scholarly journals Influence of thermal annealing on structural properties of silica aerogel super insulation material

2019 ◽  
Vol 142 (1) ◽  
pp. 321-329 ◽  
Author(s):  
Ákos Lakatos ◽  
István Csarnovics
Keyword(s):  
Thermal Properties ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Structural Changes ◽  
Heat Treatments ◽  
Thermal Treatments ◽  
Insulation Material ◽  
Structural Modifications ◽  
Construction Market ◽  
Isothermal Heat Treatments

AbstractNowadays, aerogel materials are some of the lightest thermal insulation materials available on the construction market; they are produced by the mixing of polymers with solvents since they create a gel. Insulated fibrous-enhanced forms are the most frequently used ones. The type, which is used for thermal insulation, is usually produced by mixing the glass fiber net with the liquid–solid solution. The present paper talks about the structural modifications caused by heat treatment of the aerogel-reinforced with fiberglass. The aerogel probes were subjected to thermal annealing, and once they got isothermal heat treatments for weeks at 70 °C, moreover, untreated samples were subjected to stepwise thermal treatments between 100 and 250 °C for 1 day. Both the heat treatments were executed in dryer equipment under atmospheric air. Changes both in the structure and in chemical bonds of the untreated and annealed samples were followed. Raman spectra have been obtained for the samples. The structural changes have an influence on the studied material as well as in thermal properties. The structural and thermal properties were put under investigation after executing heat treatments on them. Jumps in the thermal conductivity could be connected with some structural changes. Due to the annealing intensity of the peaks connected with Si–O, crystalline SiO is increased, while CH, CH2, CH3, –OH and others are decreased.

scholarly journals Thermal characterization of fibrous aerogel blanket

2019 ◽  
Vol 282 ◽  
pp. 01001 ◽  
Author(s):  
Ákos Lakatos ◽  
Anton Trnik
Keyword(s):  
Thermal Annealing ◽  
Thermal Insulation ◽  
Thermal Characterization ◽  
Insulation Material ◽  
Scanning Calorimetry ◽  
Solid Materials ◽  
Plastic Foams ◽  
Isothermal Heat Treatments ◽  
New Buildings

Nowadays, the application of thermal insulation materials both by the existing and by new buildings is one of the most important actions in order to reduce the energy loss of buildings. Besides the use of the conventional insulations (plastic foams and wool materials) aerogel is one of the most promising thermal insulation material. Aerogels, one of the lightest solid materials available today, are manufactured through the combination of a polymer with a solvent forming a gel. For buildings the fibre reinforced ones are the mainly used types. It is produced by adding the liquid-solid solution to the fibrous batting. In this paper changes in the thermal performance of the aerogel blanket will be followed after thermal annealing. The samples will be put under isothermal heat treatments at 70 °C for 6 weeks, as well as they will be put under thermal treatment at higher temperatures (from 70 °C till 210 °C) for 1 day. The changes in the thermal conductivity will be followed by Holometrix Lambda heat flow meter, as well as, Differential Scanning Calorimetry results will be presented. From the measured values, thermal properties will be calculated. In this paper we will try to clarify the role played by thermal annealing in thermal diffusivity.

scholarly journals Effects of the Heat Treatment in the Properties of Fibrous Aerogel Thermal Insulation

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2001 ◽  
Author(s):  
Ákos Lakatos ◽  
Attila Csík ◽  
Anton Trník ◽  
István Budai
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Structural Changes ◽  
Glass Fibers ◽  
Material Structure ◽  
Scanning Calorimetry ◽  
Plastic Foams ◽  
Isothermal Heat Treatments

Nowadays, besides the use of conventional insulations (plastic foams and wool materials), aerogels are one of the most promising thermal insulation materials. As one of the lightest solid materials available today, aerogels are manufactured through the combination of a polymer with a solvent, forming a gel. For buildings, the fiber-reinforced types are mainly used. In this paper, the changes both in the thermal performance and the material structure of the aerogel blanket are followed after thermal annealing. The samples are put under isothermal heat treatments at 70 °C for weeks, as well as at higher temperatures (up to 210 °C) for one day. The changes in the sorption properties that result from the annealing are presented. Furthermore, the changes in the thermal conductivity are followed by a Holometrix Lambda heat flow meter. The changes in the structure and surface of the material due to the heat treatment are investigated by X-ray diffraction and with scanning electron microscopy. Besides, the above-mentioned measurement results of differential scanning calorimetry experiments are also presented. As a result of using equipment from different laboratories that support each other, we found that the samples go through structural changes after undergoing thermal annealing. We manifested that the aerogel granules separate down from the glass fibers and grow up. This phenomenon might be responsible for the change in the thermal conductivity of the samples.

Silicon Recrystallization in Sipos Material Obtained by Disilane

1995 ◽  
Vol 403 ◽  
Author(s):  
J. J. Pedroviejo ◽  
B. Garrido ◽  
J. C. Ferrer ◽  
A. Cornet ◽  
E. Scheid ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Vapor Deposition ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Thermal Treatments ◽  
Structural Modifications ◽  
Pressure Chemical

AbstractConventional and Rapid Thermal Annealing of Semi-Insulating Polycrystalline Silicon layers obtained by Low Pressure Chemical Vapor Deposition (LPCVD) from disilane Si2H6 have been performed in order to determine the structural modifications induced on the layers by these thermal treatments. The study of these modifications has been carried out by several analysis methods like FTIR, XPS, TEM, RAMAN and ellipsometry. The results obtained are presented, contrasted and discussed in this work.

scholarly journals Thermal Diffusion in Fibrous Aerogel Blankets

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 823 ◽  
Author(s):  
Ákos Lakatos ◽  
Anton Trník
Keyword(s):  
Thermal Properties ◽  
Thermal Annealing ◽  
Thermal Insulation ◽  
Sol Gel ◽  
Theoretical Background ◽  
Design Stage ◽  
Scanning Calorimetry ◽  
Insulation Materials ◽  
Sol Gel Process ◽  
Transient Thermal

Nowadays, the usage of thermal insulation materials is widespread not only in the building sector but also in the vehicle industry. The application of fibrous or loose-fill insulation materials like glass wool or mineral wool as well as aerogel is well known. Aerogel-based materials are among the best solid materials for thermal insulation available today; they are prepared through a sol–gel process. For building walls, the glass-fiber-enhanced types are the frequently used ones. They are prepared by adding the liquid–solid solution to the fibrous batting, which is called a sol–gel process. In the present paper, the changes in the most important building physical properties of aerogel blankets after thermal annealing are presented. The samples were subjected to isochronal heat treatments from 70 to 210 °C for 24 h. The changes in the thermal conductivity were followed by Holometrix Lambda heat flow meter, and differential scanning calorimetry results were also recorded. From the measured values, together with the densities, the most important thermal properties were calculated, such as thermal resistance, diffusivity, effusivity (heat absorption), and thermal inertia. In this paper, we attempt to clarify the role played by thermal annealing in the transient thermal properties of aerogel materials. Besides presenting the measurement results, a theoretical background is given. The investigations of not only the steady-state but also the transient thermal parameters of the materials are momentous at the design stage.

scholarly journals The influence of polyisocyanurate (PIR) facing on the heat transfer through the corners of insulated building partitions

2020 ◽  
Vol 172 ◽  
pp. 08008
Author(s):  
Tomas Makaveckas ◽  
Raimondas Bliūdžius
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Thermal Insulation ◽  
Insulation Material ◽  
Transfer Coefficients ◽  
Thermal Insulation Material ◽  
Heat Transfer Coefficients ◽  
Thermal Bridge ◽  
The Stability ◽  
Structural Solutions

Prefabricated products made of polyisocyanurate (PIR) thermal insulation material covered with cardboard, plastic, aluminium or composite facings are used for thermal insulation of building envelopes. The facing of these products is selected according to their conditions of use, and the effect of the facing on the declared thermal properties of the product depend only on water vapor diffuse properties of the facing. However, at the corners of the building where these products are joined, facings can be in the direction of the heat flux movement and significantly increase heat transfer through the longitudinal thermal bridge formed in the corner of the building. After analysing the solutions for installation of PIR thermal insulation products on the walls and roof corners of buildings, calculations of the heat transfer coefficients of the linear thermal bridges were made, and the influence of various facings and different structural solutions on the heat transfer coefficient value of the thermal bridge was determined. Aluminium foil facing have the greatest influence, but other facings must also be considered. The structural solutions with the greatest increase in the heat transfer due to the effect of the facing were selected, and the influence to the thermal and air tightness properties of the structural solution when facing is removed were analysed, the stability of thermal properties of the thermal insulation material were analysed as well. Proposals for joining PIR thermal insulation products with heat-conductive facings in the corners of buildings were prepared.

scholarly journals Effects of termal treatment on the physical properties of Buchenavia sp. (branquilho) wood

2022 ◽  
Vol 22 (1) ◽  
pp. 95-103
Author(s):  
Laysa Teles Vollbrecht ◽  
Adriano Reis Prazeres Mascarenhas ◽  
Rafael Rodolfo de Melo ◽  
Maúcha Fernanda de Mota Lima ◽  
Ricardo Pereira Soteil ◽  
...  
Keyword(s):  
Physical Properties ◽  
Apparent Density ◽  
Basic Density ◽  
Heat Treatments ◽  
Thermal Treatments ◽  
Mean Values ◽  
Construction Market ◽  
Anisotropic Factor ◽  
Increasing Temperature ◽  
Dimensional Instability

Abstract This work aimed to evaluate the effect of heat treatment on the physical properties of wood from Buchenavia sp. The heat treatments were carried out at temperatures of 180 °C and 200 °C for 2 h. Apparent density (AD), basic density (BD), porosity (Ф), mass loss, longitudinal (LS), radial (RS), tangential (TS) and volumetric (VS) shrinkages and anisotropic factor (AF) were determined. The lowest values of basic density (0.67 g cm-3), apparent density (0.77 gcm-3), and porosity (43.3%) were observed for the wood treated at a temperature of 200 °C. Mass losses increased with increasing temperature and the highest values were observed under the condition of 200 °C (9.3%). The LS and AF was not affected by heat treatments. The mean values for RS (3.1%), TS (5.1%), and VS (9.1%) were reduced after the performance of heat treatments at temperatures of 180°C and 200°C, which did not differ from each other. The thermal treatments were able to reduce the dimensional instability of Buchenavia sp. Thermal treatments enhance the use of less prestigious Amazonian woods in the civil construction market.

Structural and thermal properties of the amaranth starch granule obtained by high-impact wet milling

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Diego Fernando Roa Acosta ◽  
José Fernando Solanilla Duque ◽  
Lina Marcela Agudelo Laverde ◽  
Héctor Samuel Villada Castillo ◽  
Marcela Patricia Tolaba
Keyword(s):  
Thermal Properties ◽  
Structural Changes ◽  
Starch Granule ◽  
Amorphous Region ◽  
Extraction Yield ◽  
High Impact ◽  
Degree Of Crystallinity ◽  
Wet Milling ◽  
Starch Structure ◽  
Structure Changes

AbstractIn this study, amaranth starch was extracted by high-impact wet milling and its structural and thermal properties and the effect of NaOH and SDS concentrations on extraction yield were evaluated. The best condition was 55 g of starch/100 g of amaranth, with a decrease from 2.5 to 3.5 kJ/g using different milling energies. The decrease in the protein content of the starch granule is due to an effect of the interaction between surfactant and alkali, preventing the destruction of granules. All starches presented a degree of crystallinity between 21 and 28%. The internal structural changes of the starch granule were monitored by attenuated total reflectance - Fourier-transform infrared (ATR-FTIR) in the region of 990 to 1060 cm−1. Spectra showed significant differences between the peaks at 1032 and 1005 cm−1, corresponding to the crystalline/amorphous region of the starch structure. Changes in viscosity profiles were observed between 0.302 and 1.163 Pa s.

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