Materials Science Forum Vol. 1129

Abstract: This research developed the modified-recycled poly (ethylene terephthalate) (modified-rPET) filament by decreasing the crosslinked-gel content inside the filament, by adding various contents of hydrophobic nanosilica (h-NS). This research also studies the viscosity, morphology, h-NS dispersion, and mechanical properties of the modified-rPET/h-NS, by using a rotational rheometer, a scanning electron microscope, a micro-XRF spectrometer, and a universal testing machine, respectively. rPET flakes were dried to deplete the moisture. Then, they were mixed with additives and h-NS at 0, 1, 2, 3, 4, and 5 pph, and were extruded to be compound using twin screw extruder. The modified-rPET/h-NS extrudates were investigated into two parts. Firstly, was observed on the process-ability, morphology, and gel content along the filament. Consequently, the viscosity, mechanical properties, and h-NS dispersion were investigated. The results showed that the best formulation that is easy to process and has the lowest gel content along the filament, was NS1. Other results, shear-thinning rheology behaviors were observed for all formulations. The mechanical properties, including ultimate tensile strength and elongation at break decreased, as the h-NS content increased. At higher content of h-NS (NS4 and NS5), the gel content increased significantly, therefore the h-NS agglomeration occurred, which was different from crosslinked gels.

Abstract: In this research, a new elastomeric dielectric material is created by integrating natural rubber (NR) with activated carbon derived from coconut shells that has been modified with copper (Ac-Cu). Here, The copper content, ranging from 0 to 2%, was meticulously examined on the AC surface through a reduction technique from copper (II) to copper (0), with the Ac-Cu concentration fixed at 15 parts per hundred of rubber (phr). Systematic investigations into the effects of the additive were conducted across various parameters, encompassing optimum curing time (t90), density, crosslink density, mechanical properties, morphology, and dielectric properties. Results revealed a notable influence of copper on the curing process, resulting in decreased cure time, and a corresponding decrease in crosslink density as the copper content increased. Interestingly, copper incorporation demonstrated a positive impact on mechanical properties. Dielectric property analysis further confirmed a direct effect of increasing copper content on the frequency range of 0.85 to 1.15 GHz. This work not only introduces a pioneering dielectric material but also provides crucial insights into the nuanced effects of copper modification, offering avenues for tailored material design in the realm of enhanced dielectric applications.

Abstract: Doping high-zinc aluminium alloys with Ti builds in-situ composites reinforced with ternary aluminides Ti (Al,Zn)₃ with a significantly grain-refined matrix. In a series of studies, Ti was introduced with Al-6 wt% Ti (AlTi6) and Zn-4 wt% Ti (ZnTi4) master alloys in amount to contribute about 3 wt% Ti in the examined alloys. The alloy microstructure has been studied using light microscopy, SEM / EDS and XRD measurements. The observed significant refinement of the alloys matrix should lead to improvement in ductility, while the in-situ reinforcement should improve tensile strength and wear properties.

Abstract: The human body needs comfort in every condition. Human health is significantly impacted by heat. The ambient air temperature rises in hot weather, which causes the human body to become fatigued and exhausted. Phase Change Materials (PCM) can solve this problem with high latent heat absorption values and a wide range of phase change temperatures. The objective is to develop a PCM-based cooling device that is safe, readily available, and easy to use in normal routine life. A personal cooling system, such as a cooling vest using PCM, can assist in preventing heat-related issues. In this study, Polyethylene Glycol-600 (PEG-600) and modified glauber salt are selected as thermal energy storage materials with melting temperatures of 18–22°C and 27°C, respectively. Graphene Oxide (GO) nanoparticles were synthesised and mixed into the PEG-600 to enhance its thermal conductivity and latent heat of fusion. GO nanoparticles were prepared by Modified Hummer’s method (MHM) and characterised by Fourier’s Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The latent heats and melting ranges of GO/PEG-600 and modified glauber salt were investigated by Differential Scanning Calorimetry (DSC). The addition of 0.6 wt.% GO to PEG-600 results in an increase in thermal conductivity of 6.1% and latent heat of 8%. The PCMs are encapsulated in aluminium packs, sealed, and kept in a cooling device. The developed cooling vest provides cooling for up to 95 minutes. The cooling vest is recharged by keeping it below 10°C for 20 minutes. The developed personal cooling device provides a passive, inexpensive, and safe cooling system by extracting heat from the human body.

Abstract: Fouling and damage of variety of surfaces including textile material is a global challenge. As textile wears next to the skin and health issues are more significant. Thus in an effort to address the issues related to textile surfaces damage, antimicrobial polymeric textile finishing was developed to impart antimicrobial functionalities to the textile fabric. The nanoprecipitation technique was done to synthesize antimicrobial polymeric nanoparticles and applied on to the cotton textile fabric via layer-by-layer self-assembled multilayers dip coating technique. The particle size and zeta potential of the nanoparticles was evaluated form dynamic light scattering analysis (DLS) as 216 nm and-11.2 mV. The antimicrobial polymeric finishing of cotton textile was done by alternate dip coating in polyelectrolytes and nanoformulation. The structural morphology and roughness of the resultant textile was studied by SEM and optical profilometery. While the surface hydrophobicity was found to increase with the number of bilayers coating of hydrophobic polymeric formulation as measured in term of contact angle θ. In-vitro antimicrobial activity was studied against gram negative E. coli and gram positive S. aureus with significant zone of inhibition against both strains. Thus surface hydrophobicity and antimicrobial activity of the textile fabric was synergistically achieved and have potential for biomedical and industrial application.

Abstract: Health care associated infections or nosocomial infections (NI) is the fourth leading cause of disease and the most common complication affecting hospitalised patients in addition to a minimum of 175,000 deaths every year in industrialised countries. The Center for Disease Control and Prevention (CDC) states that influenza is transmitted from person to person primarily via large virus-laden droplets or through direct or indirect contact with respiratory secretions when touching surfaces contaminated with influenza virus and approximately 80% of the infections are transmitted via touch surfaces. In the year 2020 the Coronavirus (Covid 19) spread has affected the global community and also caused a great concern for the people and health care workers with a global infected population of more than five million. With the ongoing population rise in the cities growing drug resistant bacteria, increasing infection rate in hospitals and communities, ageing world population strongly indicates the need to minimise the spread of infections via touch surfaces. Metals (and products manufactured from them) such as copper and silver are known to exhibit antimicrobial properties. These metals, or composites containing them, can be used as additives and incorporated into other materials such as paints, plastics and powder coatings to imbue these materials with antimicrobial properties. In this paper we present the inherent antimicrobial properties of a copper containing alloy, two alloys of hospital grade steel (304 and 316), extruded aluminium (606013), anodized aluminium (606013) and zinc clad aluminium (3003-7072). Additionally, these materials were coated in epoxy resin powder coating with and without silver based antimicrobial additive. The ability of these metal alloys to reduce the population of inoculated microorganism numbers was assessed via the international standard (ISO) 22196:2011 Measurement of antimicrobial activity on plastics and other non-porous surfaces.

Abstract: Shallow trench isolation via chemical mechanical polishing (CMP-STI) tests of Si wafers using CeO₂ slurry were studied. The impact of CeO₂ slurry's solid concentration on the SiO₂ removal rate and the selectivity ratio The effects of the solid concentration of CeO₂ slurry on the removal rate of SiO₂ and selectivity (SiO₂/Si₃N₄) were investigated. The CeO₂ abrasive was well matched to the XRD standard pattern, confirming that it had a cubic phase and the absence of any impurities. The SEM image showed that CeO₂ primary particles had a spherical-like shape with a size within 30-60 nm. Additionally, the prepared CeO₂ slurry showed a relatively high dispersion level. The wettability degree of the CeO₂ slurry on top of the Si wafer surface was also sufficient. Furthermore, results from polishing tests indicated that both the SiO₂ removal rate and the selectivity increased linearly with a rise in CeO₂ solid concentration.

Abstract: This research aims to design a sprue system for aluminum castings in sand pores for a basic form prototype in metal casting, which is a one-piece pattern with a parting line. There are several types of liquid metal gating systems available. In the design, variables were specified regarding the height of the sprue, the cross-sectional area of the sprue, the cross-sectional area of the reservoir, the cross-sectional area of the runner, and the cross-sectional area of the gating. The riser size was used as a comparison variable. Following study and design, an experiment was conducted to cast the actual casting and to analyze the behavior simulation using Cast-Designer to determine a solution. In the simulation, the following results were found: the time taken to add liquid metal; the flow behavior of liquid metal; the metal hardening time; and the formation of shrinkage cavities in the casting. Based on the results of casting experiments and behavioral simulations, it was demonstrated that the large riser significantly reduced the shrinkage of the actual casting.

Abstract: The study of aluminum casting work with market demand in the metal casting industry, designing a gating system in aluminum casting using a three-way pipe-shaped sand mold workpiece as a basic shape template in metal casting, namely a flat-face core box with a core. The gating system has a metal inlet with design variables including the pouring height, pouring basin cross-sectional area, rest basin cross-sectional area, running system cross-sectional area and inlet cross-sectional area. From the studying and designing, actual casting experiments were conducted and simulation behavior was analyzed using Cast-Designer software to make decisions and find appropriate design approaches from analyzing simulation results including liquid metal filling time, molten metal flow behavior, metal solidification time and shrinkage porosity formation of the workpiece. The results of the casting experiment and behavior simulation were able to cast the pipe workpiece which is a flat-face core box mold. The analysis results from the software can be used for actual pouring, where the fully cast mold successfully produced a complete workpiece. This can be a guideline for future improvements to reduce the shrinkage of actual cast workpieces.