Modeling the insulating properties of multicomponent solid foam-like material based on gel-forming systems

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

Download Full-text

Insulating Composites Made from Sulfur, Canola Oil, and Wool

10.26434/chemrxiv.13464842.v1 ◽

2020 ◽

Author(s):

Israa Bu Najmah ◽

Nicholas Lundquist ◽

Melissa K. Stanfield ◽

Filip Stojcevski ◽

Jonathan A. Campbell ◽

...

Keyword(s):

Tensile Strength ◽

Canola Oil ◽

Building Blocks ◽

Atom Economy ◽

Flame Resistance ◽

Sustainable Building ◽

Second Stage ◽

Wool Fibers ◽

Insulating Properties ◽

Polysulfide Polymer

An insulating composite was made from the sustainable building blocks wool, sulfur, and canola oil. In the first stage of the synthesis, inverse vulcanization was used to make a polysulfide polymer from the canola oil triglyceride and sulfur. This polymerization benefits from complete atom economy. In the second stage, the powdered polymer is mixed with wool, coating the fibers through electrostatic attraction. The polymer and wool mixture is then compressed with mild heating to provoke S-S metathesis in the polymer, which locks the wool in the polymer matrix. The wool fibers impart tensile strength, insulating properties, and flame resistance to the composite. All building blocks are sustainable or derived from waste and the composite is a promising lead on next-generation insulation for energy conservation.

Download Full-text

Methods for determining thermal insulating properties. Tests for thermal transmittance and conductance

10.3403/00165808 ◽

1987 ◽

Keyword(s):

Thermal Transmittance ◽

Thermal Insulating ◽

Insulating Properties

Download Full-text

Effect of photon irradiation on structural, dielectric, and insulating properties of Ba0.60Sr0.40TiO3 thin films

Applied Physics Letters ◽

10.1063/1.2936305 ◽

2008 ◽

Vol 92 (21) ◽

pp. 212906 ◽

Cited By ~ 26

Author(s):

Adrian Podpirka ◽

M. W. Cole ◽

Shriram Ramanathan

Keyword(s):

Thin Films ◽

Photon Irradiation ◽

Insulating Properties

Download Full-text

Study on the Effect of Helium on the Dielectric Strength of Medium-Voltage Vacuum Interrupters

Energies ◽

10.3390/en14133742 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3742

Author(s):

Paweł Węgierek ◽

Michał Lech ◽

Damian Kostyła ◽

Czesław Kozak

Keyword(s):

Comparative Analysis ◽

Test Object ◽

Pressure Range ◽

Dielectric Strength ◽

Working Pressure ◽

Medium Voltage ◽

Vacuum Interrupter ◽

Working Medium ◽

Pure Helium ◽

Insulating Properties

This paper presents the results of a comparative analysis of the dielectric strength of disconnecting vacuum interrupters operating on air and helium. The breakdown voltage Ud was measured in the pressure range from 8.0 × 10−4 Pa to 3.0 × 101 Pa for air and from 8.0 × 10−4 Pa to 7.0 × 102 Pa for helium, while varying the interelectrode distance from 1.0 to 5.0 mm. Dedicated laboratory workstations were used to determine the actual pressure values in the vacuum interrupters tested and to precisely measure and record the dielectric strength results of the test object. It was found that the helium-filled vacuum interrupter maintains its full dielectric strength in significantly larger pressure ranges, while the air-filled vacuum interrupter loses its insulating properties. Thus, it is possible to make vacuum interrupters based on the working medium associated with pure helium, with larger working pressure ratings. Under such conditions, it is easier to maintain the tightness of the device and to limit cut-off currents and overvoltages associated with vacuum switchgear.

Download Full-text

Sound-Absorbing and Thermal-Insulating Properties of Cement Composite Based on Recycled Rubber from Waste Tires

Applied Sciences ◽

10.3390/app11062725 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2725

Author(s):

Jakub Svoboda ◽

Tomáš Dvorský ◽

Vojtěch Václavík ◽

Jakub Charvát ◽

Kateřina Máčalová ◽

...

Keyword(s):

Building Materials ◽

Absorption Capacity ◽

Acoustic Properties ◽

Strength Characteristics ◽

Cement Composites ◽

Waste Tires ◽

Natural Aggregate ◽

Thermal Insulating ◽

Recycled Rubber ◽

Insulating Properties

This article describes an experimental study aimed at investigating the potential use of recycled rubber granulate from waste tires of fractions 0/1 and 1/3 mm in cement composites as a 100% replacement for natural aggregates. The use of waste in the development and production of new building materials represents an important aspect for the sustainability and protection of the environment. This article is focused on the sound-absorbing and thermal-insulating properties of experimental cement composites based on recycled rubber from waste tires. The article describes the grain characteristics of recycled rubber, sound absorption capacity, thermal conductivity and strength characteristics. The results of this research show that the total replacement of natural aggregate with recycled rubber in cement composites is possible. Replacing natural aggregate with recycled rubber has significantly improved the thermal and acoustic properties of the prepared cement composites, however, at the same time; there was also the expected decrease in the strength characteristics due to the elasticity of rubber.

Download Full-text