Study on the Methods for Measuring Closed Cell Content of Cellular Glass and its Thermal Insulation Performance

2016 ◽  
Vol 680 ◽  
pp. 68-71
Author(s):  
Chao Peng ◽  
Gui Qiang Li ◽  
Cheng Xin Sui ◽  
Hui Meng Zhang ◽  
Yu Hui Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Cell Structure ◽  
Insulation Property ◽  
Cell Content ◽  
Measuring Condition ◽  
Effect Of Pressure ◽  
Cellular Glass ◽  
Closed Cell ◽  
Insulation Performance

The principle of measuring cellular glass by automatic densimeter was studied. The effect of pressure on closed cell content was researched in order to optimize the measuring pressure. The influence of closed cell content on the insulation property was analyzed by measuring thermal conductivity. The results showed that cell structure of cellular glass can distort or even be damaged with the increasing of pressure and the first condition for obtaining accurate closed cell content was to optimize the measuring condition and determine appropriate pressure. Closed cell content affects the insulation property of the cellular glass significantly.

Bio-based Polyurethane-clay Nanocomposite Foams: Systheses and Properties

2009 ◽  
Vol 1188 ◽  
Author(s):  
Min Liu ◽  
Zoran S. Petrovic ◽  
Yijin Xu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Cell Structure ◽  
Polyurethane Foams ◽  
Mechanical And Thermal Properties ◽  
Cell Content ◽  
Modified Clay ◽  
Rigid Polyurethane Foams ◽  
Nanocomposite Foams ◽  
Organically Modified

AbstractStarting from a bio-based polyol through modification of soybean oil, BIOH™ X-210, two series of bio-based polyurethanes-clay nanocomposite foams have been prepared. The effects of organically-modified clay types and loadings on foam morphology, cell structure, and the mechanical and thermal properties of these bio-based polyurethanes-clay nanocomposite foams have been studied with optical microscopy, compression test, thermal conductivity, DMA and TGA characterization. Density of nanocomposite foams decreases with the increase of clay loadings, while reduced 10% compressive stress and yield stress keep constant up to 2.5% clay loading in polyol. The friability of rigid polyurethane-clay nanocomposite foams is high than that of foam without clay, and the friability for nanofoams from Cloisite® 10A is higher than that from 30B at the same clay loadings. The incorporation of clay nanoplatelets decreases the cell size in nanocomposite foams, meanwhile increases the cell density; which would be helpful in terms of improving thermal insulation properties. All the nanocomposite foams were characterized by increased closed cell content compared with the control foam from X-210 without clay, suggesting the potential to improve thermal insulation of rigid polyurethane foams by utilizing organically modified clay. Incorporation of clay into rigid polyurethane foams results in the increase in glass transition temperature: the Tg increased from 186 to 197 to 204 °C when 30B concentration in X-210 increased from 0 to 0.5 to 2.5%, respectively. Even though the thermal conductivity of nanocomposite foams from 30B is lower than or equal to that of rigid polyurethane control foam from X-210, thermal conductivity of nanocomposite foams from 10A is higher than that of control at all 10A concentrations. The reason for this abnormal phenomenon is not clear at this moment; investigation on this is on progress.

scholarly journals Microstructural and Chemical Analysis of Polyurethane and Polyisocyanurate Foam Insulations

2021 ◽  
Author(s):  
Umberto Berardi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Performance ◽  
Cell Structure ◽  
Polymer Degradation ◽  
Chemical Characterization ◽  
Aging Behavior ◽  
Blowing Agent ◽  
Closed Cell ◽  
Physical Attributes ◽  
Cell Foam

For some closed cell foam insulation products, the thermal conductivity increases at low temperatures, contrary to single thermal resistance values provided by manufacturers. This phenomenon has been demonstrated in various polyurethane and polyisocyanurate insulations. The reduction in thermal performance has been attributed to the diffusion of air and blowing agent through the foam and to the condensation of blowing agent. Aging processes such as freeze-thaw cycling, moisture accumulation, and polymer degradation further increase thermal conductivity. The initial cell structure plays a role in dictating the thermal performance. To further understand the loss of thermal performance in closed cell foams, microstructure and chemical characterization was performed in this study. The aging behavior of foam insulations was analyzed by imaging foams with SEM and by measuring foam. Changes in the polymer physical attributes were identified and compared to increases in thermal conductivity. This project also used gas chromatography and quantified changes in pentane concentration in polyisocyanurate foams that have undergone aging

Performance of Thermal Insulation Reflective Composite Coatings

2011 ◽  
Vol 239-242 ◽  
pp. 1771-1774 ◽  
Author(s):  
Meng Qiu Jia ◽  
Yu Hong Jin
Keyword(s):  
Aqueous Solution ◽  
Thermal Insulation ◽  
Heat Insulation ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Insulation Property ◽  
Corrosion Properties ◽  
Rutile Titanium Dioxide ◽  
Insulation Performance ◽  
Good Heat

Reflective topcoat and thermal insulation mid-coat composite coatings system was used in this work. The effect of the content of the hollow glass micro-beads and rutile titanium dioxide on the heat insulation performance and the reflectivity of the coatings were investigated, respectively. The heat insulation performance and the reflectivity of the thermal insulation reflective composite coatings (TIRCCs) were characterized by self-prepared experimental device. The results showed the good heat insulation property, and the insulated temperature reached 12-15°C, and the reflectivity was up to 95%. The anti-corrosion and anti-penetration of the TIRCCs were studied by electrochemical impedance spectroscopy (EIS) technique. The results showed that the resistance of the TIRCCs still be maintained at 108Ω·cm2 after 30 days in the 3.5% aqueous solution of sodium chloride. So The TIRCCs can be used on the surface of the steal structure for decreasing the temperature and enhancing anti-corrosion properties.

Thermal Insulation Property of Newspaper Membrane Encased Soil-Based Aerated Lightweight Concrete Panels

2011 ◽  
Vol 261-263 ◽  
pp. 783-787 ◽  
Author(s):  
Soon Ching Ng ◽  
Kaw Sai Low ◽  
Ngee Heng Tioh
Keyword(s):  
Temperature Gradient ◽  
Thermal Insulation ◽  
Lightweight Concrete ◽  
Clayey Soil ◽  
Heat Insulation ◽  
Control Panel ◽  
Insulation Property ◽  
Concrete Panels ◽  
Thermal Insulation Property ◽  
Insulation Performance

Roof and wall are known to be responsible for heat entering into a building and should therefore be thermally insulated in order to lessen energy consumption required for air-conditioning. In this study, four soil-based aerated lightweight concrete (ALC) panels each measures 750 mm (length) x 750 mm (breadth) x 70 mm (thick) with different aerial intensity of newspaper membrane encased were produced and tested on their thermal insulation property. For environmental friendly and economy reasons, clayey soil was used in place of sand to produce the ALC panels and they were tested in the Thermal Laboratory for twenty hours. Temperature gradient was computed based on the surface temperature measured during the test. The results obtained indicated that newspaper membrane encased soil-based ALC panels have superior heat insulation performance compared to control panel in terms of temperature gradient. It is found that the temperature gradient increased from 1.92 °C/cm to 2.08 °C/cm or 8.3% higher than control panel with just merely 0.05 g/cm2 of newspaper membrane encased.

The Synthesis and Application of a Novel Class of Polyols for Preparation of Polyurethane

2013 ◽  
Vol 357-360 ◽  
pp. 1441-1445
Author(s):  
Xiao Lin Li ◽  
Zheng Fang ◽  
Dong Ji ◽  
Zhi Dong Wan ◽  
Kai Guo
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Polyurethane Foams ◽  
Low Density ◽  
Cell Content ◽  
Low Thermal Conductivity ◽  
High Compressive Strength ◽  
Rigid Polyurethane Foams ◽  
Closed Cell ◽  
Rigid Foams

The synthesis of a novel class of diamine-based polyols derivatives and the potentials and the limitations of these polyols were reported. This class of diamine-based polyols with high hydroxyl values and no acid values can be used in rigid polyurethane foams. The prepared rigid foams show the properties of low density, high closed cell content, low thermal conductivity, and high compressive strength.

Study on the Thermal Insulation Performance of PAN Pre-Oxidised Fibre Felts

2020 ◽  
Vol 28 (3(141)) ◽  
pp. 27-37
Author(s):  
Xiaoming Zhao ◽  
Yuanjun Liu ◽  
Tenglong Liang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Thermal Insulation ◽  
Silica Aerogel ◽  
Orthogonal Experiment ◽  
Excellent Thermal Stability ◽  
Coefficient Of Thermal Conductivity ◽  
Insulation Performance

In this paper, an orthogonal experiment of 3 factors and 3 levels was firstly designed to prepare PAN pre-oxidised fibre felts with good thermal insulation properties; the range method was used to analyse the result of the orthogonal experiment, and finally the tensile properties and thermal stability were tested. Finally, pre-oxidised fibre felt composites for the coating of silica aerogel were prepared using the coating process to compound silica aerogel on re-oxidised fibre felts. Firstly, the influence of the content of silica aerogel on the heat insulation performance of the coated composite materials was analysed, and then a test of the coefficient of thermal conductivity, an experiment on the back temperature, and characterisations of the tensile properties and thermal stability of the composite coating of pre-oxidised fibre felt composites of the coating of silica aerogel were carried out. Results showed that through analysis of the orthogonal experiment, we can state that the best preparation process of pre-oxidised fibre needled felts was as follows: needle number – 2, needle depth – 8 mm, and needle frequency – 140 times/min. The transverse tensile strength of PAN pre-oxidised fibre needled felts prepared by crossly webbing of PAN pre-oxidised fibres was superior to the longitudinal tensile strength; thermogravimetric analysis showed that the pre-oxidised fibre needled felts had excellent thermal stability. The coefficient of thermal conductivity of the aerogel coating of the composites firstly decreased and then increased with an increase in the content of aerogel. Coated composites had the lowest coefficient of thermal conductivity when the aerogel content was 4% wt. At temperatures of 100 °C, 150 °C and 200 °C, the heating rate of the transient-state back temperature and the steady-state average temperature were both the lowest when the aerogel content was 6% wt.

Fabrication and properties of carbon/carbon-carbon foam composites

2019 ◽  
Vol 89 (21-22) ◽  
pp. 4452-4460
Author(s):  
Bin Wang ◽  
Bugao Xu ◽  
Hejun Li
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Bonding Strength ◽  
Carbon Foam ◽  
Shear Load ◽  
Foam Composite ◽  
Final Failure ◽  
Carbon Foams ◽  
Insulation Performance

This paper was focused on the development of a new composite for high thermal insulation applications with carbon/carbon (C/C) composites, carbon foams and an interlayer of phenolic-based carbon. The microstructure, mechanical properties, fracture mechanism and thermal insulation performance of the composite was investigated. The experiment results showed that the bonding strength of the C/C-carbon foam composite was 4.31 MPa, and that the fracture occurred and propagated near the interface of the carbon foam and the phenolic-based carbon interlayer due to the relatively weak bonding. The shear load-displacement curves were characterized by alternated linear slopes and serrated plateaus before a final failure. he experiment revealed that the thermal conductivity of the C/C-carbon foam composite was 1.55 W·m−1ċK−1 in 800℃, which was 95.8% lower than that of C/C composites, proving that the thermal insulation of the new foam composite was greatly enhanced by the carbon foam with its porous hollow microstructure.

scholarly journals Rigid Polyurethane Foams with Various Isocyanate Indices Based on Polyols from Rapeseed Oil and Waste PET

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 738 ◽  
Author(s):  
Aiga Ivdre ◽  
Arnis Abolins ◽  
Irina Sevastyanova ◽  
Mikelis Kirpluks ◽  
Ugis Cabulis ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Rapeseed Oil ◽  
Crosslink Density ◽  
Polyurethane Foams ◽  
Insulation Material ◽  
Cell Content ◽  
Natural Sources ◽  
Isocyanate Index ◽  
Closed Cell

Developing polyols derived from natural sources and recycling materials attracts great interest for use in replacing petroleum-based polyols in polyurethane production. In this study, rigid polyurethane (PUR) foams with various isocyanate indices were obtained from polyols based on rapeseed oil and polyethylene terephthalate (RO/PET). The various properties of the prepared PUR foams were investigated, and the effect of the isocyanate index was evaluated. The closed-cell content and water absorption were not impacted by the change of the isocyanate index. The most significant effect of increasing the isocyanate index was on the dimensional stability of the resulting foams. This is due to the increased crosslink density, as evidenced by the increased formation of isocyanurate and increase of the glass transition temperature. Additionally, the influence on compression strength, modulus, and long-term thermal conductivity were evaluated and compared with reference PUR foams from commercially available polyols. Rigid PUR foams from RO/PET polyol were found to be competitive with reference materials and could be used as thermal insulation material.

scholarly journals Effect of density, phonon scattering and nanoporosity on the thermal conductivity of anisotropic cellulose nanocrystal foams

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Varvara Apostolopoulou-Kalkavoura ◽  
Pierre Munier ◽  
Lukasz Dlugozima ◽  
Veit-Lorenz Heuthe ◽  
Lennart Bergström
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Phonon Scattering ◽  
Cellulose Nanocrystal ◽  
Foam Density ◽  
Aqueous Dispersions ◽  
Gas Conduction ◽  
Insulation Performance ◽  
Ice Templating

AbstractAnisotropic cellulose nanocrystal (CNC) foams with densities between 25 and 130 kg m−3 (CNC25 –CNC130) were prepared by directional ice-templating of aqueous dispersions. Estimates of the solid and gas conduction contributions to the thermal conductivity of the foams using a parallel resistor model showed that the relatively small increase of the radial thermal conductivity with increasing foam density can be attributed to interfacial phonon scattering. The foam wall nanoporosity and, to a lesser extent, the orientation of the CNC particles and alignment of the columnar macropores, also influence the insulation performance of the foams. The insight on the importance of phonon scattering for the thermal insulation properties of nanocellulose foams provides useful guidelines for tailoring nanofibrillar foams for super-insulating applications.

scholarly journals Cost-Effective Additive Manufacturing of Ambient Pressure-dried Silica Aerogel

2020 ◽  
pp. 1-32
Author(s):  
Zipeng Guo ◽  
Ruizhe Yang ◽  
Tianjiao Wang ◽  
Lu An ◽  
Shenqiang Ren ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Silica Aerogel ◽  
Processing Time ◽  
Ambient Pressure ◽  
Cost Effective ◽  
Supercritical Drying ◽  
Insulation Material ◽  
Market Demand ◽  
Insulation Property ◽  
Insulation Performance

Abstract The conventional manufacturing processes of aerogel insulation material is largely relying on the supercritical drying, which suffers from issues of massive energy consumption, high-cost equipment, and prolonged processing time. With the consideration of large market demand of the aerogel insulation material in the next decade, a low-cost and scalable fabrication technique is highly desired. In this paper, a direct ink writing (DIW) method is used to three-dimensionally fabricate the silica aerogel insulation material, followed by room-temperature and ambient pressure drying. Compared to the supercritical drying and freeze-drying, the reported method significantly reduces the fabrication time and costs. The cost-effective DIW technique offers the capability to print complex hollow internal structures, coupled with the porous structure, is found to be beneficial to the thermal insulation property. The addition of fiber to the ink assures the durability of the fabricated product, without sacrificing the thermal insulation performance. The foam ink preparation methods and the printability are demonstrated in this paper, along with the printing of complex three-dimensional geometries. The thermal insulation performance of the printed objects is characterized, and the mechanical properties are also examined. The proposed approach is found to have 56% reduction in the processing time. The printed silica aerogels exhibit a low thermal conductivity of 0.053 W m−1 K−1.

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