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

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

Temperature dependency of the long-term thermal conductivity of spray polyurethane foam

2021 ◽  
pp. 174425912110454
Author(s):  
Neal Holcroft
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Cellular Structure ◽  
Gas Diffusion ◽  
Temperature Dependent ◽  
Blowing Agent ◽  
Closed Cell ◽  
Wall Assembly ◽  
Cell Foam

The thermal properties of closed-cell foam insulation display a more complex behaviour than other construction materials due to the properties of the blowing agent captured in their cellular structure. Over time, blowing agent diffuses out from and air into the cellular structure resulting in an increase in thermal conductivity, a process that is temperature dependent. Some blowing agents also condense at temperatures within the in-service range of the insulation, resulting in non-linear temperature dependent relationships. Moreover, diffusion of moisture into the cellular structure increases thermal conductivity. Standards exist to quantify the effect of gas diffusion on thermal conductivity, however only at standard laboratory conditions. In this paper a new test procedure is described that includes calculation methods to determine Temperature Dependent Long-Term Thermal Conductivity (LTTC(T)) functions for closed-cell foam insulation using as a test material, a Medium-Density Spray Polyurethane Foam (MDSPF). Tests results are provided to show the validity of the method and to investigate the effects of both conditioning and mean test temperature on change in thermal conductivity. In addition, testing was conducted to produce a moisture dependent thermal conductivity function. The resulting functions were used in hygrothermal simulations to assess the effect of foam aging, in-service temperature and moisture content on the performance of a typical wall assembly incorporating MDSPF located in four Canadian climate zones. Results show that after 1 year, mean thermal conductivity increased 15%–16% and after 5 years 23%–24%, depending on climate zone. Furthermore, the use of the LTTC(T) function to calculate the wall assembly U-value improved accuracy between 3% and 5%.

Effect of Filler Types on Properties of the Natural Rubber Closed Cell Foam

2019 ◽  
Vol 886 ◽  
pp. 213-218
Author(s):  
Ekaroek Phumnok ◽  
Jakkrit Boonphang ◽  
Orrachorn Bourkaew
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Precipitated Calcium Carbonate ◽  
Elongation At Break ◽  
Blowing Agent ◽  
Compression Set ◽  
China Clay ◽  
Closed Cell ◽  
The Difference ◽  
Cell Foam

In this research, effects of filler types and their loading on properties of the natural rubber closed cell foam were investigated. The azodicarbonamide was used as a blowing agent in 4 phr loading. The filler types that are the N-330 grade of carbon black, precipitated calcium carbonate and rubber grade china clay, their loading was varied from 0 to 50 phr (part per hundred dried rubber). The physical properties of the rubber foam that are the difference torque from the oscillating disk rheometer, hardness, tear strength, 300% modulus, tensile strength, elongation at break and compression set were analyzed. The results were found that the carbon black was yielded the highest of all properties in every loading. In conclusion, the suitable filler for closed cell rubber foam is the carbon black.

Numerical Prediction of the Effective Thermal Conductivity of Open- and Closed-Cell Foam Structures

2010 ◽  
Vol 297-301 ◽  
pp. 1210-1217 ◽  
Author(s):  
Seyed Mohammad Hossein Hosseini ◽  
Andreas Öchsner ◽  
Thomas Fiedler
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Relative Density ◽  
Effective Thermal Conductivity ◽  
Linear Trend ◽  
Space Filling ◽  
Open Cell ◽  
Cell Structures ◽  
Closed Cell ◽  
Cell Foam

This paper investigates the thermal properties of metallic open-cell and closed-cell foam structures in space filling and non-space filling configurations. In both, i.e. open-cell and closed-cell structures, a linear trend depending on the relative density has been reported. However the closed-cell structures compared to open-cell ones have a higher thermal conductivity for the same relative density.

Morphological Changes of Irradiated PMMA via Supercritical Carbon Dioxide Treatments

2011 ◽  
Vol 239-242 ◽  
pp. 1510-1514
Author(s):  
Xin Long Ling ◽  
Zhong Feng Tang ◽  
Shi Rong Huang
Keyword(s):  
High Cell Density ◽  
Morphological Changes ◽  
Cell Structure ◽  
High Cell ◽  
Blowing Agent ◽  
Closed Cell ◽  
Morphology And Structure ◽  
Γ Ray ◽  
Effects Of Radiation ◽  
Quench Method

Poly (methyl methacrylate) (PMMA) sheets were radiated by60Co γ-ray in air and then irradiated PMMA foams were successfully prepared by supercritical CO2(SC CO2) as a physical blowing agent via pressure quench method. The effects of radiation dose on the cell morphology and structure of the obtained foams were studied. The results showed that the foams possessed spherically closed cell structure with uniform cell size. The γ-ray irradiated PMMA sheets had a high cell density than those virgin PMMA.

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