Papers by Keyword: Swelling

Abstract: Ramie fibre has been widely utilized, particularly in the textile industry. The application of Ramie fabric-based composites has been increasingly favored for the fabrication of lightweight structures and high-performance products. Polypropylene (PP) is commonly used to reinforce natural fibres due to its superior physical, mechanical, and thermal properties. Proper treatment of ramie fabric is crucial to ensure strong bonding between the ramie and polypropylene (PP). Alkali treatment is commonly employed to address bonding issues. In this study, ramie fabric was treated using different concentrations (5 wt%, 16.7 wt%, 28.6 wt%, and 37.5 wt%) and durations (30 minutes, 1 hour, 20 hours, and 24 hours). Subsequently, a compression molding process was employed to manufacture both the lamina and laminate. The lamina was exposed to a temperature of 170°C and a pressure of 100 kg/cm³ for three minutes, while the laminate was subjected to a temperature of 170°C and a pressure of 210 kg/cm³ for seven minutes. The results revealed an increase in tensile strength compared to pure PP tests. The single and five-layered composites showing an increase of 1.65% and 2.79%, respectively. The optimal tensile strength reached by five-layered composite was 25.82 MPa. Despite the increased strength, fibre failure occurred due to swelling. The occurrence of fibre failure and increased strength when transformed into a composite highlights the potential for further improvement of ramie fabric and polypropylene.

Abstract: Expansive soil is strongly influenced by the water content inside the soil particle , the significant changes of moisture content cause volume changes. The swelling and shrinkage potential of the soil can be indirectly identified by running the consistency limits test which are by controlling the plasticity index (IP) value and shrinkage limit (SL) value. This research aims to determine the value of liquid limit (LL), plastic limit (PL), plasticity index (IP), and shrinkage limit (SL) of soil-bentonite mixtures as expansive soil materials and analyzing the expansion potential of the modificated materials by its value. There were 5 variations of mixtures which are original soil (S), bentonite (B), 25%S+75%B, 50%S+50%B and 75%S+25%B. The results show the properties of soil-bentonite mixtures. The specific gravity and the grain size distributions were not significantly affected by the increase of the amount of bentonite. LL,PL and PI value significantly increase while SL value were decreased. Along with the increase of bentonite percentage, the activity value also increased by 1.5 to 4. It summarizes that by adding bentonite on the original soil, the expansion potential of the soil mixtures also increased.

Abstract: Environmental advantages and remarkable performance can be achieved by using ramie fibers, which demonstrates the enormous potential in fiber reinforced composites. A study was conducted to investigate the effects of chemical treatment on water absorption, thickness swelling, and hardness behavior of polyester/ramie composites. Natural fibers that were not treated or treated were prepared in unidirectional orientation, and the vacuum infusion technique was used to manufacture the composites. Comparing composites treated with both oxalic acid and alkali to untreated ramie fibers, the composites resistance to water absorption was increased by 94.68%. The evaluation of thickness swelling also revealed that the combination treatment exhibited the lowest percentage of dimension expansion. The thickness swelling of the polyester/ramie composite was reduced by 32.58% as a result of the ramie fibers being immersed in subsequent alkali and oxalic acid solutions. The findings of the Shore D Hardness test showed that after the samples were soaked for 312 hours, there was a decrease in hardness, where the smallest found in the treated samples.

Abstract: The application of membrane technology in the separation process has led to the technology's present rapid development. Nylon 6.6 polyamide membrane has hydrophilic properties and has advantages such as low fouling tendency and resistance to high temperatures. This research aims to determine the effect of pectin on the characteristics of nylon 6.6 membranes. In this study, the membrane was made from nylon 6.6 using the phase inversion technique. Modification was carried out by adding pectin at variations of 0, 0.25, 0.5, and 0.75% by weight. The IR structure characterization results of the nylon6.6-pectin membrane show the same peak for the-NH group and the OH, C-H, amide I, amide II, amide III, CH₂, and C-C groups. Membrane contact angle measurements P0, P0.25, P0.5, and P0.75 were 59.37°, 67.70°, 63.48°, and 58.00° respectively, indicating hydrophilic properties. Meanwhile, the degree of swelling after the membrane was soaked in distilled water for 24 hours showed values of 55.32%, 44.44%, 60.38%, and 63.16% for membranes P0, P0.25, P0.5, and P0.75. The P0.75 membrane has the lowest contact angle which is increasingly hydrophilic and the highest swelling value which indicates the highest absorption level compared to other variations.

Abstract: A styrene-butadiene rubber having a gradient crosslink density in the thickness direction was simply prepared by vulcanizing under a temperature gradient to study its mechanical properties and swelling behavior. The graded rubber exhibited considerable strain recovery after stress removal despite having a low crosslinked part. Notably, the graded rubber also manifested greater hysteresis loss during cyclic test compared to a homogeneously crosslinked rubber, even though they had similar initial moduli. Furthermore, anomalous swelling behavior was observed in the graded rubber. The graded rubber exhibited shape transformation upon swelling. The mechanism was thoroughly explained using gel swelling theory under constraints. This must be a common phenomenon in graded rubbers with a crosslink gradient in the thickness direction. This comprehensive research provides a novel approach for material design with tailored properties and promising applications for this potential material.

Abstract: This paper evaluated the swelling of graphite resin electrodes developed for utilization in the electrochemical treatment of gold mining wastewater. Graphite-resin electrodes were developed from used dry cells and resin using non-heat treatment processes (segregation). The Microstructure of the electrode was determined using a scanning electron microscope (Carl Zeiss Smart Evo 10) to ascertain the composition of the electrode. The swelling property of the electrodes was measured using the standard method through a combination of gold mining wastewater and chloride salt solutions. Effects of operational factors (particle size, percentage binder and compressive “compacting” pressure) on the swelling of the electrodes were monitored and evaluated statistically (using analysis of variance). Weibull probability distribution (2 and 3 parameters) was applied to the swelling through Microsoft Excel Solver and Moment Likelihood Method to ascertain the usefulness of the electrode in environmental pollution control through computation of reliability. The study revealed that the swelling was in the range of 1.48 % to 2.24 %, particle size (F_5,20 =196.48, p = 2.76 x 10^-16), percentage binder (F_4,12 =181.58, p = 1.27 x 10^-10), and compressive pressure (F_3,12 = 106.69, p = 6.43 x 10^-9) were significant factors that influence swelling of graphite-resin electrode at 95 % confidence level. the values of α and β for 2-parameters Weibull distribution are 63.162 and 15.098, and 1.265 and 10.089 for MSE and MLM methods, respectively. The Table shows that the values of α, β and θ for 3-parameters Weibull distribution are 3.679, 8.097 and 0.168, and 4.350, 7.165 and 0.198 for MSE and MLM methods, respectively. It was concluded that particle size and compacting pressure are significant factors that had an effect on the swelling of graphite resin electrodes for treatment water and wastewater.

Abstract: There are the results of studies on increasing the sedimentation stability of cement-mineral suspensions intended to fill hollow spaces in fractured rocky soils and strengthen dispersed soils, as well as to prevent filtration processes in soils.To ensure the sedimentation stability of cement-mineral suspensions, it is proposed to use the water solutions of hydroxyl-containing polymers prone to swelling as a dispersion medium (mixing water): water solutions of polyvinyl alcohol (PVA) in 4% - 8% concentration. The concentration range of polymer solution from 4% to 8% was established in order to prevent coagulation during storage and to ensure the production of polymer films from water PVA solutions.The research results showed that polyvinyl alcohol provides the high kinetic sedimentation stability of cement-mineral systems determined by hydrodynamic factors as follows: the viscosity and density of the water polymer solution. The higher the viscosity and density of the water solution of polyvinyl alcohol (concentration), the higher the sedimentation stability of cement-mineral suspensions.

Abstract: Hydrogel spheres made of sodium polyacrylate with free absorption of water can increase in volume by 100-1000 times due to the violation of the balance of forces of attraction and repulsion between the links of the gel. The addition of water will shift the balance in favor of the repulsive forces. This property will allow them to be used in cement systems as an active expanding aggregate, which will compact the structure, reduce the water-cement ratio during the formation of the cement paste structure, and then give water to the hardening cement stone. The hydrogel sphere itself will decrease in volume to its initial state and will leave the pore in its place. The resulting material can be considered aerated concrete with compacted inter-pore partitions. The advantage of this method over the traditional method of self-compacting masses is that there is no need to supply thermal energy to activate the expansion of the active aggregate, for example, by passing an electric current through the hardening mass. In this article, the properties of the hydrogel are investigated, the dynamics of the expansion of hydrogel spheres in water at different temperatures is determined.

Abstract: The article covers the research on the changing of flexo plates' deformation properties during swelling in various solvents that are used in the printing industry. The acquired data was processed with the equation from the Kelvin-Voigt model, the constant models and times of relaxation of the initial and swelled photopolymer have been determined.

Abstract: Radiation porosity through-thickness of the fuel pin cladding, made of 16Cr-19Ni-2Mo-2Mn-Nb-Ti-V-P-B steel, has been studied with scanning electron microscopy using backscattered electron (BSE) detector. The examined sample was irradiated at a temperature around 480 °С up to an integral damage dose of 87 dpa. It was shown that, due to the temperature gradient through the cladding thickness, the average size of radiation voids reduces, and their concentration increases from internal to external surface. Local nonuniformity of radiation porosity is observed in regions close to internal and external surfaces. It was shown that, non-uniformity of radiation porosity is determined by the material structure, microtwin density and high concentration of low-angle inter-granular boundaries, in particular.