Water Resistance Properties Research Articles

Investigation of the Effect of a Natural Extract From Oak Bark on the Properties of the Leather

Abstract Researchers are constantly looking for the use of new and effective types of natural dyes to reduce the impact of harmful factors from the use of synthetic dyes. In this study, the effects of a natural plant extract based on oak bark, used as a dye during the finishing process, on the physico-mechanical and hygroscopic properties of the leather were studied. Extraction was carried out by the traditional method without chemical additives using only distilled water and oak bark. The application of finishing solutions based on a standard chemical pigment and oak bark extract was carried out using an automatic rotary spray machine in combination with a drying tunnel. The physico-mechanical properties of colored leathers based on oak bark extract were determined in comparison with a standard chemical pigment and with a sample without finishing. The hygroscopicity of the leather samples were also evaluated, such as: water absorption, water penetration and color fastness to water spotting. The results of the conducted studies have shown that the samples stained with a natural dye have good physico-mechanical and water resistance properties.

Self-compliant ionic skin by leveraging hierarchical hydrogen bond association

Robust interfacial compliance is essential for long-term physiological monitoring via skin-mountable ionic materials. Unfortunately, existing epidermal ionic skins are not compliant and durable enough to accommodate the time-varying deformations of convoluted skin surface, due to an imbalance in viscosity and elasticity. Here we introduce a self-compliant ionic skin that consistently works at the critical gel point state with almost equal viscosity and elasticity over a super-wide frequency range. The material is designed by leveraging hierarchical hydrogen bond association, allowing for the continuous release of polymer strands to create topological entanglements as complementary crosslinks. By embodying properties of rapid stress relaxation, softness, ionic conductivity, self-healability, flaw-insensitivity, self-adhesion, and water-resistance, this ionic skin fosters excellent interfacial compliance with cyclically deforming substrates, and facilitates the acquisition of high-fidelity electrophysiological signals with alleviated motion artifacts. The presented strategy is generalizable and could expand the applicability of epidermal ionic skins to more complex service conditions.

Review on Properties of Natural Fiber Reinforced Polymer Composites: Effect of Gamma Radiation and Nano particles.

Materials comprised of a polymer matrix with natural fiber reinforcement are known as natural fiber reinforcement polymer composites (NFRCs). Scientists have recently become quite interested in these composite materials because they provide improved properties over conventional synthetic fiber reinforced polymer composites at a lower cost and with benefits to the environment. However, a number of factors, including gamma radiation exposure and the addition of nanoparticles, can impact the properties of NFRCs. This review will focus on the effects of gamma radiation and nanoparticles on the mechanical, thermal, and water-resistance properties of NFRCs. In order to help in the creation of new and improved NFRCs for diverse applications, this review seeks to provide a thorough understanding of the characteristics of NFRCs and how they might be impacted by gamma radiation and nanoparticles.

The influence of polysiloxane on the mechanical properties and water repellency of cotton fabrics

Cotton fabric is commonly used in the textile industry owing to good ventilation and absorption capacity. However, dirt resistance and water resistance of cotton fabrics are low. Therefore, coating cotton fabrics with water-repellent polysiloxane is a special requirement for outdoor and protective clothing products. The effects of polysiloxane content on the water resistance and mechanical properties of materials were studied. The morphology of coated cotton fabric was characterised by SEM (Scanning electron microscope), and EDX (Energy dispersive X-ray) was used to determine the presence of polysiloxane on the surface of cotton fabric. The effects of polysiloxane content on the water resistance and mechanical properties of materials were studied. Compared with raw cotton fabrics, the tensile strength of the cotton fabrics impregnated with 20%wt polysiloxane solution increased, but the elongation at break was reduced. The hydrostatic pressure (AATCC 127) and water spray test (AATCC 22) results showed that the water repellence of polysiloxane-coated cotton fabrics increased significantly compared to pure cotton fabrics. In addition, the polysiloxane content has no almost effect on the water repellency of the material. Therefore, the appropriate use of polysiloxane can contribute to minimising the cost of the product.

A novel poly(vinyl alcohol)/silica composite film with “spherical crystal interlocking structure” and its barrier and enhancement mechanism

Using the semi-crystalline poly(vinyl alcohol) (PVA) as the polymer matrix and silica nanoparticles (SNPs) as the reinforcing filler, composite films with excellent water vapor barrier, high tensile strength, visible light transmission and ultraviolet (UV) shielding performances were constructed via a simple heat treatment process, during which the films underwent dehydration cross-linking and isothermal recrystallization to form a "spherical crystal interlocking structure". Both the dosage and average particle size of SNPs significantly affected the barrier property, and the optimal values were 7 wt% and 15 nm, respectively. The heat treatment further improved the water resistance, mechanical strength, and barrier property to a great extent. Moreover, different theoretical models including Guggenheim Anderson de Boer (GAB), Brunauer Emmett and Teller (BET), Hailwood-Horribon (H-H) model, crystallinity model and Fick's law model were successfully used to explain the water vapor barrier mechanism. The water vapor permeability (WVP) of the optimized composite film was reduced to 2.20 × 10−12 g·m/(m2·Pa·s) at 37°C and 65% RH, while the tensile strength was increased up to 116.8 MPa. In addition, the absorption rate of ultraviolet of the film after heat treatment increased from 13% to 92.0%, while the transmittance of visible light remained above 78%.

Tough and Water-Resistant Bioelastomers with Active-Controllable Degradation Rates.

Biodegradable electronic devices have gained significant traction in modern medical applications. These devices are generally desired to have a long enough working lifetime for stable operation and allow for active control over their degradation rates after usage. However, current biodegradable materials used as encapsulations or substrates for these devices are challenging to meet the two requirements due to the constraints of inadequate water resistance, poor mechanical properties, and passive degradation characteristics. Herein, we develop a novel biodegradable elastomer named POC-SS-Res by introducing disulfide linkage and resveratrol (Res) into poly(1,8-octanediol-co-citrate) (POC). Compared to POC, POC-SS-Res exhibits good water resistance and excellent mechanical properties in PBS, providing effective protection for devices. At the same time, POC-SS-Res offers the unique advantage of an active-controllable degradation rate, and its degradation products express low biotoxicity. Good biocompatibility of POC-SS-Res is also demonstrated. Bioelectronic components encapsulated with POC-SS-Res have an obvious prolongation of working lifetime in PBS compared to that encapsulated with POC, and its degradation rate can be actively controlled by the addition of glutathione (GSH).

Synthesis of lignin-based polyurethane (LPU) and fabrication of degradable mulch film through LPU coating on cellulose paper

The use of non-degradable plastic mulch film causes significant environmental pollution and poses a threat to human and ecological safety. To address this issue, a viable solution is to develop bio-based and biodegradable paper mulch films to replace non-biodegradable ones in agricultural soils. In this study, a green and straightforward process was used to synthesize lignin-based polyurethane (LPU), which was then coated on cellulose paper (CP) of low basis weight of 30 g/m2 to fabricate a composite LPU/CP mulch film. An ultra-thin and lightweight LPU/CP mulch film was successfully fabricated with basis weight, thickness, and specific density of 40 g/m2, 80 µm, and 0.5 g/cm3, respectively. It was observed that surface coating was very effective in improving the physical strength of composite film as indicated by the improvement of tensile index from 19.3 N·m/g of CP to 65.0 N·m/g of LPU/CP mulch film. Moreover, LPU/CP mulch film presented excellent water resistance properties as suggested by the water contact angle of 107° and the water vapor transmission rate of 639.3 g/m2·day. LPU/CP mulch film also shows a balance between degradability and durability that it starts to break down into fractions after being buried for 28 days as a result of microbiological degradation. This work provides a feasible technology for fabricating eco-friendly, cost-effective, and biodegradable paper mulch film.

Silanized carbon quantum dots assembled porous glass and its luminescent properties

In this paper, the silanized carbon quantum dots (Si CQDs) were assembled into nano-porous glass (NPG) by solution ultrasonic method. The morphology, structure, elementary composition, luminescence properties, water-resistance and anti-ultraviolet properties were systematically studied. Concentration quenching occurs when the Si CQDs doping content exceeds 7.73 mg/g. It is found that nano-porous glass matrix can effectively disperse and protect the Si CQDs, which realizes the luminescence of Si CQDs in solid state and enhances the fluorescence emission intensity of Si CQDs. In addition, the spatial confinement effect of nano-channels in Si CQDs/NPG composites makes it obtain excellent water-resistance. At the same time, the composites show better photo-stability under continuous UV irradiation. The above results provide a basis for its application in agricultural light conversion films.

Sustainable cellulose nanofiber/hydrophobic silica nanoparticle coatings with robust hydrophobic and water-resistant properties for wood substrates

Hydrophobization of wood is pivotal for enhancing the utility of wood products. Traditional hydrophobic coatings, primarily petrochemical-based, are now being replaced by environmentally friendly silane-coupled inorganic nanoparticles. However, these alternatives face challenges like poor dispersion stability and weak wood surface adhesion. Our research introduces cellulose nanofibers (CNFs) into the condensation process of silica nanoparticles, creating a CNFs/silica nanoparticle composite. This composite exhibits remarkable dispersion stability and adjustable viscosity, leading to an improved hydrophobic silica/CNFs coating. Its versatility allows for various application methods, including spray, dip, and brush coating. Remarkably, the composite maintains a water contact angle of about 151°, demonstrating excellent water repellency, even with hydrophilic CNFs. The CNFs also enhance the interaction with wood surfaces, boosting the durability of the coating. This innovative approach not only improves storage stability and workability but also ensures uniform hydrophobicity and durable coating formation. Our findings suggest that CNFs derived from lignocellulosic biomass could ultimately be incorporated into environmentally friendly wood coating materials, significantly improving the shortcomings of conventional hydrophobic coatings while reducing dependence on petroleum-based products.

Exploring the potential of jujube seed powder in polysaccharide based functional film: Characterization, properties and application in fruit preservation

In this study, we fabricated a novel biodegradable functional film using natural polysaccharides by adding jujube seed powder as an active ingredient. Scanning electron microscopy analysis showed agglomerate formation in the film with increasing concentration of seed powder. Fourier transform-infrared spectroscopy study demonstrated an electrostatic interaction between pectin and chitosan. The water solubility and swelling degree significantly decreased from 55.5 to 47.7 % and 66.0 to 41.9 %, respectively, depicting the film's water resistance properties. Higher opacity and lower transmittance value of the film indicated its protective effect towards light-induced oxidation of food. It was observed that the fabricated active film biodegraded to 82.33 % in 6 days. The DPPH radical scavenging activity of 98.02 % was observed for the functional film. The film showed antifungal activity against B. cinerea and P. chrysogenum. The highest zone of inhibition was obtained against food spoiling bacteria B. subtilis followed by S. aureus, P. aeruginosa and E. coli. Genotoxicity studies with the fabricated film showed a mitotic index of 8 % compared to 3 % in the control film. We used the fabricated film to preserve grapefruits, and the result showed that it could preserve grapes for ten days with an increase in antioxidant activity and polyphenolic content.

Cellulose nanofibrils as a bio-based binder for wood fiber composite insulation panels with enhanced thermo-mechanical properties for structural wall sheathing applications

A low-density wood fiber insulation panel (WIP) composite was developed with 100 % petrochemical-free, bio-based binder with high mechanical strength, water resistance and thermal insulation properties. This study investigated the manufacturing process of composite WIPs made with mechanical pulp fibers with cellulose nanofibrils (CNFs), lignin-containing CNFs (LCNFs), hybridized CNFs-LCNFs, and CNFs-starch as a binder on different scales and evaluated the effects of binder type and content on the panels’ physical, mechanical, and thermal properties. All panels had excellent thermal resistivity values, which increased with the decrease in density. The WIPs made with LCNFs as binder had lower mechanical properties, but it was possible to replace 20 % CNFs with LCNFs to obtain the same performance as neat CNFs as the binder. Untreated panels had poor water resistance but the water absorption properties were significantly improved with the addition wax. The WIPs made with 5 % and 7.5 % binder content and 2 % wax addition could fulfill the criteria of regular and structural wall sheathing applications, respectively. Overall, the results confirm the potential of CNFs and LCNFs to be used as 100 % bio-based adhesives to produce eco-friendly composite WIPs with excellent thermo-mechanical properties to be used for regular and structural wall sheathing applications.

Improving water resistance and mechanical properties of starch-based films by incorporating microcrystalline cellulose in a dynamic network structure

The widespread use of starch-based films is hindered by inadequate tensile strength and high water sensitivity. To address these limitations, a novel starch film with a dynamic network structure was produced via the dehydration-condensation reaction of N, N′-methylene diacrylamide (MBA) and microcrystalline cellulose (MCC). The improvement in mechanical properties was enhanced by the incorporation of MCC, which was achieved through intermolecular hydrogen bonding and chemical crosslinking. To verify the interactions among MCC, MBA, and starch, x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD) were conducted. The results established the predicted interactions. The dynamic network structure of the film reduced the water absorption capacity (WAC) of starch and MCC hydroxyl groups, as confirmed by differential scanning calorimeter (DSC) and dynamic mechanical thermal analysis (DMTA). These analyses showed a restriction in the mobility of starch chains, resulting in a higher glass transition temperature (Tg) of 69.26 °C. The modified starch films exhibited excellent potential for packaging applications, demonstrating a higher contact angle (CA) of 89.63°, the lowest WAC of 4.73 g/g, and the lowest water vapor transmission rate (WVTR) of 13.13 g/m2/d, along with improved mechanical properties and identical light transmittance compared to pure starch films.

Preparation, formation mechanism, and performance of nitrocellulose aqueous coating based on the anti-solvent method

The organic solvent-based nitrocellulose (NC) coatings exhibit a high volatile solvent content, leading to significant environmental pollution. Whereas, existing waterborne NC-based coating have demonstrated poor water resistance and complex application methods. Therefore, this study aims to develop a green and highly water-resistant waterborne NC-based coating system utilizing a simple anti-solvent method with two environmentally friendly plasticizers, namely acetyl tributyl citrate (ATBC) and triethyl citrate (TEC), as film-forming additives. The dynamic light scattering (DLS) studies revealed that the particle size of NC-based nanoparticles increased with an increase in ATBC content, while it remained relatively constant with an increase in TEC content. Moreover, the particle size results demonstrated that the storage stability of aqueous dispersions containing NC/ATBC (NA) was superior to those containing NC/TEC (NT). Additionally, the physicochemical properties of aqueous dispersions-based films (Ndis), including film formation, hygroscopicity, water resistance, transparency, thermal stability, and mechanical properties were evaluated using solvent-based films (Nsol) as control samples. The results demonstrated that the Ndis films exhibited a dense and uniform structure, with physical and chemical properties that were essentially comparable to those of Nsol films. However, the mechanical properties of Ndis films were somewhat influenced by the nanoparticle size, leading to reduced mechanical performance when the particle size of nanoparticles in the aqueous dispersion was excessively large. The equilibrium moisture content for NA and NT films were reduced to 1.119% and 1.872%, respectively, at a relative humidity of 95%, in comparison to pure NC films (3.975%). Simultaneously, water contact angle measurements indicated an increase from 77° for pure NC film to 89° for NA film and 82° for NT film. All films exhibited superior transparency characteristics. Overall, NA films display excellent water resistance and transparency as well as good mechanical properties.

Effect of Phenolic Resin Coating Thickness on Mechanical Properties and Corrosion Resistance of Metal Materials

In the realm of petrochemical and other industries, metal materials face threats such as impact and high-temperature electrochemical corrosion. Consequently, there has been significant attention towards organic coatings that effectively attenuate impact forces while simultaneously providing a barrier against corrosive agents. The thermosetting phenolic resin 2130, known for the facile curing process, exceptional thermal stability, water resistance, corrosion resistance, and superior mechanical properties post-curing, finds extensive applications in the field of coatings. To address the challenge of depositing a complete and uniform resin coating on complex workpieces, coatings with varying thicknesses on the surface of 304 stainless steel were deposited via rotary evaporation combined with long-term low-temperature drying. The relationship between coating thickness and mechanical properties, as well as corrosion resistance, was investigated and analyzed through a comprehensive approach involving mechanical testing, electrochemical analysis, and long-term service weight loss assessment. The results demonstrated that the coatings deposited on the metal surface exhibited excellent integrity and compactness. Moreover, an increase in coating thickness led to a significant reduction in material corrosion rate. The coatings exhibited excellent substrate adhesion and flexibility, thereby providing effective protection against impact on the metal substrate. The relationship between the thickness of the coating and the surface roughness was evident, while the flexibility of the coating first increased and then decreased with the increase of coating thickness. When the coating thickness was 7 μm, the maximum surface roughness of the coating measured 0.44 μm. Under these conditions, the impact toughness of the coating reached the peak, exhibiting a ductile fracture mode and showcasing superior comprehensive mechanical properties. The findings of this study will offer theoretical support for the investigation and formulation of resin coatings in subsequent industrial production.

Bacterial cellulose/gelatin-based pH-responsive functional film for food freshness monitoring

Food safety is related to public health and environmental safety. Therefore, it is necessary to develop accurate and effective detection methods to assess food quality and safety. In this study, a pH-responsive functional film (BC/GA/FITC/PCA) was generated for the real-time and visual monitoring of shrimp freshness. Bacterial cellulose /Gelatin (BC/GA) was used as a film-forming matrix, and fluorescein isothiocyanate (FITC) and red cabbage (PCA) were used as the response signals. The addition of FITC and PCA increased the shading capacity (< 30 %) and antioxidant properties (22.8 %) of the films. WCA (82.73 ± 0.95°), WVP (1.48 × 10−11 g·cm/cm2·s·Pa) and OTR (2.42 × 10−15 cm3·cm/cm2·s·Pa) indicated that the film possessed water resistance and oxygen barrier properties. When exposed to daylight, the film underwent a color transition from purple to green as the ammonia concentration increased. In addition, the blue-green fluorescence of the films gradually increased and the detection limit was low (170 ppb). In particular, the change in film color caused by shrimp spoilage corresponded to the TVBN value. This study work provides a new strategy for controlling and monitoring food safety and has a wide range of applications in the fields of food-active packaging and smart packaging.

Developing a water-resistant cellulose-based wood adhesive based on dual dynamic Schiff base and disulfide bonds

Cellulose-based adhesives have been a research focus in the wood composites industry in view of their eco-friendly characteristics with little negative impacts on human health and ecology. Water-resistant property of the adhesives, however, is still a remaining challenge in the wood-based industries to compete with conventional petroleum-based ones. Herein, microcrystalline cellulose (MCC), a natural and renewable biomacromolecule with extensive resource, was selected as matrix material. Firstly, the hydroxyl groups on C2 and C3 in MCC were oxidized to aldehyde groups in the presence of periodate, resulting in the formation of dialdehyde cellulose (DAC). In consideration of the weak water-resistance of DAC, an integrated strategy that combined DAC with cystamine (CA), was proposed, and a water-resistant cellulose-based DAC-CA adhesive was developed through the cross-linking reaction between DAC and CA. Furthermore, in order to make the adhesive adequately exert the function for bonding of poplar veneer, we performed the interfacial treatment on the poplar veneer using sodium periodate. The performance and structural characteristics of the prepared DAC-CA adhesive were systematically and thoroughly investigated using a multi-spectroscopy technique. The results revealed that the wet bond strength of the DAC-CA adhesive for poplar veneer was higher than that of individual DAC, ranging from 0 MPa in DAC to 0.72 MPa in DAC-CA adhesive. This improvement can be attributed to the enhanced cohesion and toughness resulting from the dynamic Schiff base and disulfide bonds present in the DAC-CA adhesive. In addition, after interfacial treatment, the wet bond strength of DAC-CA adhesive for poplar veneer was dramatically improved, increasing from 0.72 MPa without treatment to 1.06 MPa with treatment. Overall, a water-resistant cellulose-based DAC-CA adhesive was prepared by a rapid and efficient method. This study may provide insights into the development and utilization of innovative wood adhesives.

One-step preparation of hydrophilic–hydrophobic asymmetric bilayer microcapsules via photopolymerization

The bilayer microcapsules with balanced water-dispersibility, water-resistance properties and outstanding mechanical properties were prepared in one step by combining “phase separation inside an emulsion droplet” with photopolymerization.

Evaluation of physicochemical properties of citric acid crosslinked starch elastomers reinforced with silicon dioxide.

Thermoplastic starch (TPS), derived from renewable resources, offers advantages such as biodegradability and lower production costs compared to petroleum-based plastics. However, its limited mechanical properties pose a challenge for broader applications. This research aims to explore the potential of enhancing the mechanical and barrier properties of TPS films through the incorporation of silicon dioxide as a reinforcement filler and citric acid as a crosslinking agent. By introducing silicon dioxide as a reinforcement filler, the mechanical strength of the TPS films is expected to be improved. Additionally, the incorporation of citric acid as a crosslinking agent is anticipated to enhance the barrier properties of the films. The combination of these additives holds promise for creating TPS films with improved performance, contributing to the development of sustainable and environmentally friendly materials in various industries. The results reveal that SiO2 improves the stiffness of the films at lower concentrations but causes brittleness at higher concentrations. In contrast, citric acid crosslinked films exhibit improved flexibility and density. Scanning electron microscopy demonstrates the morphological changes in the films, with SiO2 affecting surface roughness and aggregate formation. SiO2 reduces film thickness and transparency, while citric acid enhances water resistance and barrier properties. X-ray diffraction analysis shows a reduction in crystallinity due to the plasticization process. Fourier-transform infrared spectroscopy highlights chemical changes and antimicrobial activity is observed with citric acid against specific bacteria. The soil burial test reveals that citric acid crosslinked films exhibit slower degradation due to antimicrobial properties. The combination of SiO2 reinforcement and citric acid crosslinking enhances the overall performance of the films, promising sustainable and environmentally friendly materials for various applications.

Performance evaluation of waterborne epoxy emulsified asphalt micro-surfacing with microwave-activated waste rubber powder

As a solid renewable resource, waste rubber powder (R) applied in road engineering can help reduce the environmental pressure caused by "black pollution" and improve pavement performance. In this research, waste rubber powder was activated by microwave method, namely as MR. The content of 0%∼ 5% MR was added as a functional filler to the waterborne epoxy emulsified asphalt (WEA) micro-surfacing mixture, thereby obtaining the MRWEA micro-surfacing. Furthermore, pavement performance, durability and noise reduction property were evaluated and compared with those of WEA micro-surfacing adding non-activated R (RWEA micro-surfacing). Results show that the surface activity of MR has been enhanced effectively, and the surface hydrophobicity of MR is better than R through the contact angle test. These findings are also confirmed by Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis. Then, MRWEA micro-surfacing has good workability and cohesion due to the surface activity of MR. At the same dosage MR and R, 30 min, 60 min cohesion of MRWEA micro-surfacing mixture is greater than that of RWEA micro-surfacing mixture. Furthermore, MRWEA micro-surfacing with 3% MR has better wear resistance, rutting resistance, water resistance, durability and noise reduction properties than those of RWEA micro-surfacing with 3% R.

Catalytic hydrolysis of methyl mercaptan and methyl thioether on hydroxyl-modified ZrO2: a density functional theory study.

The purification and removal of organic sulfur from natural gas is conducive to increasing the added value of natural gas and reducing environmental pollution. In this study, the adsorption properties of methyl mercaptan (CH3SH), dimethyl sulfide (C2H6S) and H2O on the surface of hydroxyl-modified ZrO2 were investigated using density functional theory (DFT) calculations. Additionally, a reaction mechanism was proposed for hydroxyl-modified ZrO2 catalyzing the hydrolysis of CH3SH and C2H6S. The chemisorption of H2O molecules on the catalyst surface is attributed to H-O and H-Zr bonds. The chemisorption of CH3SH and C2H6S on the catalyst surface is attributed to Zr-S bonds. Competitive adsorption between the three gases exists only between CH3SH and C2H6S. It reveals the water-resistant properties of hydroxyl-modified ZrO2 in desulfurization. The adsorption energies of the three gas molecules on the hydroxyl-modified ZrO2 surface are in the order of CH3SH - (Zr) > C2H6S - (Zr) > H2O - (OH). The natural hydrolysis of CH3SH and C2H6S is a heat-absorbing process that cannot occur spontaneously. The rate-determining step for CH3SH catalytic hydrolysis is the formation of CH3O. The fracture of CH3SHO is the rate-determining step for C2H6S catalytic hydrolysis. The depletion of the surface hydroxyl groups can be replenished by the dissociation of H2O molecules. Hydroxyl-modified ZrO2 facilitated the hydrolysis process of CH3SH to a greater extent than that of C2H6S. This study provides theoretical guidance for industrial applications and the design of hydroxyl-containing hydrolysis catalysts.