Indonesian Physical Review

ENHANCED THERMAL PERFORMANCE OF POLYETHYLENE GLYCOL-BASED PHASE CHANGE MATERIALS USING ZnO

Tue, 10 Jun 2025 00:00:00 +0100

Polyethylene Glycol (PEG), an organic Phase Change Material (PCM) known for its high latent heat capacity and biocompatibility, suffers from poor thermal conductivity. This research explored the addition of ZnO (at 8 and 12 wt.%) as an enhancer and SDBS as a surfactant, utilizing a two-step homogenization process at 80°C for 4 h. X-ray Diffraction (XRD) analysis confirmed that no chemical interactions or new phases occurred. Differential Scanning Calorimetry (DSC) findings revealed an enhancement in PEG's latent heat of PEG from 214 J/g to 238.3 J/g (with 8 wt.% ZnO) and 257.7 J/g (with 12 wt.% ZnO). The thermal conductivity improved by 28.2% and 30.3%, respectively, while Thermogravimetric Analysis (TGA) demonstrated increased thermal stability. The addition of ZnO can improve the conductivity and thermal stability, while the role of SDBS is significant in increasing the latent heat, making this composite a potential candidate for Thermal Energy Storage system (TES) applications.

SYNTHESIS OF SINGLE-PHASE HYDROXYAPATITE POWDER FROM EGGSHELL WASTE VIA CO-PRECIPITATION METHOD AND ITS STRUCTURAL CHARACTERIZATION

Tue, 17 Jun 2025 00:00:00 +0100

This study aims to synthesize a single-phase hydroxyapatite powder using waste chicken eggshells as a calcium source via the co-precipitation method. The process focuses on optimizing calcination time and temperature to achieve high-purity hydroxyapatite. The co-precipitation procedure involved controlled pH adjustment and aging time, contributing to the formation of homogeneous particles. Chicken eggshells, predominantly composed of calcium carbonate (CaCO₃), were calcined at 1000°C for 15 hours to produce calcium oxide (CaO). The resulting CaO was then reacted with phosphate ions in an aqueous solution, followed by a calcination at 900°C for varying holding times of 5 and 10 hours. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis were conducted to evaluate phase composition, crystal size, and texture properties. The optimum condition was found at 900 °C for 10 h calcination, resulting in single-phase hydroxyapatite, a crystallite size of 220 nm, an average pore radius of 6.78 nm, a total pore volume of 0.02 cc/g, a surface area of 6.38 m²/g, and an average particle radius of 213.89 nm. These findings highlight the potential of this method for producing bioceramics with desirable properties for use in bone grafts and other biomedical materials.

LANDSLIDE AREA MAPPING IN DAMPIT SUBDISTRICT, MALANG DISTRICT, EAST JAVA PROVINCE USING SATELLITE IMAGERY OF GRAVITY DATA FOR DISASTER MITIGATION

Tue, 17 Jun 2025 00:00:00 +0100

Research using satellite imagery of gravity data has been conducted in the Dampit District, Malang Regency, East Java Province. This research was conducted to identify areas vulnerable to landslides. The results of this research can serve as a basis for the government to develop effective landslide disaster mitigation policies, thereby minimizing the losses incurred. The data used is TOPEX satellite gravity data in the form of Free Air Correction data, and supported by landslide vulnerable areas data from the InaRisk satellite. The research area is 23 km x 16 km with 2 km spacing between points and 184 measurement points. Furthermore, the research area is divided into four areas: Area A1, Area A2, Area A3, and Area A4. The residual anomaly value in the study area is between 82.7 mGal to 142.4 mGal. The residual anomalies are more variable due to the local nature of the anomalies. The correlation between the residual anomaly value and InaRisk satellite image data shows that Area A4 is the most vulnerable to landslides, especially if there is a trigger such as an earthquake. This is because Area A4 has a low-density value, a large fault, and is the contact area between the Mandalika Formation and Wuni Formation.