Waterproof Characteristics Research Articles

Enhanced thermal conductivity and electrical insulation by patterned self-assembly of electrospun nanofibers

Low intrinsic thermal conductivity (TC) of polymer materials has severely limited their further applicability in electronic and electrical products. To enhance the TC, a strategy for constructing nanofiller-based thermal conductive networks by patterned self-assembly of electrospun nanofibers was first proposed in this paper. By selecting a regular metal mesh as the collector, the electrostatic field-induced directional deposition of nanofibers was achieved, thereby constructing interconnected heat transfer paths aligned in at least four directions. The in-plane TC of heat-pressed electrospun polyvinylidene fluoride (PVDF) nanofibers with 20 wt% loading of boron nitride nanosheets (BNNSs) can reach 7.27 W/(m·K). Electrical insulation of the PVDF/BNNS composites has also been confirmed, showing high volume resistivity and breakdown strength, which have increased by 460.0 % and 26.6 %, respectively, compared to pure PVDF. Finally, a double-layer composite film with waterproof and easy-cleaning characteristics was prepared for electronic device packaging. This simple and efficient preparation strategy for thermal conductive networks may bring new perspectives to thermal management applications.

Advancements in Electrospun Nanofibrous Membranes for Improved Waterproofing and Breathability

AbstractElectrospun nanofibrous membranes have attracted significant interest due to their captivating waterproof and breathable characteristics, stemming from the presence of interconnected and hydrophobic channels within these enhanced textiles. These distinctive traits bestow upon them substantial potential across various domains, encompassing applications in medical dressings, masks, and protective clothing. However, they also give rise to concerns about their durability, compromised waterproofing performance, limited breathability, insufficient mechanical strength, and high production costs. Furthermore, the manufacturing processes of electrospun waterproof and breathable membranes (WBMs) may carry adverse environmental implications, necessitating improvements in sustainability and ecological compatibility. This study begins with a concise overview of the operational principles and criteria for performance evaluation relevant to electrospun WBMs, providing comprehensive guidelines to drive future research. Following this, the authors delve into a thorough exploration of typical fabrication techniques and the prevailing strategies, exemplified by noteworthy ongoing research initiatives. Last, the existing challenges are outlined to foster the development of WBMs. In addition, future research directions and perspectives are presented to expedite the advancement of WBMs and support their commercial implementation. It is anticipated that this comprehensive review will offer pragmatic recommendations for researchers dedicated to the advancement of WBMs.

Molecular dynamics study of the corrosion protection improvement of superhydrophobic dodecyltrimethoxysilane film on mild steel

Recently, superhydrophobic surfaces have received increasing interest in metal corrosion protection due to their excellent waterproofing characteristics. However, little attention has been paid to the related anti-corrosion mechanism at the molecular level. In this work, the protection behaviors provided by the superhydrophobic dodecyltrimethoxysilane for mild steel were first explored using molecular dynamics (MD) simulation in terms of silane absorption orientations and water cluster wetting behaviors. The results show that the conformations of dodecyltrihydroxysilane (DTHS) on the Fe substrate are greatly dependent on the solvent environment. Typically, the DTHS molecule adopts a “standing” orientation with the hydrophilic head attached to the Fe surface and the hydrophobic tail remaining in the polar phase, which is conducting to generate a good repulsive effect on the water droplet. Based on this, the diffusion performance of corrosive species in the superhydrophobic DTHS film was further investigated. The computational results indicate that the corrosive species are confined to specific regions of the film, which results in a decreased diffusion coefficient. Additionally, the weak movement of DTHS molecules also increases the transport resistance of the corrosive medium through the superhydrophobic DTHS film, thereby improving the corrosion protection of the underlying metal substrate. The results obtained in this work will deepen our understanding of the anticorrosion mechanism of superhydrophobic silane films.

Waterproof Flexible Pressure Sensors Based on Electrostatic Self-Assembled MXene/NH2-CNTs for Motion Monitoring and Electronic Skin.

Flexible wearable sensors to monitor human movement and for electronic skins must exhibit high sensitivity, a wide detection range, and waterproof characteristics. This work reports a flexible, highly sensitive, and waterproof sponge pressure sensor (SMCM). The sensor is made by assembling SiO2 (S), MXene (M), and NH2-CNTs (C) on the backbone of melamine sponge (M). The SMCM sensor exhibits excellent sensitivity (10.8 kPa-1), an ultra-short response/recovery time (40 ms/60 ms), a wide detection range (30 kPa), and an extremely low detection limit (4.6 Pa). Benefiting from layer-by-layer self-assembly, the sensor still exhibits excellent stability after 5000 cycles. In addition, the SMCM sensor also has excellent waterproof performance (a water contact angle of 142°), enabling it to operate unaffectedly under wet conditions. The SMCM sensor can accurately detect small body movements such as pulse and swallowing while also accurately detecting finger and elbow movements. In addition, the sensor can be designed as an array to construct an electronic skin for detecting the magnitude and distribution of external pressure. This work holds great application potential in next-generation electronic skin, fitness detection, and flexible pressure sensors.

Ultra-light-weight, anti-flammable and water-proof cellulosic aerogels for thermal insulation applications

Cellulosic aerogels (CNF) are considered naturally available thermal insulating materials as substitutes for conventional polymeric aerogels owing to their extensive sources, low density, low thermal conductivity, sustainability and biodegradability. However, cellulosic aerogels suffer from high flammability and hygroscopicity. In this work, a novel P/N-containing flame retardant (TPMPAT) was synthesized to modify cellulosic aerogels to improve their anti-flammability. TPMPAT/CNF aerogels were further modified by polydimethylsiloxane (PDMS) to enhance the water-proof characteristics. Although the addition of TPMPAT and/or PDMS slightly increased the density and thermal conductivity of the composite aerogels, those values were still comparable to the commercial polymeric aerogels. Compared with pure CNF aerogel, the cellulose aerogel modified by TPMPAT and/or PDMS had higher T-10%, T-50% and Tmax, which indicated that the modified cellulose aerogels have better thermal stability. TPMPAT modification made CNF aerogels highly hydrophilic, while TPMPAT/CNF aerogel modified by PDMS became a highly hydrophobic material with a water contact angle (WCA) of 142°. Pure CNF aerogel burned rapidly after ignition, showing a low limiting oxygen index (LOI) of 23.0% and no UL-94 grade. In contrast, both TPMPAT/CNF-30% and PDMS-TPMPAT/CNF-30% showed self-extinction behaviors with a UL-94 V-0 grade, implying high fire resistance. Combined with high anti-flammability and hydrophobicity, the ultra-light-weight cellulosic aerogels show great potential for thermal insulation applications.

The Application of Insulation and Decoration Integrated Board in The Construction of High-rise Residential Exterior Walls

Insulation and decoration integrated board is a widely used material in the construction of high-rise residential exterior walls. This material has various advantages, including insulation, waterproofing, fire prevention, environmental protection, and other characteristics, which can improve the overall performance and energy-saving effect of buildings. In addition, the integrated insulation and decoration board has advantages such as easy installation, fast construction speed, and low maintenance costs, which can save construction time and costs. In the construction of high-rise residential exterior walls, the use of insulation and decoration integrated panels can achieve fast, efficient, and safe construction, while ensuring the appearance and decoration effect of the building. Therefore, the application of insulation and decoration integrated panels in the construction of high-rise residential exterior walls has important significance and broad development prospects.

Pre-treatment of natural bamboo for use as a high-performance bio-composites via acetic acid ball milling technology

Bio-composites represent a versatile material with an inescapable solution to the creation of a low-carbon green concept. This research utilised natural Moso bamboo powder as raw material, pre-treated with acetic acid and ball-milling it with different concentrations. Thermal forming was then adopted to synthesise a compact glue-free bio-composite with excellent waterproof and mechanical characteristics. The material obtained better thermal conductivity and stronger mechanical properties after acetic acid ball milling than the untreated bio-composite, and the tensile strength was double that of the untreated bio-composite. It was also found that the water absorption rate of the pre-treated bio-composite was only 8.9% after being immersed in water for one day. Furthermore, the bamboo cell structure of the bio-composite was destroyed and more compact in the subsequent hot pressing, as observed from the micromorphology examination. In addition, the resulting bio-composite has high specific strength and demonstrates green characteristics for environmental protection. Overall, this bamboo-derived bio-composite shows desirable features that have potentially broad application prospects in construction and furniture.

Waterproof Characteristics and Technical Requirements of Prefabricated Concrete Building Exterior Wall

Waterproof Characteristics and Technical Requirements of Prefabricated Concrete Building Exterior Wall

Blended Polymer Dry Electrodes for Reliable Electrocardiogram and Electromyogram Measurements and Their Eco-Friendly Disposal Led by Degradability in Hot Water.

To increase the human lifespan, healthcare monitoring devices that diagnose diseases and check body conditions have attracted considerable interest. Commercial AgCl-based wet electrodes with the advantages of high conductivity and strong adaptability to human skin are considered the most frequently used electrode material for healthcare monitoring. However, commercial AgCl-based wet electrodes, when exposed for a long period, cause an evaporation of organic solvents, which could reduce the signal-to-noise ratio of biosignals and stimulate human skin. In this context, we demonstrate a dry electrode for a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based blended polymer electrode using a combination of PEDOT:PSS, waterborne polyurethane (WPU) and ethylene glycol (EG) that could be reused for a long period of time to detect electrocardiography (ECG) and electromyography (EMG). Both ECG and EMG are reliably detected by the wireless real-time monitoring system. In particular, the proposed dry electrode detects biosignals without deterioration for over 2 weeks. Additionally, a double layer of a polyimide (PI) substrate and fluorinated polymer CYTOP induces the strong waterproof characteristics of external liquids for the proposed dry electrodes, having a low surface energy of 14.49 mN/m. In addition, the proposed electrode has excellent degradability in water; it dissolves in hot water at 60 °C.

Waterproof Characteristics of Fire Pumps for Fire-fighting Vehicles

The water shooting performance of existing fire pump vehicles was found to be insufficient when extinguishing fire at the Go-yang Reservoir, and thus, the need for a high-pressure pump was raised. Therefore, the National Fire Agency enforced the standard for high-pressure pumps as 4.0 MPa; further, they categorized fire pumps into general pumps and high-pressure pumps. In this study, an empirical experiment was conducted on the water shooting characteristics of a high-pressure pump by manufacturing a device equipped with a high-pressure pump that conformed to the abovementioned standards. A water shooting test similar to fire suppression activities was conducted by connecting fire hoses and nozzles at a straight distance of 300 m. The experiment confirmed that, based on the pump pressure of 1.5 MPa, the tip pressure considerably fluctuated during water shooting, and the difference in pressure loss rate at the low-pressure and high-pressure outlets was confirmed. Because these characteristics threaten the safety of fire-fighters during field activities, a need was confirmed for technology development that can improve the limit on the tip pressure increase in the high pressure pump standard and the rapid pressure increase.

Water Repellency/Proof/Vapor Permeability Characteristics of Coated and Laminated Breathable Fabrics for Outdoor Clothing

This study examined the water repellency (WR), waterproof, and water vapor permeability (WVP) characteristics of twelve types of laminated and coated woven fabrics for outdoor clothing. These characteristics were compared with the fabric structural parameters, such as cover factor, thickness, and weight, and surface modification (finishing) factors, such as coating, laminating, and Teflon treatments. In addition, an eco-friendly process for surface modification was proposed followed by a summary. Superior waterproof-breathable characteristics with 100% water-repellency were achieved in specimen 3 in group A by treatment with a hydrophilic laminated finish using nylon woven fabric with a cover factor between 0.7 and 0.9 in a 2.5-layered fabric, which was the best specimen with waterproof-breathable characteristics. A high WVP in the coated and laminated fabrics was observed in the fabrics with a low weave density coefficient (WDC) and low thickness per unit weight of the fabric, whereas superior water repellency and waterproof characteristics were observed in the high-cover-factor (WDC) fabric with appropriate fabric thickness. The determination coefficient (R2) from regression analysis between the WVP and fabric structural parameters indicated a higher contribution of the fabric structural parameters than surface modification factors, such as coating and laminating to the WVP in the coated and laminated fabrics. Furthermore, the cover factor was the most important factor influencing the WVP of the waterproof-breathable fabrics. Of twelve coated and laminated fabrics, the laminated nylon and nylon/cotton composite fabrics showed superior WVP with high WR and waterproof characteristics. Accordingly, based on the WR, waterproof, and WVP characteristics of the coated and laminated breathable fabrics, the laminating method, as an eco-friendly process, is recommended to obtain better waterproof-breathable fabrics.

Site‐Selective Occupancy of Eu2+ toward High Luminescence Switching Contrast in BaMgSiO4‐Based Photochromic Materials

AbstractLuminescent inorganic photochromics have great potential applications in 3D optical memory due to their excellent thermal stability and chemical resistance. Nevertheless, constructing inorganic photochromics with a high luminescence switching contrast remains challenging for optical information storage. Understanding inherent relationships between microenvironment changes, photophysical material properties, and rational control of their luminescence properties are crucial to address these issues. This paper proposes an effective strategy to significantly improve the luminescence switching contrast by more than 300% by site‐selective occupancy engineering on BaMgSiO4:Eu2+ photochromic materials. An effective energy transfer process is established between luminescent and photochromic units, which may provide new insights for designing high‐performance optical storage systems. The fabricated flexible films exhibit excellent waterproof, flexibility, and stretchability characteristics, accompanied by reversible color switching and larger color contrast. Optical data storage can be not only visually encoded and decoded on the flexible films by 405 and 532 nm LED excitation, respectively. Writing, erasing, and reading strategies for flexible films are particularly suitable for complex application environments in optical storage and rewritable flexible devices.

2D Metal Zn Nanostructure Electrodes for High‐Performance Zn Ion Supercapacitors

AbstractRecent supercapacitors show a high power density with long‐term cycle life time in energy‐powering applications. A supercapacitor based on a single metal electrode accompanying multivalent cations, multiple charging/discharging kinetics, and high electrical conductivity is a promising energy‐storing system that replaces conventionally used oxide and sulfide materials. Here, a hierarchically nanostructured 2D‐Zn metal electrode‐ion supercapacitor (ZIC) is reported which significantly enhances the ion diffusion ability and overall energy storage performance. Those nanostructures can also be successfully plated on various flat‐type and fiber‐type current collectors by a controlled electroplating method. The ZIC exhibits excellent pseudocapacitive performance with a high energy density of 208 W h kg−1 and a power density from 500 W kg−1, which are significantly higher than those of previously reported supercapacitors with oxide and sulfide materials. Furthermore, the fiber‐type ZIC also shows high energy‐storing performance, outstanding mechanical flexibility, and waterproof characteristics, without any significant capacitance degradation during bending tests. These results highlight the promising possibility of nanostructured 2D Zn metal electrodes with the controlled electroplating method for future energy storage applications.

Optimal Manufacture Formulas for Waste Tire after Pyrolysis and Lightweight Composites after its Combustion Utilization in Sequence through Statically Analyses

The present research will be included in molding condition of temperature, pressure etc. in addition to heat of combustion test and improve strength of the Lightweight Composites by the adhesives with waste tire after pyrolysis. The results can serve as a reference to the Waste tire pyrolysis ash Lightweight Composites by production process design. Basically, take extrusion molding technique and sintering, the Lightweight Composites are produced for the ash from the Waste tire pyrolysis after combustion utilization. This study uses the Taguchi Methods to find the best formula, from product performance analysis and process technology manufacturing, The Lightweight composite material meets the expectations of the commercial market, As a reference for future research. This study use three variable, include adhesive, molding temperature, molding pressure .In the choice of adhesive, the study selected chemically modified starch adhesive, Melamine - urea - formaldehyde co - condensation resin, Isocyanate adhesives. This study was learned by Taguchi rule, the best formula for the Isocyanate adhesives, molding temperature at 135°C, molding pressure at 3.5kg/cm2. In the above conditions made by the lightweight composite material, with excellent bending strength and water resistance, In the fire performance on the more traditional wood-plastic board. From the commercial market point of view, the lightweight composite materials not only have the characteristics of fire resistance, good bending resistance, waterproof characteristics. In the material cost, because the processing technology to enhance, effectively reduce manufacturing costs, more commercial market competitiveness.

NUMERICAL SIMULATION OF RELATIVE HUMIDITY IN A MASONRY WALL APPLYING THREE DIFFERENT WATERPROOFING MEMBRANES

The analysis by numerical simulations can be applied to building materials subjected to different climatic conditions to envisage the influence of environmental factors in terms of drying time, water absorption and thermal performance of materials. Currently there is a wide variety of new building materials used for insulation, waterproofing and rehabilitation, each contributing in a specific way to constructions improvement during their service life. In time, every building is subjected to degradation due to the action of environmental factors. One of these is water due to its continuous acting under all forms of aggregation: vapour, liquid, solid, each having particular influence on the building s elements. The present paper highlights a numerical simulation of hygrothermal waterproofing characteristics for three different membranes applied on a brick masonry basement wall. The simulation was performed using WUFI2D 3.2 computer software. The information extracted from the analysis results made reference to the materials performance while subjected to moisture transfer processes.

Feasibility study of silica bead thermoluminescence detectors (TLDs) in an external radiotherapy dosimetry audit programme

PurposeInvestigating the feasibility of using low-cost commercially available silica beads as novel thermo-luminescence dosimeters (TLD) for postal dosimetry audit. MethodsA mail-based dosimetry audit was designed to assess the positional and dosimetric accuracy of SABR-lung treatment delivery using alanine and EBT3-film, placed in a CIRS-anthropomorphic thorax phantom. In conjunction, the silica beads were dosimetrically characterised as TLDs and cross-calibrated against the alanine. A CT-scan of the phantom with pre-delineated volumes was sent to 20 RT centres and used to create a SABR plan using local current protocols and techniques. The silica beads were held in an insert, designed to match that of the alanine holder and ionisation chamber to give the same measurement length. The doses determined by the silica beads were compared to those measured by alanine, the local ionisation chamber, film and the TPS calculation. ResultsThe mean percentage difference between the doses measured by the silica beads and the calculated doses by the TPS was found to be 0.7% and differed by 0.6%, 0.7%, and 1.3% from the alanine, film and local ionisation chamber measurements respectively. ConclusionsResults obtained with the silica beads agree well with those obtained from conventional detectors including alanine, film and ionisation chambers. This together with the waterproof and inert characteristics and minimal dose fading associated with silica bead TLDs confirm their potential as a postal dosimetry audit tool in both water and plastic phantoms which could withstand challenges of temperature and humidity variation, as well as postal service delays.

Highly Stretchable and Waterproof Electroluminescence Device Based on Superstable Stretchable Transparent Electrode.

Realization of devices with enhanced stretchability and waterproof properties will significantly expand the reach of electronics. To this end, we herein fabricate an elastic transparent conductor that comprises silver nanowires (AgNWs) on a hydroxylated polydimethylsiloxane (PDMS) substrate covered by polyurethane urea (PUU), which is fully compatible with both materials. Carboxylic acid groups of PUU was designed to form hydrogen bonds with the carbonyl groups of poly(vinylpyrrolidone) on the AgNW surface, resulting in an enhanced affinity of AgNWs for PUU. Exceptionally strong hydrogen bonds between PUU and the hydroxylated PDMS thus facilitate the achievement of water sealable, mechanically stable, and stretchable transparent electrodes. To fabricate stretchable electroluminescence (EL) devices, ZnS particles were mixed with PUU, and the mixture was coated onto the AgNWs/hydroxylated PDMS, followed by a face-to-face lamination with another identical electrode. The devices could be stretched up to 150% without a severe reduction in the emission intensity, and they survived 5000 cycles of 100% stretch-release testing. The high adhesion between PUU and PDMS even in water is responsible for the good waterproof characteristics of the EL devices. These results pave the way for realization of fully stretchable and waterproof electronic devices.

A review of polyvinyl alcohol derivatives: Promising materials for pharmaceutical and biomedical applications

In recent years, a technological breakthrough in the pharmaceutical and biomedical fields have been reflected in the development of more complex, safe and effective dosage forms to improve the administration, delivery, disposition and stability of drugs, as well as at creating more biocompatible and biodegradable materials. As a result, modified release devices and functional coatings which improve the effectiveness and efficacy of drugs have been generated. This advancement has been achieved by physical or chemical modification of natural or semisynthetic polymers which stabilize and protect drugs against harsh environmental factors. Therefore, the development of novel excipients with a high functionality and robustness has become an important quest. Among these materials, polyvinyl alcohol is one of the most versatile and biocompatible, since by chemical or physical modification its properties are modulated, improving drug stability, drug targeting, and ensures patient compliance. Freezing-thawing cycles, heat treatment and formation of composites are the most significant physical modifications to improve the performance of polyvinyl alcohol. On the other hand, the chemical modifications by cross-linking with aldehydes, carboxylic acids, sodium tetraborate, epichlorohydrin have enhanced the physical and mechanical properties, such as the oil sorption ability, oxygen and waterproof characteristics, mechanical strength, drug diffusion and rate of swelling. Key words: Polyvinyl alcohol, composites, crosslinking, pharmaceutical and biomedical applications.

예방적 유지보수를 위한 소수성 저점도 AP 표면처리재 개발

PURPOSES : Surface treatment is a favorable method in the pavement preventive maintenance. This study (Part I) aimed to develop the low viscosity filling material for waterproof characteristics and high penetrable and weather resistance, and a series of companion study (Part II) presents the coating characteristics and performance analysis using field and lab tests. METHODS : Hydrophobic characteristics of the advanced surface treatment material are observed and measured the filling depth and the permeability for sand and asphalt pavement specimen using the water absorption test and permeability test, X-RAY CT test. Color difference for the weather resistance using ultraviolet ray accelerated weathering test is compared with asphalt pavement specimens. RESULTS : The developed material shows the decreased water absorption and increased impermeable effect because of the hydrophobic characteristics. It is found that the filling depth is about 6mm and weather resistance is better than asphalt pavement specimen. CONCLUSIONS : The advanced hydrophobic - low viscosity filling treatment material is developed in this study (Part I) to improve the waterproof characteristics and high filling capacity and weather resistance for the pavement preventive maintenance.

Microfabricated environmental barrier using ZnO nanowire on metal mesh

In this study, a waterproof environmental barrier for microsensor package has been developed using metal mesh covered with zinc oxide (ZnO) nanowire. A near superhydrophobic surface with two-dimensional array of holes has been fabricated by hydrothermal growth of ZnO nanowire on an off-the-shelf steel use stainless (SUS) mesh. For a twill-woven SUS wire mesh having wire thickness of 30 µm and gap of 33 µm, a maximum contact angle of 160.40° and a minimum contact angle hysteresis of 15.23° have been achieved using ZnO nanowire grown on the wire surface and further deposition of FC film. The mesh was able to withstand a maximum water pressure of 2,459.8 Pa. The measured height of ZnO nanowire was approximately 2–3 µm. The fabricated SUS mesh covered with ZnO nanowire has been assembled with a microphone package, and waterproof characteristics have been measured by cyclic dipping test at various water levels. For a microphone package having two acoustic ports on top and bottom covered with fabricated mesh, no visible change in acoustic characteristics has been observed up to 1,372.9 Pa of water pressure. Total volume of the package was 6.8 × 9.8 × 1.9 mm3.