Effects of Polymer Structure on K-Factor Aging of Rigid Polyurethane Foam

Booth, L.D.; Lee, W.M.

doi:10.1177/0021955x8502100102

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…Our experiments gave resistance values 5-10% higher for such aging as compared to room temperature aging for 180 days. Similar results were reported by Booth and Lee [2] for certain rigid polyurethane foams. Other workers have not seen such a difference.…”

Section: Prior Artsupporting

confidence: 91%

Aged Thermal Resistance of Extruded Polystyrene Foams An Approach of a Small, Newer Manufacturer

Divis¹

1990

Journal of Thermal Insulation

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New plastic foam insulation manufacturers or products encounter the problem that long age thermal performance data cannot be available, such as 5 years old. A method for estimating long-term thermal performance of extruded polystyrene foams based on computer curve fitting against a menu of classic techmcal equations is presented and compared with actual measurements at 5 years after insulation manufacture. The effect of closed cell content, deviation of the foam from ideal uniformity, and foam density is discussed. The method permits estimation of long age thermal performance using relatively short age measurements without detailed and accurate knowledge of gas permeabilities, foam cell morphology, and deviations from ideal foam uniformity.

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Section: Prior Artsupporting

confidence: 91%

Aged Thermal Resistance of Extruded Polystyrene Foams An Approach of a Small, Newer Manufacturer

Divis¹

1990

Journal of Thermal Insulation

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“…The other four specimens were each placed in air at the following conditions: 1) 60°C, < 10% RH (humidity uncontrolled); 2) 60°C, 40% RH; 3) 60°C, 60% RH; and 4) 60°C, 75% RH. A temperature of 60°C was selected because of its historical popularity in several other aging studies [8][9][10][11]. 4.…”

Section: Conditioning Environmentsmentioning

confidence: 99%

Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam Co-Blown with CCl3F and CO 2

Zarr

Nguyen

1994

Journal of Thermal Insulation and Building Envelopes

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Measurements of density and apparent thermal conductivity are presented for specimens cut from rigid polyisocyanurate (PIR) foam co-blown with trichlorofluoromethane (CCl 3 F) and carbon dioxide (CO 2 ) Eight specimens, nominally 580 by 580 by 27 mm, were prepared from two boards (1.2 by 2.4 m by 50 mm) of foam laminated with permeable facers. Four specimens were placed in an ambient condition of 22°C and 40% relative humidity (RH). The other four specimens were each placed in one of the following environments: 1) 60°C and < 10% RH; 2) 60°C and 40% RH; 3) 60°C and 60% RH; and 4) 60°C and 75% RH. Measurements of apparent thermal conductivity at 24°C were conducted over a period of 372 days at approximately 50-day intervals. Curves of specimen mass, volume, density, and thermal conductivity versus time are presented, and the implications of changes in these properties are discussed.

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“…It is well recognized that the decrease in foam cell size is usually accompanied by the decrease in thermal conductivity following a mostly linear relationship [20][21][22]. In this context, a control of cell nucleation during foaming is a key factor for the control of the cellular morphology and consequently of the foam insulating efficiency.…”

Section: Nucleation Mechanismmentioning

confidence: 99%

The morphology of rigid polyurethane foam matrix and its evolution with time during foaming – New insight by cryogenic scanning electron microscopy

Reignier

Alcouffe

Méchin

et al. 2019

Journal of Colloid and Interface Science

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This paper presents an investigation of the morphology of growing polyurethane (PU) rigid foams during the very first seconds of the process by cryogenic scanning electron microscopy (cryo-SEM) performed at -150°C. The heterogeneous nature of the initial mixture has been revealed with the presence of sub-micron size physical blowing agent droplets (isopentane), µm size dispersed phase nodules, and large air bubbles dispersed in a continuous matrix. Following the evolution of the microstructure during foaming by cryo-SEM suggested that the isopentane liquid droplets (undissolved part of the physical blowing agent) did not vaporize to create their own bubbles. These observations were confirmed by showing that the number of air bubbles per unit volume (∼10 6 bubble/cm 3 ) was similar to the cell population density of the final foam (∼10 6 cell/cm 3 ), while the number of isopentane droplets initially present was found to be six orders of magnitude higher (∼10 12 droplet/cm 3 ). This all means that isopentane molecules initially dissolved in the continuous phase diffuse into the preexisting air bubbles with no energy barrier to overcome (non-classical nucleation) whereas the isopentane droplets simply act like reservoirs. Finally despite our best efforts, there is still some doubt whether polymeric 4,4'-diphenylmethane diisocyanate (PMDI) is dispersed in the polyol phase, or polyol dispersed in PMDI.

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Effects of Polymer Structure on K-Factor Aging of Rigid Polyurethane Foam

Cited by 10 publications

References 6 publications

Aged Thermal Resistance of Extruded Polystyrene Foams An Approach of a Small, Newer Manufacturer

Aged Thermal Resistance of Extruded Polystyrene Foams An Approach of a Small, Newer Manufacturer

Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam Co-Blown with CCl3F and CO 2

The morphology of rigid polyurethane foam matrix and its evolution with time during foaming – New insight by cryogenic scanning electron microscopy

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