Key Engineering Materials Vol. 824

Abstract: Waste lignin (WL) obtained from paper mills, was studied for its potential application in preparing carbon nanoparticles (CNPs) with high porosity. This was done by impregnation of 0, 5, 10 and 20% concentrations of phosphoric acid under various carbonization temperatures (600, 700, 800 and 900°C). The physicochemical properties of CNPs were characterized through nitrogen sorption, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). Nitrogen sorption revealed that the condition using 10% concentration of phosphoric acid treatment at a carbonization temperature of 700°C formed carbon nanoparticles with a highly porous structure (Surface area 27.65 m²/g and pore volume 0.07 cm³/g). Additionally, in order to high surface area, porosity and concentrated carbon nanoparticle.

Abstract: In tissue engineering, biomaterials used for bone tissue substitutes attract increasing interests, especially for finding biologically active compounds that can activate proliferation of osteoblastic MG63 cells. The evaluation of the impact of a soluble yeast-derived β-(1-3), (1-6)-D-glucan (BG) extracted from distillery waste yeast sludge on viability and proliferation of MG63 cells was studied. Spray dried BG prepared from alkaline extraction was used as supplementary activator in osteoblastic cell culture system. The composition of BG was characterized using FTIR spectral analysis and BG analysis assay kit. MG63 human osteoblast cell-line was cultured on Dulbecco’s modified’s medium supplemented with various concentrations of BG ranging from 0.1 to 1.0 mg/mL. The cells were cultured up to 7 days under a humidified 5% CO₂ atmosphere at 37°C and monitored the level of proliferation at pre-determined intervals. Results showed that increase in BG concentration substantially promoted MG63 cell proliferation. Optimal concentration was identified and found at 0.3 - 0.7 mg/mL. Results revealed that BG could be further utilized for the upregulation of osteoblastic proliferation positively related to the acceleration of bone regeneration.

Abstract: The composite materials of biodegradable polymer, poly(lactic acid) (PLA) and fatty acid modified eggshell 15 phr were prepared using a twin screw extruder. Eggshell was modified with different types of fatty acids i.e. propionic acid and oleic acid. Samples were shaped by an injection molding machine to prepare the specimens for mechanical testing. A scanning electron microscope was used to characterize the fracture surface of the composites to ascertain their morphological properties. A universal testing machine and an impact tester were used to investigate the mechanical properties. From the investigation, it was found that the dispersion of eggshell modified with fatty acid in PLA matrix is more uniform than unmodified eggshell. Young’s modulus and tensile strength of the composites between PLA and eggshell modified with propionic acid are higher than neat PLA and PLA/eggshell modified with oleic acid. On the other hands, the relative amount of elongation at break and impact strength of PLA/eggshell modified with propionic acid composite are lower than the composites of PLA and eggshell modified with oleic acid.

Abstract: Vast quantities of marigold flowers are often discarded as waste at sacred places and temples after religious ceremonies in Thailand. This has motivated us to examine the utilization of waste marigold flowers as a precursor for the synthesis of porous carbons by hydrothermal carbonization (HTC) and pyrolysis. Waste marigold flowers were hydrothermally treated at 180 °C for 2, 12, and 24 h. The resultant hydrochars were subsequently pyrolyzed at 800 °C under argon (Ar) atmosphere. Based on X-ray diffraction and Raman spectroscopy analyses, the samples exhibited an amorphous phase regardless of HTC time. With increasing HTC time, the marigold surface became rougher and more ruptured. This resulted in the development of a porous structure, thereby increasing surface area. The specific surface area of carbon samples increased from 118 to 281 m²/g with HTC increasing from 2 to 24 h, respectively. Increase of specific surface area mainly resulted from the development of a microporous structure at longer HTC times. Our results offer guidelines to control surface area and porosity through the adjustment of HTC conditions.

Abstract: Bacterial cellulose (BC), produced by some bacteria has received attention because its high purity and robust characteristics enable its use in medicine and industry. This study aimed to screen bacteria capable of producing BC from fruits, and to optimize the BC production in both traditional YE yeast fermentation and Schramm and Hestrin (SH) media. The rice washing drainage without any pretreatment as the sole carbon source in the yeast medium was also investigated for BC production in both static and agitated cultures. The bacterial strain Li1 isolated from apple (Malus pumila) was identified as Komagataeibacter (Gluconacetobacter) nataicola based on 16S rDNA sequence analysis. K. nataicola Li1 cultured in a YE medium produced significantly more BC than that in a SH medium in the static culture. Moreover, the weight yields of dry BC films obtained from rice washing drainage and YE media in the static cultures were not significantly different. However, in the agitated culture, the weight yields of dry BC films were more significant in the YE medium than in rice washing drainage medium. In addition, the structure and properties of BC were determined using SEM, FTIR, DSC and XRD. This study shows that rice washing drainage can be used as the carbon source for BC production by K. nataicola Li1.

Abstract: In this work, polyethersulfone (PES) was blended with bio-based polymers, PLA (hydrophobic polymer) and PEG (hydrophilic polymer), in order to improve the antifouling properties of PES membranes. This was done by way of non-solvent induced phase separation. Membrane properties such as morphology, hydrophilicity/hydrophobicity, adsorption fouling and mechanical properties were characterized. All blended membranes displayed higher hydrophilicity than that of pristine PES. This was confirmed by lower water contact angle and higher water adsorption. It was found that membranes with 5 wt% PLA/PEG gave a water contact angle of 65.1° and water adsorption for 4.94. These were the best values obtained. These modifications yielded low protein adsorption leading to reduce membrane fouling. Adding a greater amount of PLA/PEG reduced the membrane pore size, enhanced hydrophilicity and improved the antifouling capability

Abstract: Used fixing reagent, from X-ray laboratories of hospitals is often contaminated with numerous chemicals. Silver (Ag (I)) ion is the major contaminant present in used fixing reagent. This work determined the Ag (I) ion and chemical oxygen demand (COD) in used fixing reagent of X-ray laboratory. The removal of Ag (I) ion was done by electrolysis and followed with the adsorption onto crab shell chitosan (CSC) and black rice husk ash (BRHA). The Ag (I) ions in an used fixing reagent was analyzed by flame atomic absorption spectrophotometry (FAAS) at λ = 540 nm. The COD was measured by reflux technique and the results indicated that the initial concentrations of Ag (I) ions and COD values were 5,634.66 ± 179.74 mg L^-1 and 182,821.28 ± 5759.04 mg L^-1, respectively. The optimum voltage and time for electrolysis were 2 volts and 10 hrs. After the electrolysis had been done, 82.28% of the Ag (I) ions were removed, while the COD was reduced by 51.76%. After the adsorption experiment was applied, 72.16% of the Ag (I) ions were adsorbed onto CSC and 51.83%. onto BRHA. The COD was reduced 37.04% and 34.08% by CSC and BRHA, respectively. Therefore, these two techniques, electrolysis and adsorption, are appropriated techniques for Ag (I) ions recovery and the COD reduction of the used fixing reagent discharged from X-ray laboratories.

Abstract: This research is focused on the effect recycling dust (RD) on properties and performance of brake pad composites. Recycling dust was produced from grinding process of in-finishing products to standard thickness and was used as a new friction material in brake pads. Based on a simple experimental formulation, the proper type of recycling dust reused in brake pad formula was investigated by changing recycling dust type in mixing process. In the experiment, the properties of brake pads, hardness, density, porosity, and Young’s modulus were measured. Furthermore, the morphology and composition of recycling dust will be characterized by X-Ray Fluorescence (XRF), and Scanning Electron Microscopy (SEM). The developed composite brake pad showed that the value of density and compressibility increased while the value of hardness and Young’s modulus decreased by adding 10wt% of recycling dust to commercial brake pad formulation. Hence, the benefit of this work is using recycling dust as one of alternative fillers in disc brake pad materials without compromising the quality and performance.

Abstract: Hot molding is one of the most important processes for the manufacture of friction materials in automotive brake systems. That is because it has direct impacts on the physical and mechanical properties. Porosity and compressibility affect properties like brake vibration. This then affects brake noise. Therefore, the objective of this work was to study the effects of hot molding conditions on the porosity and compressibility of friction materials. The crucial parameters; molding pressure, temperature and holding time were varied in the hot molding process. Porosity and compressibility were investigated and analyzed in relation to the manufacturing parameters using statistical analysis. The results and the correlation coefficients (R²) show that molding pressure and holding time are the most significant effects on porosity and compressibility. They indicate that the hot molding parameters can adequately explain porosity and compressibility.