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Rice straw is considered an agricultural waste harmful to the environment, which is abundant in most parts of the world. From this point, the present study is devoted to preparing new composites of two types of glue based on rice straw as a plentiful, low-cost matrix. Straw glue samples were prepared by mixing 20% wt. of rice straw with 80% wt. of animal glue (RS-An) and polyvinyl acetate (RS-PVAC) at different thicknesses of 1, 2, and 3 cm. The chemical composition of the prepared samples was identified by energy dispersive X-ray analysis and their morphology was examined using a scanning electron microscope. The mechanical test explored that RS-An and RS-PVAC respectively required a stress of 25.2 and 25.5 MPa before reaching the breaking point. γ-ray shielding performance was analyzed and determined at numerous photon energies from 0.059 to 1.408 MeV emitted from five-point γ-rays sources using NaI (Tl). Linear attenuation coefficient was calculated by obtaining the area under the peak of the energy spectrum observed from Genie 2000 software in the presence and absence of the sample. The experimental results of mass attenuation coefficient were compared with theoretical data of XCOM software with relative deviation ranging from 0.10 to 2.99%. Geant4 Monte Carlo simulation code was also employed to validate the experimental results. The relative deviation of XCOM and Geant4 outcomes was 0.09–1.77%, which indicates a good agreement between them. Other radiation shielding parameters such as half value layer (HVL), tenth value layer, and mean free path were calculated in three ways: experimentally, theoretically from the XCOM database, and by simulation using Geant4 code. Additionally, effective atomic number (Zeff), effective atomic number (Neff), equivalent atomic number (Zeq), and buildup factors were evaluated. It was confirmed that the γ-ray shielding properties were further boosted by mixing rice straw with the animal glue compared to the synthetic one. [ABSTRACT FROM AUTHOR]

Pyrolyzed organic matter, commonly referred to as biochar, generally has positive effects on plant growth and can enhance early seedling development. Biochar-based seed coatings may thus be beneficial, specifically under adverse soil conditions such as high soil salinity. Using a series of lab and greenhouse experiments, we evaluated germination and early plant development in radish (Raphinus sativa) seeds coated with conifer-feedstock slow-pyrolysis biochar. Following the precedent of prior studies, polyvinyl acetate (PVAc) was used as the binding agent. Biochar-based seed coatings reduced germination rates and radicle extension in Petri dish trials; however, leaching of coated seeds largely eliminated this effect. PVAc applied in solution inhibited seed germination to a similar extent, suggesting that toxicity of PVAc or chemical products derived from it is the main mechanism for germination inhibition. A meta-analysis of published literature also indicates negative effects of biochar-based seed coatings using PVAc. In greenhouse trials, the same biochar seed coatings improved aspects of plant growth and physiological status relative to controls, specifically enhancing root development. We conclude that biochar-based seed coatings have promise in promoting early seedling growth and potentially in combating salinity stress in agronomic and restoration applications. However, our findings contraindicate PVAc use as a binding agent. Further research is needed to test non-phytotoxic, readily biodegradable binding agents and to optimize biochars and seed coating processes for specific applications in agronomy and ecological restoration. [ABSTRACT FROM AUTHOR]

Global poultry waste production is substantial, with billions of poultry raised annually for meat and egg production, resulting in significant feather waste. Conventional poultry waste disposal methods are restricted due to environmental concerns. Meanwhile, wood-composite panel industries face raw material shortages, emphasizing the need for sustainable, renewable fiber sources. In this study, in the core layer of panels, wood particles were replaced with 5 wt% clean duck feathers without pretreatment to take advantage of feather attributes like hydrophobicity, thermal insulation, and sound damping as an alternative construction material. Three adhesives—urea-formaldehyde (UF), polymeric 4,4′-diphenylmethane diisocyanate (pMDI), and polyvinyl acetate (PVAc)—were examined for resin–feather compatibility. The control panels in this study were identical but wood was not replaced with feathers. The results revealed that wood–feather particleboard with pMDI and PVAc resins meets the requirements of the relevant standard for P2 boards (where applicable) concerning their modulus of rupture (MOR: 11 N·mm−2), modulus of elasticity (MOE: 1600 N·mm−2), internal bond (IB: 0.35 N·mm−2), and screw withdrawal resistance (SWR). However, those produced with UF resin did not meet the standards for IB and MOE. Furthermore, the physical properties showed similar water resistance and thickness swelling to control panels with pMDI. Notably, substituting 5 wt% wood with feathers improved thermal insulation by approximately 10% for UF and pMDI resins. Additionally, particleboard with feathers demonstrated improved sound absorption at high frequencies, ranging from 2500 to 500 Hz, particularly with pMDI resin, approaching Class B classification according to EN ISO 11654:1997. This study identifies the higher compatibility of pMDI over PVAc and UF adhesives for feather-based composite materials in construction applications. [ABSTRACT FROM AUTHOR]

Structural connections are one of the most important parts influencing the overall performance of a wooden structure. The way of design of these can lead both to increasing and decreasing internal stresses occurring in the load-carrying elements and total deformations of the structure. Typical mechanical joints in wooden structures are defined as plastic hinges or, at best, semi-rigid. The innovative hybrid proposed in the paper with adhesive added between elements can be much stiffer than a typical connection, which can lead to assuming rigid joint and significant reduction in stresses and deformations of a structure. The research comprised 30 specimens in three groups (10 per each group: reference - without adhesive, hybrid with one-component PUR - polyurethane adhesive and hybrid with one-component PVAc - polyvinyl acetate adhesive) tested on the MTS 809 testing machine up to failure. An innovative idea was to connect elements initially by applying an accurately predicted tightening torque value to bolts. This resulted in obtaining enough clamping pressure between elements for adhesive curing, with none other equipment. The load was applied in parallel-to-grain wood direction. The results showed that utilising hybrid connection caused, both for PUR and PVAc adhesive, a huge increase in stiffness. When comparing to the reference no-adhesive, bolted connection, this was 2365% stiffer (nearly 24 times). Load-carrying capacity was higher too, however, the increase was not that significant and was at the level of 14.4% and 27.1%, for PUR and PVAc adhesives, consecutively. Worth noting is that the hybrid connection could continue to work after adhesive failure with 60% higher stiffness than the reference one and its load-carrying capacity was only 10% lower than the reference. Hybrid connections of this type can potentially serve as structural joints because of the innovative concept of combining components. Steel plates can be covered with adhesive and then inserted between wooden parts. Next, the tightened bolts can work as clamps producing enough pressure for adhesive curing, enabling the joint to be assembled directly on the construction site. Despite the mentioned advantages, before providing the connections' design methods, the idea needs to be tested towards various effects influencing wooden structures. Incorporating numerical modelling can be extremely important too. [ABSTRACT FROM AUTHOR]

The formation of a higher number of hydrogen bonds in the structured polyvinyl acetate film compared to the unstructured one was established by means of infrared spectroscopy method. It was concluded that the structured polyvinyl acetate film has a higher cohesive strength than unstructured. It was revealed that the films subjected to moisture loads (with the amount of sorbed moisture lower than the swelling limit of the adhesive film) would show greater cohesive strength compared to the films which were not subjected to moisture loads due to the formation of a higher number of hydrogen bonds. Based on the obtained results, it was predicted that the system «structured film after moisture loads/wood substrate» would exhibit the highest adhesive strength, explained by an increase in the number of hydrogen bonds between the film components and the wood cellulose. It was theoretically predicted that in order to provide high cohesive and adhesive strengths of polyvinyl acetate adhesive joints of wood ensuring, moisture saturation should be lower than the saturation limit of the wood fiber and the adhesive film simultaneously. [ABSTRACT FROM AUTHOR]

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Repercussion of overutilizing the fossil fuels and petrochemicals resulted in global warming and polluted environment. Hence, in the quest for alternative sources of raw materials for developing greener adhesives, renewable and natural polymers like polysaccharides have a huge potential. In particular, the traditional water-based emulsion wood adhesive employs colloid-like polyvinyl alcohol for stabilizing polyvinyl acetate (PVAc) emulsion. Researchers have recently become interested in utilizing xanthan gum, a naturally occurring polymer, in place of stabilizers. Here, the effects of xanthan gum addition as a stabilizer for PVAc homopolymer-based wood adhesives on performance properties were investigated. Emulsion polymerization technique was employed to synthesize xanthan gum stabilized PVAc homopolymer emulsion. Hence, the present work investigates the applicability of xanthan gum added 0.5% and 1% as a colloid for the synthesis of PVAc wood adhesives. Effect of the addition of xanthan gum as a colloid on physical, thermal, and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC), and pencil hardness test of films. Emulsions in varying xanthan gum concentrations were prepared, and a universal tensile machine was utilized to measure the shear strength of the PVAc homopolymers applied to wood. As the concentration of xanthan gum increased, the adhesives' viscosity increased. The drastic increase in water resistance with increasing xanthan gum content was confirmed by water contact angle measurement. The use of xanthan gum improved the PVAc films' hardness as well. When compared to a pristine sample, the tensile shear strength with 1 wt% of xanthan increased by 50% after 6 h of bonding in dry environment and by 61% in wet conditions (as per EN 204). The study's overall conclusion highlights the enhanced adhesive performance of xanthan gum stabilized PVAc emulsion-based adhesives. [ABSTRACT FROM AUTHOR]

Amongst water-based emulsion adhesives, polyvinyl acetate (PVAc) emulsion is majorly employed in the non-structural bonding of interior or exterior furniture and joinery industries. However, PVAc emulsion requires plasticizers, which inherently have challenges resulting in deteriorating thermal and mechanical properties. Hence, the present work focuses on formulating a plasticizer-free adhesive by copolymerizing vinyl acetate with butyl acrylate (BA). The physical, thermal, and mechanical properties of BA-incorporated adhesives were analyzed by viscosity, pH, water contact angle, pencil hardness test of films, and differential scanning calorimetry. Optimizing strategy by varying the content of BA was evaluated. The shear strength of the samples on the wood specimen was verified in dry conditions at various intervals, and in wet conditions as per EN 204 standard. The viscosity of the adhesives exhibited a positive shift, as the concentration BA increased. The hardness of PVAc films was also altered positively by the addition of BA. Water contact angle measurement unveiled the hydrophobic nature of BA incorporation. The performance of the newly formulated adhesive tested on dry conditions showed enhanced tensile shear strength, and the values were maximum for 1 wt. % BA sample. Tensile shear strength value measured at dry conditions after 7 d of drying displayed an increment of ∼5.5% on 1 wt. % BA sample, compared to pristine adhesive. Analysis at wet conditions also corroborated enhanced performance with BA incorporation. Hence by optimizing the content of BA, a new concept of PVAc emulsion adhesive without any plasticizer can be formulated, with enhanced water resistance and performance. [ABSTRACT FROM AUTHOR]

Facade-rendering mortars and their painting layers are constantly exposed to weather and, therefore, influence the hygrothermal behavior of buildings. The characterization and assessment of coating materials is fundamental, seeking adequacy in their selection, especially regarding moisture and temperature. Considering the exposure conditions of the facades, risks of damages, such as mold development, may be avoided by an assertive evaluation and selection among different types of paints. In this context, this paper experimentally determined essential properties related to the hygrothermal behavior of painted mortars and simulated their resulting performance when applied on exposed facades in three Brazilian cities in distinct bioclimatic zones. Hygrothermal simulations were carried out using the software WUFI Pro 6.6. Six different types of paints were studied, among which satin acrylic paint (SAP) led to the lowest water vapor permeability and matte polyvinyl acetate (PVA), silicate (SIL), lime (LP), and hydrated lime with white glue (HLG) paints led to the highest. Matte acrylic paint (MAP), PVA, SIL, LP, and HLG had similar impacts on the vapor transmission of mortar renderings. In the simulations, reference (REF) and LP specimens generally resulted in the highest water contents throughout the year, followed by SIL and HLG. SAP led to the lowest water content and a more homogeneous curve than the other paints. Among the studied cities, Macapá, which has the highest annual normal rainfall sum and mean relative humidity, also had the highest mean total water content values over time, followed by Porto Alegre and Petrolina. In general, no probable mold development is expected. However, caution should be taken when extrapolating the results for climate or construction conditions different than the simulated ones. [ABSTRACT FROM AUTHOR]

Chitosan Schiff base/polyvinyl acetate (CSB/PVAc) and its Fe2O3 (CSB/PVAc@Fe2O3) nanocomposite were fabricated and characterized using different techniques, including FT-IR, XRD, SEM/EDS, BET, TGA, and DSC. They were used as suitable adsorbents for removing eosin yellow (EY), and Fluorescein (FS) dyes from the aqueous solution. The adsorption experiments were optimized by varying the essential parameters: pH solution, adsorbent dose, and contact time. Under optimum conditions (pH = 3 and 0.02 g dose of sorbents), the maximum removal efficiency was 75.65% and 95.53% for EY and 80.51% and 93.46% for FS using CSB/PVAc and CSB/PVAc@Fe2O3, respectively. Kinetic studies used pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The experimental data obeyed the intra-particle diffusion model. The adsorption data were analyzed using the Langmuir and Freundlich isotherms. According to the results, the experimental data fitted well with the Freundlich model as a heterogenous process. Finally, the removal efficiency of the new adsorbet CSB/PVAc@Fe2O3 become less active (< 7%) towards EY and FS dyes after 5 runs. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the versatility of thermophilic esterase for treating raw papermaking whitewater with organic solvents at high temperatures. Thermophilic esterase from a metagenomic library was immobilized on a chitosan/macroporous resin composite carrier using a covalent crosslinking approach in conjunction with deep eutectic solvent (DES). The stability and tolerance of the immobilized thermophilic esterase were greatly enhanced by DES. Immobilized thermophilic esterase resulted in significant 85.35% and 88.02% reductions in the average particle size and pitch deposit contents, respectively. Furthermore, clear decreases in turbidity, chemical oxygen demand and biochemical oxygen demand were found, indicating an optimal treatment outcome for all the commercial enzymes that were examined. The superior efficacy of thermophilic esterase in the treatment of raw whitewater was found to be due to the effective removal of colloidal substances such as polyvinyl acetate. Therefore, this research had significant potential for the enzymatic treatment of raw whitewater. [ABSTRACT FROM AUTHOR]

This study investigates the development of biomaterial healing patches, specifically focusing on the elastomer characteristics and hyperelastic parameters of polyvinyl acetate in lab-made skin. Three sets were evaluated: plain PVAc (Set A), a mix of PVAc with Polysiloxanes (Set B), and a combination of PVAc with PVM-MA &CMC (Set C). Mechanical properties and hyperelastic behavior were assessed using ASTM D412 type-C standard and a 40 mm/min tensile test. Set A shows higher tensile stress (0.072 MPa) and higher tensile strain (1.1324) than Sets B and C. The Mooney-Rivlin and Ogden models were identified as suitable for elastomer characteristics among various hyperelastic models; specific constants for Set A were validated through these models: μ = -0.0211, α = -2.2919 for the Ogden model, C1 = - 0.0036, C2 = 0.0300 for the Mooney-Rivlin model. These findings reveal similarities in mechanical characteristics between studied materials previously developed to mimic skin seen in the pattern of the hyperelastic graph, which has significant implications in developing skin-mimicking compounds for medical applications. The paper establishes potential advances in surgical practices through medicinally treated artificial skin but underscores further research into behavior when used within artificial skins in this technology sector. [ABSTRACT FROM AUTHOR]

Poly(vinyl chloride) undergoes dechlorination in the presence of triethylsilane (Et3SiH) and a catalytic amount of [Cp2Zr(NPh2)][CH3B(C6F5)3] (1 b) at 40–80 °C, with up to 91 % efficiency. Stoichiometric reactivity studies conducted on cyclohexyl chloride as a model suggest that 1 b dechlorinates PVC by initial chloride abstraction, followed by hydride transfer to the cationic PVC chain from Et3SiH. Consumer items such as pipe fitting, vinyl disc or electric cable insulation undergo either dechlorination or hydrosilylation of the carbonyl‐containing copolymer (polyvinyl acetate) or plasticizer (phthalate). [ABSTRACT FROM AUTHOR]

Significant variations in climate exist between the northern and southern regions of China, resulting in varying degrees of decay observed in wooden relics unearthed from different areas. The preservation of wooden cultural artifacts in humid environments is influenced by numerous factors including regional environmental conditions (such as temperature, humidity, and biological mold), and site structural characteristics, among others, making the conservation efforts more specialized and intricate. This study utilizes the example of the unearthed wet outer coffin wooden cultural relics from the Tomb of Marquis Yi of Zeng to demonstrate a method involving the use of polyvinyl acetate (PVAc) composite material for the reinforcement and protection of such artifacts. Through a comprehensive analysis of various analytical techniques including scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR), density increase rate, wood compression strength along the grain, hydrophobic property, and other micro and macro properties, it was determined that: The combination of PVAc and shellac as a reinforcement agent has been shown to enhance the mechanical properties of wooden cultural relics while also maintaining minimal color variation, increased biocompatibility, and durability. This method is particularly well-suited for fortifying and preserving damp wooden cultural relics that exhibit varying degrees of decay. The findings offer significant insights and potential avenues for further research on the preservation methods for large wooden cultural artifacts discovered in the middle and lower regions of the Yangtze River dating back to the Warring States Period. [ABSTRACT FROM AUTHOR]

Mastitis is an infectious disease condition resulting in inflammatory reaction which occurs when a large number of leukocytes migrate into the mammary gland. Mastitis causes significant financial losses for the global dairy industry. The present study aimed at development of transdermal film comprising of Azadirachta indica extract for treatment of mastitis, which is economical, safe and will not emerge multidrug resistance amongst pathogens. Azadirachta indica extract was prepared by sonication method. The extract was evaluated for minimum inhibitory concentration against gram-positive and gram-negative organisms. Transdermal films with Azadirachta indica extract were prepared with ethylene vinyl acetate and polyvinyl acetate then subjected for the physical characterization, drug content, In vitro dissolution, tensile strength and antibacterial activity. The minimum inhibitory concentration of extract displayed 5mg/ml. Based on quantification of azadirachtin by UV spectrophotometer 100 mg of extract was incorporated in each transdermal film. Transdermal films of Azadirachta indica extract possessed desirable physical properties, and exhibited the drug release of 91.54% in 8 hours. Transdermal film of Azadirachta indica showed sensitivity with a zone of inhibition of 19mm, 16mm, 19mm and 22mm against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa respectively. Data obtained revealed that transdermal films of Azadirachta indica extract exhibited good drug release profile and desirable physical properties, with good antibacterial activity. The present work reveals that transdermal film of Azadirachta indica extract can be considered for the treatment of mastitis. [ABSTRACT FROM AUTHOR]

The chemical and physical properties of protonated polyaniline (PANI)‐based films, including PANI‐emeraldine salt (ES) and PANI/polyvinyl acetate (PVAc) films, before and after pH treatments are characterized and compared. Protonated PANI‐based films are prepared by spin coating. The effects of pH value and immersion time on the film properties are investigated to gain a better understanding of their performance in pH sensing. The films are characterized based on color, morphology, chemical structure, phase state, and protonation state. Protonated PANI‐based films exhibit a color change from green to dark blue as deprotonation occurs in solutions with higher pH. The highly porous structure of PANI/PVAc films is slightly affected by the pH of the solution. However, the globular structure of the PANI‐ES films forms cracks with increasing immersion time. PANI/PVAc films exhibit better stability in acidic and neutral solutions than in alkaline solutions because of the hydrolysis of PVAc. Compared with the negligible differences in the PANI/PVAc film in buffers with different pH, PANI‐ES exhibits noticeable changes. Therefore, PVAc improves the stability and performance of PANI for pH‐sensing applications. [ABSTRACT FROM AUTHOR]

Conventional adhesives often emit volatile organic compounds (VOCs), which have a negative impact on human health. In this paper, an environmentally‐friendly supramolecular adhesive PD which has high adhesive and low VOCs emission is prepared by the reaction between polyethyleneimine (PEI) and 3,4‐dihydroxybenzaldehyde (DBA). PD containing abundant catechol groups exhibit excellent adhesion to wood substrates and is able to reach a maximum shear strength of 5.20 ± 0.39 MPa. One factor is attributed to multiple reactions between PEI, and DBA and oxidation of DBA. These reactions construct a complex three‐dimensional cross‐linked structure which is very helpful to improve the bonding performance of the adhesive. Another reason refers to the fact that a large number of catechol groups in PD can form a lot of hydrogen bonds with the amino group in PEI and the hydroxyl group in the wood substrate. These hydrogen bonds play an important role in enhancing shear strength. PD adhesives have a stronger bond strength than commercial chloroprene rubber (CR, Pattex‐PXL) and polyvinyl acetate adhesives (PVAc, JUJU‐8708) and have lower emissions of VOCs. As an environmentally‐friendly adhesive for wood‐based substrates, this adhesive may have potential applications in the wood processing industry. [ABSTRACT FROM AUTHOR]

In this study, quartz crystal microbalance (QCM) gas sensors, coated with electrospun polyvinyl acetate (PVAc) nanofibers, were employed to monitor the spoilage level of cultured Pacific white shrimp. The sensors exhibited a sensitivity range of 0.63 to 1.61 Hz/ppm when detecting trimethylamine vapor, a key biomarker for shrimp spoilage. Significant resonance frequency shifts were observed in the as‐prepared sensors when exposed to amine gases released by long‐stored shrimps. These shifts underline the significance of low‐temperature storage for shrimps. While color changes in the shrimps stored at ambient temperature (25 °C) become noticeable to the naked eye after 6 hours, the sensor detects sample deterioration much earlier, registering a prominent frequency shift (178 Hz) within only 3 hours of storage. This outcome suggests the potential of nanofiber‐coated QCM sensors as early‐stage food freshness indicators. [ABSTRACT FROM AUTHOR]

Amphiphilic cross-linked poly (vinyl alcohol-methyl methacrylate) (PVA-PMMA) copolymer nanoparticles (NPs) were prepared using a two-step process. Unlike other polymers, which are typically produced via direct polymerization, PVA is produced from the hydrolysis of polyvinyl acetate (PVAc). Therefore, in the first part of the project, copolymeric PVAc-PMMA NPs were prepared by using the radical emulsion polymerization method in different concentrations of BDOD (0–10% mol.) and water: methanol compositions. Conversion degree, morphology, particle size, and polymerization rate of non-agglomerated samples were evaluated. The optimal sample that synthesized in water: methanol % (90:10) as polymerization medium and 2.5% mol. crosslinker was hydrolyzed by 0.6 M NaOH solution. To confirm the hydrolysis reaction, FE-SEM, FT-IR, DLS, 1H NMR, and TGA tests were performed. The optimal sample was loaded by methotrexate (MTX), and drug release investigated at different times by UV-vis spectrophotometry. The sustained and pH-responsive profile of drug release in vitro was observed, and 47.24% of the drug was released at pH = 7.4 and 65.39% at pH = 5.8 after 96 h. Also, the MTT assay and dual-fluorescent acridine orange/propidium iodide assay showed that drug-loaded nanocarriers exhibited anticancer activity as applied to MCF-7 cells. [ABSTRACT FROM AUTHOR]

In this paper, we employ direct numerical simulations for studying the dynamics of two different, but miscible polymeric drops undergoing impact-driven coalescence with one of the drops making a head-on collision on an underlying drop. We consider two separate cases: (1) a PMMA (poly-methylmethacrylate) drop impacting a PVAc (polyvinyl acetate) drop and (2) a PVAc drop impacting a PMMA drop. For each case, three separate Weber numbers (We = 0, 1, 10) are considered. The interplay of finite impact speed and the specific wetting characteristic of the underlying drop leads to fascinating fluid dynamics. For example, for the case of the PMMA drop impacting on the PVAc drop, the strong wetting behavior of the PVAc drop ensures the impact-driven formation of an accelerated disk consisting of separate layers of PMMA and PVAc. Also, there is the generation of significant capillary waves at the drop–air interface, which in turn causes significant undulations of the drop–drop interface created due to such head-on collision. On the other hand, for the case of the PVAc drop impacting on the PMMA drop, the relatively weaker wetting behavior of the PMMA drop ensures that there is no formation of an accelerated disk; rather (for large We), the PVAc drop flows on top of the PMMA drop, forms a "canopy-like" structure, and wets the solid forming a transient core–shell structure (with PMMA core and PVAc shell). Our results raise the possibility of fabricating highly complicated multi-polymeric-material components by rapid curing of the drops in their post-impact configurations. [ABSTRACT FROM AUTHOR]

In order to enhance dispersity and compatibility of the carbon nanomaterials in polar/non polar solutions and polymers, carbon nanotube and graphene were modified using ethyl acetate as a monomer by free radical polymerization. The effects of coatings on carbon nanomaterials were characterized by infrared spectra, thermogravimetric analysis, scanning electron microscope, and Raman spectrum. Through infrared spectra, the coated carbon nanomaterial exhibited a characteristic absorption peak of vinyl acetate, and a significant weight loss occurred at 170~240 °C in the thermogravimetric curves. From Raman spectrum, the ID/IG of the modified carbon nanotubes and graphene decreased from 1.730 and 1.040 to 1.090 and 0.985, respectively, indicating an increase in the degree of graphitization. The results indicate the success of vinyl acetate modified carbon nanomaterials. Dispersity and compatibility of modified carbon nanomaterials were assayed by ultraviolet spectra, discovering that the coated carbon nanomaterials exhibit excellent dispersibility and stability. The results indicated that the surfaces of carbon nanomaterials were coated by polyvinyl acetate via in-situ polymerization. The structures of carbon materials were not destroyed by coating process and their properties were kept. When the mass ratios of polyvinyl acetate to carbon materials were 1:1 and 2:1, the results of coating were excellent. Furthermore, the modified carbon nanomaterials possessed the perfect dispersity and stability. [ABSTRACT FROM AUTHOR]

Real-time detection of formaldehyde in the atmosphere remains challenging. The available gaseous formaldehyde sensing methods offer limited sensitivity, selectivity, and robustness. We modified a quartz crystal microbalance (QCM) system for selective detection of formaldehyde in air. The QCM surface was functionalized with polyvinyl acetate (PVAc) nanofibers and doped with 2, 4, and 6 wt% aniline to improve the selectivity and sensitivity of the sensor. The chemical content and morphological structure of PVAc nanofibers doped with aniline were confirmed by Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscopy (SEM). The results showed that the modified QCM sensor had a sensitivity of 0.056 Hz ppm−1 with a response and recovery times of 200 s and 90 s, respectively. It gave limits of detection (LOD) and limit of quantification (LOQ) of 28 ppm and 96 ppm, respectively. Moreover, the modified QCM was selective towards formaldehyde compared to the other gases. The current workplace exposure limit (WEL) for formaldehyde is 2 ppm, with a time-weighted average over eight hours. Future work will focus on improving the reported QCM sensor to meet the required LOD for formaldehyde detection in the environment and industrial sites. [ABSTRACT FROM AUTHOR]

Maize starch, polyvinyl alcohol, glucose, and magnesium stearate are used as tablet excipients, acetylsalicylic acid as probe, polyvinyl acetate, and calcium alginate as protective membranes. By changing the proportions of the excipients, the nature and the thickness of the protective membrane, it was possible to optimize the formulation of a controlled release tablet. The mechanism and the kinetics of release of the active ingredient are evaluated using kinetic models: zero order, Higuchi, first order, Hixson–Crowell and Krosmeyer–Peppas. The representation of the released quantities using Krosmeyer–Peppas seems to be the most appropriate to describe the release mechanism (R2 ~ 1). The k and n values, Krosmeyer–Peppas, indicate that drug release is complex. The release rate of the AI is controlled by the erosion of the membrane and the relaxation of the chains of polymers constituting it. The solubility parameters (δ), according to Hansen, of the hydroxylated ingredients, predict compatibility and stability. [ABSTRACT FROM AUTHOR]

Wood wettability, the process of liquid interaction with wood surfaces, is influenced by wood surface chemistry, structure, ambient conditions, and temperature. Understanding how temperature impacts wood wettability is crucial for high-temperature manufacturing processes. In this study, the sessile drop method was employed to explore the dynamic wettability of Chinese fir wood using three different liquids (water, glycerol and polyvinyl acetate (PVAc)) across a range of temperatures (25, 40, 60 and 80 °C). By considering spreading, penetration and evaporation, we revealed that the dynamic wettability of Chinese fir was strongly dependent on temperature and the type of liquid. Temperature elevation enhances wettability, leading to reduced contact angles and increased penetration ratios. Water exhibited the highest wettability, followed by glycerol, with PVAc being the least wetting agent. Notably, after 180 s of wetting at 80 °C, the measured contact angles were 0° for water, 45° for glycerol, and 120° for PVAc. When accounting for evaporation, the penetration of water decreased from 57 % to 47 % (25 °C) and 100 % to 62 % (80 °C). The activation energies for the penetration of water and PVAc into Chinese fir exhibited variations, with values of 35.3 and 158.3 kJ/mol, respectively. These comprehensive wetting results, covering spreading, penetration and evaporation, provide valuable insights into wood–water and wood–adhesive interactions, particularly when exposed to high-temperature conditions. [ABSTRACT FROM AUTHOR]

In recent decades, due to high market demand and multiple environmental concerns, attention has been focused on the use of starch as renewable raw material for adhesives elaboration. Particularly, the origin and film-forming properties of Achira (Canna edulis) starch make it a potential representative for the development of bioadhesives. In this study, achira starch modified by acid hydrolysis and subsequent derivatization with urea was used to prepare adhesives for plywood substrates. For this purpose, the modified starch and polyvinyl alcohol (PVA) were used to prepare several formulations with different proportions of components. Afterwards, they were characterized in terms of physicochemical and mechanical properties. The formation of starch carbamates was confirmed not only by the results of nitrogen content, but also by infrared spectroscopy through the presence of N-H and C=O groups. On the other hand, viscosity increased with PVA content due to the interaction of hydroxyl groups, while starch had the opposite effect. Shear strength showed higher values at higher concentrations of PVA and starch. From the perspective of mechanical behavior, the results showed similarities with a commercial adhesive based on polyvinyl acetate (PVAc), as well as with other bio-based adhesives from studies conducted under comparable conditions. [ABSTRACT FROM AUTHOR]

DTDA‐THA (tris(hydrazin‐1‐ium)5,5′‐(hydrazin‐1‐ide‐1,2‐diylbis((1H‐tetrazole‐5,1‐diyl)))bis(tetrazol‐2‐ide)) is a novel type of poly‐nitrogen energetic material characterized by high nitrogen content, high enthalpy of formation, and low sensitivity. To research the application of DTDA‐THA in polymer‐bonded explosives (PBXs) and improve the safety performance of DTDA‐THA in composite explosives, this study calculated the binding energies between ethylene‐vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), polyvinyl acetate (PVAc) and DTDA‐THA via density functional theory, respectively. Three types of PBXs molding powders were prepared through the direct method. For further investigation, the moisture absorption of molding powders, the forming density, and the compressive strength of the grains under different binders were characterized. The result of the simulation shows higher binding energy between the crystal surface (2 −1 2) and different binders. The comprehensive order of the binding energies between different binders and the crystal surface of DTDA‐THA was DTDA‐THA@EVA>DTDA‐THA@PVB>DTDA‐THA@PVAc. The experimental results show that the addition of binder reduced the hygroscopicity of DTDA‐THA and improved the sensitivity and mechanical properties of the molding powders. Under the same binder proportion, the formulation prepared by PVAc had a higher molding density, while the formulation prepared by PVB exhibited the best compressive strength. [ABSTRACT FROM AUTHOR]

Effective enhancement of the mechanical properties of cohesionless soils is crucial for diverse geotechnical applications, given their inherent vulnerability to load-induced failure due to the absence of inter-particle bonding. Soil failures pose significant risks to both human lives and infrastructure, necessitating the development of environmentally friendly soil improvement methods. Conventional techniques often entail invasive processes and substantial carbon emissions. In response, contemporary approaches seek to minimize environmental impact while preserving organic material characteristics. This study investigates the synergistic effect of polyvinyl acetate (PVA) and enzyme-induced carbonate precipitation (EICP) treatment for enhancing the mechanical properties of cohesionless natural sands. Beach and river sands were treated with varying proportions of PVA in conjunction with an optimized EICP solution for yielding the best results. Unconfined compressive strength (UCS) tests were conducted at 7, 14, and 28-day curing intervals to assess the performance of the soil-polymer-EICP composites (SPEC). The results demonstrated substantial improvements in compressive strength and elastic modulus with increasing PVA content. For beach sand, after 7 days of heat curing, the peak strength increased from 0.89 MPa to 11.07 MPa for composites with 1% and 11% PVA, respectively. Similarly, for river sand, the peak strength increased from 0.87 MPa to 8.96 MPa under the same conditions. The findings also highlighted the softening behavior induced by PVA with heat curing over the period. This softening phenomenon was attributed to the thermo-plastic characteristics of the polymer film induced by temperature conditions.

Environmental considerations coupled with fossil fuel depletion encouraged research community to implement green protocol by partially or fully replacing petrochemicals. This is valid in case of adhesive research and development, where partial replacement of colloidal stabilizer, polyvinyl alcohol (PVA), is replaced by an abundant and sustainable material, corn starch (S). The work here investigates the effect of adding PVA and S blends formulated for polyvinyl acetate (PVAc)-white glue for wood adhesives. To enhance overall properties, boric acid, citric acid, glyoxal, and glutaraldehyde were employed as crosslinkers at a low concentration (0.1 wt.%). The presence of free hydroxy groups of PVA-S blend provides a site for the crosslinkers. Crosslinked blends are formulated with PVAc binder, plasticizer, and preservatives forming a wood adhesive. Various characterization techniques were employed for measuring physical and thermo-mechanical properties. Crosslinking was proved with dynamic mechanical analysis. Enhancement in performance properties was shown by the increase in tensile shear strength on bonded wood substrates and wet tack analysis. Tensile strength of bonded wood after 8 h. showed 16% increment for citric acid-incorporated sample, 13% for glutaraldehyde, 8% for boric acid, and ~ 7% for glyoxal crosslinked wood adhesive. Moreover, crosslinking consolidated polymer chains, which resulted in enhanced thermo-mechanical properties. Overall, the crosslinked samples showed better physical, mechanical, and thermal properties when compared to the non-crosslinked adhesive. Hence, this study can be a potential in the further development of sustainable white glue for wood bonding applications. [ABSTRACT FROM AUTHOR]

This study aimed to reinforce a polyvinyl acetate-D3 (PVAc-D3) adhesive to improve its mechanical and thermal properties. The goal was to reach a polyvinyl acetate-D4 (PVAc-D4) adhesive performance that could make PVAc-D3 more attractive and add value to wood products. PVAc-D3 was modified by adding 0.05% and 0.5% (wt.) of multi-walled carbon nanotube particles (MWCNTs) as well as 0.5% and 2.5% (wt.) of lignosulfonate (LIGNO) particles. Adhesive blends were compared to neat PVAc-D3 and PVAc-D4, evaluating their physical–chemical properties. Also, they were analyzed using Fourier transform infrared spectroscopy (FT-IR) and mechanical dynamic analysis (DMA) with a storage module (E′). The blends were used to fabricate laminated wood pieces, pressed at 60 and 120 min (min), to be tested at shear strength under dry, elevated temperature and vacuum-pressure conditions. Delamination and adhesive penetration were determined by microscopy. Incorporating fillers into PVAc resulted in a decrease in viscosity. FT-IR evidenced that the PVAc-D4 adhesive had a bigger cross-linked degree than the other adhesive samples. The DMA showed that LIGNO and MWCNT fillers help increase E′ at the bond line, reaching a higher stiffness level than neat PVAc-D3. In dry conditions, specimens glued with D3-LIGNO 0.5% at 120 min reached shear strengths that were 100%, 28%, and 3% higher than the standard requirement, PVAc-D4, and neat PVAc-D3, respectively. Also, those glued with D3-MWNTC 0.05% reached shear strengths that were 91%, 21%, and 3% higher than the standard requirement, D4, and neat D3, respectively. Only PVAc-D4 reached the standard requirement for elevated temperature and vacuum-pressure conditions. Delamination of ≤5% (standard requirement) was achieved by wood specimens glued with neat PVAc-D3, D3-MWNTC 0.5%, D3-LIGNO 0.5%, and PVAc D4 adhesive samples. In this study, it was found specific ranges of average penetration (AP) to ensure a glue line good quality. To conclude, LIGNO and MWCNT particles improved the PVAc-D3 adhesive's performance in dry conditions, but they were not very relevant to the D3 adhesive's behavior. At high temperatures, the LIGNO filler worked very well as a thermic stabilizer compared to the MWCNT filler. The solubility of the reinforcing agent can affect an adhesive's blend quality and its cohesion properties. An adequate penetration depth procures a good quality bond between an adhesive and substrate with less possibilities of delamination. An extensive pressing time may cause a weak interphase and poor mechanical properties in an adhesive bond in the presence of humidity. [ABSTRACT FROM AUTHOR]

Traditional materials are often selected and used in the construction of houses and buildings based on local knowledge that has been tested for centuries. The use of sago leaf stalks as a building material has several advantages. They are generally easy to find in tropical areas and have natural properties that allow good air circulation, thereby helping to keep the indoor temperature cool. In addition, this material is also environmentally friendly because it can decompose properly and can be renewed naturally. In an effort to preserve these cultural and traditional values, we can take several steps. First, public education and awareness about the advantages of traditional building materials need to be improved. Organizing workshops or seminars to share knowledge about the use of traditional materials and their benefits can help increase people's appreciation of these materials. The use of sago stalks as building materials can be part of cultural conservation and environmental preservation efforts. By combining traditional knowledge with modern innovation, we can create building solutions that are environmentally friendly, sustainable and maintain our cultural heritage. By using PVAc filler, this study aims to study its effect on the physical properties of the resulting composite material. Variations in the composition of the mix will enable the identification of changes in the characteristics of the composite board and efforts to obtain optimal physical properties. [ABSTRACT FROM AUTHOR]

In comparison with conventional polyvinyl acetate (PVAc) homopolymer-based adhesives, the water-resistant PVAc glues used in the wood adhesive industry today demonstrate high resistance to both water and heat. These glues contain acrylic acid (AA), N-methylolacrylamide, and vinyl ester of versatic acid as co-monomers. Here, PVA-stabilized polyvinyl acetate-acrylic acid and PVA-stabilized polyvinyl acetate-methacrylic acid copolymer emulsions were synthesized using batch emulsion polymerization. Additionally, PVA solution, aluminium nitrate, plasticizer, and preservatives are used to make the adhesive samples. The PVAc-MAA-based adhesive and the PVAc-AA-based adhesive sample are compared. The copolymerization and crosslinking reaction has been studied using Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) was used to determine the polymer films' glass transition temperatures (Tg). The tensile shear strength of wood joints in dry and wet conditions was determined in accordance with the EN 204-205 standard to evaluate the performance of the crosslinked emulsion-based adhesive. It was observed that using the acid group's reaction under acidic conditions, AA and MAA provided sites for crosslinking the chains. The AA-based adhesive's significantly higher glass transition temperature than the MAA-based adhesive's was shown by differential scanning calorimetry data, and this result was confirmed by film hardness testing. According to EN 204, the AA-based adhesive's tensile shear strength increased by ~ 11% after 24 h of bonding in a dry environment and by ~ 15% in wet environments when compared to an MAA-based adhesive. A crosslinked network structure developed as a result of the reaction between the acid groups in the copolymer chains, the free hydroxyls in PVA, and the added aluminium nitrate. In comparison with PVAc-AA-based wood adhesive, PVAc-MAA crosslinked adhesive demonstrated excellent product stability despite slightly lower water resistance. [ABSTRACT FROM AUTHOR]

The present study illustrates a simple and universally applicable method of synthesizing a new thermal stimuli-responsive thermoplastic shape memory polymer (SMP) and its composites through solvent casting method followed by the hot-pressing technique using polymers like polyvinyl acetate, polysulfone and polystyrene. The process parameters have been optimized to get a uniform film without any phase separation. Polyaniline (PANI), Al2O3, TiO2 and their combinations with PANI such as Al2O3–TiO2, Al2O3–PANI, and TiO2–PANI have been used as fillers to obtain the shape memory polymer composites (SMPCs). Under the thermal stimulus, the shape recovery rate of the SMPC containing Al2O3–PANI hybrid filler was faster, having a quick response time (150 s) compared to the response time of the neat SMP (210 s). Moreover, the SMP containing Al2O3 + TiO2 filler exhibited a higher Young's modulus (˃ 62%) compared to the neat SMP. The maximum stress of 37 MPa and 4.5% recoverable strain was observed in the SMP containing Al2O3 + TiO2 hybrid filler. Interestingly, no stored strain evolved upon cooling below Tg. The effect of physical aging on the mechanical and thermomechanical properties of SMP and its composites was studied. The synthesized SMP polymer is environmentally friendly and showed an excellent shape memory effect exhibiting a high Tg (~ 80 °C), self-healing property and good mechanical properties. Due to the multifunctional properties of the newly designed SMP and its composite, it may be a promising material for load-bearing applications. [ABSTRACT FROM AUTHOR]

Manufacturing long-chain branched polymers enhances the quality of products at the cost of production time, translating into high manufacturing costs. In this manuscript, we study the cost-versus-quality trade-off while optimizing the operating conditions for large-scale industrial production of Polyvinyl acetate (PVAc). PVAc polymerization is emulated using a large system of stiff differential equations resulting in time-expensive function evaluation. Thus, we aim to achieve the Pareto optimality using Multi-Objective Bayesian Optimization (MOBO) that introduces q-Expected Hyper-Volume Improvement (qEHVI) as the novel acquisition function. Comparison with Non-dominated Sorting Genetic Algorithm-II (NSGA-II), applied to the high-fidelity model, resulted in a similar Pareto front with only 1% of the high-fidelity calls required by NSGA-II. The results indicate the efficiency of MOBO for PVAc optimization and present a real-world application of a generic method that can be implemented to solve time-expensive multi-objective optimization in manufacturing processes [ABSTRACT FROM AUTHOR]

Mastitis is an infectious disease condition resulting in inflammatory reaction which occurs when a large number of leukocytes migrate into the mammary gland. Mastitis causes significant financial losses for the global dairy industry. The present study aimed at development of transdermal film comprising of Azadirachta indica extract for treatment of mastitis, which is economical, safe and will not emerge multidrug resistance amongst pathogens. Azadirachta indica extract was prepared by sonication method. The extract was evaluated for minimum inhibitory concentration against gram-positive and gram-negative organisms. Transdermal films with Azadirachta indica extract were prepared with ethylene vinyl acetate and polyvinyl acetate then subjected for the physical characterization, drug content, in vitro dissolution, tensile strength and antibacterial activity. The minimum inhibitory concentration of extract displayed 5mg/ml. Based on quantification of azadirachtin by UV spectrophotometer 100 mg of extract was incorporated in each transdermal film. Transdermal films of Azadirachta indica extract possessed desirable physical properties, and exhibited the drug release of 91.54% in 8 hours. Transdermal film of Azadirachta indica showed sensitivity with a zone of inhibition of 19mm, 16mm, 19mm and 22mm against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa respectively. Data obtained revealed that transdermal films of Azadirachta indica extract exhibited good drug release profile and desirable physical properties, with good antibacterial activity. The present work reveals that transdermal film of Azadirachta indica extract can be considered for the treatment of mastitis.

Pyrolyzed organic matter, commonly referred to as biochar, generally has positive effects on plant growth and can enhance early seedling development. Biochar-based seed coatings may thus be beneficial, specifically under adverse soil conditions such as high soil salinity. Using a series of lab and greenhouse experiments, we evaluated germination and early plant development in radish (Raphinus sativa) seeds coated with conifer-feedstock slow-pyrolysis biochar. Following the precedent of prior studies, polyvinyl acetate (PVAc) was used as the binding agent. Biochar-based seed coatings reduced germination rates and radicle extension in Petri dish trials; however, leaching of coated seeds largely eliminated this effect. PVAc applied in solution inhibited seed germination to a similar extent, suggesting that toxicity of PVAc or chemical products derived from it is the main mechanism for germination inhibition. A meta-analysis of published literature also indicates negative effects of biochar-based seed coatings using PVAc. In greenhouse trials, the same biochar seed coatings improved aspects of plant growth and physiological status relative to controls, specifically enhancing root development. We conclude that biochar-based seed coatings have promise in promoting early seedling growth and potentially in combating salinity stress in agronomic and restoration applications. However, our findings contraindicate PVAc use as a binding agent. Further research is needed to test non-phytotoxic, readily biodegradable binding agents and to optimize biochars and seed coating processes for specific applications in agronomy and ecological restoration.

Freeze-thaw cycles have a significant negative effect on the engineering behaviour of soil in cold regions. In this study, the compressive strength of stabilized, poorly graded sandy soil used in road pavement that was subjected to different freeze-thaw cycles was studied. Samples with three different particle shapes were stabilized with a binder developed by mixing polyvinyl acetate (PVAc) and ethylene glycol monobutyl ether (EGBE). The PVAc/EGBE weight ratio was 2:1, and PVAc was added at 1%, 2%, and 3% of the dry weight of the soil, with the effect of up to ten freeze-thaw cycles evaluated. Results showed that the addition of binder decreased optimum moisture content and increased compressive strength. An increase in particle roundness results in a decrease in the magnitude of compressive strength but increases the soil composite ductility. Changing particle shape from angular to rounded resulted in a more significant decrease in compressive strength than changing from rounded to well-rounded. The decrease in compressive strength is most significant between the first and fourth freezing-thawing cycles and marginal between the fourth and tenth. The negative effect of increasing the roundness of particles is compensated by increasing binder percentages.

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Light Paulownia seamless-edged glued solid wood panels (SWPs), single-layered and three-layered, were analyzed in this study. Both panel types were calibrated at a thickness of 19 mm, a dimension very often in demand on the SWP market, but produced with other wood species (for example, spruce, pine, larch and fir). The panels were bonded with melamine-urea formaldehyde, polyurethane and polyvinyl acetate resins. The panels were tested for their physical (density) and mechanical (modulus of rupture, modulus of elasticity, compressive shear strength and wood breakage rate) properties. For the single-layered panels, the mechanical and physical properties did not differ significantly and were similar to massive Paulownia wood. For the three-layered panels, the adhesive application of polyurethane influenced positively all SWP properties. Considering the differences in density, these composites failed to achieve the performance of one- and single-layered panels made of spruce. The results of these findings recommend Paulownia SWPs to be used as lightweight and sustainable core materials in sandwich structures for the furniture and packaging industry, sport articles or non-load-bearing constructions. [ABSTRACT FROM AUTHOR]

This study deals with the contact erosion investigation and mechanical properties of both the un-stabilized and polyvinyl acetate (PVAc)-stabilized dispersive embankment layer. To this end, in addition to performing the specific dispersivity identification tests, i.e. pinhole and double hydrometer tests and contact erosion test for measuring the contact erosion parameters, a series of basic geotechnical tests was carried out. The microstructural changes with the aid of scanning electron microscopy (SEM) test and financial analysis were studied respectively to understand underlying mechanisms of stabilization and to estimate the economic benefits owing to PVAc addition. The results indicated that 2% PVAc content was the most effective proportion such that it decreased the dispersion potential, mass loss, and settlement of the dispersive soil by 69.6%, 70.5%, and 68.5% respectively, and at the same time, the strength of the samples increased by 107.4% only after 7 days of curing. The reaction between the polarity carboxyl hydrophilic group of PVAc and the hydroxyl group of the soil led to form the strong hydrogen bonds, and therefore, the structure stability and strength of the soil were enhanced. The formation of reticulated membrane structures and stronger bonds between soil particles, as documented by SEM images, testified to the excellent efficiency of PVAc in dispersive soil stabilization. Finally, the accuracy of available correlations between soil dispersivity and contact erosion parameters was examined, and then, the correlations were developed to cover a broad range of soils by using the results of this study. [ABSTRACT FROM AUTHOR]

The chemical conversion of gypsum into synthetic hydroxyapatite is an attractive approach to enhance the value of gypsum, a lowcost material, which can be discreetly implanted. The addition of biopolymers improves the resistance of the materials both before and after conversion. In this study, hydroxyapatite was produced from gypsum using a fixed water-to-gypsum ratio (w/g) of 0.7, along with gypsum/polymer composites. The polymers employed were polyhydroxybutyrate (PHB) and polyvinyl acetate (PVAc) at various mass ratios. Two methods were used to create the bodies: molding the paste and subtractive manufacturing. Mechanical compression tests were conducted both pre- and post-conversion to evaluate the impact of the conversion on material resistance and to compare it with the strength of subtractive manufacturing composites. For the gypsum/PHB composite, the best result was achieved at a 1% polymer concentration, yielding a resistance of 9.1 ± 0.4 MPa, while for gypsum/PVAc, a compressive strength of 9.3 ± 0.3 MPa was obtained at a 2% polymer concentration. [ABSTRACT FROM AUTHOR]

Thermal modification of wood changes its chemical, physical, and structural properties, which may affect adhesive bondline quality and bonding performance. This research compared the effect of thermal modification on the adhesive bonding performance of poplar (Liriodendron tulipifera) wood. Samples were prepared from thermally modified and unmodified yellow poplar using one-component polyurethane (PUR) and polyvinyl acetate (PVA), as they are adhesives used in wood products. Microscopic properties of the bondlines were investigated to understand shear performance and durability. Adhesive line thickness, penetration, shear strength, and moisture durability were measured, and failure modes were recorded. Thermal modification negatively affected the wood and adhesive interaction by reducing penetration (31.2% in PUR and 29% in PVA), therefore creating a thicker adhesive line (70% in PUR and 2% in PVA) and consequently causing a significant reduction in the shear strength of both adhesive types (27% in PUR and 36% in PVA) compared with non-modified specimens. The PUR adhesive had higher shear strength than PVA by 2.7% in non-modified and 14% in thermally modified wood. [ABSTRACT FROM AUTHOR]

Climate change is one of the main factors influencing the research of environmentally friendly materials. This is why the use of engineering fibers as a reinforcement technique in wood, in order to increase its mechanical properties, has recently been investigated. This research presents the results obtained from the use of carbon and basalt fiber fabrics as a reinforcement for microlaminated Radiata Pine wood panels at a laboratory scale using the adhesives epoxy resin and polyvinyl acetate. Tests were carried out in comparison to the control boards, relating the physical properties obtained in terms of thickness swelling by 48 h-water immersion with a decrease of 19% for the polyvinyl acetate and carbon fiber matrix reinforcement, about the mechanical properties evaluated, a better performance was obtained for the epoxy resin and carbon fiber matrix reinforcement and in terms of flexural stiffness and strength (in flatwise), tensile strength and Janka hardness, with an increment of 31%, 38%, 56% and 41%, respectively. [ABSTRACT FROM AUTHOR]

The temperature resistance of glued timber, which is crucial for glued wood construction, represents a significant assessment criterion. To gain insights into this aspect, this study utilized methods such as a shear strength test in accordance with EN 302-1:2013-06 under thermal loading (from 20 °C to 200 °C), and Differential Scanning Calorimetry (DSC) to determine the glass transition temperature (Tg). An increase in thermal load resulted in a decrease in shear strength and an increase in wood breakage. A hierarchy of adhesive groups was established based on strength performance and wood failure percentage (WFP) at 200 °C. Thermoset adhesives (MF: Melamine Formaldehyde, PRF: Phenol Resorcinol Formaldehyde) led the ranking, followed by elastomer adhesives (1C-PUR: One-Component Polyurethane, EPI: Emulsion Polymer Isocyanate), with thermoplastic adhesive (PVAc: Polyvinyl Acetate) last. Thermoset adhesives further cured under heat. PUR adhesives exhibited higher strength performance at 150 °C and lower temperatures. [ABSTRACT FROM AUTHOR]

Environmental remediation of xenobiotic pollutants is an important issue in industrialized society. Catalyst‐mediated pollutant photodegradation using solar light shows promising results. Titanium dioxide nanoparticles (TiO2 NPs) are a well‐known standard for mineralizing organic water pollutants. Its use as a sludge pointed out the need to support this photocatalyst to ease both its use and recovery. Polymers represent a viable solution because of their versatility, stability, and cheapness. The in situ radical bulk polymerization approach to the development of TiO2‐based thermoplastic nanocomposites for xenobiotic photodegradation enhances the photocatalytic performance of the semiconductor nanoparticles. The versatility and efficiency of these systems pave the way for their industrial applications as photocatalytic coatings for large‐scale surfaces. To shed light on the influences of the chemical nature of the polymer matrix on the photocatalytic efficiency of the nanosystems, polyvinyl acetate, polymethyl methacrylate, and polystyrene are investigated as supports for TiO2 NPs. The obtained TiO2‐containing nanocomposites are characterized by thermal analyses, UV‐vis, Raman, and X‐ray photoelectron spectroscopies, dynamic light scattering, and contact angle measurements. The photocatalytic activity of the nanosystems in the form of thin films is investigated against pollutants in water solutions, and shows clear differences in the photodegradation efficiency among the nanocomposites having different chemical natures of polymers. [ABSTRACT FROM AUTHOR]

Exploitation of fossil fuels has resulted in the declination of petrochemicals, which catalysed chemical industries to search for substitute raw material sources. The major raw materials used in wood adhesives, such as hydrocarbons like vinyl acetate (VAc) and polyvinyl alcohol (PVA), would be gradually replaced by renewable natural polymers. Starch, being a naturally abundant polymer, has been explored in wood adhesives. However, starch grafted polyvinyl acetate (PVAc) emulsion-based adhesive has inferior properties, such as poor water resistance, weak adhesion. Hence, to mitigate the issues, emulsion polymerization of acrylic acid (AA) as a co-monomer in starch stabilized PVAc-based wood adhesives has been investigated. Further, the sample is formulated with PVA, plasticizer, and preservatives. It was observed that AA provided sites for cross-linking the chains via reaction of the acid group at acidic conditions. Various analyses were further carried to study the effects of addition of AA and aluminium nitrate on stability and water-resistance of starch stabilized emulsion. Differential scanning calorimetry result showed a substantial increase in glass transition temperature, with the addition of starch in the copolymer emulsion, which is also confirmed in film hardness testing. Reaction between acid group in the copolymer chains, the free hydroxyls of starch and PVA, and the added aluminium nitrate resulted in a cross-linked network structure. The adhesion properties were evaluated by measuring the tensile shear strength of wood joints in dry and wet conditions. The cross-linked adhesive with starch showed improved water resistance, mechanical properties, and stability, unlike PVA stabilized cross-linked wood adhesives. [ABSTRACT FROM AUTHOR]

The effectiveness of two ways to reduce the vibration and sound emission of a high-pressure laminate plate has been investigated. It has been found that the inclusion of viscoelastic polymer polyvinyl acetate film in the laminate structure or constrained damping layer treatment based on polyvinyl acetate film and aluminum foil or plastic leads to a significant improvement in its vibroacoustic characteristics. The greatest reduction in vibration and sound emission was achieved by applying a coating with aluminum foil whose thickness was six times less than that of the damped laminate plate. [ABSTRACT FROM AUTHOR]

Modified polyvinyl acetate P(BA-VAC) emulsion was prepared by emulsion synthesis method using soft monomer butyl acrylate. The influences of modified emulsion on setting time, water absorption, flexural strength, compressive strength, compression ratio, bond strength and skid resistance of cement mortar were studied. The results show that the modification of mortar by P(BA-VAc) can prolong the setting time of cement mortar, significantly reduces the water absorption and compression-flexure ratio, and increases the bond strength and skid resistance. The main reason for the great improvement of the properties of mortar is that a dense network structure formed by emulsion particles filling the pores in mortar. [ABSTRACT FROM AUTHOR]

The performance of engineered wood products is highly associated with proper bonding and an efficient cutting method. This paper investigates the influence of CO2 laser cutting on the wetting properties, the modified chemical component of the laser-cut surface, and the strength and adhesive penetration near the bondline. Beechwood is cut by the laser with varying processing parameters, cutting speeds, gas pressures, and focal point positions. The laser-cut samples were divided into two groups, sanded and non-sanded samples. Polyvinyl acetate adhesive (PVAc) was used to bond the groups of laser-cut samples. After assembly with cold pressing, the tensile shear test was carried out. Numerical modelling was carried out to determine the partial elongation and shear strain of the glue line. Based on this, the shear modulus and linear elasticity of the glue line were estimated. Scanning electron microscopy was used to assess the adhesive penetration into the porosity structure of the laser-cut samples, and the depth of the heat-affected zone. The laser-cut surface was analysed by Fourier transform infrared spectroscopy. The wetting properties of the laser-cut surface were investigated by using a contact angle goniometer. The numerical model of the strain-stress curve confirmed the experimental model. The highest modulus of the linear elasticity of the glue in the numerical calculation belongs to the joint containing laser-cut samples at a gas pressure of 21 (bar). The penetration depth of PVAc adhesive into the porosity structure of the laser-cut samples was similar to that of sawn samples. The deepest heat-affected zone in the laser-cut samples was 150 μm. A PVAc drop disappeared immediately on the laser-cut surface without sanding, but gradually on the sanded surface. In contrast, the drop on the sawn surface remained with an angle of 32°-48°. The degradation of hemicellulose and lignin was proven by the lower intensity of the C=O and C-O Bonds, compared to the sawn surface. [ABSTRACT FROM AUTHOR]

This study proposes a novel quartz crystal microbalance-based sensor using polyvinyl acetate nanofibers overlaid with maltodextrin to enhance sensitivity toward trimethylamine (TMA) gas. The sensor demonstrated a remarkable increase in sensitivity by 8.3 times, with a detection limit of 15.6 ppm. The enhanced sensitivity is due to reversible intermolecular Lewis acid–base interaction between active groups of maltodextrin and TMA gas molecules. Moreover, the sensor exhibited good selectivity, stability, and fast response and recovery times of 141 s and 116 s, respectively. The proposed sensor offers a promising alternative to conventional methods for accurately monitoring TMA gas levels in the air. [ABSTRACT FROM AUTHOR]