Correlation between cell wall buckling and deformation banding in a closed-cell foam

2019 ◽  
Vol 170 ◽  
pp. 177-182 ◽  
Author(s):  
H.W. Chai ◽  
H.Y. Li ◽  
X.H. Xiao ◽  
J.Y. Huang ◽  
S.N. Luo
Keyword(s):  
Cell Wall ◽  
Deformation Banding ◽  
Closed Cell ◽  
Wall Buckling ◽  
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 Study of Physical Properties and Shock Absorption Abilities of Starch Polymer Foam as Cushioning Material for Packaging

2018 ◽  
Vol 225 ◽  
pp. 06010
Author(s):  
N. Amir ◽  
Mohamed Syakir Mohamed Hisham ◽  
Kamal Ariff Zainal Abidin
Keyword(s):  
Average Density ◽  
Curing Process ◽  
Polymer Foam ◽  
Shock Absorption ◽  
Open Cell ◽  
Lack Of Information ◽  
Closed Cell ◽  
Open Cell Foam ◽  
Cell Foam ◽  
Cushioning Material

Lack of information about the formulation and fabrication process of starch polymer foam and lack of study in the shock absorption ability of starch polymer foam were the reasons this research was executed. In this project starch polymer foam was produced to be used as cushioning material for packaging. Starch polymer foam were developed from starch, polyvinyl alcohol (PVA), urea, citric acid, and deionised water. Water amount with drying and curing process were the variables manipulated to produce the best starch polymer foam. It was determined then, that the optimized ratio of starch:PVA:citric acid was 1:1:4. The amount of water used was 10 ml/gram of starch/PVA weight. The suitable foaming mixing was done at a speed of 1500 rpm for 40 minutes. Drying process was done at 70°C for 24 hours, followed by curing process at 100°C for 1 hour to produce closed-cell foam. While for the open-cell foam, the foam was dried and cured at 100ºC for 6 hours. The open-cell and closed-cell foams produced were cut to 6 cm height x 6 cm width x 0.5 cm thick. The average density was calculated and then the foams were subjected to weight drop destructive test. The test was done by placing a foam on top of a piece of mirror, and a weight is dropped onto the foam, with increasing height until the mirror break. Three weights were used with mass of 50 g, 100 g and 200 g. The starch foams were compared to polyurethane and polystyrene foams in terms of the minimum height that can cause the mirror to break. The results showed that starch closed-cell foam absorbed the highest impact energy followed by polystyrene foam, starch open-cell foam and polyurethane foam.

Open-Cell Foam Metal Production and Characterization by Aluminum Solid Mold Investment Casting

2019 ◽  
Author(s):  
Kerem Altug Guler
Keyword(s):  
Investment Casting ◽  
Replication Process ◽  
Open Cell ◽  
Metal Fabrication ◽  
Cell Structures ◽  
Closed Cell ◽  
Small Complex ◽  
Open Cell Foam ◽  
Foam Metal ◽  
Cell Foam

Foam metals can be categorized in two basic classes: open-cell and closed-cell structures, which both have different numerous unique properties. Up to the present, several production processes have been developed for each class. Investment casting is known as a replication process for open-cell foam metal fabrication. Solid mold, which can be evaluated as a subtechnique of the investment casting, is specialized especially for small complex shapes with ultrathin sections. This work is a presentation of aluminum open-cell foam production with solid mold investment casting using two different kinds of patterns. The first one is “burnable,” in which liquid metal directly fills the shape of pattern and the second is “leachable,” in which metal takes the form of intergranular network shape of porous salt preforms.

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

Closed Cell Foam: A Sound Barrier and More

2005 ◽  
Author(s):  
Mark Smith ◽  
Waldemar Semrau
Keyword(s):  
Sound Barrier ◽  
Closed Cell ◽  
Cell Foam
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