Search Results (11)

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. Full article

Microencapsulated phase change materials (MCPCM) as a green energy storage material not only prevent leakage of phase change materials but also increase the heat transfer area of phase change materials. Extensive previous work has shown that the performance of MCPCM depends on the shell material and MCPCM with polymers, as the shell material suffers from low mechanical strength and low thermal conductivity. In this study, a novel MCPCM with hybrid shells of melamine-urea-formaldehyde (MUF) and sulfonated graphene (SG) was prepared by in situ polymerization using SG-stabilized Pickering emulsion as a template. The effects of SG content and core/shell ratio on the morphology, thermal properties, leak-proof properties, and mechanical strength of the MCPCM were investigated. The results showed that the incorporation of SG into the shell of MUF effectively improved the contact angles, leak-proof performance, and mechanical strength of the MCPCM. Specifically, the contact angles of MCPCM-3SG were reduced by 26°, the leakage rate was reduced by 80.7%, and the breakage rate after high-speed centrifugation was reduced by 63.6% compared to MCPCM without SG. These findings suggest that the MCPCM with MUF/SG hybrid shells prepared in this study has great potential for application in thermal energy storage and management systems. Full article

The crosslinked poly(acrylic acid-co-acrylamide)-grafted deproteinized natural rubber/silica ((PAA-co-PAM)-DPNR/silica) composites were prepared and applied as coating materials for fertilizer in this work. The crosslinked (PAA-co-PAM)-DPNR was prepared via emulsion graft copolymerization in the presence of MBA as a crosslinking agent. The modified DPNR was mixed with various contents of silica (10 to 30 phr) to form the composites. The existence of crosslinked (PAA-co-PAM) after modification provided a water adsorption ability to DPNR. The swelling degree values of composites were found in the range of 2217.3 ± 182.0 to 8132.3 ± 483.8%. The addition of silica in the composites resulted in an improvement in mechanical properties. The crosslinked (PAA-co-PAM)-DPNR with 20 phr of silica increased its compressive strength and compressive modulus by 1.61 and 1.55 times compared to the unloaded silica sample, respectively. There was no breakage of samples after 80% compression strain. Potassium nitrate, a model fertilizer, was loaded into chitosan beads with a loading percentage of 40.55 ± 1.03% and then coated with the modified natural rubber/silica composites. The crosslinked (PAA-co-PAM)-DPNR/silica composites as the outer layers had the ability of holding water in their structure and retarded the release of fertilizer. These composites could be promising materials for controlled release and water retention that would have potential for agricultural application. Full article

In this work, the emulsified liquid membrane (ELM) extraction process was studied as a technique for separating different pollutants from an aqueous solution. The emulsified liquid membrane used consisted of Sorbitan mono-oleate (Span 80) as a surfactant with n-hexane (C₆H₁₄) as a diluent; the internal phase used was nitric acid (HNO₃). The major constraint in the implementation of the extraction process by an emulsified liquid membrane (ELM) is the stability of the emulsion. However, this study focused first on controlling the stability of the emulsion by optimizing many operational factors, which have a direct impact on the stability of the membrane. Among the important parameters that cause membrane breakage, the surfactant concentration, the emulsification time, and the stirring speed were demonstrated. The optimization results obtained showed that the rupture rate (Tr) decreased until reaching a minimum value of 0.07% at 2% of weight/weight of Span 80 concentration with an emulsification time of 3 min and a stirring speed of 250 rpm. On the other hand, the volume of the inner phase leaking into the outer phase was predicted using an artificial neural network (ANN). The evaluation criteria of the ANN model in terms of statistical coefficient and RMSE error revealed very interesting results and the performance of the model since the statistical coefficients were very high and close to 1 in the four phases (R_training = 0.99724; R_validation = 0.99802; R_test = 0.99852; R_all data = 0.99772), and also, statistical errors of RMSE were minimal (RMSE_training= 0.0378; RMSE_validation = 0.0420; RMSE_test = 0.0509; RMSE_all data = 0.0406). Full article

The desalting process of an electrostatic desalting unit was studied using the collision time of two droplets in a water-in-oil (W/O) emulsion based on force balance. Initially, the model was solved numerically to perform a process analysis and to indicate the effect of the main process parameters, such as electric field strength, water content, temperature (through oil viscosity) and droplet size on the collision time or frequency of collision between a pair of droplets. In decreasing order of importance on the reduction of collision time and consequently on the efficiency of desalting separation, the following variables can be classified such as moisture content, electrostatic field strength, oil viscosity and droplet size. After this analysis, a computational fluid dynamics (CFD) model of a biphasic water–oil flow was developed in steady state using a Eulerian multiphase framework, in which collision frequency and probability of coalescence of droplets were assumed. This study provides some insights into the heterogeneity of a desalination plant which highlights aspects of design performance. This study further emphasizes the importance of two variables as moisture content and intensity of electrostatic field for dehydrated desalination by comparing the simulation with the electrostatic field against the same simulation without its presence. The overall objective of this study is therefore to show the necessity of including complex phenomena such as the frequency of collisions and coalescence in a CFD model for better understanding and optimization of the desalting process from both process safety and improvement. Full article

Plant diseases reduce crop yield and quality, hampering the development of agriculture. Fungicides, which restrict chemical synthesis in fungi, are the strongest controls for plant diseases. However, the harmful effects on the environment due to continued and uncontrolled utilization of fungicides have become a major challenge in recent years. Plant-sourced fungicides are a class of plant antibacterial substances or compounds that induce plant defenses. They can kill or inhibit the growth of target pathogens efficiently with no or low toxicity, they degrade readily, and do not prompt development of resistance, which has led to their widespread use. In this study, the growth inhibition effect of 24 plant-sourced ethanol extracts on rice sprigs was studied. Ethanol extract of gallnuts and cloves inhibited the growth of bacteria by up to 100%. Indoor toxicity measurement results showed that the gallnut and glove constituents inhibition reached 39.23 μg/mL and 18.82 μg/mL, respectively. Extract treated rice sprigs were dry and wrinkled. Gallnut caused intracellular swelling and breakage of mitochondria, disintegration of nuclei, aggregation of protoplasts, and complete degradation of organelles in hyphae and aggregation of cellular contents. Protection of Rhizoctonia solani viability reached 46.8% for gallnut and 37.88% for clove in water emulsions of 1000 μg/mL gallnut and clove in the presence of 0.1% Tween 80. The protection by gallnut was significantly stronger than that of clove. The data could inform the choice of plant-sourced fungicides for the comprehensive treatment of rice sprig disease. The studied extract effectively protected rice sprigs and could be a suitable alternative to commercially available chemical fungicides. Further optimized field trials are needed to effectively sterilize rice paddies. Full article

The aim of this study is the development of an emulsification device for two immiscible liquids with a total volume of approximately 3 mL. The heart of the device is a piston, with an aluminum plate fixed at its tip, which moves periodically up and down inside a rectangular cell. The plate geometry (uniform or non-uniform height) affects significantly both the emulsions stability and the size of the droplets of the prepared emulsions. Five parameters are examined during testing (surfactant type, surfactant concentration, proportion of immiscible liquids, piston stroke frequency, duration of emulsification) and all of them appear to have an important role in the resulting droplet size distribution. A macroscopic theoretical model is developed for the determination of the main hydrodynamic parameters of the innovative device. It is shown that the non-uniform height plate achieves higher shear rates when compared to the uniform height plate because of the smaller gap between the plate and the cell walls. However, the benefits of the higher shear rate are overturned by the larger effective breakage time encountered in the uniform height plate resulting from the larger surface area of its sides. The results of the emulsification experiments are analyzed using the parameter values derived by the developed model. Full article

Double emulsions are very promising for various applications in pharmaceutics, cosmetics, and food. Despite lots of published research, only a few products have successfully been marketed due to immense stability problems. This review describes approaches on how to characterize the stability of double emulsions. The measurement methods are used to investigate the influence of the ingredients or the process on the stability, as well as of the environmental conditions during storage. The described techniques are applied either to double emulsions themselves or to model systems. The presented analysis methods are based on microscopy, rheology, light scattering, marker detection, and differential scanning calorimetry. Many methods for the characterization of double emulsions focus only on the release of the inner water phase or of a marker encapsulated therein. Analysis methods for a specific application rarely give information on the actual mechanism, leading to double emulsion breakage. In contrast, model systems such as simple emulsions, microfluidic emulsions, or single-drop experiments allow for a systematic investigation of diffusion and coalescence between the individual phases. They also give information on the order of magnitude in which they contribute to the failure of the overall system. This review gives an overview of various methods for the characterization of double emulsion stability, describing the underlying assumptions and the information gained. With this review, we intend to assist in the development of stable double emulsion-based products. Full article

Polyacrylate/silica hybrid emulsions were prepared by blending aqueous silica nanoparticles with polyacrylate emulsion, which were used for coating urea granules. After incorporating 1.0 wt.% silica nanoparticles into polyacrylate emulsion, preliminary solubility of CRU was decreased from 38.3% to 2.2%, and the release duration was extended from 8 to 27 days. The hybrid coating remarkably delayed the release of urea via improving wear-resistance due to the enhanced hardness, reducing water vapor permeability because of the tortuous diffusion pathway, and less breakage of CRU granules resulted from higher glass transition temperature. Meanwhile, the processibility was improved, which prevented particle agglomeration during coating. Therefore, aqueous silica nanoparticles have potential application in polymer emulsion coated controlled-release fertilizers. Full article

We provide a facile and low-cost method (F-L) to fabricate a two-dimensional positive master using a milling technique for polydimethylsiloxane (PDMS)-based microchannel molding. This method comprises the following steps: (1) a positive microscale master of the geometry is milled on to an acrylic block; (2) pre-cured PDMS is used to mold the microscale positive master; (3) the PDMS plate is peeled off from the master and punctured with a blunt needle; and (4) the PDMS plate is O₂ plasma bonded to a glass slide. Using this technique, we can fabricate microchannels with very simple protocols quickly and inexpensively. This method also avoids breakage of the end mill (ϕ = 0.4 mm) of the computerized numerical control (CNC) system when fabricating the narrow channels (width < 50 µm). The prominent surface roughness of the milled bottom-layer could be overcomed by pre-cured PDMS with size trade-off in design. Finally, emulsion formation successfully demonstrates the validity of the proposed fabrication protocol. This work represents an important step toward the use of a milling technique for PDMS-based microfabrication. Full article

An oscillatory emulsification system for the production of oil in water emulsions using a commercially available low-cost woven metal microscreen (WMMS) is investigated. The system allows for independent control of both the oscillation frequencies and amplitudes such that it provides two degrees of freedom for controlling the emulsion properties. The investigations included the production of both surfactant and particle-stabilized emulsions. The average droplet size was found to decrease when both the oscillation frequency and amplitude was increased. For surfactant-stabilized emulsions, using bi-surfactants in both the continuous and dispersed phases resulted in a smaller droplet size due to lower interfacial tension. For particle-stabilized emulsions, both the hydrodynamics of the system and the hydrophobic and hydrophilic nature of the stabilizing particles influenced the interfacial properties at the oil–water interface, which in turn affected the final droplet size and distribution with potential droplet breakage. In absence of the latter, a simple torque balance model can be used to reasonably predict the average emulsion droplet size. Full article