Measuring the Impact of Experimental Parameters upon the Estimated Thermal Conductivity of Closed-Cell Foam Insulation Subjected to an Accelerated Aging Protocol: Two-Year Results

2010 ◽  
pp. 126-126-18
Author(s):  
Therese Stovall
Keyword(s):  
Thermal Conductivity ◽  
Accelerated Aging ◽  
Closed Cell ◽  
Experimental Parameters ◽  
The Impact ◽  
Cell Foam

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%.

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

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.

A Study Into LDPE as an Undersurfacing Material for Injury Prevention and Risk Minimisation in Children’s Playgrounds

2003 ◽  
Author(s):  
David Eager
Keyword(s):  
Injury Prevention ◽  
Test Method ◽  
Risk Minimisation ◽  
Absorption Properties ◽  
Closed Cell ◽  
Height Of Fall ◽  
Absorbing Material ◽  
The Impact ◽  
Impact Absorption ◽  
Cell Foam

Low Density Polyethylene (LDPE) closed-cell foam is used extensively as an impact absorbing material for injury prevention and risk minimisation in a variety of applications, including children’s playground undersurfacing, padding for trampoline frames, and other fall zones. This paper presents and analyses the data from numerous impact tests performed on samples of LDPE of select different product thicknesses (10, 20, 30 and 40 mm), nominal Relative Densities (30, 45, 60 and 75 kg/m3) and drops or free height of fall (100 mm steps in heights from 300 to 2100 mm). The impact absorption properties of LDPE are characterized using the Australian and New Zealand Standard AS/NZS 4422: Playground Surfacing — Specifications, Requirements and Test Method. The gmax and HIC results are presented both graphically and numerically. This paper also discusses uses and limitations of LDPE with particular emphasis on injury prevention and risk minimisation.

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

Effect of Relative Density on the Dynamic Impact Behaviors of Closed-Cell Foam

2016 ◽  
Author(s):  
Shilong Wang ◽  
Yuanyuan Ding ◽  
Changfeng Wang ◽  
Zhijun Zheng ◽  
Jilin Yu
Keyword(s):  
Shock Wave ◽  
Relative Density ◽  
Impact Velocity ◽  
High Velocity ◽  
Wave Speed ◽  
Material Parameter ◽  
Dynamic Strain ◽  
Closed Cell ◽  
The Impact ◽  
Cell Foam

Dynamic behaviors of closed-cell foam are investigated with cell-based finite element models based on the 3D Voronoi technique. The typical deformation feature of cellular structures under high-velocity impact is layer by layer collapse, like a shock wave propagating in the specimen. The one-dimensional velocity distribution of the structure is calculated to characterize the propagation of shock front and thus the shock wave speed is determined quantitatively. It is found that the shock wave speed has intense dependence on the impact velocity for a specific relative density. The difference between the shock wave speed and the impact velocity is asymptotic to a constant as the impact velocity increases. This constant can be therefore regarded as a dynamic material parameter. The influence of relative density on this dynamic material parameter is investigated. The results show that the shock wave speed at a specific impact velocity increases with the increase of the relative density of cellular structure in a certain extent. An expression of the shock wave speed with respect to the impact velocity and relative density is obtained. The dynamic strain hardening parameter is lower than that in the quasi-static one, which indicates different mechanisms of the deformation under high-velocity and quasi-static loadings.

Sign in / Sign up

Export Citation Format

Share Document