Water Resistance Properties Research Articles

Effect of Structural Design on the Pore Structure, Water Resistance, and Mechanical Properties of Engineered Wood/Bamboo Laminated Composites.

An important principle in rational manufacturing design is matching the properties of composites to their intended uses. Herein, six laminated composites (LCs) were manufactured using fibrous moso bamboo and poplar veneer units, and their pore structure, water resistance, and mechanical properties were evaluated. The LC density (640-1290 kg/m3) increased significantly with increasing bamboo veneer unit content. The LC surface texture and roughness depended on the density and type of surface layer. With increasing LC density, the water absorption rate (WAR), width swelling rate (WSR), and thickness swelling rate (TSR) decreased exponentially and the mechanical properties increased linearly. This behavior was closely related to the changes in pore structure caused by density. Notably, the water resistance and mechanical properties of the LCs with densities higher than 910 kg/m3 were superior to the highest levels specified in GB/T 20241-2006 for ''laminated veneer lumber'' and GB/T 30364-2013 for "bamboo scrimber flooring". Thus, these engineered materials are promising for outdoor structures and flooring.

Mechanical and water resistance performance of physically cross-linked poly(vinyl alcohol) composite with poly(dopamine) modified cellulose nanocrystals

A novel strategy was developed for the construction of physically cross-linked poly(vinyl alcohol)- PVA composite reinforced by poly(dopamine) modified cellulose nanocrystals (PDA@CNCs) with robust mechanical and water resistance property. The PDA@CNC hybrid had improved thermal stability and the rod-like morphology of CNCs was well preserved after the PDA modification. The Young’s modulus, tensile strength and water resistance property of physically cross-linked PDA@CNC/PVA composites were obviously improved compared with the composites without cross-linking. The improved properties of the PDA@CNC/PVA composites were attributed to the destruction of intramolecular hydrogen bond and reconstruction of intermolecular hydrogen bonds as well as ferric ions coordination cross-linking interactions. The excellent mechanical and water resistance property of the developed PDA@CNC/PVA provides a path way for the development of water induced-mechanically adaptive PDA@CNC functional nanocomposites for applications such as direct ink writing in 3D/4D printing.

Effect of tannin on the bonding performance and mildew resistance of soybean meal-based adhesive

For improving the water resistance, bonding performance, and anti-mildew property of the soy protein-based adhesive (SPA), in this research, based on cross-linking enhancement theory, soybean meal flour as the main raw material, self-synthesizing triglycidylamine (TGA), and larch tannin (LT) were used to build efficient crosslinking water-resistant structure and develop SPA. The effect of LT addition on the physical properties, bonding strength, and anti-mildew property of the resultant adhesive was investigated. The results showed that the residual rate of SPA with 4 % LT and 3 % TGA was improved by 2.1 % and the corresponding moisture absorption rate was reduced by 20.1 % compared with the SPA only modified by 3 % TGA. In addition, the SPA with 4 % LT and 3 % TGA had a 42.3 % increase in bonding strength, reaching 1.11 MPa, which satisfied the standard requirements of interior use plywood (≥ 0.7 MPa). The improved water-resistant bonding performance is mainly because interaction forces, such as hydrogen bonds, ionic bonds, and covalent bonds, formed between tannin and protein, and under the cross-linking effect of TGA, the whole cross-linking system forms a dense network structure. LT not only had a reinforcing effect on the SPA but also could prolong the pot life of the adhesive for 60 h due to the phenolic hydroxyl groups of tannin. Compared with the commercial anti-mildew agents, the mildew resistance before and after curing is the following: 1,2-benzisothiazole in-3-one > LT > sodium tetraborate > potassium sorbate. • An easy-to-produce, high-performance, and environmentally friendly bio-adhesive was developed. • The incorporation of larch tannin enhanced the cohesion and mechanical properties of adhesives. • The resultant adhesive has better water-resistant bonding performance and an anti-mildew effect. • Effectively extend durability of plywood prepared by adhesive and storage period of the SPAs.

Biomass-based functional film integrated with nitrogen-coordinating boronic ester and cellulose-barium titanate nanohybrids

Although renewable and biodegradable biomaterials have received considerable attention as sustainable alternatives to traditional petrochemical plastics, their production and application have been limited due to insufficient mechanical properties and high hydrophilicity. In this study, we report a green and facile strategy for the preparation of a gelatin-based film with enhanced mechanical strength, water resistance, and electrochemical properties. The nitrogen-coordinating boronic ester (BN), prepared from diethanolamine and boronic acid, acted as a dynamic glue linkage. Introducing hydrophobic long-chain fatty acids of stearic acid (SA) formed a cross-linked network with BN and gelatin through bioconjugation, effectively improving the film’s water resistance. Moreover, nanofibrillated cellulose assisted the dispersion of BaTiO3 particles as a hybrid enhancement nanophase to enhance the performance of the composite film. The toughness and tensile strength of the as-prepared composites reached 22.35 MJ/m3 and 23.30 MPa, which were 424.6 % and 193.1 % higher than the neat gelatin film. Attractively, incorporating BaTiO3 nanoparticles with a high-dielectric constant endowed the film with excellent electrochemical performance. In addition, the hybrid film exhibited substantially enhanced ultraviolet-blocking properties and thermal stability. This multifunctional gelatin-based film is expected to significantly advance the industrial production and application of biomaterials in hydrogels, adhesives, and coatings.

Correlation between interfacial adhesion and functional properties of corn stalk cellulose-reinforced corn starch-based biodegradable straws

To study correlation between interfacial adhesion and properties of corn starch/corn stalk cellulose (CSC) biodegradable straws, the interfacial adhesion and functional properties of the starch-based straws with different cellulose contents were analyzed and compared. The results showed that the starch/CSC straw with 1 % CSC (SC1) had the highest interfacial adhesion between starch and cellulose, resulting in higher mechanical properties and water resistance. Compared to starch/CSC straw with 0 % CSC, water absorption rate of SC1 decreased by 13.0 % (4 °C, 1 h) and 18.4 % (25 °C, 1 h), respectively. The fracture strength and fracture deformation increased by 47.8 % and 59.6 %, respectively. The strength increased by 3.93 (4 °C, 30 min) and 1.53 (25 °C, 30 min) times after soaking, respectively. The soil degradation rate of SC1 was 89.5 % on the 20th day and thermal degradation rate was 79.6 % at 600 °C. The SC1 with better properties (soil degradability, water resistant and mechanical properties) was as economical as paper straw.

Effect of Coating Process on Properties of Two-Component Waterborne Polyurethane Coatings for Wood

Acrylic acid has good environmental weather resistance, water resistance, alcohol resistance, dirt resistance, and other properties. An acrylic acid dispersion with a core–shell structure was prepared and reacted with a polyisocyanate-type curing agent to prepare a waterborne polyurethane topcoat suitable for wood. The prepared two-component polyurethane topcoat was used in combination with a waterborne primer and a waterborne sealing primer and applied to Pine (Pinus strobus) boards to carry out gloss, wear resistance, and adhesion experiments. The effects of different coating amounts and spraying times on the comprehensive properties of the wood coatings were studied. The experimental results showed that when the self-made two-component polyurethane topcoat for wood was matched with the primer and the sealing primer, the coating amount of the sealing primer had little effect on improving the adhesion and wear resistance but had a significant effect on the gloss. The spraying times of the primer and the topcoat greatly impacted the adhesion, but they had no decisive impact on the improvement of the gloss. When the coating amount was 60 g/m2 for the waterborne sealing primer, 100 g/m2 for waterborne primer, and 120 g/m2 for the self-made topcoat and the coating was sprayed twice, the comprehensive performance of the obtained film on the wood was the best. This research on the preparation and coating process optimization of the two-component waterborne polyurethane coatings for wood can provide a technical basis for the application of two-component waterborne polyurethane topcoats for wood.

Influence of Dielectric Barrier Discharge Cold Plasma Treatment on Starch, Gelatin, and Bacterial Cellulose Biodegradable Polymeric Films

The environmental damage caused by plastic packaging and the need to reduce pollution requires actions to substitute plastic materials for more sustainable and biodegradable materials. Starch, gelatin, and bacterial cellulose films are three potential biodegradable polymeric films for use in packaging. However, these materials need improvements in their physical, chemical, and mechanical properties to be used in packaging. In this work, these films were treated with cold plasma to evaluate the effects of treatment conditions on several physical, chemical, and mechanical properties. The dielectric barrier discharge plasma technology was applied with varying treatment times (0 to 20 min) and excitation frequencies (50 to 900 Hz) at 20 kV. The optimal excitation frequency for starch films (50 Hz) was different from the optimal frequency for gelatin and bacterial cellulose films (900 Hz), indicating a high dependency on the treatment in this variable that is often neglected. Plasma treatment improved the hydrophobicity, surface morphology, water resistance, and mechanical properties of all three films, with the advantage of not recurring to chemical or biological additives.

Nitrogen-Doped Porous Carbon from Biomass with Efficient Toluene Adsorption and Superior Catalytic Performance.

The chemical composition and surface groups of the carbon support affect the adsorption capacity of toluene. To investigate the effect of catalyst substrate on the catalytic performance, two different plant biomasses, banana peel and sugarcane peel, were used as carbon precursors to prepare porous carbon catalyst supports (Cba, Csu, respectively) by a chemical activation method. After decorating PtCo3 nanoparticles onto both carbon supports (Cba, Csu), the PtCo3-su catalyst demonstrated better catalytic performance for toluene oxidation (T100 = 237 °C) at a high space velocity of 12,000 h-1. The Csu support possessed a stronger adsorption capacity of toluene (542 mg g-1), resulting from the synergistic effect of micropore volume and nitrogen-containing functional groups, which led to the PtCo3-su catalyst exhibiting a better catalytic performance. Moreover, the PtCo3-su catalyst also showed excellent stability, good water resistance properties, and high recyclability, which can be used as a promising candidate for practical toluene catalytic combustion.

Improving water resistance and mechanical properties of waterborne acrylic resin modified by 3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl ether

3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl ether (TMBPDGE) modified waterborne acrylic resin with excellent water resistance and mechanical properties was synthesized by a homogeneous solution polymerization. Infrared analysis revealed that TMBPDGE could successfully participate in the synthesis. On this basis, the experimental conditions such as polymerization method, solid content, monomer addition method and curing temperature are optimized by using the results of immersion test, contact angle, tensile strength, elongation at break and hardness determination. The optimal amount of TMBPDGE is investigated and the resin is further characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The experimental results show that when the amount of TMBPDGE is 10 wt%, the water resistance and mechanical properties of the resin are greatly enhanced, and the cured resin film modified by TMBPDGE can withstand the soaking in water for more than 35 days, while that of film without modification is only one day. The tensile strength can reach 9.12 MPa, which is 2.2 times than that of the film without modification. Based on the enhanced properties, the modified resin provides a great potential in the fields of wood coatings, which require good water resistance and mechanical properties.

Incorporation of silver nanoparticles/curcumin/clay minerals into chitosan film for enhancing mechanical properties, antioxidant and antibacterial activity

It is popular that natural organics are served as green reducing and end-capping reagent for synthesis of functional nanoparticles. In this study, curcumin, a natural pigment, was employed to prepare silver nanoparticles (AgNPs) as a coloring, reducing and end-capping agent by an eco-friendly, economic and facile approach in the presence of different clay minerals, including palygorskite, montmorillonite and mixed-dimensional palygorskite clay. It was found that the phenolic hydroxyl groups or carbonyl groups of curcumin played a crucial role to reduce silver ions into AgNPs with the ginger color. Meanwhile, incorporation of clay minerals could induce the in-situ heterogeneous nucleation of AgNPs on the surface or/and interlayer of the involved clay minerals. It effectively prevented from the aggregations and resulted in uniform dispersion of AgNPs with a diameter of 30–40 nm. Furthermore, the as-prepared nanocomposites exhibited a higher antioxidant (>90%) and antibacterial activity. Due to the synergistic effect of each component among the nanocompositions, the nanocomposites derived from different clay minerals were employed as multifunctional nanofillers to design functional chitosan composite films. By contrast, the chitosan composite films containing curcumin-capped AgNPs/mixed-dimensional palygorskite clay nanocomposites exhibited the best mechanical properties, antioxidant and antibacterial activities. Compared with the chitosan films, the tensile strength and elongation at break of composite films increased by 15.90 MPa and 27.27%, respectively. The inactivation rate of the composite films against Escherichia coli and Staphylococcus aureus had reached 100%. Therefore, the obtained composite film with the ginger color exhibited excellent mechanical, water resistance, antioxidant and antibacterial properties, and it was expected to develop a great potential functional packaging materials.

Material properties and water resistance of inorganic–organic polymer coated cellulose paper and nanopaper

Cellulose-based materials represent a renewable, biodegradable, and environmentally friendly alternative to plastic from fossil resources. Nanopaper is a strong and lightweight material formed from cellulose nanofibrils (CNFs). Paper and nanopaper have been considered as excellent alternatives to plastics for use in agriculture and for packaging applications. However, common for both paper and nanopaper is their hydrophilic character, and consequently, poor water-resistance properties. ORMOCER®s are a class of inorganic–organic polymers with excellent barrier and protective properties used for a range of coating applications. Here we present ORMOCER®-coated paper and nanopaper. The coated papers and nanopapers are characterized, both in terms of their morphology, hydrophobicity, and mechanical properties. We demonstrate that the pressure used during the pressing and drying of paper and nanopaper influence their tear and tensile—properties, and that the morphology of the coated nanopaper differs significantly from that of the coated paper. While the ORMOCER® was impregnated within the porous network of the paper, a well-defined two-layered morphology was obtained with the coated nanopaper. Further, the biodegradability of the nanopaper with and without coating was assessed. The degradation study demonstrated that both the pressure used during the pressing and drying of the nanopaper, and the composition of the ORMOCER®, influenced the rate of degradation. Taken together, ORMOCER®-coated paper and nanopaper are promising for the preparation of materials that are both water-resistant, renewable, and biodegradable.

A smart film incorporating anthocyanins and tea polyphenols into sodium carboxymethyl cellulose/polyvinyl alcohol for application in mirror carp

Multifunctional food packaging films were developed based on polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), tea polyphenol (TP) and black carrot anthocyanin (CA). Results of Zeta potential, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction showed that CA enhanced the stability of the particle dispersion system through hydrogen bonding and electrostatic interactions, promoted the compatibility between TP and PVA-CMC (PC) substrates, and enhanced the binding between the components of the films. Because of the interaction of TP and CA, PC-TP-CA films had better water resistance and water vapor barrier properties, thermal stability, antioxidant and antimicrobial properties. PC-CA and PC-TP-CA films exhibited excellent UV-blocking properties. They also showed distinct color responsiveness in the pH range of 2–13, significant sensitivity to ammonia vapor in a short period of time and excellent color stability over 20 days of storage under different conditions. When the film was applied to fish, it was found that PC-TP-CA film could extend the shelf life of fish by 1–2 days and successfully monitor the freshness of the fish in real-time. Considering all the physical and functional properties, the non-toxic and biodegradable PC-TP-CA film has excellent potential as a new multifunctional food packaging material in the future.

Modified natural rubber latex film-forming enhances bamboo scraps/magnesium oxychloride composites

Bamboo scraps/magnesium oxychloride composites are new low carbon and environmentally friendly building materials. Its development not only reduces carbon dioxide emissions, but the use of bamboo scraps can improve bamboo utilization rates and play important roles in protecting the environment. However, in some environments, water resistance is problematic and mechanical strength decreases, thereby seriously affecting applications in architectural settings. Natural rubber latex (NRL) can be coated after dehydration and film forming, and modified by surfactants to improve cement properties. In this study, natural rubber latex modified by sodium dodecyl sulfate (S-NRL), was used as a modifier to improve bamboo scraps/magnesium oxychloridee composite properties. The results showed that after S-NRL addition, latex films formed by water loss not only filled voids in bamboo scraps/magnesium oxychloride composites, but also generated surface negative charges. These were adsorbed by magnesium (Mg2+) ions, at strength phase-5, and formed surface waterproof protective films to prevent water erosion. Thus, composite mechanical and water resistance properties were enhanced; when S-NRL was at 0.3%, mechanical strength and water resistance properties were at a maximum after curing for 28 days.

Fabrication of multifunctional materials based on chitosan/gelatin incorporating curcumin-clove oil emulsion for meat freshness monitoring and shelf-life extension

A new multifunctional film with active and intelligent effects was developed by incorporating curcumin-clove oil emulsion into natural materials. The basic properties, functional characteristics, and pH/NH3-sensitivity of films were investigated, and then these films were applied to extend shelf-life and monitor freshness of meat. Curcumin solution and emulsion illustrated significant color variations at different pH values. The incorporation of emulsion improved the UV–vis barrier and water resistance properties of films, which blocked most of UV-light and its water contact angle reached 100.03°. Meanwhile, the films had stronger mechanical strength and higher thermal stability, with elongation at break reaching 79.18 % and the maximum degradation temperature rising to 316 °C. Moreover, emulsion made films have a slow-release effect on clove oil, which not only enhanced the antioxidant property but also significantly improved their antibacterial activity. Additionally, the multifunctional films presented a significant color response to acidic/alkaline environments over a short time interval and could be easily identified by naked eyes. Finally, the films effectively extended the shelf-life of fresh meat by 3 days at 4 °C and visually monitored freshness through color changes in real-time. This knowledge provides insights and ideas for the development of novel food packaging with both active and intelligent functions.

Fabrication and properties of inspired green modified cellulose/cassava starch blend

Cassava starch (CS) has poor water resistance and it is limited to use in applications such as food packaging and medical materials. Lactic acid (CL) modified cellulose was used to improve the properties of CS. In particular, incorporating CL in CS significantly improved the water resistance and mechanical properties. The ester linkage of this sample was confirmed using ATR-FTIR. After the addition of CL, the moisture content and absorption ratio decreased dramatically. The good interfacial adhesion between CS and CL was examined by SEM. The specimen in the presence of CL with 100/0.5 CS/CL has the maximum swelling ratio of 450%. The highest strength was found at 11 MPa when using 100/7.5 CS/CL. The moisture content and absorption decreased as a function of the CL. Finally, the modified CS/CL film could prolong banana shelf life because of the decrease in the respiratory rate of the bananas. An improved CS film can improve the shelf life of bananas by reducing the exhalation ratio of the bananas. The banana CS/CL coating has a good preservative effect on bananas up for 7 days with minimal black/yellow spotting. Also, the biodegradation of CS film occurred easily in natural soil because of its good water absorption. The biodegradation of the CS/CL blend occurred in a range 65–100%. • The good interfacial adhesion between CS and CL was examined by SEM. • The highest strength was found at 11 MPa. • The banana CS/CL coating has a good preservative effect on bananas up to 7 days. • The biodegradation of the CS/CL blend was occurred in ranging with 65–100%.

Numerical study on effects of large curved superhydrophobic surfaces on droplet post-impact dynamics

Droplet impact on curved solid surfaces is a widely observed phenomenon. Curved surfaces with large object-to-droplet ratios, termed size factor, are expected to impose influence on the droplet post-impact dynamics. In this work, droplet impact on curved surfaces with a range of size factors is simulated. The simulation results show that both the size factor and initial impact velocity can significantly affect the post-impact dynamics of the droplet. Three post-impact dynamics states, stick state, bounce state, and shatter state are identified and found to highly depend on the size factor and impact velocity. Besides, the spreading dynamics, contact time for bouncing droplets, and the detachment velocity also depend on the size factor and initial impact velocity to some degree. Splashing of droplet at higher impact velocity is also discussed. The current study could inspire the design of functional surfaces with water-resistant and anti-icing properties in relevant applications.

Corn: Its Structure, Polymer, Fiber, Composite, Properties, and Applications.

Biocomposite materials have a significant function in saving the environment by replacing artificial plastic materials with natural substances. They have been enrolled in many applications, such as housing, automotive engine components, aerospace and military products, electronic and circuit board components, and oil and gas equipment. Therefore, continuous studies have been employed to improve their mechanical, thermal, physical properties. In this research, we conduct a comprehensive review about corn fiber and corn starch-based biocomposite. The results gained from previous studies were compared and discussed. Firstly, the chemical, thermal, and mechanical properties of cornstarch-based composite were discussed. Then, the effects of various types of plasticizers on the flexibility of the cornstarch-based composite were addressed. The effects of chemical treatments on the properties of biocomposite using different cross-linking agents were discussed. The corn fiber surface treatment to enhance interfacial adhesion between natural fiber and polymeric matrix also were addressed. Finally, morphological characterization, crystallinity degree, and measurement of vapor permeability, degradation, and uptake of water were discussed. The mechanical, thermal, and water resistance properties of corn starch and fibers-based biopolymers show a significant improvement through plasticizing, chemical treatment, grafting, and cross-linker agent procedures, which expands their potential applications.

Preparation and characterisation of soy protein isolated particle film homogenised at different pressures

SummaryThe aim of this article was to study the effect of homogenisation pressure on the microstructure of soy protein isolated (SPI) particles, the size of SPI particles and the properties of SPI particle films. Particle films were prepared by homogenising SPI particles at different pressures (0, 60, 70, 80, 90 and 100 MPa), and their optical properties, water resistance and mechanical properties were investigated. With increasing homogenisation pressure, the particle size of SPI decreased from 5123 to 295.7 nm, more homogeneous and compact network structures with good integrity were gradually constructed, and α‐helices and β‐turns transited to β‐sheets and random coils. Compared to natural SPI films, the opacity value and swelling ratio of SPI particle films were reduced by 48% and 31%, respectively, and the mechanical properties increased by 47% at 90 MPa. This study offered a theoretical basis for the application of protein particle films.

Investigation of Atomic Layer Deposition Post-Coating Properties of Phosphorescent SrAl2O4: Eu2+, Dy3+ Fibers Produced By Electrospinning

In this research, phosphorescent SrAl2O4:Eu2+, Dy3+ fibers were produced by electrospinning and coated with atomic layer deposition (ALD) technique to enhance the photoluminescence (PL) properties, and water & thermal resistance. Particle form of Eu2+-activated strontium aluminate phosphors possess many remarkable features that have been reported over and over, for example, nontoxic, stable, efficient. PL enhancement and stability in water of these particles were provided by nano encapsulation process by ALD that has just been published in our previous paper. In this study, for the first time, SrAl2O4 based long persistence phosphor fibers were coated with the ALD method to both improve their PL and provide water & thermal resistance property. In this successfully carried out study, luminescence, optic, chemical and structural properties of phosphor in fiber form were investigated in detail. These improved submicron afterglow fibers which are SrAl2O4:Eu2+, Dy3+ based are promising materials for applications such as solar cells, luminescent labels for bioimaging, mechanoluminescence sensor, etc.

Hierarchical fiber with granular-convex structure for highly efficient PM2.5 capture

Air pollution has seriously affected human health and the atmospheric environment. Preparation of fiber membrane with hierarchical structure provides an advanced method for high-performance air filtration. However, indistinctive secondary structure and complicated preparation present constantly in the formation of fiber with hierarchical structure, inevitably limited in the application of air filtration. In this work, a typical granular-convex structure was created in the surface of thermal-crosslinked sodium phytate/polyvinyl alcohol (T-PANa/PVA) fiber via green preparation. Unique secondary structure endowed fiber with efficient physical interception and polar adsorption, which exhibited excellent the removal of air pollutants (removal of PM2.5 high than 99.9% while low air resistance of 36.5 Pa). In addition, due to the exist of crosslinked network, T-PANa/PVA fiber membrane expresses water-resistant and mechanical properties. This work provides a positive strategy to fabricate hierarchical fiber membranes via green preparation for high-performance air filtration, which is expected to substitute traditional air filtration materials and adapt to the sustainable development of future.