Determination Of Water Absorption Research Articles

Eco-Friendly Bamboo-Based Composites

The study focuses on obtaining bamboo-based composite materials and new environmentally friendly binders with different degrees of silylation (15-35%) at different pressures and temperatures. The synthesis was carried out using silylated polystyrene (poly[trimethoxy(4-vinylphenethyl)] silane) and styrene as a binder and reinforcing agent in the presence of organic/inorganic additives, antioxidants and antipirene. Poly[trimethoxy(4-vinylphenethyl)] silane, a solid brown substance, was synthesized via an alkylation reaction of vinyltrimethoxysilane and polystyrene, in the presence of anhydrous AlCl3. This paper presents the development of composites for ecological purposes (eco-composites) using bamboo fibers and their basic mechanical properties. The surface structures of the new composites were studied by several techniques including electron microscopy, energy dispersive X-ray microanalysis, bending test, Charpy impact test, thermogravimetry study, and water absorption determination. The new composites are characterized by good mechanical properties, thermal resistance, ecological purity, and water absorption capacity much smaller than the water absorption of existing particle boards.

JUSTIFICATION OF THE POSSIBILITY OF USING THERMOMODIFIED VENEER IN AN ENVIRONMENT WITH HIGH HUMIDITY

Thermally modified wood is widely used in the woodworking industry, as it has increased resistance to environmental factors (humidity, temperature). The effect of high temperature on wood causes a decrease in water adsorption by reducing the available free hydroxyl groups of carbohydrates. The reduction in hygroscopicity contributes to the treated material size stability, as swelling and shrinkage are mainly associated with the phenomena of absorption and water desorption. The study of natural weathering always takes many years. Therefore, to study the resistance of thermodified wood to environmental influences, artificial weathering is used - modeling of external factors (cyclic change of UV light and moisture). The effectiveness of the thermodified veneer use as a material for lining the furniture facades which working in different temperature and humidity conditions was established. The values of moisture and water absorption on the samples of oak veneer, which have previously undergone the heat treatment process, have been determined. It was found that the samples of oak veneer gained the most moisture from the environment in the first two days. The weight of unmodified veneer increased by 0.06 g, similar results showed veneer modified at temperatures of 160 and 190 °C. Thermodified veneer at a temperature of 250 °C for the first two days gained twice less. By the end of the experiment (next 11 days), the samples of ordinary and modified veneer at all temperatures absorbed the same amount of moisture. Untreated veneer and thermodified at temperatures of 160 and 220 °C absorbed 50-66 % of its initial weight, and modified at 250 °C – 20-36 %. Control samples of veneer during the determination of water absorption gained 98 % of the initial weight. Samples modified at 160 °C – 10, 20, 30 min showed the best result – reducing the value to 94 %, 93 % and 91 %. There is a slight improvement in water absorption after exposure to temperature 220 °C for 10, 20, 30 min – 91 %, 91 % and 90 %. Values water absorption at the level of 90 %, 89 % and 86 % were recorded in veneer samples modified at 250 °C.

Production and characterization of black charcoal from Bambusa vulgaris (Yellow Bamboo) and potentiality for advance applications

Issues of air and water pollution and necessity of health care are becoming serious problem as the inter country and global industrialization accelerates. Finding solutions and speedy addressing to these problems via sustainable management and expansion of woody and non woody forest crops, extraction, eco and health friendly products development is increasingly important. Environmentally and health friendly bamboo charcoal has greater potential and upcoming demand in the globe. Evaluation of higher carbonation temperature and characterization of charcoal properties compared to traditional carbonation temperature pave the way for modification of surface and absorbance properties of bamboo charcoal and expansion of areas applications. This paper provides a scientific research about the optimum carbonation temperature to produce charcoal from Bambusa vulgaris (yellow bamboo). The bamboo culm was carbonized at four differed temperatures ranging from 600 to 950oC. Products of charcoal were characterized by SEM micrograph analysis, modules of rupture (MOR), calorific value, density, bulk density, density determination and water absorption determination. Optimum carbonization temperature to gain maximum property enhancement of bamboo charcoal was observed around 700 and 850 oC. By changing carbonization temperature charcoal properties can be change. Removal and solidification of carbon in the flue gas during manufacturing and convert into usable foam of product development pave the way for the expansion of charcoal manufacturing industry without harmful damage to the environment.

Antifungal applications for nano-additives synthesized with a bio-based approach

Filamentous fungi are microorganisms that cause deterioration of structural materials due to their ecological plasticity and vegetative functions. Functionalised sol-gel based products can be used to control this kind of biodeterioration through the association to antifungal active additives which are trapped in the siloxane crosslinking. Bioactive additives and materials to control microbial growth have been gaining more attention over the years. However, due to the concern about their toxicity, bio-based approach has been explored. The aim of the present research was to obtain antifungal additives with nanoparticles synthesised with aqueous extract of Senna occidentalis L and silver or copper salts to obtain a functionalised sol-gel based product to control the biodeterioration of bricks. Nanoparticles were characterised by UV–vis spectroscopy, transmission electron microscopy and x-ray diffraction. Silver nanoparticles (15 nm) showed higher stability over time and proved to be active against Aspergillus versicolor and Cladosporium cladosporioides which were isolated from brick wall. The strains were selected due to their high frequency in mycobiota of biodeteriorated structural building materials. The silver nanoparticles were successfully integrated in a silane-based matrix to be applied in bricks. The samples were characterised by surface tension determination, contact angle measurement, water absorption determination, scanning electron microscopy and energy dispersive x-ray spectroscopy. Bricks with the lower concentration (2%) of the functionalised silane (3-mercaptopropyltrimethoxy) showed to be efficient to prevent fungal biofilm development with 100% of inhibition against both strains.

Preventing thermal degradation of PVC insulation by mixtures of cross‐linking agents and antioxidants

ABSTRACTPoly(vinyl chloride) (PVC) is widely used—in spite of HCl formed from it at elevated temperatures. PVC wire and cable insulation has poor thermal stability, causing the plasticizer to separate from the PVC chains and produce an oily residue, lowering the tensile elongation at break and thus increasing brittleness. One uses cross‐linking agents and antioxidants, as well as mixtures of both, to improve the thermal stability of the plasticizer and tensile properties of PVC after thermal exposure. We performed tensile tests, tribological tests, profilometry, scanning electron microscopy (SEM), and water absorption determination before and after thermal exposure at 136 °C for 1 week. After adding the agents, elongation at break increased by 10 to 20% while the wear rate and water absorption were lower than for the control sample. Less voids are seen in the SEM images after adding these two kinds of agents. The thermal resistance of the PVC cable insulation is best enhanced by combinations of cross‐linking agents and antioxidants. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48816.

Nafion® and polyaniline composite modification with Li and Mg ions

Modification of Nafion®-based samples with polyaniline (PANI) and positive charged ions could potentially allow achieving good proton conductivity at higher working temperatures what is observed in typical polymer electrolyte membrane fuel cells.In this work Nafion® polymer was modified with 1% polyaniline emeraldine salt and Li and Mg ions containing solutions. The influence of activation process and the type of ions on composites’ proton conductivity was investigated. To define the best composition the physiochemical properties of synthesized materials were determined by the means of thermogravimetric analysis, impedance spectroscopy, determination of water absorption and its kinetics, and FTIR. From the original samples the best results of σ=155 mS/cm were shown by Nafion®/PANI membrane what was modified by Li+ reduction solution. This membrane also had better thermal characteristic compared to other researched samples: membrane degradation starts on higher temperature interval.

Evaluation of granulability and absorbtivity of biomass in agglomeration mixture

The granulability and absorbtivity of sawdust and coke breeze were investigated. These properties are important within the preparation of agglomeration charge. They have a significant impact on plynodynamic batch conditions. Ability of materials to wet is a fundamental condition of granulability of materials. Wettability and water absorption of wood with liquids is generally significantly affected by their chemical structure. The important factors affecting the wetting process are undoubtedly the wood moisture content, the value of the surface tension of liquid media and their chemical composition. With increasing moisture content of wood, the time to equilibrium rises. Determination of water absorption and granulability of sawdust was conducted to seek their possible use as a partial replacement of coke dust in the production of the agglomerate. Experiments have been realized with alder, oak and pine sawdust and reference material−coke breeze. These materials were divided to four classes of granularity: supplied material, 1−2 mm, 0.5−1 mm and less than 0.5 mm. And different liquid media were used: water 16 °C, water 60 °C, soapy water, lime milk and surfactant.

Use of mechanically-activated kaolin to replace ball clay in engobe for a ceramic tile

Abstract Ceramic engobe is an intermediate layer between the substrate and the glaze of a ceramic tile. It is basically composed by plastic material, clays, and non-plastic material, feldspar and frit. Light-colored clays with good plasticity and low-fire temperature are used in ceramic engobe formulations, typically ball clays. However, these clays contain different accessory minerals, which can adversely affect the opacity and the whiteness. The use of washed kaolin, with a lower content of accessory minerals, tends to lead to higher opacity and whiteness. In addition, its mechanical activation can increase the plasticity, allowing its use as a replacement for ball clay. The aim of this study was to investigate the effect of the use of mechanically-activated kaolin to replace ball clay in an engobe employed in the production of ceramic tiles. Samples of kaolin were activated by high energy mill (1 and 4 h, at 500 rpm) and characterized by surface area and particle size measurements, crystallography, infrared spectroscopy and differential scanning calorimetry. Cylindrical specimens of four ceramic engobe formulations were submitted to splitting tensile strength and bulk density tests. The specimens were fired in a laboratory kiln and characterized through the determination of water absorption, bulk density, relative density and by reflectance spectrophotometry. Crystallographic analysis with Rietveld refinement and microstructural analysis by scanning electron microscopy were also carried out. After the high energy milling, the kaolin had less crystallinity and the specific surface area increased from 4.6 to 46.1 m2/g. The use of mechanically-activated kaolin as a replacement for ball clay in a ceramic engobe increased the mechanical strength, crystalline phase content and whiteness.

Limiting properties in the characterisation of mixed recycled aggregates for use in the manufacture of concrete

Recycling of construction and demolition waste (CDW) has become a widespread concern in Spain for the last years, as a way to preserve natural resources and achieve a better control of waste disposal sites. Specific applications which make use of mixed recycled aggregates are of great importance, as this types of aggregates constitute the majority of the total production. Structural and non-structural concrete is one of the possible applications, being this the main goal of our study. This paper presents a study on the physical and chemical characteristics of mixed recycled aggregates which have been obtained from different CDW treatment plants of Spain. Correlations between the different properties were investigated in order to find criterions of acceptance for recycled aggregates to be used in concrete. The comparison between the properties offers the possibility of pre-selecting a great quantity of mixed recycled aggregates, these being suitable for either structural and non-structural concrete. The determination of water absorption and the gypsum content are good indicators in order to evaluate the quality of the mixed recycled aggregates for its application in the production of concrete.

Lignin role in a complex polyolefin blend

Materials with enhanced surface, thermal properties and degradation characteristics have been obtained by incorporation of the epoxy-modified lignosulfonate (LER) in the binary polyolefin mixture (70 PP/30 PE). The LER content varied from 2.5% to 40%. All properties (mechanical, thermal and surface properties) depend on LER content. The mechanical properties are less influenced for LER content up to 10 wt.% while at high LER amount they decreased. The surface properties show a maximum for 20 wt.% LER and assess that the biocompatibility is improved in 0 −20 wt.% LER content range. The behavior of the polyolefin/lignin blends during soil burial test has been monitored. The changes of the polymer blends properties have been investigated before and after soil burial test, by determination of water absorption or weight losses, and by the measurements of the physical-mechanical and surface properties. The physico-mechanical indices for buried samples decrease indicating the initiation of the degradation process. The response of Vicia X Hybrida hort plant to the presence of the blends buried in closed vicinity to its roots has been followed, too, showing a weak negative influence on the physiological processes of the plants.

Determination of water absorption of ceramic ware by a vibration method

Determination of water absorption of ceramic ware by a vibration method

Determination of the Water Absorption of Crude Rubber and of Vulcanized Rubber

Abstract In the introduction the purpose of the investigation is described which is the development of a method suitable for the determination of the water absorption of crude and vulcanized rubber, and which, in conjunction with ash and nitrogen determinations is especially adapted to the testing of purified rubber. The conditions which affect the results of water determinations are reviewed, with special reference to the formulas of Taylor and Kemp, which make it possible, within certain limits, to compare results obtained by different determination methods. The reasons for selecting the foregoing method of determination of water absorption are described. It is pointed out that water absorption depends to different degrees on the time of vulcanization. In the rubber-sulfur mixture which was chosen, the influence of the degree of vulcanization is small, so that it is sufficient to vulcanize all types of rubber for the same length of time. At the same time it is shown that the results obtained by immersion of rubber for 7 and 25 hours at 80° C. still sufficiently agree with the values computed from the formulas of Taylor and Kemp. A method of measuring water absorption is described in detail. The question arises to what extent rubber manufacturers may use this method, in conjunction with ash and nitrogen determinations, method for estimating the quality of purified rubber. Rubber manufacturers are urged to give their opinion of this proposed method. Some other method will be considered if it should appear that manufacturers prefer this other method.