Papers by Keyword: Recycle

Abstract: The plastics from municipal solid waste (MSW) were modified to improve cleanness for adding value. The stir and sonication were performed as cleaning processes. Xylene, tetrachloroethylene, chloroform, acetone and toluene were used as solvent cleaning. The most suitable cleaning process was sonication method with cleaning time of 5 min and the appropriate solvent was xylene for washing the plastic wastes for further study in terms of thermo-mechanical and rheological properties. The cleaning process was successful as evidence in thermogravimetric analysis (TGA) results. The properties of new plastics, cleaned plastic wastes and plastic wastes were compared and analyzed. Tensile strength of the specimens from plastic wastes was slightly decreased; however, elongation and impact strength of cleaned plastic wastes and plastic wastes sharply dropped as compared to new plastics. Tensile modulus of cleaned plastic wastes was slightly better than that of new plastics. Thermal stability of plastic waste was slightly lower than that of new plastic. Shear storage modulus (Gʹ), shear loss modulus (Gʺ) and shear viscosity (η) of new plastics showed the maximum value; on the other hand, those properties of cleaned plastic wastes and plastic wastes were similar. The cleaning method with solvent did not destroy thermo-mechanical and rheological properties of the cleaned plastic wastes.

Abstract: The paper was removed due to copyright misconduct (missing consensus from all co-authors)

Abstract: The paper was removed due to copyright misconduct (missing consensus from all co-authors)

Abstract: In the plastic industry, recycling waste from production is normal practice for reducing waste and cost. When they were reproduced, their mechanical properties are changed. These changes may affect the quality of the end product. Hence, this work studied the mechanical, thermal and rheological properties of recycled biodegradable poly (butylene succinate) (PBS) with reproduction of 10 cycles. The results showed that tensile strength was slightly increased with increasing reproduction cycle until 6^th cycles and reduced in the further cycles, respectively. The elongation at break was abruptly decreased with an increase of the cycle number. Moreover, the hardness was quite constant in the lower cycle number but it was slightly decreased in the higher one. Melt flow index (MFI) measurements indicated a significant change in the material after 2^rd recycles. The results on thermal properties measurement showed that degree of crystallinity decreased in the 6^th cycles.

Abstract: Natural opal, an amorphous, hydrous form of silica (SiO₂-n-H₂O), has been one of the favored precious gemstones for many centuries. Though beautiful, opal is very fragile and is damaged quite easily. Thus, opals of all varieties have been synthesized experimentally and commercially. The objective of this project was to synthesize and to compare crystalline opals. In this work, the development of powder sintered glass ceramics process based on soda lime silica glass waste with metal oxide powder enable jewelry applications. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1,000°C), whereas glass/metal powder interactions resulted in the formation of color agent crystals, provide enhancing optical properties. Several techniques were applied for characterization of the ingots. The chemical analysis was performed by Energy Dispersive X-ray Fluorescence (ED-XRF). The mineralogical compositions of the samples were determined by X-ray diffraction analysis. Raman spectroscopy was applied for optical characterization. The results were compared with a natural common opal. The present investigation demonstrated that the common opal with both color and colorless appearance can be synthesized by the technique, as the crystalline phase of opal structure was identified by XRD measurement. There is a great potential for such materials with novel functionalities for artificial gemstone application, i.e. opal forming.

Abstract: Adsorption of Cr(VI) and desorption of the Cr that was adsorbed using persimmon gel was examined. Most of the Cr(VI) was adsorbed at a pH value of 2, and a part of that was reduced to Cr(III) in the solution using persimmon gel, which has many polyhydroxyphenyl groups. A small amount of Cr was desorbed using some acidic or alkaline reagents at 30 °C. However, all of the Cr adsorbed using persimmon gel was desorbed at reflux temperature as Cr(III) using 1M HCl. Cycles of Cr(VI) adsorption and desorption as Cr(III) cycles were repeated 9 times. The adsorption of Cr was quantitatively repeated until 8 times and desorption of Cr was almost quantitatively repeated until 9 times.

Abstract: Cutting fluid is commonly used during metal cutting process for cooling and lubrication. Fluid types are generally classified into mineral or fatty oils and water miscible oils. In Japan, the former is called water-insoluble coolants, and the latter is called water-soluble coolants. Water-insoluble coolants are specified as dangerous material by the Japanese law due to its flammability. Therefore, the water-insoluble coolants are not appropriate for unmanned operation of machine tools. Therefore, the usage rate of water-soluble coolants is increasing. Water soluble coolants are diluted with a water by several ten times. The waste management of the water-soluble coolant become important for environment-conscious green manufacturing. We have been developing a recycling system for water-soluble coolants. In the recycle system, water is extracted from the waste coolant and the water is then reutilized as a diluent of a new coolant. We have developed various types of chemical or bio-chemical water recovery methods for recycling systems. We found a commercially available amine-free water-soluble coolant is suitable for the recycling system. The processing time, processing cost, and the biochemical and chemical oxygen demand of the extracted water are improved by the amine-free water soluble coolant compared with a conventional amine-containing coolant. However, its corrosion inhibition performance was poor in general machining applications. Our cooperative company developed a prototype of a corrosion-inhibition-improved amine-free water-soluble cutting coolant. The prototype coolant showed a good stability and cooling and lubricating performances, and its recyclability was as good as that of conventional amine-free coolants. In this study, we focused on repeated recycling of the prototype coolant. We repeatedly applied the water recycling process to the recycled coolant. The recyclability of the prototype coolant was not affected by repeated recycling; however, process residues increased with the number of recycles, and a deterioration was noticed in the corrosion-inhibition performance of the coolant diluted with recycled water.

Abstract: Tool steel grade JIS; SKD-11 is a well-known raw material for making a high wear resistance of blanking tool in stamping industry. One problem in the blanking process is the high cost of raw material for making punch and die. Therefore, in this study, behavior of wear phenomenon and ability of recycle on the punch of blanking die process were investigated. In the first section, phenomenon and mechanism wear of blanking punch were observed. We found that mechanism of wear on blanking punch was adhesion wear, since high amount of chromium content in the punch has compatibility of elements. The second section, recovery punch was designed by annealing, resize and quenching process by using the new punch from the first section. From the recovery punch results, it was found that the wear resistance of recovery punch decreased slightly but it was strong enough to continue in blanking process. However, the recycle process of tool steel depends on a quality and amount of the product.

Abstract: Mg alloy chips produced by machining processes are fine and active, and thus difficult to recycle by melting. The treatment of Mg chips is one of the concerns for expansion of the application of Mg alloys. Therefore, suitable processing for Mg chips is necessary. Mg alloys have the disadvantage of poor corrosion resistivity, and high reactivity with water, leading to the hydrogen and Mg hydroxide. This hydrolysis reaction is enhanced by the presence of NaCl in water. In this study, hydrogen was produced by the hydrolysis reaction of Mg chips generated by machining and seawater. Furthermore, ball milling was performed to enhance the formation of hydrogen. The hydrolysis reaction combined with the ball milling produced 795mL of hydrogen for 1g of Mg chips after 120 min. However, only 180 mL of hydrogen was obtained by the reaction without ball milling; a notable improvement in hydrogen formation was observed. A similar result was obtained for AZ91 chips. It is believed that the combined process of hydrolysis and ball milling is useful for the production of hydrogen with the disposal of Mg chips.

Abstract: The global warming is one of the most serious problems. The decrease of CO₂ emissions in our daily life is an important subject today. Recently, an application of water retentive materials as a paving material has attracted a great deal of attention in Japan. This material is effective for reducing heat island phenomenon, which is also a recent problem in many cities in Japan. Water retained in the material during rainfall evaporates when heated by sunshine. The latent heat absorbed by evaporating water works to cool the surroundings. The water retentive ceramic products are expected to be useful for building materials as well as pavements. Several performances are required on the water retentive ceramics when it is used as building materials. Its cost and quality are the important factors. Porous ceramic materials formed by pressing without firing is one of ideal low cost and eco-friendly candidates. The porous ceramics is also expected to be produced from recycled ceramic materials. By optimizing its composition and forming method, a water retentive material with high performance was developed. The trial product had the properties as follows; fracture toughness: 1300N, bending strength: 175N/cm, water absorption: larger than 30%, and precision in size (length): +-0.5mm for 150mm. The product showed also enough frost resistance. In this paper, the fundamental properties of the porous ceramics prepared without firing are discussed with referring to the results of the field experiments.Another subject recently studied by several tile manufactures in Japan is the glazed tile with high solar reflectance. The exterior walls covered with such a high solar reflectance tile keeps the surface temperature of the wall lower under the strong sunshine of summer. It is effective against heat-island phenomenon. In this paper, the outline of the research results on visible and infrared reflectance of many kinds of glazes is also discussed.