Materials Science Forum Vol. 1102

Abstract: Functionally graded structures from natural rubber foams were constructed and evaluated in this study. The structures were assembled based on density gradient achieved by stacking layers of natural rubber foams with different densities. Both physical and computational structures were constructed and assembled through experimental work and computer-aided design (CAD) modelling, respectively. Finite Element Analysis (FEA) simulation were conducted on two different assembled structures under compressive deformation mode using Ogden foam hyper-elastic model available in the simulation software package. Experimental result found that the middle section foam with 4/16/4 stacking sequence was deformed significantly compared to that of foam with 16/4/16 stacking sequence. The FEA simulation results indicated that Ogden foam hyper-elastic model is useful in representing deformation at low strain region as the results were in good agreement with those of obtained from the experimental foam compression tests especially for foam with 16/4/16 stacking. The study was able to show that FEA analysis is a good approach to supplement limitation that are encountered by experimental approach in understanding deformation behaviour of functionally graded natural rubber foams.

Abstract: In this study, polylactic acid (PLA) blended with 30 wt% styrene-butadiene-styrene (SBS) (70PLA/30SBS) was added with different fillers; Erbium Oxide (Er₂O₃), Halloysite Nanotubes (HNT) and Tungsten Carbide (WC₂) to investigate the effect of the filler on the shape fixity (R_f) and shape recovery (R_r) at different deformation and recovery times, rheological and morphological properties. The tubular structure of HNT led to the reduction of R_f when immersed longer during the deformation phase. Meanwhile, the presence of Er₂O₃ improved the R_r and R_r with longer deformation and recovery times, respectively. The blend with HNT has the highest viscosity while the blend with 70PLA/30SBS-Er₂O₃ indicated lower viscosity than the unfilled blend. All filled blends indicated the sea-island structure with the SBS droplets in PLA continuous phase. The elements identification made on the surface of the samples illustrates that the fillers were well-distributed in 70PLA/30SBS blends. The insignificant improvement of shape memory in the presence of the thermal conductive fillers due to the dominance of the restriction of chain motion due to the presence of fillers compared with increment of thermal conductivity at low filler loading.

Abstract: Graphene oxide (GO) exhibits a wide range of outstanding mechanical, electrical, and physical characteristics, and it is of substantial interest to impart such qualities onto polymeric materials such as poly (methyl methacrylate) PMMA for wider specialized functionalization. The attention of this work is on the development of emulsion polymerization procedure to prepare PMMA-GO nanocomposite and the effect of sodium dodecyl sulphate (SDS) surfactant dosages incorporated during the polymerization, on the effect of PMMA surface interactions in oil. The grafting efficiency is quantified using the Fourier-transform infrared spectroscopy (FTIR), and the effect of surfactant concentration on PMMA-GO stability is examined using UV-Visible spectroscopy, zeta potential and particle size analyses using the Malvern Zetasizer. The surfactant free emulsion has a better stabilization in terms of zeta potential analysis compared to emulsion of PMMA-GO with 0.32, and 0.4 wt. % of SDS. The polymerized PMMA-GO can be used as a model system to alter wax crystallization at low temperatures in oil and gas industries.

Abstract: The particle size of the rice straw and boiling duration play an essential role in the applicability of this material. They affect the rice straw’s mechanical properties, which is one of the critical parameters in bio-based material development. In order to have a clear insight into the effect, rice straw particle materials form without a hot press machine route to avoid bias due to the material response to the pressure and heat transfer effect. The rice straw particle incorporates corn starch as a bio-adhesive with an equal composition ratio. It turns out that finer particle sizes (mesh 60 and 40) achieve higher tensile strength compared to mesh 18 particles. The optimum boiling duration is two hours. Longer boiling times reduce the mechanical properties of rice straw particle-based materials.

Abstract: The current technological need is the use of eco-friendly and biodegradable composites. It seeks to increase the use of natural resources to engineer composite materials to be better than before. This study aims to analyze the effect of ramie fiber orientation for ramie composites (in this study 45⁰ and 0⁰) on tensile strength and impact strength and find the best orientation angle with higher power and impact value than the other fiber angles on ramie composite. The fiber used in this study was ramie fiber, and the matrix used was Yukalac 157 BQTN-EX polyester resin. This research method uses the experimental process of conducting experiments and testing. The results showed that the 0⁰ angle direction composite achieved the highest average tensile strength value of 54.3 N/mm², and the impact strength showed the highest average impact strength value of 0.0168 J/mm², performed by the 0⁰ composites.

Abstract: Oil soluble polymeric-based dispersants have been extensively used in engine oil lubrication formulation due to their inherent properties, such as modifiable viscosity, compatibility, and effectiveness. However, the underlying mechanism of how the dispersant stabilizes soot particles in engine oil is still not fully understood, and discovering this mechanism is crucial for engine oil formulation technology. This review discusses the interactions between colloidal particles induced by two PIBSA-derived dispersants, namely PIBSI and PIBSAE. The effectiveness of these dispersants in stabilizing colloidal particles in oil systems depends on the chemical functional groups present on the main chain. The spectrum of colloidal interactions, ranging from Derjaguin, Landau, Verwey and Overbeek (DLVO) to non-DLVO theory, is predominantly influenced by the equilibrium between dispersant concentration and the overall system viscosity. This phenomenon can eventually reverse colloidal stabilization and result in more serious issues, such as engine wear and tear.

Abstract: Self-propagating intermediate temperature synthesis (SIS) is a process that utilizes exothermic reactions to initiate and maintain component combustion so as to produce low porosity values and high hardness. It is necessary to know about the heat transfer phenomenon because SIS has a weakness, namely the high exothermic rate and very fast combustion rate which requires a high level of control. In addition, compression or compaction needs to be done because this method is expected to produce a homogeneous particle density distribution. The phenomenon of heat transfer and pressure that occurs in the SIS process is a simplification of the self-propagating high-temperature synthesis (SHS) process, which can be simulated and analyzed using engineering software based on finite element analysis. Stress simulation that occurs with the addition of weight percent titanium 5%, 10% and 20% using a pressure of 171 MPa and produces a normal stress. The heat transfer simulation that occurs uses a temperature of 750 ^°C, 850 °C, and 950 °C with a processing time of 2 hours with variations in the addition of weight percent titanium 5%, 10%, and 20% which results in an effect on heat flux and temperature distribution. Samples that were given the addition of 20% titanium by weight were given a pressure of 171 MPa to produce a normal stress of-230.44 MPa with the lowest porosity value of 22.63%. Samples processed at 850 °C with the addition of 10% weight percent titanium produced the lowest heat flux value of 0.0027220 W/m².

Abstract: Steel produced by PT. Krakatau steel is the most used product in construction applications to compete with the other structural steel and have the minimum standard. PT. Krakatau Steel produced the steel with 0.08% carbon as JIS 3302 grade SGC 400 standards, resulting in low yield and tensile strength. This study aims to investigate the effect of temperature and the number of cycle spheroidizing on mechanical properties and microstructure. Steel with 0.08% carbon heated at 580, 650, and 720 °C for 6 minutes each cycle (3 cycles) and subsequently cooled by forced air with a 3 °C/s cooling rate. At a temperature of 580 °C on cycles 1, 2, 3, and 650 °C in the third cycle 3, resulting in mechanical properties that meet the JIS G 3302 grade SGC 400 standards.

Abstract: Zircon (ZrSiO₄) is one of Indonesia's most abundant mineral reserves that have yet to be fully utilized since zircon mine production in Indonesia is only 110.000 tons/year while Australia produces zircon up to 500.000 tons/year. Indonesia has 167 million tons of zircon sand reserves, especially in West Kalimantan. One of the most efficient methods of zircon sand processing in terms of energy use and environmental pollution is the alkali fusion of NaOH. This study used zircon sand with NaOH, a stoichiometric ratio of 1:4 (excess 1.5), to be roasted in a muffle furnace at 600°C for 120 min. The following process is washing the frit with water, and the frit is dissolved with aquades with ratio frit: H₂O=1g:10 ml at 30°C and stirring 300 rpm for 60 min. The frit leaching solution is filtered to obtain Na₂ZrO₃. The water-wash product is leached using HNO₃ as the leaching agent with the ratio of water-wash product: HNO₃=1:5, the acid concentration is 6 M, at 90°C, agitation use 260 rpm with the variation of time 60, 120, 180, 240, and 300 minutes. The pregnant leach solution is deposited with NH₄OH and calcinated. According to the results of this experiment, the optimum time to obtain high Zr extraction is 240 minutes. This research produced single-phase zirconia with a cubic crystal structure containing 91.23% ZrO₂ and 1.18% SiO₂.