Water Absorption Properties Research Articles

Mechanical, thermal, and water absorption properties of HDPE/barley straw composites incorporating waste rubber

This study investigates the mechanical, thermal, and water absorption properties of high-density polyethylene (HDPE) composites filled with barley straw and varying amounts of waste rubber. The research aims to develop sustainable materials that repurpose agricultural and industrial waste while addressing resource scarcity and waste management challenges. Composites were prepared using a twin-rotor mixer and hydraulic press, with waste rubber content varying from 0 to 20 wt%. Mechanical properties were evaluated through tensile testing, thermal behavior was analyzed using TGA, DTG, and DSC, and long-term water absorption was measured. Results show that increasing waste rubber content from 0 to 20% led to a decrease in tensile strength (11.3 to 8.9 MPa) and tensile modulus (1760 to 790 MPa), while relative extension increased (2.4–5.9%). Thermal analysis revealed a slight reduction in onset degradation temperature (270 °C to 240 °C) and increased char residue (8–18%) with higher rubber content. Water absorption decreased significantly, from 12 to 13% to 6–7% after 600 h of immersion, as waste rubber content increased. These findings demonstrate that incorporating waste rubber into HDPE/barley straw composites results in materials with enhanced flexibility and water resistance at the cost of some strength and stiffness. In conclusion, the results of this study offer a clear pathway for the development of sustainable polymer composites that have broad potential applications across industries like construction, marine infrastructure, automotive, and packaging. By replacing traditional, resource-intensive materials with eco-friendly alternatives, these composites not only provide functional benefits but also support global efforts toward sustainable development and environmental conservation.

Waterborne cellulose acetate pickering emulsion generation mediated by cellulose nanocrystals for paper coating applications

There is a continually increasing demand for alternatives to single-use, non-degradable, and synthetic plastic packaging. Environmentally friendly paper products offer a potential solution, but typically do not meet stringent demands for barrier and other physical property performance unless coated with polymeric films, usually polyolefins. Replacing conventional plastic film coatings with bio-based polymer alternatives, such as cellulose acetate, can provide competitive barrier property performance while also providing sustainability benefits. Furthermore, water can be used as a coating medium for added environmental and coatability advantages. In this study, 10 wt% Pickering emulsions of cellulose acetate dispersed in water and stabilized via cellulose nanocrystals (CNC) were generated. Rheological behavior, particle size, stability, and particle morphology were analyzed, as was the effect of modifying the CNCs using (2-Dodecen-1-yl)succinic anhydride over several weeks. Unbleached kraft paper was coated and compared to polyolefin coated and uncoated paper. Water vapor permeability, grease resistance, water absorption, and wet mechanical properties were all investigated, displaying promising properties for barrier paper coating. The grease kit test yielded a result of 10/12 for the coated paper versus 0/12 for uncoated, and water Cobb value showed a 60 % improvement. Lastly, the performance of the coated paper as a food takeout container coating was explored, with convincing results demonstrating a strong avenue of applicability. Overall, the waterborne cellulose acetate Pickering emulsion formation and its paper coating application yielded promising results for sustainable packaging development.

Gulf toadfish (Opsanus beta) urinary bladder ion and water transport is enhanced by acclimation to higher salinity to serve water balance.

Marine teleosts experience ion gain and water loss in their natural habitats. Among other tissues, the urinary bladder epithelium of marine fishes has been shown to actively transport ions to facilitate water absorption. However, transport properties of the urinary bladder epithelium of marine fishes and its plasticity in altered ambient salinities is relatively under-investigated. We describe urinary bladder epithelium electrophysiology, water flux, and expressions of ion transporters in urinary bladder tissue of Gulf toadfish (Opsanus beta) acclimated to either 35 ppt or 60 ppt seawater. Water absorption in bladder sac preparations increased ~ 350% upon acclimation to 60 ppt. Increases in water transport coincided with a significant ~ 137% increase in urinary bladder tissue mucosal-to-serosal short circuit current (Isc) and a ~ 56% decrease in tissue membrane resistance. Collectively, these metrics indicate that an active electrogenic system facilitates water absorption via Na+ (and Cl-) transport in urinary bladder tissue. Furthermore, pharmacological inhibition of urinary bladder tissue Isc and expression of a suite of ion transporters and channels previously unidentified in this tissue provide mechanistic insights into the transport processes responsible for water flux. Analysis of water transport to overall Gulf toadfish water balance reveals a modest water conservation role for the urinary bladder of ~ 0.5% of total water absorption in 35 ppt and 1.9% in 60 ppt acclimated toadfish. These results emphasize that electrogenic ion transport facilitates water-absorptive properties of the urinary bladder in Gulf toadfish - a process that is regulated to facilitate water homeostasis.

Effect of kaolin ratio on wear, water absorption, acidic resistance, and mechanical properties of thermoset composites

Natural fiber reinforced composites are easy to decompose in nature compared to synthetic fiber reinforced composites. However, due to environmental effects, natural fibers cannot maintain their properties for a long time. This situation has led researchers to search for natural but non-degradable materials. Kaolin is one of the most abundant minerals in nature and is an easy material to obtain. This study investigated the use of kaolin as a potential natural additive for polymer composites. In this direction, different proportions by weight of kaolin were added to two different polymer matrices (polyester and polyvinylester) materials. Mechanical tests were performed on the samples, and a series of tests were carried out to understand the acid resistance, wear resistance and water absorption properties of the samples. Also, SEM images of the fracture surface, wear surface, and surface exposed to the acidic solutions were taken and examined. According to test results, kaolin improved compression strength while reducing tensile and flexural strength. However, serious improvements have been achieved by nearly 45% and 115% in the tensile modulus and nearly 84% and 218% in the flexural modulus of polyester and polyvinylester composites, respectively. Also, kaolin improved acid resistance and wear properties and reduced the water absorption rate of the composites.

An overview of the effects of water and moisture absorption on the performance of hemp fiber and its composites

AbstractResearchers compare natural hemp fibers with synthetic fibers because of their distinct physical and mechanical properties, which have been well established over time. Hemp fibers are a versatile type of plant fiber commonly used in structural composites and have shown promise in various applications which include packaging, construction, and automotive parts. However, designing hemp‐based composite components presents challenges due to factors related to the plant's origin, growth conditions, age, stem position, separation methods, and the irregularity of fiber cross‐sections. This review aims to provide a comprehensive analysis of research on the performance of hemp fibers and their composites concerning moisture and water absorption. It reviews and analyzes important research on the water and moisture absorption properties of hemp fibers. The article also explains the critical properties of hemp fibers, the various factors affecting these properties, the role of hemp fibers in reinforcement composites, and how relative humidity and swelling characteristics impact hemp fiber composite components. Additionally, it highlights potential areas for future research.Highlights Effects of moisture on hemp fiber's structural properties. Mechanisms of water and moisture absorption in hemp fibers. Impact of moisture on hemp fiber reinforced composites. Key factors in selecting matrices for hemp fiber composites. Future prospects for hemp fiber composites in various applications.

Anti-tumor effects of ellagic acid and mesenchymal stem cell-conditioned medium on breast cancer cells on the 3D printed PCL/agarose scaffolds

Numerous investigations have demonstrated that natural bioactive compounds, such as flavonoids, exhibit synergistic effects with anticancer agents utilized in clinical practice. Stem cell therapies play a critical role in the domain of oncology; nevertheless, conflicting results have surfaced regarding the potential pro-cancer or anti-cancer characteristics of mesenchymal stem cells. The primary aim of the current investigation was to examine the anticancer efficacy of ellagic acid (EA) alone or in combination with adipose tissue stem cells derived conditioned medium (ADSCs-CM) on human breast cancer cells. In order to overcome the potential effects of two-dimensional (2D) culture, a three-dimensional (3D) printed polycaprolactone (PCL)/agarose scaffold is utilized to evaluate cancer cell behavior. More recently it was reported this scaffold had open and interconnected pores, as well as good water absorption and mechanical properties. Assessment of MCF-7 cancer cell viability was conducted through MTT assay, flow cytometry, cell cycle assay, and quantitative real-time PCR within a 3D cell culture framework. The outcomes revealed a reduction in cancer cell viability across all treatment cohorts in comparison to the control group. Particularly noteworthy was the significantly enhanced effect of the EA and CM combination relative to each component administered individually. Flow cytometry assessment using annexin V/PI staining indicated a decrease in cancer cells, particularly evident in the combination-treated group. Furthermore, the mRNA expression levels of BAX, BCL2, vascular endothelial growth factor (VEGF), and caspase 3 genes were consistent with pathways associated with apoptosis. Consequently, the synergistic anti-proliferative impact of EA in conjunction with ADSCs-CM on MCF-7 cells has been substantiated. These findings have two important implications for breast cancer research; highlight the utility of the PCL/agarose scaffold as a cancer model and suggest new avenues for the development of adjuvant anticancer therapeutic approaches.

Study on properties and CO2 emission of self-pulverizing calcium sulfoaluminate (SPCSA) after carbonization curing

The extensive use of Portland cement (OPC) has resulted in a steady rise in CO2 emissions from the construction industry, posing a significant climate threat. While adopting low-carbon cement enriched with belite minerals holds promise for substantial CO2 emission reduction in the cement industry, the limited early hydration activity of C2S constrains its engineering applications. Carbon capture, storage, and utilization (CCUS) technology, capable of rapidly developing the strength of C2S, opens up a new avenue for utilizing low-carbon cement. This study evaluated the properties of self-powdering calcium sulfoaluminate (SPCSA) cements with different C2S contents, and the carbon emissions during production and application were analyzed. The samples' carbonation area, compressive strength, and capillary water absorption properties were tested. The carbonation products and pore structures were also characterized using XRD, TGA, SEM, and Low-NMR. The results show that when the molar ratio of C4A3S̅ to C2S is 1:12 (S̅12), the compressive strength and CO2 sequestration of SPCSA are 69.78 MPa and 0.15 g/g, respectively. When CCUS technology is adopted, the CO2 emission during the production and application of SPCSA is 585.78 kg/t, much lower than that of OPC of 878.28 kg/t. This is significant as a reference for realizing carbon neutrality in the cement industry.

The microscopic reinforcement mechanism of Zhuhai soft soil by cement-based stabilizer: From microscopic characterization to molecular dynamics simulation

In this study, Zhuhai soft soil is taken as the research object, and it is reinforced by pure Qiancheng (Q.C.) stabilizer, pure cement, cement and Q.C. crosslinking stabilizers. The hydration heat, XRD, thermogravimetric analysis, and infrared spectrum were used to analyze the types and amounts of hydration products of reinforced soil. Additionally, SEM and low-field NMR were used to observe the micro-morphology and analyze the pore distribution of solidified soil. The results show that the pure Q.C. stabilizer can only produce Ca(OH)2 at an early stage; The hydration degree of pure cement soil is not high, and there only is a fraction of C-S-H and Ca(OH)2 generated in soil. However, the chemical reaction in crosslinking stabilizer soil is intense, generating more ettringite (ETT) and C-S-H. The crystal structure of ETT contains crystallized water, which requires more binding water in soft soil to generate ETT. Besides, ETT can fill the pores in soil particles and reduce the porosity of solidified soil. The water absorption properties of Na-montmorillonite (MMT) and ETT are studied by molecular dynamics simulation (MD) to explore the microscopic solidification mechanism. The MD results indicate that the water contact angles of MMT and ETT are 25°and 8°, respectively. ETT/water are mainly connected by hydrogen bonds, while Na-O bonds bound Na-MMT/water. Furthermore, the adhesion work between ETT and water is 3.40 times MMT/water, which proves that ETT has a more stable water retention capability. Based on the experiments and MD results it is concluded that the ETT is the key to reinforcing soft soil. Understanding the mechanism of soil–water interaction in the process of reinforcement will be beneficial to put forward the reinforcement scheme for soil and optimize the proportion design of the cement-based solidified system.

On the incorporation of waste ceramic powder into concrete

This study investigates the potential use of waste ceramic powder as a filler in concrete. Different percentages of waste ceramic powder were added to the concrete, and the compressive strength and water absorption properties were assessed. Failure mechanisms were analyzed using scanning electron microscopy (SEM). The findings revealed that incorporating 5% ceramic powder into concrete increased its compressive strength by approximately 12.5%. However, adding more than 5% ceramic powder led to a proportional decrease in strength. Additionally, water absorption increased when the ceramic content exceeded 5%. SEM analysis showed that higher ceramic content weakened the adhesion of the ceramic particles, and noticeable aggregation was observed.

A method of pretreating incineration ashes containing metallic aluminium using NaOH to mitigate volume expansion under highly alkaline conditions

Globally, millions of tonnes of incineration ashes are produced with a substantial portion remaining underutilized in low-value applications or disposed in landfills. Many types of fly ashes and bottom ashes contain metallic aluminium (Al0), which causes volume expansion when the ashes are used in alkali-activated materials and as a supplementary cementitious material due to the generation of hydrogen gas at high-pH conditions. This phenomenon significantly restricts the potential applications of these ashes. To address this issue, ashes can be pretreated with NaOH to oxidize the metallic aluminium (Al0) before their utilization. This study focuses on investigating the effect of the NaOH pre-treatment duration on fly ashes from the co-combustion of recovered solid fuel, peat, and wood. A pre-treatment process was conducted using 8 mol/L aqueous NaOH solution to treat the fly ash for up to 60 minutes. The formed slurry was subsequently used to prepare alkali-activated material by mixing it with bottom ash and employing either sodium silicate or sodium carbonate as an alkali activator. The NaOH pre-treatment demonstrated a 100 % metallic aluminium conversion into oxidized form resulting enhancement in mechanical performance, microstructure, and water absorption properties. The proposed method offers a highly efficient and rapid solution for eliminating the drawbacks caused by the presence of metallic aluminium and it can be conveniently implemented on construction sites. Concurrently, this study also explores the leaching behaviour of heavy metals during alkali-activation. Significant reductions in the leaching of Ba, Cr, Cu, Mo, and Pb were observed, highlighting the environmental remediation potential of alkali-activation methods.

Cotton-like antibacterial polyacrylonitrile nanofiber-reinforced chitosan scaffold: Physicochemical, mechanical, antibacterial, and MC3T3-E1 cell viability study

Bio-scaffolds, while mimicking the morphology of native tissue and demonstrating suitable mechanical strength, enhanced cell adhesion, proliferation, infiltration, and differentiation, are often prone to failure due to microbial infections. As a result, tissue engineers are seeking ideal scaffolds with antibacterial properties. In this study, silver nanoparticles (AgNPs) were integrated into cotton-like polyacrylonitrile nanofibers via a polydopamine (PDA) interlayer (Ag@p-PAN). These Ag@p-PAN nanofibers were then incorporated into the chitosan (CS) matrix, developing an antibacterial CS/Ag@p-PAN composite scaffold. The composite scaffold features an interconnected porous morphology with fiber-infused pore walls, improved water absorption and swelling properties, a controlled degradation profile, enhanced porosity, better mechanical strength, strong antibacterial properties, and excellent MC3T3-E1 cell viability, adhesion, proliferation, and infiltration. This study presents a novel method for reinforcing CS-based scaffolds by incorporating bioactive nanofibers, offering potential applications in tissue engineering and other biomedical fields.

Underwater image restoration via attenuated incident optical model and background segmentation

Underwater images typically exhibit low quality due to complex imaging environments, which impede the development of the Space-Air-Ground-Sea Integrated Network (SAGSIN). Existing physical models often ignore the light absorption and attenuation properties of water, making them incapable of resolving details and resulting in low contrast. To address this issue, we propose the attenuated incident optical model and combine it with a background segmentation technique for underwater image restoration. Specifically, we first utilize the features to distinguish the foreground region of the image from the background region. Subsequently, we introduce a background light layer to improve the underwater imaging model and account for the effects of non-uniform incident light. Afterward, we employ a new maximum reflection prior in the estimation of the background light layer to achieve restoration of the foreground region. Meanwhile, the contrast of the background region is enhanced by stretching the saturation and brightness components. Extensive experiments conducted on four underwater image datasets, using both classical and state-of-the-art (SOTA) algorithms, demonstrate that our method not only successfully restores textures and details but is also beneficial for processing images under non-uniform lighting conditions.

Enhancing antifungal and antibacterial properties of denture resins with nystatin-coated silver nanoparticles

Long-term oral health issues caused by fungi and bacteria are a primary concern for individuals who wear dentures. Denture stomatitis, primarily caused by Candida albicans (C. albicans), is a prevalent condition among denture users. Metal nanoparticles exhibit improved antimicrobial effectiveness and fewer adverse effects. This study aimed to evaluate the antifungal and antibacterial effects of nystatin-coated silver nanoparticles (Nys-coated AgNPs) embedded in acrylic resin as a more biocompatible material for denture resins. AgNPs and Nys-coated AgNPs were synthesized and characterized using UV-Vis, SEM, EDX, and DLS. Specimens of polymethyl methacrylate (PMMA) with three different concentrations of Nys, AgNPs, and Nys-coated AgNPs (0.1%, 1%, 10% w/w) were prepared. The water absorption properties of the disks and drug release were investigated for 14 days and 120 h, respectively. The hydrophilic and hydrophobic properties of the samples and their contact angles were evaluated using the sessile drop technique. The antifungal and antimicrobial activity of the prepared discs was studied against C. albicans and Streptococcus mutans, respectively. Adding Nys-coated AgNPs decreased the contact angle of discs from 67° to 49°. Furthermore, the water absorption rates of the different discs were not significantly different from those of the control groups. Results showed that Nys-coated AgNPs (10% w/w) in PMMA effectively inhibited C. albicans growth better than Nys composites (10% w/w). Additionally, Nys-coated AgNPs composites, as well as AgNPs-containing composites, showed considerable antibacterial activity against S. mutans. Nys-coated AgNPs (10% w/w) had no toxic effect on NIH3T3 cells. In conclusion, Nys-coated AgNPs could be considered a good candidate for incorporation into denture resins to address chronic oral diseases.

Sodium alginate-g-polyacrylamide hydrogel for water retention and plant growth promotion in water-deficient soils

Natural polymer-based hydrogels are preferred as soil water retention agents due to their inherent biocompatibility and biodegradability. Generally, these natural polymers are chemically modified by graft polymerization of vinyl monomers to improve their water absorption and retention properties. Among the polysaccharides used to prepare natural hydrogels, those based on sodium alginate (Alg) stand out for their high-water absorption and retention capacity, as well as for their ability to promote plant growth. The main objective of this study was to develop a biodegradable alginate-based hydrogel as a water retainer to promote plant growth under water deficit conditions. The synthesis was achieved by grafting poly(acrylamide) (PAM) onto Alg backbone, using bisacrylamide as chemical crosslinker and different ratios of alginate:acrylamide (Ac). In addition, Eucalyptus nitens seedlings were used as a model plant to evaluate the effect of alginate-g-polyacrylamide (Alg:PAM) hydrogel application to the growing medium on plant survival, growth, and physiological responses under both well-watered and water-deficient soil conditions. The maximum degree of swelling (65 g/g) was obtained for the hydrogel prepared. The pseudo-second order model described the water uptake kinetics of the hydrogel. The degradability of Alg:PAM hydrogel reached up to 85 % in 5 weeks in soil and occurs by breaking the glycosidic bonds of the alginate. The E. nitens seedlings cultivated with different doses of Alg:PAM hydrogel (4:1 Alg:Ac) showed higher values of height and root diameter relative growth, survival and photosynthetic responses in comparison to non-treated plants. The results indicate that Alg:PAM hydrogel (4:1 Alg:Ac) has promising applications in forestry as a water retention and seedling growth promoter under water deficient conditions.

Exploring the effects of fiber content and length on mechanical, free vibration, electrical, and water absorption properties of Phoenix sp. fiber‐reinforced polyester composites

AbstractThis work addresses the experimental investigation of the mechanical, free vibration, electrical resistivity, and moisture uptake characteristics of Phoenix sp. fiber‐reinforced polyester composites (PFRPC) fabricated using the compression molding method. The polyester matrix (PM) was added with Phoenix sp. fibers (PSFs) of different content (5, 10, 15, 20, and 25 wt%) and length (10, 20, and 30 mm) and studied their effect on the aforesaid properties. The results reveal that the composites having 20 wt% of 20 mm length PSFs exhibited optimum mechanical properties. At this loading, the ultimate tensile strength and modulus were 48.36 MPa and 2.86 GPa, respectively, while the flexural strength and modulus were 83.89 MPa and 2.91 GPa, respectively. Furthermore, this composite exhibits an impact strength of 22.04 kJ/m2 and an interlaminar shear strength of 41.88 MPa. The increase in PSF content and length resulted in greater stiffness and decreased mass of the composites, leading to an enhanced natural frequency. The inclusion of PSFs showed a decline in electrical resistivities due to their moisture‐absorbing capability. In contrast, the hydrophilic behavior of PSFs led to a rise in the water absorption rate of the composites due to the increase in fiber variables. Scanning electron microscopy examination shows that short fiber‐reinforced composites have more fiber pull‐outs due to the limited area of contact, whereas long fiber‐added composites possess better bonding with the PM.Highlights Various properties of Phoenix sp. fiber/polyester composites were investigated Increase in fiber content enhanced the mechanical performance of composites Variation in fiber length has only minimal effect on composite properties Phoenix sp. fiber/polyester composites exhibit better insulating property

Mechanical, free vibration, electrical, and water absorption properties of vinyl ester composites reinforced with Phoenix sp. fibers: Influence of eco‐friendly sodium bicarbonate treatment

AbstractEnvironmentally sustainable and eco‐friendly natural fiber‐reinforced polymer composites have become the materials of interest in replacing synthetic fibers. However, weak interfacial interaction between hydrophilic natural fibers and hydrophobic polymer matrix limits their commercial applicability. Improving the interfacial interaction using environmentally friendly chemical treatments would be beneficial for both industries and the environment. In this study, vinyl ester‐based composites were made by incorporating Phoenix sp. fibers in different content (5, 10, 15, 20, and 25 wt%) and lengths (5, 10, 15, and 20 mm). To improve the interfacial interactions, the fibers were treated with eco‐friendly sodium bicarbonate solution at different durations (24, 120, and 240 h) prior to reinforcing. The fabricated composites were characterized by mechanical, free vibration, electrical resistance, and water uptake properties. The results reveal that both fiber content and fiber length have a significant effect on the above properties. Specifically, the composites incorporated with 20 wt% of 15 mm length fibers offered better properties. Further, the composites added with 120 h treated fibers have the maximum tensile strength (61.35 MPa) and modulus (4.13 GPa), flexural strength (152.63 MPa) and modulus (10.24 GPa), impact strength (24.67 kJ/m2), and natural frequency (56.72 Hz). This improvement is mainly due to the improved interfacial bonding, which was evidenced in morphological analysis. Based on the findings, the eco‐friendly treated sustainable Phoenix sp. fibers could be used as a promising reinforcement material for fabricating light weight polymer composites for various industrial applications.Highlights Various properties of Phoenix sp. fiber/epoxy composites were investigated. Interfacial bonding is enhanced through eco‐friendly chemical treatments. Vibration behavior of composites improved due to high stiffness of treated fibers. Composites with treated fibers have excellent electrical and water resistance.

Wood-fiber insulation boards (WFIB) produced with hardwood and softwoods species and polylactic acid (PLA) fibers as a binder

ABSTRACT Wood fiber insulation boards (WFIB) produced with natural binders have been gaining recognition as an eco-friendly material, however there is limited information on the effect of different wood fiber and sustainable binders on WFIB production. This study investigates the impact of density, wood fiber origin, and pertinency of polylactic acid (PLA) as a binder. Flexible WFIB with densities of 80, 100 and 120 kg/m3 were produced by hot-press method with fibers of pine and spruce as softwoods, and beech and birch as hardwoods. Bicomponent fibers, composed by two concentrical layers of polylactic acid (PLA) were utilized as a renewable-origin binder at a proportion of 10%. Technological properties such as short-term water absorption, compression test and thermal tests properties were assessed. The density of the WFIB significantly influences the water absorption, compression strength, and thermal conductivity, with all these values increasing as the density rises. Insulation boards made from hardwood fibers showed greater water absorption and compression values compared than their softwood counterparts. Softwood-WFIB single-samples with a density of 80 kg/m3 reported lower thermal conductivities than hardwoods ones. The present study shows the promising feasibility of producing flexible wood fiber insulation boards from natural fibers and polylactic acid as a renewable binder.

Effects of Postmanufacture Conditioning on the Mechanical and Hygroscopic Properties of Extrusion Printed Wood–Sodium Silicate Composites

Abstract Additive manufacturing of wood–sodium silicate composites could aid in mitigating the carbon footprint of the building and construction industry. However, the effect of postmanufacture conditioning on the mechanical and physical properties of additively manufactured wood–sodium silicate composites is not well understood. This study investigated eight different postmanufacture drying processes, including: ambient indoor and outdoor conditions, oven-drying at two different temperatures, microwave drying, alcohol-induced dehydration using ethanol and denatured alcohol, and desiccant drying. Each postmanufacture conditioning treatment was assessed in terms of total moisture extraction and moisture extraction rate as well as the flexural strength, flexural stiffness, and hardness of the wood–sodium silicate samples after drying. In addition, the water absorption and volumetric swelling properties of the additively manufactured wood–sodium silicate samples were assessed via water submersion tests. The postmanufacture conditioning treatments were found to significantly affect the mechanical and physical properties of the samples. A universal ranking system was established based on cumulative rankings of each evaluated characteristic. Samples dried in ambient outdoor conditions achieved the best overall ranking and had the smallest carbon footprint. However, ovendried samples had the best flexural properties. Future studies investigating hybrid approaches in which composites are sequentially subjected to different drying methods will likely provide the most desirable mechanical and physical properties of wood–sodium silicate composites.

Strategies to control humidity sensitivity of azobenzene isomerisation kinetics in polymer thin films

Azobenzenes are versatile photoswitches that garner interest in applications ranging from photobiology to energy storage. Despite their great potential, transforming azobenzene-based discoveries and proof-of-concept demonstrations from the lab to the market is highly challenging. Herein we give an overview of a journey that started from a discovery of hydroxyazobenzene’s humidity sensitive isomerisation kinetics, developed into commercialization efforts of azobenzene-containing thin film sensors for optical monitoring of the relative humidity of air, and arrives to the present work aiming for better design of such sensors by understanding the different factors affecting the humidity sensitivity. Our concept is based on thermal isomerisation kinetics of tautomerizable azobenzenes in polymer matrices which, using pre-defined calibration curves, can be converted to relative humidity at known temperature. We present a small library of tautomerizable azobenzenes exhibiting humidity sensitive isomerisation kinetics in hygroscopic polymer films. We also investigate how water absorption properties of the polymer used, and the isomerisation kinetics are linked and how the azobenzene content in the thin film affects both properties. Based on our findings we propose simple strategies for further development of azobenzene-based optical humidity sensors.

Analysis of wettability and contact angle of sodium bicarbonate impregnated wooden surfaces

Scots pine and spruce wood samples were vacuum impregnated with 3, 5, and 9% sodium bicarbonate solution. Contact angle measurements were made by dropping 0.05 mL of pure water and 3% saltwater solution onto the material’s surface. The surface roughness of each sample was measured, and that of Scots pine control samples was higher than that of spruce samples, but the surface roughness values of spruce wood were higher in the samples impregnated with sodium bicarbonate. When pure water or saltwater solution was dropped onto the samples, it was observed that as the waiting times increased, the contact angle value decreased, the droplet height decreased, and the droplet width increased. It was found that the contact angles were higher in the control samples of both tree species than in the samples of 5% and 7%. The contact angles of 9% impregnation solution, pure water, and salt water were higher than the control samples. As the solution ratio increased on the surfaces impregnated with sodium bicarbonate, the contact angle also increased, and the wettability behavior decreased accordingly. Sodium bicarbonate solution is effectively used in the impregnation process for pine and fir woods, making the materials more resistant to water under outdoor conditions. This solution significantly reduces the risk of deformation of wood by increasing the contact angle and reducing its water absorption properties.