Water Resistance Properties Research Articles

Hydrophobic deep eutectic solvent-based eutectogels for underwater sensing

Eutectogels derived from deep eutectic solvents (DESs) exhibit great potential for the fabrication of flexible sensors. However, the hygroscopicity of eutectogels hinders their applications in underwater sensing. In this work, a hydrophobic eutectogel with exceptional long-term underwater stability is produced through one-step polymerization of lauryl methacrylate and glycidyl methacrylate in a hydrophobic DES. The hydrophobic gel network and hydrophobic DES fulfill the eutectogel with outstanding water resistance (water contact angle > 110°) and excellent mechanical properties in an aqueous environment, thus leading to extraordinary durability (over 1000 testing cycles). Additionally, based on this eutectogel, underwater strain and pressure sensors with high sensitivity, rapid responsiveness, and superior durability were fabricated for accurate real-time monitoring of human activity. Furthermore, it has been demonstrated that the eutectogel sensor can transmit information through Morse code, performing as a wearable underwater communicator. This research provides an exemplary way for a demonstration method of hydrophobic eutectogel for durable underwater applications.

Sodium alginate/guar gum based nanocomposite film incorporating β-Cyclodextrin/persimmon pectin-stabilized baobab seed oil Pickering emulsion for mushroom preservation

The poor biological, mechanical and water-resistance properties of sodium alginate/guar gum film (SG) limit its application in food preservation. To overcome this disadvantage, we added β-Cyclodextrin/persimmon pectin-stabilized baobab seed oil Pickering emulsion (BOPE) to enhance the mechanical and water resistance properties of SG film, and added green synthesized silver nanoparticles (AgNPS) and Lycium ruthenicum extract (LA) to improve the biological properties of the film. The properties of BOPE was optimized using Box–Behnken design (BBD). Scanning electron microscope and Fourier transform infrared results revealed the change of structure and molecular interaction in the SG film after the addition of AgNPS, LA, and optimized BOPE. The 2.0%BOPE-loaded film containing AgNPS/LA with the enhanced mechanical, barrier, BO retention, and biological properties not only improved the preservation effect on mushroom (A. bisporus), but also maintained structural stability. Thus, the 2.0%BOPE-loaded SG/LA/AgNPS film has considerable potential in active packaging applications.

Tannic Acid and Ca2+ Double-Crosslinked Alginate Films for Passion Fruit Preservation.

In this study, the interaction of different concentrations of tannic acid (TA) (10%, 20%, and 30% w/w) and Ca2+ with alginate (SA) was utilized to create double-crosslinked SA films. The resulting films were evaluated for their optical, mechanical, water resistance, and barrier properties, and their microstructure and intermolecular interactions were also characterized. The SA films containing 20% TA showed the best mechanical properties, with an observed increase in tensile strength of 22.54%. In terms of water vapor permeability, the SA film containing 30% TA exhibited the highest barrier property, which was 25.36% higher than that of the pure SA film. Moreover, TA demonstrated a strong UV absorption ability, resulting in a nearly 0% UV transmittance of the SA film at 280 nm. It can be seen that SA films containing 20% TA have excellent barrier and mechanical properties, and the development of such films will be applied to the storage and packaging of fresh food. It is worth noting that this work also investigated the effect of SA coatings containing different concentrations of TA on the preservation of passion fruits for 7 days. The results revealed that passion fruits treated with SA coatings containing a 30% TA concentration maintained a better appearance on the 7th day and had the lowest weight loss and crumpling indices of approximately 8.98% and 2.17, respectively, compared to the other treatment groups. Therefore, based on the overall results, the addition of 30% TA to SA coatings proved to be more effective and can be considered a promising approach for delaying fruit senescence and decay.

Silver Bionanocomposites as Active Food Packaging: Recent Advances & Future Trends Tackling the Food Waste Crisis

Food waste is a pressing global challenge leading to over $1 trillion lost annually and contributing up to 10% of global greenhouse gas emissions. Extensive study has been directed toward the use of active biodegradable packaging materials to improve food quality, minimize plastic use, and encourage sustainable packaging technology development. However, this has been achieved with limited success, which can mainly be attributed to poor material properties and high production costs. In the recent literature, the integration of silver nanoparticles (AgNPs) has shown to improve the properties of biopolymer, prompting the development of bionanocomposites. Furthermore, the antibacterial properties of AgNPs against foodborne pathogens leads towards food shelf-life improvement and provides a route towards reducing food waste. However, few reviews have analyzed AgNPs holistically throughout a portfolio of biopolymers from an industrial perspective. Hence, this review critically analyses the antibacterial, barrier, mechanical, thermal, and water resistance properties of AgNP-based bionanocomposites. These advanced materials are also discussed in terms of food packaging applications and assessed in terms of their performance in enhancing food shelf-life. Finally, the current barriers towards the commercialization of AgNP bionanocomposites are critically discussed to provide an industrial action plan towards the development of sustainable packaging materials to reduce food waste.

A tough bio-adhesive inspired by pearl layer and arthropod cuticle structure with desirable water resistance, flame-retardancy, and antibacterial property

Petroleum-derived formaldehyde resin adhesives are serious hazards to human health and depend on limited resources. Abundant, cheap and renewable biomass materials are expected to replace them. However, the contradictory mechanisms of high mechanical strength and fracture toughness affect the use of bioadhesives. Herein, a biomimetic soybean meal (SM) adhesive inspired by the structure of insect cuticles and shell pearl layer was proposed. Specifically, chitosan (CS@DA) modified 3,4-dihydroxybenzoic acid (DA, rich in catechol moiety) was anchored on molybdenum disulfide nanosheets (MoS2) to construct a biomimetic structure with copper hydroxide and SM substrate (SM-MoS2/CS@DA-Cu). Schiff base, ionic, and hydrogen bonding strengthened the cohesion of the adhesive. The ordered alternating stacking “brick-mortar” structure stimulated the lamellar sliding and crack deflection of MoS2, synergistically reinforcing the toughness. Compared to SM adhesive (0.57 MPa and 0.148 J), the wet shear strength and adhesion work of the SM-MoS2/CS@DA-Cu were 1.68 MPa and 0.867 J, with 194.7 % and 485.8 % increases, respectively. The multiple antimicrobial effects of CS@DA, Schiff base, and Cu2+ increased the applicability period of the adhesive to 40 days. The adhesive also displayed favorable water resistance and flame retardancy. Therefore, this peculiar and efficient biomimetic structural design inspired the development of multi-functional composites.

Magnesium oxychloride cement with hydrophobic pore network for utilizing as oil well cement

Magnesium oxychloride cement (MOC) possesses some excellent characteristics, which can be used as oil well cement, to deal with the complex environmental conditions in oil and gas wells. However, the water resistance property of MOC is poor. In this study, a new type of magnesium oxychloride cement (MOC) with improved water resistance was developed by modifying the pore structure of pure MOC using hydrophobic admixtures. To assess the performance of the new MOC, a range of tests were performed, including compressive strength, softening coefficient, capillary water absorption, pore size distribution, mineral composition and microstructure analysis. The results showed that the pore size distribution of the MOC was altered from a large pore-dominant structure to a small pore-dominant one. The hydrophobic admixture and the gel substance formed on the strength-providing phases prevented them from water erosion, resulting in enhanced strength and water resistance. This new type of MOC has the potential to be used in challenging environments, such as oil and gas wells and underwater structures.

An ultra-thin and highly efficient electromagnetic interference shielding composite paper with hydrophobic and antibacterial properties

Facing the increasing electromagnetic interference (EMI) pollution in the living environment, it is a new trend to explore an efficient EMI shielding material with facile fabrication and a wide range of application scenarios. A hydrophobic composite paper composed of silver nanowires (AgNWs) and kapok microfibers cellulose (MFC) was modified by methyl trimethoxy silane (MTMS) through a simple method. As a result, the composite paper has a good EMI shielding effectiveness (EMI SE) of 61.7 dB with electrical conductivity of 695.41 S/cm. The modification of MTMS improved the thermal stability performance of composite paper, which also increased its water contact angle to 113°. The free silver ions (Ag+) released from AgNWs can kill surrounding microbial bacteria, endowing the composite paper with good antibacterial property. Water resistance and antibacterial property enable MTMS/AgNWs/MFC composite paper to cope with complex application environments.

Effect of K2WO4 on structure and properties of low melting glasses in K2O–Fe2O3–P2O5 system as sealing materials

New phosphate glasses based on the K2O–Fe2O3–P2O5 system, with variable K2WO4 content in place of Fe2O3, are prepared through the melt quenching route. The thermal and structural characteristics and water resistance properties are studied for sealing applications by means of XRD, DSC, and FTIR spectroscopic and dilatometry measurements. The results showed an amorphous nature and a linear increase in the parameters of the glass density and molar volume with the addition of K2WO4. While the glass transition (Tg), crystallization (Tc) temperatures, the thermal stability (ΔT), and the relative criterion (H) values were decreased are decreased. Inversely, the ΔCp values were markedly increased with growing NBO bonds that led to markedly increase in the O/P ratio. Also, the coefficient of thermal expansion (CTE) is increased (from 124 to 211 × 10−7/oC). The glass with high K2WO4 content is a suitable sample for excellent sealing properties with a low transition temperature (Tg < 300 °C), a very low melting point, and a high thermal expansion value (211 × 10−7/oC). As well, the durability values of the examined samples decreased, but they were in the range of those for commercial sealing glass. The study offers fresh suggestions for the development of sealant materials that are both low-temperature and environmentally safe.

Study on mechanism of cellulose nanocrystals on hydrophobic phthalocyanine green in aqueous phase

Phthalocyanine green is a hydrophobic pigment with excellent properties, which is usually dispersed in the organic phase. However, most organic phases are volatile and harmful to the environment and organisms. Therefore, phthalocyanine green dispersed in the aqueous phase has development potential. In this work, cellulose nanocrystals (CNCs) were used as dispersant and stabilizer to disperse phthalocyanine green in the aqueous phase. Phthalocyanine green was added to CNCs colloid to prepare phthalocyanine green suspensions with good dispersibility and stability. The particle size, zeta potential, absorbance and microstructure of the phthalocyanine green suspensions were tested and analyzed. The results showed that CNCs had good dispersibility and stability to phthalocyanine green due to charge repulsion and steric hindrance. The phthalocyanine green suspensions were nano-sized and had well compatibility with different types of coating forming substances. The coatings of the mixture had good water resistance, adhesion and mechanical properties. The suspensions had the application property and could be mixed with coating forming substances to prepare coating materials. As a renewable and easily degraded biomass resource, CNCs are expected to become a new dispersant and stabilizer for pigment.

The Standard for Assessing Water Resistance Properties of Lubricating Grease Using Contact Angle Measurements

Many grease-lubricated machines operate in wet environments, and are vulnerable to contamination because of water exposure. Reports suggest that even the presence of 1% water in grease reduces the life of a bearing by 90%. Nevertheless, only a few qualitative tests and standards are available to characterize the water resistance properties of greases. In this paper, we propose a standard for evaluating the water resistance properties of greases by studying their hydrophobic and hydrophilic nature via a custom-designed apparatus for measuring the grease contact angle. In this approach, a water droplet is dispensed onto the surface of the grease and the contact angle of the droplet is studied. For this purpose, an apparatus was designed, built, and tested with twelve different greases. To validate the efficacy of the test method and setup, tests were performed at two different locations by independent operators. From the obtained contact angle values, the authors propose categorizing a grease’s water-resistance properties into five different grades that can be set as guidelines for the industrial user when selecting a grease for machinery operation in a wet environment. The classification of the water-repellent properties of greases, using the proposed standard is compared with existing ASTM standards used for evaluation of grease properties in the presence of water.

Sustainable ultra‐strong thermally conductive wood‐based antibacterial structural materials with anti‐corrosion and ultraviolet shielding

AbstractIn light of the uprising global development on sustainability, an innovative and environmental friendly wood‐based material derived from natural pinewood has been developed as a high‐performance alternative to petrochemical‐based materials. The wood‐based functional material, named as BC‐CaCl2, is synthesized through the coordination of carboxyl groups (−COOH) present in pinewood with calcium ions (Ca2+), which facilitates the formation of a high‐density cross‐linking structure through the combined action of intermolecular hydrogen bonds. The as‐prepared BC‐CaCl2 exhibits excellent tensile strength (470.5 MPa) and flexural strength (539.5 MPa), establishing a robust structural basis for the materials. Meanwhile, BC‐CaCl2 shows good water resistance, thermal conductivity, thermal stability, UV resistance, corrosion resistance, and antibacterial properties. BC‐CaCl2 represents a viable alternative to petrochemical‐based materials. Its potential application areas include waterproof enclosure structure of buildings, indoor underfloor heating, outdoor UV resistant protective cover, and anti‐corrosion materials for installation engineering, and so forth.image

Water-resistant, antibacterial, PDA@ZnO/PLA cellulose composite paper with thermoformability

A method for the preparation of thermoformable and water-resistant antibacterial cellulose composite paper is proposed by immobilizing synthetic PDA@ZnO on the cellulose surface and allowing PLA to penetrate into the cellulose network. The mechanical properties, thermoformability, water resistance and antibacterial properties of cellulose composite papers were investigated. The results show that the 8 % PDA@ZnO/PLA cellulose composite paper achieved the tensile strength of 14.14 MPa, the water contact angle of 105 deg., the water absorption of 34.3 % and exhibited excellent antibacterial activity against E. coli. In addition, the composite paper can achieve the transformation of cellulose network from two-dimensional to three-dimensional and synthesize three-dimensional packaging materials directly by thermoforming, which have potential for wide application.

The Effect of Different Waste Material Binders in Relation to Khaya Senegalensis Solid Fuel Pellet Quality

Fuel pellets are an attractive renewable energy source derived from biomass sources thanks to their uniformity and ease of handling. However, raw biomass and waste material binders have several drawbacks, which include poor physical properties, particularly low density and compositional heterogeneity, which restrict their wider use as a general source of energy. Besides, due to the low energy density, low bulk density, and uneven shape and size of raw biomass, it is very difficult to store and transport biomass in its original form, which decreases transport efficiency. This study investigated the effect of waste material binders (rice husk, corn cob, and sugarcane bagasse) on the mechanical and thermal properties of Khaya Senagalensis pellets. The mechanical and thermal properties were determined according to ASTM standards. Waste material binders have affected pellet quality such as density, bulk density, moisture content, durability, compressive strength, shatter index, water resistance, ash content, volatile matter, fixed carbon, and calorific value. From the analysis, sugarcane bagasse as a binder shows the highest quality pellet in terms of mechanical properties. Sugarcane bagasse produces the highest density (0.967g/cm3), bulk density (0.4094), durability (99.71%), shatter index (98.85%), water resistance (98.35%), and thermal properties, which are the highest volatile matter (94.71%) and the lowest ash content (1.71%). In a nutshell, sugarcane bagasse is a good binder that gives a positive impact to the K.senegalensis pellets in terms of storage and transportation compared to corn cob and rice husk binder.

Active and intelligent collagen films containing laccase-catalyzed mulberry extract and pickering emulsion for fish preservation and freshness indicator

Given the growing emphasis on food safety, the need for functionalized packaging is becoming more prominent. Cinnamon essential oil (CEO)-based Pickering emulsions can impart excellent anti-bacterial and anti-oxidant activities to collagen films through slow-release actives, but the resultant films exhibit reduced water resistance and mechanical properties that may limit their application. In this study, oxidized mulberry extract (OME) was prepared by laccase oxidation and used as an enhancer to improve the physicochemical properties of CEO-based Pickering emulsion collagen films. The incorporation of OME enhanced the tensile strength (79.18–106.35 MPa) and water resistance (water vapor permeability, 2.82–2.30 × 10−11 (g·m−1·s−1·Pa−1); water sorption, 524.57%–201.28%) of the films. The films also exhibited superior light-blocking, antioxidant, and antibacterial activities as well as pH sensitivity. When the COL-PE/OME 4 film was used for fish preservation, a four-day extension of shelf life was observed and the film showed a visible color change (ΔE > 5) from red (day 0) to blackish-green (day 12) reflecting the degree of freshness of the stored fish. These findings indicate the potential of the functionalized collagen films for fish preservation and indicators of freshness.

High-performance bamboo scrimber composite prepared from heat-treated Bambusa chungii units with different resin contents for outdoor use

In this study, bamboo scrimber composites (BSCs) was prepared using two types of bamboo units and a phenolic (PF) resin, and the effect of heat treatment on water resistance and mechanical properties was investigated. The results showed that heat treatment significantly improves dimensional stability but degrades mechanical performance owing to a change in chemical composition and decreased porosity. Furthermore, the water resistance increases with an increase in resin content. The WAR and TSR of BSC-T-II reached 3.74% and 3.72%, respectively, at 25 wt% resin content. Heat treatment modification does not significantly improve the flame retardancy of BSCs, and future studies should consider treating bamboo with flame retardants. The BSCs have the potential to replace nonrenewable synthetic materials for outdoor use by optimizing heat treatment, bamboo unit processing, and resin content.

Vanillin cross-linked chitosan/gelatin bio-polymer film with antioxidant, water resistance and ultraviolet-proof properties

Cross-linking is the most promising method for preparing high-performance chitosan/gelatin bio-polymer film. In this work, vanillin cross-linked chitosan/gelatin bio-polymer (CGGV) film with good mechanics, water resistance, antioxidant and ultraviolet-proof property was prepared. The micro-structure, physical and functional properties of CGGV film were studied. Results showed that vanillin as a cross-linking agent provided a compact inner micro-structure through Schiff base and hydrogen bond interaction. Moderate cross-linking significantly improved mechanical strength, thermal ability, hydrophobicity of the films and reduced the water vapor permeability, swelling ratio and water solubility. Especially, CGGV films showed stronger ultraviolet-proof properties and possessed potent radical scavenging activity. Therefore, CGGV film is suitable to protect per-mature fruits and could be used as novel multifunctional packaging in the agriculture and foods industry.

Development of a hydrophobic cement mortar with controllable strength: Preparation and micro-mechanism analysis

The widespread utilization of hydrophobic concrete in applications is often hindered by the significant decrease in mechanical properties observed when traditional modifiers are added to cement mortars. To address this issue, the present study introduces a novel hydrophobic additive called modified mica powder (MMAP). This additive has been developed specifically to enhance the water and corrosion resistances of cement mortar. To determine the optimal mix ratio, the effects of modifiers, particle sizes of MAP, and various preparation methods of MMAP were investigated. These parameters were analyzed in relation to the mechanical properties and water absorption characteristics of the MMAP modified cement mortar. As a result of the experiments, it was found that the capillary water absorption of the MMAP modified cement mortars was reduced by 23.5%-64.4% in comparison to that of the unmodified ones. More importantly, the MMAP had no adverse effect on the mechanical properties of the cement mortar, which was superior to that of the MAP addition using conventional methods. furthermore, the microscopic characteristics of both MMAP and MMAP modified cement mortar were examined using techniques such as FTIR, SEM, and EDS. Through these analyses, insights into the hydrophobic mechanism of the MMAP modified cement mortar were obtained, shedding light on the underlying processes and interactions responsible for its enhanced water resistance properties.

STUDY OF WATER INFLUENCE ON WATERPROOFING MATERIAL "POLYISOL-M"

The paper presents the results of experiments to study the properties of water absorption and water resistance of the waterproofing material "Polyisol-M". As a result of experimental analysis the water absorption capacity of the waterproofing material "Polyisol-M" with thickness of 5 mm was 0,59 %, and the value of mass loss was 2,42 %, therefore it was recommended to use it in production.

Study on hydroxypropyl corn starch/alkyl ketene dimer composite film with enhanced water resistance and mechanical properties

This study aimed to address the limited applicability of starch-based films in food packaging due to their inherent hydrophilicity, by developing a highly hydrophobic and mechanically reinforced film through compositing with alkyl ketene dimer (AKD). The FTIR analysis confirmed the successful introduction of AKD into the starch backbone via esterification by forming a β-keto ester linkage. Notably, the incorporation of AKD resulted in significant improvements in the modified film (S80A20), by exhibiting a higher water contact angle (WCA) of 128.28° and a reduced water vapor permeability (WVP) to 0.81×10-10 (g m/m2 s Pa). These enhancements were attributed to the inherent low surface energy of AKD and the increased surface roughness caused by AKD recrystallization. Moreover, the mechanical properties of the films were also enhanced due to the chemical crosslinking and intermolecular hydrogen bonding, as supported by the results of relaxation temperatures and molecular dynamics simulations. Considering the environmentally friendly and biodegradable nature of all components, the prepared hydrophobic films will hopefully be applied in food packaging.

Enhancement of the mechanical properties and water barrier properties of thermoplastic starch nanocomposite films by chitin nanofibers: Biodegradable coating for extending banana shelf life

Starch-based films have limited applications due to their hydrophilicity and poor mechanical performance. Herein, thermoplastic starch (TPS) nanocomposite films with chitin nanofibers (ChNFs) extracted from shrimp-shell waste were successfully fabricated using a solvent casting method. We investigated the effects of the ChNF loadings on the physical, mechanical, and water vapor barrier properties of the nanocomposite films. The well-dispersed ChNFs within the soft matrix associated with the formation of interfacial bonding between ChNFs and starch facilitated the efficient stress transfer from the soft matrix to the stiff ChNFs. Additionally, the presence of ChNFs created tortuous pathways within the films, which could impede the diffusion of water molecules. This resulted in a significant improvement in the mechanical properties, wettability, water resistance, and water vapor barrier properties of the nanocomposites. Compared to the results obtained from the neat TPS films, the TPS nanocomposites reinforced with ChNFs exhibited a 300% higher tensile stress, a 603% Young's modulus, and a considerable increase in the water contact angle, shifting from 86.2° to 98.6°. Furthermore, the ChNF-reinforced nanocomposite films showed no fragmentation after being soaked in water for 12 h under vigorous stirring, whereas the neat TPS films disintegrated under the same conditions. Interestingly, we found that coating a suspension of TPS and ChNFs on bananas effectively delayed their aging, preventing the color change from green to yellow. This promising result demonstrates the potential of the developed coating to extend the shelf life of fresh food produce, reducing food waste and the reliance on single-use petroleum-based packaging.