ORCID Profile
0000-0003-1053-2548
Current Organisation
Institut Teknologi Sepuluh Nopember
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 04-2019
Publisher: Wiley
Date: 12-06-2019
DOI: 10.1002/APP.48130
Publisher: Wiley
Date: 29-07-2022
DOI: 10.1002/APP.52923
Abstract: The thermomechanical and optical properties of poly(methyl methacrylate) (PMMA)/quartz and PMMA/zircon composites at filler content variations of 0, 1, 2.5, and 5 wt% have been studied. The silica quartz and zircon powders were derived from local sands collected from Tanah Laut, South Kalimantan, and Kereng Pangi, Central Kalimantan, Indonesia, respectively. The nanoquartz and nanozircon fillers (herewith were designated as quartz and zircon respectively) were obtained by milling these powders for 15 h. Dynamic mechanical analysis was used to acquire the storage modulus and glass transition temperature as the thermomechanical properties of the PMMA/quartz and PMMA/zircon composites. Meanwhile, the optical properties were determine using ultraviolet–visible spectroscopy. Results indicate that zircon fillers can improve the storage modulus of the composites up to 1.85 times that of PMMA alone. Zircon is more effective than silica in improving the storage modulus of PMMA. Implementing the degradation rate model shows us that all the composites have nearly the same degradation behavior in the glassy region. Moreover, the addition of fillers decreases the band gap energies.
Publisher: IOP Publishing
Date: 05-2023
Abstract: Ultra-high-density zircon (ZrSiO 4 ) ceramics were prepared using the spark plasma sintering (SPS) technique of zircon nanopowder with the addition of three different sintering agents, i.e., Bi 2 O 3 , V 2 O 5 and B 2 O 3 . The effect of each agent and the SPS parameters (temperature and pressure) on phase composition, microstructure, thermal and mechanical properties of the ceramics were evaluated. The identified crystalline phases of the sintered ceramics were zircon and monoclinic zirconia. The addition of a sintering agent affects the structure of zircon ceramics, i.e. the lattice parameter and the crystallite size. The sintered ceramics reached relative densities up to 99.9% of the theoretical one when V 2 O 5 or B 2 O 3 was added. SEM observations confirmed the densification of the zircon ceramics. We found the ceramics exhibited thermal conductivity ranging from 0.39 to 0.61 Wm −1 K −1 at 373 K while the coefficient of thermal expansion was 2.3–4.0 × 10 −6 /°C and the Vickers hardness was obtained to be 9.52–12.66 GPa. The Young’s ( E ), bulk ( B ), and shear ( G ) moduli, Poisson’s ratio ν, Pugh’s ratio B/G , and the ratio of H V 3 / E * 2 of the ceramics are in a range of 240 − 288 GPa, 207 − 267 GPa, 91 − 109 Pa, 1.95 − 2.45, and 0.011 − 0.019 respectively. We found that high-density, quasi-ductile zircon ceramics can be synthesized at a low sintering temperature and short holding time.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Wiley
Date: 25-08-2021
DOI: 10.1002/APP.51565
Abstract: The thermomechanical properties of polyethylene glycol (PEG) composites filled with various zircon sizes were studied. The zircon powders were derived from natural (well‐known as puya) sand collected from Kereng Pangi, Central Kalimantan, Indonesia. The effects of the zircon size and content were examined to understand the thermomechanical properties of the composites using dynamic mechanical analysis in shear mode. Pure zircon powders with micron to nanometer sizes were prepared. The microzircon powders were prepared by heating zircon at 500, 1000, and 1200°C. Moreover, the nanozircon powders were prepared by a wet milling method with milling times of 5, 10, and 15 hours. Furthermore, the composites were prepared by a wet mixing method. According to elemental analysis of scanning electron microscopy/energy dispersive X‐Ray spectroscopy (SEM/EDX) data, it was found that the various zircon sizes caused different distribution effects, that is, in general, the smaller the size was, the better the distribution. Filler size variation also affected the thermomechanical properties of the composites. The addition of microzircon heated at 1200°C had the lowest storage moduli ( G' ), that is, 154.90 MPa and 155.55 MPa for 5 wt.% and 10 wt.%, respectively. Moreover, the maximum value of G' was obtained for the composite with the addition of nanozircon milled for 10 h (Z10h), that is, 679.27 MPa and 706.37 MPa for 5 and 10 wt.%, respectively. The addition of nanozircon slightly reduced room‐temperature G' , presumably due to the agglomerated filler, as confirmed by the SEM/EDX data. Moreover, a decrease in zircon size caused an increase in the melting temperature ( T m ) of the matrix. In contrast, 15 h of milling had a minor effect on T m and G' , whereas the loss modulus ( G" ) decreased with the addition of nanozircon. The effects of filler size on the thermomechanical properties of PEG/zircon composites are discussed in detail.
Publisher: Wiley
Date: 15-08-2023
DOI: 10.1002/APP.54536
Abstract: Zircon‐filled poly(methyl methacrylate) (PMMA) composites were synthesized, and their physical properties after ambient heat treatments were investigated. The sub‐micron zircon filler was obtained by purifying local zircon sand. The heat treatments were at 25°C (untreated), 55°C, and 70°C, around the glass transition temperature of PMMA. The crystal and molecular structures of the s les were investigated using X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The thermomechanical, optical, and thermal (between RT and 550°C) properties of all composites were examined using dynamic mechanical analysis (DMA), UV–Vis spectroscopy, and differential thermal/thermogravimetric analysis (DT/TGA) instruments. XRD patterns showed that there were no crystal structure changes. FTIR peaks were reduced due to the heat treatment indicating the presence of PMMA molecular degradation in the heat‐treated s les. Meanwhile, DMA data showed that the heat‐treated s les exhibit a much lower room temperature storage modulus, that is, up to half as compared to the untreated ones. Furthermore, the heat treatment also affects the optical properties, including a slight drop of transmittance in UV‐A and visible regions but a slight increase of transmittance in UV‐B and UV‐C regions. Finally, the differential scanning calorimetry/thermogravimetry (DSC/TG) data show that the heat‐treated pure PMMAs become more challenging to undergo thermal degradation (i.e., mass drop).
Publisher: Wiley
Date: 16-12-2020
DOI: 10.1002/APP.50384
No related grants have been discovered for Allif Hilmi.