Basuki Wirjosentono

Friction stir welding was introduced by The Welding Institute of United Kingdom in 1991 as a solid connection technique and the application of friction stir wel Friction stir welding was introduced by The Welding Institute of United Kingdom in 1991 as a solid connection technique and the application of friction stir wel

This study aims to develop an effective Friction Stir Welding (FSW) method for composite material of High-Density Poly-Ethylene (HDPE) Pipes. The development of welding tool, there was the addition of an external heating source on the shoulder and probe/pin to overcome the problem of lack of heat resulting from friction between the tool and the material to be welded. The case study was conducted to join the short fiberglass-HDPE composite with a type of ratio of 30% by weight of short fibre and 70% by weight of HDPE, which optimizing parameters such as rotating speed, welding speed, and preheating temperature. The FSW joining process for short fiberglass-HDPE composite sheets was carried out using a Fanuc Series 21i-M CNC milling machine as the driving tool with rotational speed (o) varied in 3 conditions, namely 600 rpm, 800 rpm and 1000 rpm, and welding speed (v) or feeding at 5 mm/minutes and 10 mm/minutes. The temperature was controlled according to the liquid point of High-Density Poly-Ethylene, which was 130oC, and raised to 150oC and 170oC. The 12 pieces of thermocouple were used along the track on the material and jig plates at the top, middle and bottom. Then, the results of joining the sheets were made in the form of specimens with sizes according to ASTM 3039. The tensile tests of the specimens were carried out at a rate of 0.01 mm/s. The results showed the highest tensile strength was an average value of 24.52 MPa at a rotational speed of 800 rpm, the feeding of 5 mm/min and the temperature of 130oC. The lowest tensile strength was an average value of 17.54 MPa at a temperature of 170°C with a speed of 600 rpm.

Ocean thermal energy conversion (OTEC) is a new source of future energy that is clean and environmentally friendly with zero emissions. It is very potential to be developed in Indonesia, which is located at the equator. to meet the electricity needs of the outermost and remote islands that are not currently covered by the main power plants in Indonesia. Indonesia has deep seas around the islands with temperatures of 5°C and surface temperatures above 25-28°C, so a temperature difference of 20°C can be obtained easily for OTEC power plants. Cold water supplied to the OTEC plant with a capacity of 2 MW at sea level requires a pipe with a diameter of 4 m and a length of 500 m. The pipeline must be insulating, not floating, corrosion-resistant, and resistant to current loads. Current is a very serious concern with the potential to cause pipe failure. The pipe material being investigated is a short fiberglass High-density polyethylene composite. In this study, a simulation of the effect of current on the composite pipe was carried out to obtain an overview of the stress that occurs and the proper pipe dimensions used. The highest current speed in Indonesian water is found in the Makassar Strait from July to September at 0.8 m/s at a depth of 100 m. Based on the OTEC Pro Simulation software for a capacity of 2 MW, resulted in the pipe size is 4 m and the pipe length is 500 m which refers to the temperature profile. In the simulation, the calculation of the dynamically moving current becomes the drag force on the pipe, and with the Autodesk inventor, it is known that the deflection in the pipe, and the yield stress cause failure in the pipe. Subsequently, from the deflection and yield stress data, a pipe thickness of 20-30 cm is obtained for the short fiberglass-HDPE composite material which is safe to use as an OTEC cold water pipe with a capacity of 2 MW. Pipes with a thickness smaller than 15 cm are too thin for a diameter of 4 m because the pipe wall has already experienced a deflection in a horizontal position and pipes with a thickness of > 30 cm are known from the simulation that the pipes cannot be connected rigidly and the pipes also experience stress due to current and pipe weight. so that the stress becomes greater in the pipe.

Efforts to utilize and improve the value of pulp waste have been done by using primary sludge (still containing cellulose) and fly ash as a filler to produce composite foam polystyrene (PS)-based as sound absorbent. In this study, the composite foam was produced by mixing primary sludge and fly ash with several compositions such as PS, PS/PS-g-MA/primary sludge/fly ash (80/10/10/0), (80/10/7/3), (80/10/5/5), (75/10/10/5), and (75/10/12/3). The composite was characterized based on ISO 11654:1997, mechanical properties, thermal analysis using TGA and DSC, morphology using SEM, crystallinity using XRD, and chemical analysis using FTIR. The results showed that the band at 1600.63 cm-1 was sharper due to a chemical reaction being formed between PS, primary sludge, and fly ash. The XRD analysis showed a new diffraction peak in the 2 = 21-24o. The morphology analysis showed that primary sludge and fly ash were uniformly dispersed into PS, increasing the mechanical properties and decreasing the melting point of the PS foam composite. The sound-absorbing composite produced had qualified ISO 11654:1997 on the rating level of the sound absorption coefficient on materials for rooms with sound absorption classes D and C with the value of w 0.328-0.793.

Nanocellulose is a materials that have useful in many fields especially in pharmaceutical field and biomedical field. Nanocellulose is produced from alpha-cellulose from oil palm empty fruit bunches. Alpha-cellulose obtained oil palm empty fruit bunches by 3 steps. It is pulping, delignification, and bleaching procces. Nanocellulose produced using acid hydrolysis and dyalysis procces. The result tested by Particle Size Analyzer, nanocellulose distribution particle size is 98.7 nm.

Polyvinylchloride (PVC) resins have been used widely as electrical insulating cables, which required standard engineering specifications and have been exposed against heat and harsh environment even under fire. Sepiolites (Sep) clays, which contain hydrous magnesium silicates, have been utilized as fillers for rubber blends to improve mechanical, morphological and thermal properties of the blends. In this works dioctylphthalate (DOP)-plastisised PVC resins have been blended with various loading of sepiolite clays in reflux reactor of tetrahydrofuran (THF) solution under stirring at optimum condition. Mechanical, morphological and thermal properties of the resulted dried resins were characterized. It was found that optimum result of the PVC resin with improved tensile strength and considerable elongation at break was obtained when loadings of Sepiolites: 10 phr (per hundred resin) in constant 30 phr loading of DOP. Morphological measurement of fracture surface of optimum PVC resin exhibited finely distributed of sepiolite filler, whereas that of its corresponding higher loading of sepiolite showed the presence and voids due to pullout of agglomerated bigger size sepiolite filler. Thermogravimetric analysis (TGA) of the PVC resins containing increased loadings of sepiolite fillers indicated decreased total weight loss and increased char residue at their decomposition temperature when compared to those of PVC resins without filler and, which revealed their better thermal stability.

Cold water pipes (CWP) used in ocean thermal energy conversion installations must be able to withstand wave loads, deep seawater currents, and the weight of the

The copper-tin alloy in the Heat Exchanger system plays an important role in maintaining physical properties due to direct contact with the working fluid. In ad

The search for nanofillers in polymer industries to improve composite material properties for several purposes has increased significant interest. In this study, dioctyl phthalate-plasticized polyvinyl chloride (PVC) reinforced either with sepiolite or MgO was produced in which the characteristic of composite sepiolite/MgO-filled was compared. Sepiolite and MgO were added into PVC matrices with 5, 10, and 20 phr concentrations. The product was characterized using analytical techniques such as SEM, TGA, DSC, and the mechanical properties regarding ASTM D 638 Type IV. The tensile strength of the composite increased with the presence of sepiolite and MgO. The highest result showed at the concentration of 5 phr. However, the elongation at the break of the composite decreased with the addition of MgO. The morphology analysis showed that PVC-filled sepiolite had a rough surface with a sharp fracture, but no sharp fracture was found in the PVC-filled MgO. At a concentration of 5 phr, both sepiolite and MgO increased the thermal properties of PVC with a residue of PVC control, PVCSepiolite, and PVC-MgO at 14.74%, 19.34%, and 26.33% respectively.

This study was done to evaluate a new technique to determine the presence of methamphetamine in the hair using nano bentonite-based adsorbent as the filler of extraction column. The state of the art of this study was based on the presence of silica in the nano bentonite that was assumed can interact with methamphetamine. The hair used was treated using methanol to extract the presence of methamphetamine, then it was continued by sonicating the hair sample. Qualitative analysis using Marquish reagent was performed to confirm the presence of methamphetamine in the isolate.The hair sample that has been taken in a different period confirmed that this current developing method can be used to analyzed methamphetamine. This method has an average recovery percentage by 104%. This result was also supported by the precision, linearity, LOD and LOQ, i.e. 0.0775; 0.968; 0.00000256 and 0.000000775, respectively.