Papers by Keyword: Moisture Absorption

Abstract: This study investigates the degradation of adhesion between aluminum alloy and epoxy resin under high-temperature and high-humidity conditions. As next-generation power modules increasingly demand enhanced reliability, understanding the factors that affect metal/resin adhesion has become crucial. In this work, fourier transform infrared spectroscopy and adhesion strength testing were employed to evaluate the chemical and mechanical changes occurring at the interface during accelerated aging. FT-IR analysis revealed that the peak intensity of the carbonyl C=O peak in the epoxy resin decreased with aging time, while the aromatic C=C peak remained largely unchanged. The degree of moisture absorption, calculated from the ratio of these peak intensities, increased with the progress of aging. In addition, moisture uptake was found to weaken hydrogen bonding at the A1050/epoxy resin interface, and this effect was more pronounced in specimens with thinner resin layers. Adhesion strength tests showed a significant reduction in adhesive strength with prolonged exposure to high humidity and temperature. Fracture surface observations further indicated a shift in failure mode from cohesive to interfacial with aging. These results suggest that moisture-induced chemical changes at the interface contribute to the degradation of adhesion.

Abstract: An experimental study of the physical and mechanical properties of untreated and acetylated wood was conducted. The effect of acetylation on wood density was investigated. It was established that the density of the samples generally decreases after acetylation. As the level of acetylation increases, the fiber saturation point decreases in both conifers and hardwoods. Acetylation of wood helps to reduce the sorption properties of wood. The amount of swelling was analyzed. For untreated wood (aspen and alder), the volume swelling index is at the level of 7.5 %. Acetylation contributes to the stability of the geometric dimensions of structures, as the volume swelling index for aspen decreased by 4 times, for alder – by 2 times. An increase in the amount of swelling along the fibers is observed in all samples. Regarding the nature of the destruction of the samples during compression, the aspen (both untreated and acetylated) only crumples without visible signs of destruction. In some samples of alder, partial exfoliation is visible. It was found that acetylation has an ambiguous effect on the mechanical properties of wood of both species.

Abstract: The use of environmentally safe technologies in the plywood production encourages the use of dry powder mixtures of polyester resin used for gluing veneer. The work presents the results of studies of some characteristics for plywood, which was product on the basis of polyester resin. As a result of experimental studies, the expediency of manufacturing plywood on dry adhesive mixtures of polyester resins has been substantiated. Since the limit of static bending strength along the fibers of the plywood face layers exceeds the standard value. The resistance to chipping on the glued layer of plywood also did not decrease and exceeds the standard value both after dry exposure and after soaking. The studied plywood is characterized by reduced moisture absorption properties. This is due to the thermal modification of the veneer. It was established that with an increase in the modification temperature to , moisture absorption decreases by more than 3.5 %. Thus, the obtained research results allow us to purposefully solve further problems related to the creation of new technologies for the wood products manufacture and to determine the conditions of their operation at various facilities.

Abstract: This study was examined the moisture absorption property of green composite using surface treated wood flour for sustainable development goals (SDGs) of product. Constituent materials of green composite were Japanese cedar flour and poly (lactic acid). The lumber of Japanese cedar was cut by hand saw for wood flour. The surface treatment of wood flour was conducted by stone mill. The number of cycle was 400 cycles. The maximum addition amount of wood flour was 20wt%. Molding method of green composite was vacuum compressive method. The moisture absorption test of green composite was conducted by using KNO₃ solution. The maximum test time was four weeks (672 hours). The environmental temperature was room temperature. The humidity was 93%. As a result, following conclusions were obtained. In case of test time 672 hours, coefficient of moisture absorptions of green composites using non and surface treated wood flour 1.0wt.% were similar to that of poly (lactic acid). But, the coefficient of moisture absorption of green composite using surface treated Japanese cedar flour 20wt.% was larger than that of green composite using non-treated Japanese cedar flour 20wt.%. The water penetration probably occurred at interface between Japanese cedar flour and matrix. Therefore, the moisture absorption property of green composite using surface treated Japanese cedar flour 20wt% was affected by water penetration at interface between Japanese cedar flour and matrix.

Abstract: Reducing the toxicity of plywood encourages the use of dry powder mixtures of polyester resin, as its dissolution in organic matter reduces environmental safety. The paper presents the results of studies of free surface energy and its components (polar and dispersed) for plywood, which is made on the basis of polyester resin. The sequences of polarity change and their ratio to the main component of wood after the formation of plywood board at high temperature, which are consistent with the structural and functional features of thermally modified wood. The resulting plywood is characterized by a reduced property of water absorption, because the free surface energy is reduced by 2.3 times and the polarity by 2 times, which is due to the thermal modification of the veneer. Thus, when applying a comprehensive approach to the study of wettability, polarity, interfacial tension, you can choose stable technologies for new wood products and expand its scope.

Abstract: This work presents a non-steady state and three-dimensional mathematical modeling to predict moisture transport (based on the Langmuir-Type Model) inside the vegetable fiber-reinforced composite materials. The numerical solutions of the governing equations have been obtain using the finite-volume method. The model was apply for vegetable fiber-reinforced polymer composites. Emphasis to the geometrical dimension effect of the composite in the water absorption process was given. Results of the average moisture content, free and entrapped water molecules concentration kinetics and free and entrapped water molecules concentration distributions inside the material along the process are shown and analyzed. In the distributions of the analyzed properties, it was observed that the geometric dimensions of the composite has influence in the water absorption process.

Abstract: Wound dressing is the application of a sterile pad to protect a wound from further harm and promote healing. Over the past decades, various materials including calcium alginate, hydrogel, hydrocolloid and gauze based wound dressing materials have been developed. Unfortunately, shortcomings such as potential allergic reaction, high cost, short shelf life and scarcity have been associated with their use. In developing countries such as Ghana, sterilized gauze is commonly used in wound dressing but it causes scar formation and traumatic pain during removal. In addressing the issues of cost and availability, there may be local materials like cassava (Manihot esculenta) with the ability to aid in wound healing. Cassava is a cheap staple crop grown in Africa which is rich in carbohydrate, fibre and minerals. This research characterized three genotypes of cassava (IITA-TMS-GAEC-160006 (IT6), IITA-TMS-GAEC-160004 (IT4) and Afisiafi (Afi)). These genotypes have been studied in terms of their fibre content, fluid absorption capacity, hemolytic ability and their ability to promote rapid blood coagulation (coagulation time). Fibre samples were soaked in deionized (DI) water and PBS (Phosphate buffered saline) and at different time intervals the swollen samples were weighed. Fibre samples were also brought into contact with human blood and toxicity of samples determined. The results reveal that the rate of absorption of fluid by fibres in both DI water and PBS ranges between 0.66-0.93 g/min and fibres are generally non-toxic to blood cells. The fibre properties were compared with gauze and from these, some genotypes of cassava fibre were recommended for further research towards the design of a wound dressing material.

Abstract: Biodegradable plastic are renewable packaging technology that are bio-based made of starch. The use of starch as a manufacture of bioplastic has great potential due to in Indonesia has various biodiversity of starch-producing plants. The objective of this research was to determine effect of cassava starch addition to hardness, density, moisture absorption, and biodegradability of bioplastic. The methods is a synthesis of bioplastic using a casting procedure ie mixing cassava starch at various concentrations 2%, 3%, 4%, and 5% (b/v) into the glycerol. This was demonstrated of bioplastic hardness and density of 31.56; 46.78; 52.34; 67.99 Shore A and 1.164; 1.178; 1.184; 1.191 g/cm3. Revealed that complete decomposition could be achieved on the 12, 13, 14, and 15 days. It shows that the cassava starch addition can improve hardness, density, moisture, and accelerate the decomposition process.

Abstract: The effect of moisture, water absorption on a single short span beam of glass fiber reinforced polymer (GFRP) was examined under room temperature, 27°c. The aim of the study is to investigate the mechanical properties of composite under wet condition. The composite were cut into rectangular shape with a dimension of 78 mm long, 26 mm width and 3.5 mm depth. The moisture content of eight specimens was experimentally reduced as the glass fiber content increased. In this investigation, the flexural strength and modulus of composites were determined throughout the three-point bending test. The specimens were rigged up horizontally as supported beams and loaded vertically at the geometric center. Thus, the results were developed into loading versus deflection and relationship for each specimen. The samples were considered to have failed when the curves were in steady decline section. Failure mechanisms were observed in categories; face yield, core yield and fiber tear.

Abstract: Starch is the most important polysaccharide and has become the major component of many food industries as well as textile, paper, cosmetic and certain industries that engage in adhesive, thickening, stiffening and gelling agents. However, native starch has limited function and therefore is recommended to modify its physical and chemical properties to meet the consumers’ needs. In this study, the native starch was chemically modified to determine its behavior and characteristics after using hydrolysis process of acid hydrolysis method. There were three types of starch that has been studied - potato, cassava and corn. These starches undergone hydrolysis process using hydrochloric acid and their characteristics were determinedthrough moisture absorption test and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. For moisture absorption test, hydrolyzed starch tends to absorb more surrounding moisture than native starch. This behavior resulted from the increase of hydrophilic character of starch after being modified. The FT-IR analysis shows that hydrolyzed starch content got more hydroxyl group than the native starch due to the breakdown of hydrogen bond between the starch molecules after the acid hydrochloric treatment.