Dynamic tensile and shear storage moduli of PEG/silica‐polymorph composites

Zainuri

et al. 2019

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Polyethylene glycol (PEG)/quartz (denoted as BP/Q) composites have been investigated as candidates of phase change materials (PCMs) due to their thermomechanical properties around the glass transition temperature as well as thermal properties between 30 and 600 C. Quartz (q-SiO 2 ) powders were extracted from local sand in Tanah Laut, Pelaihari, South Kalimantan, Indonesia. The composites were prepared by dispersing q-SiO 2 powders in the PEG matrix followed by the wet mixing process. The thermal properties of the composites were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while the thermomechanical properties were examined using a dynamic mechanical analyzer (DMA) in a three-point bending mode around the PEG glass transition temperature range (−100-50 C). The morphology and interface bonding were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From the DSC measurement, the endothermic peak of the composites showed a shift of approximately 7-12 C toward higher temperatures than that of the pure polymer. The melting enthalpy values (ΔH m ) of the BP/Q composites covered the required PCM application range, that is, between 139 and 182 J/g. The TGA of the composites showed that thermal degradation occurs in the range of 250-450 C. We found that solid-solid PCMs (ssPCMs) were successfully fabricated with the addition of 10 and 20 wt% q-SiO 2 . From DMA characterization, the BP/Q 20 wt% composite exhibited the maximum E' and the minimum energy dissipation (E"). Its E' value was approximately 250 MPa more than that of the pure PEG. The glass transition (T g ) temperatures of PEG and BP/Q composites (5, 10, and 20 wt%) were around −24.5, −19.1, −17.1, and − 5.3 C, respectively. In addition, the E" and tan δ values decreased with q-SiO 2 filler content. Furthermore, the Cole-Cole plots of the BP/Q composites revealed a better interfacial bonding between the q-SiO 2 and the PEG matrix in the composites with higher silica content. A compact morphology was shown by the BP/Q 20 wt% composite due to high silica concentration.

Section: Methodsmentioning

confidence: 72%

“…Natural silica sand purification has been reported previously (the process of which has also been reported recently …”

Section: Methodsmentioning

confidence: 97%

“…The detailed sample preparation has also been described before . The PEG polymer matrix was melted at 60 °C.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal and dynamic mechanical properties of polyethylene glycol/quartz composites for phase change materials

Zainuri

et al. 2019

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Zirconia‐dispersedpolyethylene glycol composites with a lowtemperature‐degradationrate

Muwwaqor

et al. 2020

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The effect of tetragonal‐zirconia nanoparticle inclusion on the temperature‐dependent storage modulus, or the temperature‐degradation rate, of polyethylene glycol (PEG)‐based composites was investigated using shear‐mode dynamic mechanical analysis (DMA) at temperatures ranging from room temperature up to 75°C. We carried out further investigations in the rubbery area in terms of the characteristic of the degradation rate with temperature and compared it with silica‐quartz‐filled PEG composites, which exhibited a potential as phase‐change materials (PCMs). The investigation began by plotting the shear storage modulus (G′) of the composites and observing the slopes of the curves in the range of the rubbery area, which were assumed to follow a straight‐line equation. Then, we completed the investigation by developing and introducing a temperature‐dependent storage modulus model in the rubbery area for describing the storage modulus of such filler‐dispersed PEG/inorganic composites, to yield the degradation rates of the composites. The new model includes parameters k1 and C that are associated with the degradation rate and the amount of a filler, respectively. The model shows a satisfactory agreement with the experimental data of G′ in the rubbery area, being parameter k1 is associated with a linear degradation rate.

Filler‐size‐dependent dynamic mechanical properties of polyethylene glycol/zircon composites

Nurmalasari

et al. 2021

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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 roomtemperature 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. K E Y W O R D Snano-and micron-sized filler, PEG, thermomechanical properties, zircon