Electrical, dielectric, and optical properties of Sb2O3–Li2O–MoO3 glasses

International audienceTemperature and frequency dependencies of DC and AC conductivities, dielectric response, static permittivity, optical absorption edge, infrared absorption spectrum, density, and temperatures of glass transition and crystallization for lithium molybdenum–antimonite glasses, (80 − x)Sb2O3–20Li2O–xMoO3, where x = 0–40, are measured and discussed. The DC conductivity increases with increasing concentration of MoO3. At 150 °C, it ranges from 5 × 10− 11 S/m up to 3 × 10− 8 S/m. Polaron hopping between Mo5 + and Mo6 + ions contributes, probably, to the DC conductivity. Ionic conductivity by Li+ ions is also present. The conduction activation energy monotonously decreases from 1.15 eV, at x = 5, down to 0.91 eV, at x = 40. In all glasses with x > 0, the conduction activation energy is close to a half of the indirect allowed optical gap. The pre-exponential factor, σ0, goes through a sharp maximum close to the composition (x = 20) with both the highest glass transition temperature and the largest thermal stability range. The frequency dependence of the AC conductivity is composed of three components — the DC conductivity and two AC components. For x = 35 and 40, the activation energy of electrical relaxation is equal to 0.954 ± 0.008 eV and the pre-exponential factor of relaxation times is equal to (4 ± 1) 10− 14 s. The static relative permittivity ranges from 17.4 to 23.0. Strong extrinsic absorption bands in infrared region originate from hydroxyl ions, CO2 impurities, and silicon–oxygen vibrations. The UV–visible indirect allowed absorption edge shifts from 2.6 eV to 2.1 eV with increasing MoO3 content. With increasing MoO3 content the glasses darken, from a light yellow color, at x = 0, to a deep brown color, at x = 40

An Experimental Determination of Coupled Thermal and Moisture Expansion of Plasters

The objective of this paper is to evaluate, together with adsorption and desorption processes, moisture and temperature induced deformations of two plasters. The measurements are performed for moisture content from the dry state to the saturation water content and temperature range of 5 – 60°C. The coupled temperature and moisture induced length differences are measured using LVDT MACRO SENSOR SBP 375040

Investigation of physical properties of polymer composites filled with sheep wool

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software.Internal Grant of Tomas Bata University in Zlin [IGA/FT/2024/002]; European Union [CZ.10.03.01/00/22_003/0000048

Monitoring of vulcanization process using measurement of electrical properties during linear increasing temperature

The article presents the possibilities of diagnostics of irreversible chemical reaction vulcanization in case of laboratory prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our work is focused on the measurement of current rheologic parameters (torque at defined shear deformation) and selected electrical parameters (DC conductivity) during linear increasing temperature. The individual steps of vulcanization are well identified by means of measurements of rheologic parameters, while significantly affecting the value of the electrical conductivity. The value of the electrical conductivity increases with the increasing of rate of the crossbridging reactions during vulcanization. The rate of the heating affects both types of measurements. When the rate of the heating is increasing the temperature of the beginning of networking step of reactions and also the rate of vulcanization grow. The sensitivity of the both types of measurements allows a good mathematical description of the temperature dependence of the torque and the electric conductivity during the vulcanization of rubber mixtures based on SBR

The Relationship Between Mechanical and Electrical Properties During Vulcanisation of SBR Based Rubber

The aim of this paper is description of vulcanization process by monitoring of selected electrical and mechanical parameters. The experiments have shown that the vulcanization process can be qualitatively and quantitatively evaluated on the basis of measurements of mechanical (standard procedure in rubber industry) and also electrical parameters. The results obtained for model system SBR rubber mixture under conditions of linear heating are presented also

Testing wireless electro-osmosis used for dehumidification in civil engineering

Paper presents and explains the differences between non wireless and wireless electro-osmosis. Based on information provided by companies that use electromagnetic fields of different frequencies, the device was designed, built and tested in the basement of a historic building and in the laboratory. The experiments confirmed (in all evaluated tests) that the wireless electro-osmosis does not affect the amount of water in porous materials

Electrical and dielectric properties of Sb2O3-V2O5-K2O glasses

International audienceElectric measurements, including temperature dependencies of direct electrical conductivity and temperature dependencies of complex electrical modulus, have been implemented using Sb2O3-V2O5-K2O glass samples. These glasses absorb ambient humidity but their resistance to water attack depends on composition. The significant decrease of conductivity up to 100 °C can arise from water desorption. Cycling measurements of direct electrical conductivity versus temperature were also implemented. They show that the 30Sb2O3-30V2O5-40K2O and 70Sb2O3-30K2O glasses are irreversibly damaged with the formation of the hydrated layer. In addition, it was observed that the evolution of DC conductivity is ruled by Arrhenius relation, while activation energy decreases as Sb2O3 concentration increases