Excellent Weather Resistance Research Articles

A durable self-cleaning superhydrophobic coating fabricated using the preset grid-spraying method

Herein, a new durable superhydrophobic coating was prepared using the preset grid-spraying method which was low cost and simple. To achieve the regular continuous grid structure which had protection and support function to the coatings, the sieve mesh was preset on the substrate with hot pressing process. After spraying the superhydrophobic coating on the substrate of the preset mesh followed by curing, a superhydrophobic coating was obtained. The surface morphology of the superhydrophobic coating prepared using the preset grid-spraying method was primarily composed of the regular grid structure and island-like structure with the micro-nano scale rough structure on them. Compared with the superhydrophobic coating prepared with the traditional spraying method, the mechanical stability of the superhydrophobic coating, which was prepared using the preset grid-spraying method, was considerably higher along with good hydrophobic properties. The superhydrophobic coating demonstrated superhydrophobic properties after 170 cycles of the sandpaper abrasion test, which was about 300 % higher than the traditional superhydrophobic coating. Furthermore, the superhydrophobic coating prepared using the preset grid-spraying method had excellent self-cleaning performance and weather resistance. Self-cleaning efficiencies of this superhydrophobic coatings on kaolin and sand were 99.2 % and 98.9 %, respectively. Even after 170 cycles of the sandpaper abrasion test, the self-cleaning efficiency of superhydrophobic coatings on kaolin and sand remained over 85 % and 90 %, respectively. The coated surface still showed superhydrophobic properties after 30 days of the outdoor placement experiment. Showing excellent comprehensive properties and low cost, the superhydrophobic coating prepared using the preset grid-spraying method had a board application prospect.

Preparation and study of polyvinylidene fluoride film with high UV aging resistance

Abstract Polyvinylidene fluoride materials were widely used in the preparation of solar panel films due to their excellent weather resistance and heat resistance. In this work, Polyvinylidene fluoride films with UV absorbers (PF/UV films) were prepared by customized extrusion equipment. The properties of these films were demonstrated with a scanning electron microscope (SEM), water contact angle (WCA), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), and tensile strength tester. Furthermore, the SEM observation suggested that PF/UV films had smooth surfaces without significant defects. The WCA results illustrated that PF/UV films had better hydrophobicity than polyvinylidene fluoride films. The TGA and DSC curves indicated that the initial decomposition temperature and the melting temperature of the PF/UV film were 365.1°C and 169.2°C, respectively. Furthermore, the results of UV transmittance indicated that the UV aging resistances of PF/UV film were higher than that of polyvinylidene fluoride film.

Micro-injection molding applied to production of optical products-example of lens

Abstract Injection moulding is essential for the mass production of plastic products. This study focuses on the application of micro-injection moulding to produce optical products using self-designed moulds and core structure processing techniques. The chosen material for injection is acrylic PMMA, renowned for its excellent finish, weather resistance, heat resistance, transparency, and gloss. Post-injection, the products were evaluated for their optical properties. The TRIZ analysis provided insights into problem-solving directions and cost reduction strategies. The implementation of a one-mould, four-cavity design enabled mass production, significantly enhancing production efficiency.

Wet Spinning/UV Dual-Curing enabled 3D printable fiber for intelligent electronic devices

Conductive fibers are widely used in wearable sensors and implantable devices in real life due to their excellent properties of softness and lightweight. However, most conductive fibers obtained through the simple blending of polymer elastomers and inorganic conductive particles often leads to issues such as uneven conductor distribution and poor mechanical performance. Herein, the composite fiber consists of deep eutectic solvents (composed of choline chloride and 2-hydroxyethyl methacrylate) and thermoplastic polyurethane was prepared by wet spinning/ ultraviolet dual-curing method. The uniform distribution of deep eutectic solvents and the resilience of thermoplastic polyurethane ensure that the fiber material can maintain stable signal monitoring capability when subject to various strains over the long term. The composite fiber as motion sensor with an ultra-wide operating range (0–710 %), fast response time (186 ms), long lifetime (stable after 5 months), wide temperature range and excellent weather resistance. It is worth mention that the dual curing process combined with 3D printing technology, allows for the fabrication of flexible sensors in a variety of shapes. 3D printing sensors can be produced underwater to achieve different sensitivities, enabling customization to meet the requirements of applications. This innovative study holds tremendous potential for the next generation of flexible electronic products, such as human motion monitoring and information transmission.

Design of ZnS nanospheres antireflective structure for mid and far infrared applications

Developing high-performance mid and far infrared antireflection films is a significant requirement in the field of infrared optics. This study successfully prepared AR films composed of ZnS nanospheres for mid and far infrared bands using a combination of hydrothermal and sol-gel methods. Initially, ZnS nanospheres with uniform size and good monodispersity were synthesized via the hydrothermal method and subsequently coated on CdSe substrate through dip coating. The refractive index of the ZnS film is adjusted between 1.36 and 1.52. A significant AR effect was observed in ZnS nanospheres film on CdSe substrate at 3–5 μm and 8–14 μm, and the reflectance is approximately 3 % which is about 25 % lower than that of the uncoated sample. Upon coating with a TiO2 protective layer, the reflectivity further decreased to about 0.6 % and the film demonstrated excellent weather resistance and mechanical properties. This work provides a novel approach for the preparation and regulation of mid and far infrared AR film, significantly contributing to the development of optical film.

Evaluating the efficiency of functionalized zinc oxide based curing system for polychloroprene composites and analyzing its effect on curing, physical, and morphological properties for the application in specialty power transmission belts

Polychloroprene rubber (CR) is one of the most abundantly used elastomer in power transmission belt section due to its excellent oil resistance, weather resistance, antistatic and dynamic properties. However, due to the negative impact of Zinc Oxide (ZnO) used with CR rubber towards marine environment, it is necessary to minimize the use of ZnO in CR based rubber compounds. Functionalized-ZnO(F–ZnO) being emerged as a suitable replacement for regular ZnO in rubber compounding, the effect of F–ZnO on the curing, mechanical and morphological properties of polychloroprene (CR) based composites to use in power transmission belt applications are evaluated in this work. The curing properties of F–ZnO based composites were characterized using various techniques and results were reported as a comparison with the properties of conventional ZnO (C– ZnO) based CR composites. Properties of various ZnO were analyzed using X-ray Diffraction (XRD) analysis and Field-Emission Scanning Electron Microscopy (FESEM) studies. The replacement of C–ZnO with F–ZnO help to reduce 80 % of Zn content from the end products without effecting the cure time and cross-link density of the same. 5 PHR of C– ZnO from regular compound is replaced with 1 and 3 Phr of F–ZnO and its effect on power transmission belt properties were analyzed thoroughly.

High‐strength, recyclable and healable polyurea/aramid fiber elastomeric composites

AbstractThe demanding and rigorous modern work environments present significant challenges to the protective capabilities of engineering materials. Polyurea elastomers often face limitations in terms of inadequate strength and a lack of weather resistance, however, polyurea composites holds great promise in addressing these issues. This study prepared modified ultrafine aramid short fibers using a mechanochemical method. Subsequently, in‐situ polymerization was utilized to combine the modified ultrafine aramid short fibers (M‐AF) with polyurea, resulting in the synthesis of a composite material characterized by recyclability, robust weather resistance, and favorable mechanical properties. Subsequently, intensive researches were conducted on the mechanical properties, recyclability, self‐healing performance, weather resistance, and chemical medium resistance of the composites. The composite at 0.1 wt% of M‐AF exhibited improvements in tensile strength (27.2 ± 0.8 MPa) as well as obviously enhanced impact performance (428.8 ± 6 kJ/m2), and recovered most of its mechanical properties after recycling and self‐healing. Moreover, the composite exhibits excellent weather resistance and chemical resistance, enabling it to uphold its exceptional protective performance even in the face of challenging environments.Highlights Ultrafine aramid fibers were prepared using a simple mechanochemical method. Mechanochemical methods were employed to surface modify aramid fibers. The composites have good strength, recyclability, weather resistance.

Enhancing weatherability and mechanical properties of tung oil wood finishes through natural rubber modification via the Diels-Alder reaction

Tung oil is commonly utilized for coating protection in wooden products, often attracting attention for its appearance, antimicrobial capabilities, and insect-resistant coatings. However, its poor mechanical properties and poor weather resistance stem from excessive self-crosslinking of surplus conjugated double bonds and molecular chains, resulting in poor film wrinkling. Therefore, this study introduces natural rubber via the Diels-Alder reaction to consume the residual double bonds in tung oil, resulting in tung oil/natural rubber composite coatings (NRTO) with excellent mechanical properties and weather resistance. The results indicate that NRTO exhibits excellent mechanical properties, including high elongation (32 %) and strong adhesion (4.55 MPa). Furthermore, NRTO demonstrates outstanding acid resistance and UV aging resistance. Given its many benefits, NRTO film emerges as a promising candidate for substantially protecting wood surfaces in demanding environments.

Facile Preparation of Impalement Resistant, Mechanically Robust and Weather Resistant Photothermal Superhydrophobic Coatings for Anti-/De-icing.

Photothermal superhydrophobic coatings hold great promise in addressing the limitations of conventional superhydrophobic anti-icing coatings. However, developing such coatings with excellent impalement resistance, mechanical robustness and weather resistance remains a significant challenge. Here, we report facile preparation of robust photothermal superhydrophobic coatings with all the above advantages. The coatings were prepared by spraying a dispersion consisting of fluorinated silica nanoparticles, a silicone-modified polyester adhesive and photothermal carbon black nanoparticles onto Al alloy plates followed by thermal curing. Thermal curing caused migration of perfluorodecyl polysiloxane from within the coatings to the surface, effectively maintaining a low surface energy despite the presence of the adhesive. Therefore, combined with the hierarchical micro-/nanostructure, dense yet rough nanostructure, adhesion of the adhesive and chemically inert components, the coatings exhibited remarkable superhydrophobicity, impalement resistance, mechanical robustness and weather resistance. Furthermore, the coatings demonstrated excellent photothermal effect even in the -10 °C, 80 % relative humidity and weak sunlight (0.2 sun) environment. Consequently, the coatings showed excellent passive anti-icing and active de-icing performance. Moreover, the coatings have good generalizability and scalability. We are confident that this study will accelerate the practical implementation of photothermal superhydrophobic coatings.

High‐performance ZSR/P(MMA/BA) composites with enhanced thermal and excellent water resistance properties

AbstractAcrylate had developed rapidly because of its excellent chemical resistance, high‐gloss surface, and weather resistance. However, the poor heat resistance of acrylate limited its application in coatings. To overcome this problem, an organic–inorganic hybrid polymer of zirconium silicone resin (ZSR)‐modified acrylate has been successfully synthesized by solution polymerization. The results indicated that the heat resistance of acrylate was significantly improved due to the SiOSi and SiOZr structures of ZSR and the increased cross‐linking density induced by ZSR. After the incorporation of ZSR, the decomposition temperatures of 5% of acrylate increased from 300.4 and 349.2°C. The performance of the ZSR/(P(MMA/BA)) showed no significant change in uniformly heating at 200°C for 24 h. The composite films showed hydrophobicity, with the contact angles increasing to more than 90°. The S4 sample displayed the outstanding comprehensive performance, that is, 5% weight loss at 341.3°C, water contact angle of 97.9°, elongation at break of 852%, and tensile strength of 9.9 MPa. The high‐performance heat resistant coating is a promising material for application in architecture, decoration, and mechanical equipment.

Assessment of color and contact angle changes in waterborne stained wood under natural weathering condition of South Korea’s summer climate

This study aimed to develop a waterborne stain (WBS) that protects against weathering and increases resistance of wood to fungi when exposed to heavy rainfall. The WBS was prepared using an antibacterial agent, insect repellent, and copper nanoparticle solution (CN) as a surface coating agent. The WBS was applied on larch and hemlock wood, and changes in color and wettability due to natural and artificial weathering were evaluated. A gray-blue spot developed on the untreated wood surface within 30 d of outdoor exposure, which then spread over the entire wood surface, and the wood eventually turned black. Resistance to fungi increased when CN alone was applied; however, the CN surface was oxidized and turned gray after 30 d and 90 d for larch and hemlock, respectively. The water contact angle was increased due to leaching. The application of CN followed by WBS prevented wood discoloration under ultraviolet light and the wood showed excellent weathering resistance capacity. The prevention of wood discoloration and resistance to fungi by CN were confirmed, which could guide the development of a paint that can prolong protection from weathering of wood exposed to heavy rainfall events.

In-situ synthesis and performance evaluation of novel color coatings for galvanized steel

Traditional hot-dip galvanized coatings, typically single-silver in color, present increasing aesthetic challenges in diverse applications, while prevailing organic coating methods involve complex processes with high energy consumption and pollution emissions. In this study, a novel hot-dip process for in-situ synthesis of color coating on steel was proposed, capable of producing various uniform color coating. The microstructure of color coatings on steel was systematically examined, and an assessment of their corrosion and weather resistance was conducted. The results demonstrate the sequence of typical color variation is gold, purple, blue, cyan, red, green, and grey. By controlling the immersion temperature range, and regulating the final stable color of the oxide film. The coloration mechanism mainly is attributed to the light interference on the Mn oxide film. The cyan and brown coatings mainly consist of the dense rod-like ζ-FeZn13 phases which provide a structural foundation for corrosion resistance. Furthermore, the brown coating exhibited excellent weather resistance.

Experimental study on strength, durability, hydraulic and toxicity characteristics of soil treated with mine tailings based geopolymers for sustainable road subgrade application

This article explores the utilization potential of three distinct mine tailings (MT) viz.; red mud (RM), iron tailings (FeT), and zinc tailings (ZT) as geopolymer binders to stabilize the soil for road subgrade application. The strength and durability of soil treated with various MT-based geopolymers are examined through a succession of unconfined compressive strength (UCS), California bearing ratio (CBR) and alternate wetting-drying tests respectively. Furthermore, permeability tests are also conducted to examine the hydraulic response of soil amended with MT-based geopolymers. Finally, leaching study is performed to examine the geo-environmental implications of various geopolymer specimens. The experimental results reveal that the UCS of untreated soil is increased from 0.39 MPa to 5.24 MPa, 5.13 MPa and 3.78 MPa with the use of RM, FeT, and ZT-based geopolymers respectively. The study further shows a 26-fold, 19-fold, and 15.8-fold increase in the soaked CBR values of soil when it is stabilized with RM, FeT, and ZT-based geopolymers respectively. In contrast to untreated soil, soil stabilized with MT-based geopolymers exhibit excellent weathering resistance to alternate wetting-drying cycles showcasing its exceptional durability under challenging environmental conditions. Irrespective of the MT content, curing environment, and the alkali activator concentrations, soil treated with MT-based geopolymers is found to satisfy both the strength (i.e. UCS = 0.75–1.5 MPa and CBR > 5%) as well as durability criteria (i.e. % loss in mass < 10%) specified by Indian Road Congress for subgrade soil. Moreover, the leaching study shows the concentrations of toxic elements (Zn, Cd, Fe, Pb, Ni etc.) to be within the permissible limits specified by USEPA thereby dispelling any environmental concerns associated with the use of MT-based geopolymers.

Mg-Al layered double hydroxides film coating for efficient biomimetic stealth

Most biomimetic stealth materials have difficulty in achieving the “homochromatic and homospectral” of green vegetation and therefore have low spectral similarity to green vegetation and are easily detected and identified by hyperspectral imaging techniques. Hence, there is an urgent need to develop “homochromatic and homospectral” bionic materials for the hyperspectral stealth. Based on the generation mechanism of spectral curves of green vegetation in the 400–2500 nm band, environmentally friendly functional fillers with excellent weather resistance and stealth coatings with Mg-Al layered double hydroxide films were prepared. The cosine value of the near-infrared spectrum of stealth coatings and plant leaves reached 0.997, achieving the “same color and spectrum” as the green vegetation. The spectral cosine values of the 30 days outdoor stealth coatings and green leaves can still reach 0.984, demonstrating excellent weather resistance. These stealth coatings provide new insights into the application of hyperspectral materials in biomimetic camouflage.

Molecular design and properties of a P‐N synergistic flame retardant epoxy resin curing agent

AbstractThe utilization of epoxy resin (EP) is widespread across various industries. Nevertheless, its combustibility restricts its broader utilization. Additive flame retardants have proven effective in enhancing EP flame retardancy in recent decades. However, poor weather and aging resistance have always been the defects of added flame retardants. A reactive flame retardant (VPD) was synthesized from 3, 5‐diamino‐1, 2, 4‐triazole and phenylphosphonic dichloride, and was used to prepare VPD/EP flame retardant epoxy thermosets. The mechanical properties of the VPD/EP flame retardant epoxy thermosets are lower than those of pure epoxy, because the distance between molecules of VPD is increased compared with that of DDM, the cross‐linking density of the polymer after curing is decreased, and the intermolecular force is reduced. The VPD/EP flame retardant epoxy thermosets have a 40% reduction in total heat release compared to pure EP, an increase in limiting oxygen index value from 24.7% (pure EP) to 29.4%, and a V‐1 rating in UL‐94 testing. The obtained EP has not only good flame retardancy but also better weather resistance and aging resistance than additive flame retardants.Highlights An intrinsic flame‐retardant P and N coacting EP was designed and synthesized. The intrinsic flame‐retardant EP has excellent weather and aging resistance. The presence of the P, the residual char generated by combustion is denser.

Phosphorus-based flame retardant acrylic pressure sensitive adhesives with superior peel strength and transfer characteristics

Acrylic pressure sensitive adhesives (PSAs) are widely utilized in various fields due to their excellent thermal, weather, and oil resistance. However, due to their flammability, they are vulnerable to fire, which brings a critical challenge for their application in various industries. Here, new phosphorus-based acrylic PSAs which show excellent flame retardancy are demonstrated, without sacrificing adhesion properties. By controlling the monomer composition based on five different monomers, we synthesized seven acrylic copolymers for PSAs, and investigated the correlation between monomer composition and adhesion characteristics in terms of peel strength and transfer characteristics. Among seven polymers, A5H5 which exhibits the highest peel strength (1117 gf/in.) and superior transfer characteristics (transfer area 8.30 %) is selected for further investigation. The phosphorous-based acrylic PSAs are prepared through addition of different amounts of dimethyl methylphosphonate in A5H5 polymeric matrix, and thoroughly investigated in terms of flame retardancy and adhesion characteristics in terms of peel strength and transfer characteristics. The phosphorus-based PSA (A5H5-D30) exhibited superior flame retardancy of V-0 rating under the UL-94 characterization method. Furthermore, the A5H5-D30 present excellent film transfer characteristic showing a transfer area of 0 % and residue of 0 wt% in air without massive decrease in peel strength (991 gf/in.).

Bio-inspired “rigid and flexible” structure design for robust superhydrophobic composite and its application

The mechano-chemical-physical robustness is essential for the practical applications of a superhydrophobic coating. However, the superhydrophobic coatings obtained following general design principles hold inherent vulnerability. In this work, inspired by the pangolins’ combination of the rigid armour and the flexible flesh, we propose a new universal “rigid and flexible” design strategy for preparing a superhydrophobic coating with intrinsic mechano-chemical-physical robustness by introducing both rigid and flexible components. As a proof-of-concept, a robust superhydrophobic “rigid and flexible” coating is fabricated using rigid corundum particles and flexible rubber particles. In our design, the rigid component (i.e. corundum particles) provides the protection for the entire structure from mechanical wear, while the flexible component (i.e. rubber particles) endows the structure excellent deformability to eliminate stress under impact, thus having a synergistical advantage in adapting to various mechanical destructions. The as-obtained superhydrophobic “rigid and flexible” coating show superior mechano-chemical-physical robustness against various harsh conditions including 1200 cycles of 2 Kg (40 KPa) linear abrasion, tape-peeling, knife-scratching, water-jetting and chemical corrosion. In addition, the “rigid and flexible” superhydrophobic coating exhibits an excellent weathering resistance and anti-icing properties. Our “rigid and flexible” design strategy will provide a new insight for the development of robust superhydrophobic materials and broaden its application scenarios.

Effect of UV Exposure on the Mechanical Properties of Polyurethane-Coated Fabrics

Polyurethane materials can be used industrially in different ways, some of which can be used as textile materials or as auxiliary materials applied to textile materials. Polyurethane stands out as a widely used polymer for coating textile products used in outdoor applications, because of high stability at low temperature, flexibility, no or very little volatile organic component content, high water resistance, pH stability, excellent solvent resistance, weather resistance, and many other chemical and mechanical properties. In the study, cotton, polyester, and viscose fabrics were coated with polyurethane and aged under UV light to investigate the causes and behaviors of the mechanical degradation effects of UV on the coating material and fiber. The results indicate that the PU coating process improves the mechanical properties of textile materials while being exposed to UV rays deteriorates the fabric structure. The deterioration in the structure of raw and coated fabrics with the effect of UV increased the air permeability. According to the results of DSC analysis, the increase in the time of UV exposure did not create significant differences in terms of thermal degradation temperatures in both cotton and viscose fabrics. The glass transition temperatures (Tg) increase with more exposure to UV rays, and the UV exposure time had a negative effect on the melting temperature (Tm) and enthalpy (ΔH) of coated polyester fabrics.

Durable superhydrophobic coatings for prevention of rain attenuation of 5G/weather radomes

Superhydrophobic coatings are expected to solve the rain attenuation issue of 5G radomes. However, it is very challenging to design and construct such superhydrophobic coatings with good impalement resistance, mechanical robustness, and weather resistance, which remains as one of the main bottlenecks hindering their practical applications. Here, we report the design of superhydrophobic coatings with all these merits mentioned above by spray-coating a suspension of adhesive/fluorinated silica core/shell microspheres onto substrates. The core/shell microspheres are formed by phase separation of the adhesive and adhesion between the adhesive and fluorinated silica nanoparticles. The coatings have an approximately isotropic three-tier hierarchical micro-/micro-/nanostructure, a dense but rough surface at the nanoscale, and chemically inert composition with low surface energy. Consequently, the coatings show excellent impalement resistance, mechanical robustness and weather resistance compared with previous studies, and the mechanisms are revealed. Furthermore, we realize large-scale preparation, extension, and practical application of the coatings for efficiently preventing rain attenuation of 5G/weather radomes. By taking these advantages, we believe that the superhydrophobic coatings have great application potential and market prospect. The findings here will boost preparation and real-world applications of superhydrophobic coatings.

Effect of barium strontium titanate modification on the dielectric-breakdown properties of phenyl-vinyl binary composite silicone rubber

Silicone rubber has been widely used in electric power equipment for its excellent insulation performance and weather resistance. However, the weak breakdown characteristic of silicone rubber limits its application in high-voltage grade power equipment. In this paper, the nano-modification system of silicone rubber based on a binary composite matrix of “phenyl-vinyl” was constructed. On the one hand, the benzene ring structure is introduced to improve the breakdown strength of the matrix. On the other hand, barium strontium titanate (BST) is used to improve the permittivity of composite, reducing the electric field shared by silicone rubber. The experimental results show using binary composite silicone rubber as the matrix, the appropriate amount of BST filling can greatly improve the permittivity of the composite. When the BST content is 30 wt%, the permittivity of the binary composite reaches the maximum value of 3.98, which is about 49.06% higher than that of vinyl silicone rubber. Accordingly, the electric field strength shared by silicone rubber insulation will decrease significantly. Meanwhile, the moderate amount of BST in the matrix can improve the breakdown strength. This work is an important guideline for the performance improvement of silicone rubber for high-voltage power equipment.