into mosquito surveillance and control tools.

Development of Flexible Rare Earth–Fe–B Rubber Magnets toward Efficient Utilization of Ce, La, and Y Elements

The microstructure, magnetic properties, corrosion and aging resistance, and mechanical properties of Nd–Fe–B, (Nd, La, Ce)–Fe–B, and (Ce, La, Y)–Fe–B rubber magnets have been investigated. For Nd–Fe–B magnets, increasing particle size and filling ratio of magnetic particles not only improves the overall magnetic properties but also increases the tensile strength. Using the Nd26.4Fe67.6Co5B powder with particle size of 75–106 μm and filling ratio of 90%, the optimum magnetic properties with the coercivity Hcj = 738.2 kA m−1, remanence Jr = 0.51 T, and maximum energy product (BH)max = 43.5 kJ m−3 are obtained. The magnet also exhibits an enhanced tensile strength of 4.52 MPa owing to its compact and uniform microstructure. In addition, the magnetic properties of Hcj = 518 kA m−1, Jr = 0.34 T, and (BH)max = 20.6 kJ m−3 are obtained in the partial high‐abundance (Nd, La, Ce)–Fe–B rubber magnet, which is superior to some of commercial Nd–Fe–B rubber magnets. For full high‐abundance (Ce, La, Y)–Fe–B magnet, these values are 320 kA m−1, 0.27 T, and 10.5 kJ m−3, respectively. Despite its lower magnetic properties than Nd‐based rubber magnets, (Ce, La, Y)–Fe–B rubber magnet exhibits a competitive advantage over the Nd‐containing magnets in terms of corrosion resistance and aging resistance performance. Moreover, (Ce, La, Y)–Fe–B magnet shows a tensile strength of 7.86 MPa, which is nearly 74.2% and 56.8% higher than the Nd–Fe–B and (Nd, La, Ce)–Fe–B rubber magnets. The present results indicate that the Ce, La, and Y elements can be reasonably selected to manufacture flexible rare earths–Fe–B rubber magnets with a high performance/cost ratio and good performance stability.

Improving anti-aging performance of terminal blend rubberized bitumen by using graft activated crumb rubber

Abstract The appearance of terminal blend rubberized bitumen (TB) has improved a series of defects of traditional rubber bitumen, such as high viscosity, poor storage stability. Therefore, its wide application prospect is self-evident. However, different degrees of thermal-oxidative aging problem still exist in the process from production to use of TB, which seriously affects the service life of pavement. To improve the anti-aging performance of TB, grafting activated crumb rubber (GACR) was obtained by using acrylamide, and then compounded with TB. Firstly, TB was prepared in the self-developed nitrogen protection device. Secondly, GACR modified bitumen (GACR-MB), TB/CR composite modified bitumen (TB/CR) and TB/GACR composite modified bitumen (TB/GACR) were developed in the atmospheric environment. Finally, the performance of four kinds of crumb rubber modified bitumens before and after aging was compared and analyzed by testing high and low temperature rheological properties. The results show that GACR slowed down the formation rate and aggregation degree of asphaltenes and other macromolecular substances, and TB/GACR showed excellent aging resistance.

Minor additions of Sn suppress the omega phase formation in beta titanium alloys

A critical characteristic of β-Ti alloys is the inevitable formation of ω-precipitates during certain heat treatments which leads to embrittlement, or even to a complete loss of ductility. Therefore, alloy design with the goal to inhibit the elementary ω-formation process is of utmost importance. Here, we propose a design strategy for prototypical β-type Ti–Cr–(Mo) alloys to alleviate this problem using only minor additions of Sn. Upon addition of Sn, we observed an extensive deceleration or even suppression of the ω-formation kinetics during isothermal ageing. Furthermore, the internal friction response of the elementary formation process indicated a decisive reduction of potential ω-nucleation sites, while the activation energy of the process remained almost unchanged. The results show, that the addition of Sn can significantly increase the width of the time–temperature process window and the long-time ageing resistance of β-Ti alloys, opening up huge opportunities for advanced alloy design and manufacturing routes.

Physical, Rheological, and Anti-Ultraviolet Aging Performance of Layered Double Hydroxides + Styrene Block Copolymer-Modified Asphalt Binders

To determine the preparation parameters of layered double hydroxides (LDHs) + styrene butadiene styrene block copolymer (SBS)-modified asphalt binders (MABs) in engineering applications and identify the structure of LDHs used in asphalt modification, this paper investigated the physical, rheological, and UV aging resistance of LDHs + SBS MABs under various preparation parameters. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and an ultraviolet-visible spectrophotometer (UV-vis) were used to characterize the structure and UV resistance of LDHs and D-LDHs (dissolving from LDHs + SBS MABs). The mechanical properties of LDHs + SBS MABs were studied based on penetration, ductility, softening point, and rotational viscosity tests. The rheological performance and UV aging resistance of LDHs + SBS MABs were assessed using the bending beam rheometer (BBR) test, direct tensile test (DTT), dynamic shear rheometer (DSR) test, and FTIR. The results demonstrated that the crystal and chemical structures of LDHs remain unchanged before and after use in asphalt modification. The optimal preparation parameters of LDHs + SBS MABs were as follows: a preparation temperature of 170 °C, a shearing time of 60 min, and a shearing rate of 4000 r/min. The high-temperature performance of LDHs + SBS MABs improved significantly with LDHs added, and the low-temperature performance slightly decreased. The viscosity of LDHs + SBS MABs with 4 wt% LDHs at 135 °C was 1.920 Pa·s, which was 47.4% higher than that of SBS MABs. The DTT results indicated that SBS MABs have the highest fracture energy (FE) value of 4873 J/m2, showing the best low-temperature cracking resistance. In comparison, the FE values of MABs doped with 3 wt% and 4 wt% LDHs are 4518 J/m2 and 4248 J/m2, respectively, just 7.3% and 12.8% lower than that of ABs without LDHs. The complex modulus aging index (CMAI) of MABs doped with 4% LDHs is 14.3%, which is 15.9% lower than that of SBS MABs, indicating that the anti-ultraviolet aging performance of LDHs + SBS MABs has been improved. FTIR analysis demonstrated that the relative content of C=O (RCC) and S=O (RCS) of LDHs + SBS MABs decreased drastically compared with SBS MABs, indicating that the UV aging resistance of LDHs + SBS MABs was largely enhanced. Furthermore, the segregation test result of 3wt% LDHs + SBS-modified asphalt is 0.3 °C, showing the best compatibility with asphalt.

Multifactorial Aspects of Adiponectin in Non- Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a significant worldwide health issue strongly associated with obesity and metabolic syndrome. It underscores the critical role of adiponectin, a significant adipokine, in the disease's intricate progression. NAFLD's complexity stems from its interplay with factors like obesity, diabetes, and metabolic syndrome, with reduced adiponectin levels commonly observed in NAFLD patients, influenced by age, gender, lipid profiles, and insulin resistance. Adiponectin's versatility in mitigating insulin resistance, inflammation, and liver fibrosis makes it a focal point in NAFLD research, while recent studies introduce spexin, a neuropeptide, as a potential correlate, adding to the understanding of metabolic disorders. To tailor treatment approaches, recognizing the factors affecting adiponectin levels, such as genetics, lifestyle, and comorbidities, is crucial. Lifestyle changes and specific medications offer promise in improving NAFLD outcomes by modulating adiponectin. The article underscores adiponectin's central role in the complex NAFLD landscape and the need for further research to fully grasp its mechanisms and therapeutic potential in managing this prevalent liver disease, emphasizing the importance of rebalancing adipokines and enhancing metabolic health.

Synergistic effect of surface modified nano-zinc oxide and organic vermiculite on long-term ultraviolet and thermal-oxidative aging resistance of different asphalt binders

Asphalt pavement will be subjected to the action of thermal, oxygen and ultraviolet during long-term service, which in turn causes the ultraviolet and thermal-oxidative aging of asphalt simultaneously. Based on the long-term aging mechanism, the double retarding effect of surface modified nano-zinc oxide (ZnO) and organic vermiculite (OEVMT) in different stages of long-term aging was utilized in the research. This work investigated the synergistic effect of ZnO and OEVMT on rheological properties and chemical structures of base asphalts (70# and SK-70) and polymer modified asphalts (SBS modified asphalt and SBR modified asphalt) after long-term ultraviolet and thermal-oxidative aging. Dynamic shear rheological (DSR), bending beam rheological (BBR) and Fourier infrared spectroscopy tests were utilized to study the DSR properties, BBR properties at low temperature and chemical structures, respectively. Meanwhile, the synergistic effect mechanism was analyzed. Results showed that the effect of 1 % ZnO to resist the long-term ultraviolet aging of 70# base asphalt approximates that of 3 % OEVMT, while the long-term thermal-oxidative anti-aging ability of 1 % OEVMT for 70# base asphalt is equivalent to that of 3 % ZnO. Besides, compared with 2 % ZnO or 2 % OEVMT, 1 % ZnO + 1 % OEVMT shows a better long-term ultraviolet and thermal-oxidative aging resistance for different asphalt binders, indicating its synergistic effect in strengthening the anti-aging performance of asphalt. Moreover, 1 % ZnO + 1 % OEVMT not only can effectively retard the oxidation rate of asphalt in the process of long-term aging, but also inhibit the degradation degree of modifiers in SBS modified asphalt. The research could propose a new design idea to effectively solve the long-term aging problem of asphalt.

Effect of silica filler on peroxide cured ethylene propylene diene terpolymer insulation for large rocket motors

AbstractNon‐compatibility with double base propellant and nitrate ester plasticized polyether based propellant and poor aging resistance limit the overall life of sulfur cured EPDM insulation and warranted the development of peroxide cured EPDM insulation in order to reap the full benefits of EPDM insulation. This article describes the effect of silica filler on the physical, mechanical, thermal, and ablative properties of peroxide cured EPDM insulation, free from chlorosulphonated polyethylene and filled with conventional precipitated silica, which has been validated for the requirements of large composite rocket motor casing. Significant findings, which have been corroborated by instrumental techniques viz. DSC, TGA, FTIR, and SEM are presented in this article.

Preparation and properties of ternary rare earth co-stabilized zirconia ceramics for dental restorations

High fracture toughness and excellent hydrothermal aging resistance are the characteristics required for dental ceramic materials, but the widely used dental ceramic currently (3Y-TZP) does not exhibit. Aiming to solve this problem, a ternary rare earth co-stable zirconia ceramic (1.5Y5.5Ce0.3La-ZrO2) was prepared by a coating method based on a co-doping strategy. The sintering process, densification evolution, mechanical properties, resistance to hydrothermal aging and biocompatibility of 1.5Y5.5Ce0.3La-ZrO2 ceramic were studied. The results show that 1200 °C is the best pre-sintering temperature, and the machinability and controllability of shrinkage can meet the needs. When the final sintering temperature is 1600 °C, it has the best performance. Compared with 3Y-TZP, the bending strength is about 8.7% higher (912.48 MPa), and the fracture toughness is about 76.6% higher (10.49 MPa m1/2). Furthermore, its resistance to hydrothermal aging is significantly enhanced, greatly extending the service life of the material. The biosafety of 1.5Y5.5Ce0.3La-ZrO2 ceramics was evaluated, and the results showed that the material had no cytotoxicity. To sum up, 1.5Y5.5Ce0.3La-ZrO2 ceramics is a promising dental biomaterial, which has a broad application prospect in oral restoration.

Investigation of aging resistance for dental resin composites with and without glass flakes.

Outstanding physical-mechanical properties and aging resistance are key requirements for dental resin composite since it will be placed in the oral environment for a long time. In this work, a new dental resin composite mainly modified by glass flakes was fabricated, and the aging resistance was evaluated by comparing with commercial composites without glass flakes. The new dental resin composite was produced through hand blending of inorganic glass flakes/Si-Al-borosilicate glass (58wt%:7wt% of dental resin composite), POSS-MA (5wt% of resin matrix), Bis-GMA/TEGDMA(64.4wt%:27.6wt% of resin matrix), and CQ/EDMAB (0.9wt%:2.1wt% of resin matrix) together. The flexural strength, elasticity modulus, and hardness, as well as wear were tested for evaluating the aging resistance of different dental resin composite. Among 6 kinds of commercial composites in this study, after 6-month water storage, the maximum percentage of performance degradation is that the flexural strength decreased 39.96%, elasticity modulus decreased 51.53% and hardness decreased 12.52%. In contrast, the new synthesized material decreased 14.53%, 20.88%, and 0.61%, respectively, and performed lesser wear depth compared to some other groups (P < 0.05). It was observed that the new dental resin composite performed better performance stability and wear resistance when compared with commercial dimethacrylate-based or low shrinkage dental resin composite tested in this study. This possibly paves a path for designing tailored dental composite for practical application. Since the aging resistance of dental resin composite modified by glass flakes is superior, it has the potential to be used for promoting the durability of dental resin composite.

Green synthesized clavate-shaped ZnO modified silk fabric with aging resistance and outstanding antibacterial and UV-shielding properties

Silk, a popular luxury textile with many years of history, is easy to embrittle and adsorb bacteria when stored for a long time or exposed to sunlight, which affects its service life. To improve the silk fabrics with excellent antibacterial activity, washing and aging durability, and UV shielding, multifunctional silk fabrics were designed and fabricated via a green finishing approach. Here, we proposed a simple strategy to fabricate silk fabrics with multi-functions via coating clavate-shaped ZnO nanoparticles (ZF-silk fabrics) by dipping and pressing for cycles. The scanning electron microscope (SEM), fourier transform infrared (FTIR), ultraviolet visible spectrophotometry (UV–Vis), and X-ray diffraction (XRD) were used to analyze the structure and properties of fabricated ZF-silk fabrics. Compared with raw silk fabric, the fabricated ZF-silk fabrics represented excellent UV shielding, good tensile strength, and superior antibacterial activity. Notably, the ZF-silk fabrics had good washing stability and aging resistance. In addition, the ZF-silk fabrics possessed superior antibacterial activity before and after aging treatment (under UV radiation for 72 h). Therefore, the durable and multifunctional ZF-silk fabrics indicate great potential for achieving to realize a long service life of the fabrics.

Construction of transparent PAM/PVA interpenetrating network hydrogel for designing fireproof glass with superior heat insulation and aging resistance

The decorative and fireproof performance degradation of the grouting fireproof glass exposed to UV irradiation limits its application in the fire protection of buildings. To solve this issue, a transparent polyacrylamide/polyvinyl alcohol (PAM/PVA) interpenetrating network hydrogel was designed to prepare grouting fireproof glass with enhanced theheat insulation and anti-aging properties. The results show that the light transmittance of PAM/PVA interpenetrating network hydrogel decreases with the increased content of PVA, and a proper content of PVA in the PAM/PVA interpenetrating network is beneficial to maintain high optical transparency in the resulting hydrogel. Heat insulation test shows that the PAM/PVA interpenetrating network improves the water-locking ability of the resulting hydrogels, and the fireproof glass containing 3 wt% PVA shows the lowest backside temperature of 92.6 °C at 3600 s, which is 51.9% lower than that of fireproof glass with PAM only. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis show that the PAM/PVA interpenetrating network hydrogel improves the thermal stability and charring ability of hydrogel, and the hydrogel containing 3 wt% PVA exhibits the best charring effect among the samples, showing the highest residual yield of 39.2 % at 800 °C. The analyses of decomposition products and char residues show that the PAM/PVA interpenetrating network hydrogel can extend the heat absorption process of water evaporation and improve the gas flame retardant efficiency. Accelerated aging test shows that the presence of PVA greatly slows down the blistering and yellowing phenomenon of fireproof glass, thus endowing the fireproof glass with the super durability of fire resistance. Especially, the backside temperature at 3600 s and light transmittance of the sample containing 2 wt% PVA after 168 h aging test only changed 19.2 °C and 1.9 %, respectively, compared to the those of unaged sample.

A novel method to improve anti-aging properties of SBS modified bitumen by zinc oxide/expanded vermiculite composite: Influence of zinc oxide particle loadings

Styrene-butadiene-styrene copolymer modified bitumen (SBSMB) has been commonly used in pavement construction for its excellent performance. However, during construction and service life, SBSMB is inevitably subjected to thermal-oxidative or ultraviolet aging as a result of factors in the environment like heat, light and oxygen. This study investigated the effects of zinc oxide/expanded vermiculite composite (Z/E) on SBSMB, in particular the effects of Z/E with different zinc oxide (ZnO) particle loadings on SBSMB. And Z/E with different ZnO particle loadings were prepared and characterized by X-ray fluorescence spectrometer, field emission scanning electron microscope, UV–Visible spectrometer and Fourier transform infrared spectrometer tests. To age bitumen samples, thin film oven test, pressure aging vessel and ultraviolet aging tests were used. Eventually, the effects of Z/E with various ZnO particle loadings on the storage stability, physical, rheological and anti-aging properties of SBSMB were investigated. According to the results, Z/E with different ZnO particle loadings are successfully prepared. There are uniform ZnO particles on the surface of expanded vermiculite and ZnO particle loadings are increased with the concentration of the ZnO precursor solution. Furthermore, the high-temperature performance of SBSMB is enhanced, but the low-temperature performance is slightly affected by Z/E. Whatever the aging mode, the introduction of Z/E can obviously reduce the viscosity aging index, softening point increment, complex modulus aging index and increase phase angle aging index of SBSMB, demonstrating that the aging resistance of SBSMB are significantly enhanced. It was determined that SBSMB with 29.5 wt%Z/E had the best aging resistance.

An antistatic agent based on polyionic liquid applied to nylon 6

In order to improve the electrical conductivity of nylon 6 (PA6) and avoid misfires and explosions caused by static charge accumulation, a quaternary ammonium salt polyionic liquid (PIL) antistatic agent was synthesized in this paper. The surface resistance of PA6 was reduced to 108 Ω with the addition of 2 wt% antistatic agent, and the mechanical properties and aging resistance of the substrate were improved. Meanwhile, the morphology and crystallinity of PIL/PA6 composites were further characterized by scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and X-ray diffraction (XRD). It is worth noting that the quaternary ammonium salt polyionic liquid antistatic agent synthesized in this paper has the advantages of excellent antistatic effect, durability, low cost, and simple reaction condition, so it has a broad application prospect in the antistatic aspect of PA6.

Effect of isoindole derivative pigments with planar macroconjugated structure on the UV resistance of HDPE

Different colors of high-density polyethylene (HDPE) natural gas pipelines, water supply pipelines, geomembranes in small communities, garden agriculture, and large factories, play a differentiation, warning, decorative aesthetic, and other aspects of the role. However, little research has been done on HDPE that can be used for long periods and in a variety of colors other than black and white. Phthalocyanine pigments with a large planar conjugate structure are often used in modern artists' paints because of their good stability and are hopeful for use in HDPE. For this reason, in this paper, phthalocyanine blue with a high lightfastness rating was selected. Pure HDPE and HDPE with pigment were compared by color difference, carbonyl index (CI), mechanical properties, and thermomechanical properties before and after UV irradiation. After irradiation for 2000 h, the latter not only did not fade easily but also maintained 82 % elongation at break. At the same time, the carbonyl index was much lower, representing the addition of pigments to inhibit the photo-aging process. Hindered amine light stabilizers (HALS) were also added to the matrix to further improve the ultraviolet (UV) stability along with ultraviolet light absorber (UVA). Addition of HALS and pigments had a positive effect on the UV stability of HDPE, but the excess of HALS had a negative effect on color stability, dispensability and tensile strength. Addition of UVA had little effect on HDPE/Blue/HALS. Finally, the mechanism of the phthalocyanine blue pigment in improving the light aging resistance of HDPE was investigated by ultraviolet spectroscopy. HDPE/Blue/HALS prepared in this work had a low CI and high elongation at break of all formulations at 2000 h of irradiation, indicating that it maintains good performance over a long period of time. The low color change and dispersion uniformity of that under prolonged irradiation met the long-term aesthetic needs of HDPE.

Evaluation of quantum dot composite graphene /Titanium oxide enhanced UV aging resistance modified asphalt

The long-term ultraviolet radiation of asphalt pavement leads to performance degradation, which seriously affects the service life. However, inorganic nanoparticles as anti-ultraviolet aging modifiers can only respond to some ultraviolet light, resulting in not high absorption rate of ultraviolet light. In this study, a variety of nano-quantum dots were introduced to modify graphene/titanium dioxide to further improve the ultraviolet absorption capacity of inorganic nanoparticles and slow down the aging of asphalt pavement caused by ultraviolet light. The effect and mechanism of the special heterojunction structure formed by a variety of quantum dots on the aging resistance and rheological properties of asphalt were investigated. The results show that the introduction of various quantum dots improves the ultraviolet absorption capacity of nano-TiO2. Although the thermal stability of nanographene/titanium dioxide composites decreases, its initial decomposition temperature is much higher than the test temperature of the asphalt mixture. From the macroscopic rheological test, the nano-graphene / titanium dioxide composite material further expands the improvement effect on the high-temperature rheological properties of asphalt, and secondly slows down the low-temperature crack resistance of nano-TiO2 modified asphalt. From the microscopic test, the introduction of various quantum dots greatly reduces the sulfoxide index (SI), carbonyl index (CI) and root mean square roughness Sq of modified asphalt, effectively slowing down the aging effect of ultraviolet light on asphalt, and ensuring the service state of asphalt pavement in a complex environment.

Physicochemical and quantum chemical studies of the thermal-oxidative aging resistance of bitumen modified with isocyanate-based reactive additive

The use of methylene diphenyl diisocyanate (MDI)-based additives to prepare isocyanate-modified bitumen (IMB) provides an effective solution for achieving energy savings and performance improvements. However, the thermal-oxidative aging properties of bitumen modified with isocyanate additive have not been well discussed, which limits the fundamental understanding of its durability-related performance. To promote the understanding of the aging mechanism of IMB, experimental investigations and quantum chemical calculations were conducted to investigate the aging properties of IMB. IMB samples were prepared and aged under controlled laboratory conditions. The evolutions of aging behaviors were examined through physical and chemical approaches. The role of noncovalent intermolecular interactions in delaying oxidation was interpreted through density functional theory (DFT)-based theoretical calculation. The results revealed that amide-related bonds can be generated due to the chemical interactions between isocyanate and bitumen compounds. Chemical reactions tend to reduce the potential sites for oxidative attacks, thereby inducing delayed oxidation of IMB. Consequently, lower chemical and rheological aging indexes can be observed in IMB, and chemical crosslinking can provide effective support for the elastic response after aging. In addition, the noncovalent interactions between isocyanate and bitumen molecules can result in a lower tendency towards oxidation, which provides a cooperative effect on the inhibition of aging. The findings of this study offer insights into the aging behaviors of IMB and provide references for the design of chemically modified bitumen.

Durability improvement mechanism of polymer cement protective coating based on functionalized MXene nanosheets modified polyacrylate emulsion

Polymer cement coatings (PCCs) have a wide range of applications in the field of concrete protection. Excellent durability of the PCCs is extremely essential for protecting the concrete in long-time service life. However, one of the most popular polymer emulsion, polyacrylate based cement coatings show insufficient durability and restrict their wide application in complicated and harsh environment. In this study, the novel two-dimensional nanomaterial MXene was incorporated to PCCs for improving the durability of the PCCs, the MXene was functinalized by vinyl triethylsilane (VTEO) (V-MXene) followed by in-situ seed emulsion polymerization method to synthesize the V-MXene modified polyacrylate emulsion. The effects of V-MXene incorporation on the rheological property, mechanical properties, bonding strength, UV aging resistance, saltwater immersion resistance, thermal aging resistance of PCCs were systematically investigated and the durability improvement mechanism was revealed. When the V-MXene dosage is 0.15 wt%, the tensile strength and bonding strength of the PCCs increased by 28.76 % and 30.84 % as compared with the blank samples, respectively. The introduction of V-MXene to PCCs can remarkably improve the UV aging resistance, saltwater immersion resistance, heat resistance. The V-MXene can decrease the UV radiation energy absorbed into the PCCs, and can create a “labyrinth effect”, prolonging the penetration path of water and corrosion ions. The V-MXene can also enhance the cross-linking density of the polymer phase combined with organic and inorganic interpenetrating networks, thereby enhancing the thermal stability of PCCs. This research provides a feasible strategy for the fabrication of high performance PCCs with excellent durability.