Thermal insulation and stability of polysiloxane foams containing hydroxyl-terminated polydimethylsiloxanes

Zhang, Chunyu; Qu, Lijie; Wang, Yingnan; Xu, Tianlu

doi:10.1039/c8ra00222c

Cited by 30 publications

(25 citation statements)

References 47 publications

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“…In recent years, numerous studies have focused on the thermal aging mechanism of insulation paper. Although the aging process and its mechanism on oil–paper in transformers have been investigated [8,9,10,11,12,13,14,15,16,17,18], the thermal stability of meta-aramid insulation paper in transformers at operating temperature has not been analyzed. Therefore, it remains important to examine the thermal stability and thermal aging mechanism of crystalline and amorphous regions in meta-aramid insulation paper.…”

Section: Introductionmentioning

confidence: 99%

Molecular Simulation on the Thermal Stability of Meta-Aramid Insulation Paper Fiber at Transformer Operating Temperature

Tang

et al. 2018

Polymers

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The influence of the thermal field of a transformer during operation on the thermal stability of meta-aramid insulation paper was studied through molecular dynamics simulations. Models of the crystalline and amorphous regions of meta-aramid fibers were constructed using known parameters. The model of the crystalline area was verified by comparing X-ray diffraction results with experimental data. The reasonableness of the simulation results was judged by the variation of energy, temperature, density, and cell size in relation to the dynamic time. The molecular dynamics simulations revealed that the modulus values in the crystalline regions were two to three times higher than those in the amorphous regions at various temperatures. In addition, the incompressibility, rigidity, deformation resistance, plasticity, and toughness of the crystalline regions were obviously higher than those of amorphous regions, whereas the toughness of the amorphous regions was better than that of the crystalline regions. The mechanical parameters of both the crystalline and amorphous regions of meta-aramid fibers were affected by temperature, although the amorphous regions were more sensitive to temperature than the crystalline regions. The molecular chain motion in the crystalline regions of meta-aramid fibers increased slightly with temperature, whereas that of the amorphous regions was more sensitive to temperature. Analyzing hydrogen bonding revealed that long-term operation at high temperature may destroy the structure of the crystalline regions of meta-aramid fibers, degrading the performance of meta-aramid insulation paper. Therefore, increasing the crystallinity and lowering the transformer operating temperature may improve the thermal stability of meta-aramid insulation paper. However, it should be noted that increasing the crystallinity of insulation paper may lower its toughness. These study results lay a good foundation for further exploration of the ways to improve the performance of meta-aramid insulation paper.

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Section: Introductionmentioning

confidence: 99%

Molecular Simulation on the Thermal Stability of Meta-Aramid Insulation Paper Fiber at Transformer Operating Temperature

Tang

et al. 2018

Polymers

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“…We tested this capability by comparing temperature measurement using the transparent sensor and a thermocouple placed at different distances from the LED array when illuminating porcine skin ( Figure 3 F). For thermal insulation and encapsulation, the LED array is embedded within PDMS (Sylgard 184, Dow Corning USA) ( Figure 3 H), which minimizes heat transfer to the sensor due to resistive heating of the LED array ( Zhang et al., 2018 ). Applying 36 dBm to the transmitter coil at a distance of 3 cm from the patch, thermal measurements from the transparent sensor detect tissue heating with a response time about 10 s earlier than the thermocouple.…”

Section: Resultsmentioning

confidence: 99%

A wireless optoelectronic skin patch for light delivery and thermal monitoring

et al. 2021

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Summary Wearable optoelectronic devices can interface with the skin for applications in continuous health monitoring and light-based therapy. Measurement of the thermal effect of light on skin is often critical to track physiological parameters and control light delivery. However, accurate measurement of light-induced thermal effects is challenging because conventional sensors cannot be placed on the skin without obstructing light delivery. Here, we report a wearable optoelectronic patch integrated with a transparent nanowire sensor that provides light delivery and thermal monitoring at the same location. We achieve fabrication of a transparent silver nanowire network with >92% optical transmission that provides thermoresistive sensing of skin temperature. By integrating the sensor in a wireless optoelectronic patch, we demonstrate closed-loop regulation of light delivery as well as thermal characterization of blood flow. This light delivery and thermal monitoring approach may open opportunities for wearable devices in light-based diagnostics and therapies.

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“…The MAPOSS contents were 0, 0.5, 1.0, 1.5, 2.0, and 2.5 wt%, which were marked as S1, S2, S3, S4, S5, and S6, respectively. The reaction equation [ 24 ] is shown in Figure 2 and the reaction flow chart is shown in Figure 3 .…”

Section: Methodsmentioning

confidence: 99%

Effects of Polyhedral Oligomeric Silsesquioxane (POSS) on Thermal and Mechanical Properties of Polysiloxane Foam

Zhang

et al. 2020

Materials

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The thermal and mechanical properties of polysiloxane foam are greatly improved by the addition of acrylolsobutyl polyhedral oligomeric silsesquioxane (MA0701, hereinafter referred to as MAPOSS), which has double bonds. The morphologies and properties of the polysiloxane composite foam were characterized. The average cell diameter of the composite foams decreased, while the cell density increased with increasing MAPOSS. Meanwhile, MAPOSS can enhance thermal conductivity and thermal stability. Thermal conductivity increased by 25%, and the temperature at the maximum weight loss rate increased from 556 °C to 599 °C. In addition, MAPOSS also promoted heterogeneous nucleation by functioning as a nucleating agent, which can increase cell density to improve the mechanical properties. The compressive strength of the composite foam increased by 170% compared with that of pure foam. In the composite, MAPOSS increased the cross-linking density by acting as a physical cross-linking point and limited the movement of the segments.

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Thermal insulation and stability of polysiloxane foams containing hydroxyl-terminated polydimethylsiloxanes

Abstract: The thermal insulation and stability of polysiloxane foam was improved by an easy operating method.

Cited by 30 publications

References 47 publications

Molecular Simulation on the Thermal Stability of Meta-Aramid Insulation Paper Fiber at Transformer Operating Temperature

Molecular Simulation on the Thermal Stability of Meta-Aramid Insulation Paper Fiber at Transformer Operating Temperature

A wireless optoelectronic skin patch for light delivery and thermal monitoring

Effects of Polyhedral Oligomeric Silsesquioxane (POSS) on Thermal and Mechanical Properties of Polysiloxane Foam

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