Anisotropic thermal expansion of bio-based rigid low-density closed-cell polyurethane foams

Andersons, J.; Grube, Rudolf; Vēvere, Laima; Cabulis, Peteris; Kirpļuks, Miķelis

doi:10.1016/j.jmrt.2021.12.094

Cited by 10 publications

(6 citation statements)

References 38 publications

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“…For that, we use the dilatometry tests of a PU polymer with the same formulation as above (but slightly different bio-polyol functionality), characterizing its linear thermal expansion due to reduction in temperature from RT to ca. −150 °C . As an example, thermal strain ε of a PU polymer, determined with respect to specimen length at T 0 = 20 °C, as a function of temperature is shown in Figure a.…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis method of ETOFA_TMP bio-based polyol is described in ref , and the common characteristics of all bio-based polyols are summarized in Table S1. The other reagents necessary for rigid PU foam development were used as purchased, as detailed in ref .…”

Section: Methodsmentioning

confidence: 99%

“…Materials. Rigid bio-based PU foams with different molecular weight per branching unit M c were developed using bio-based polyols with differing OH group functionalities as described in ref 16. For completeness and ease of reference, we briefly recapitulate the approach pursued.…”

Section: Methodsmentioning

confidence: 99%

“…However, when only a qualitative comparison of samples of similar composition is sufficient, it is possible to make some simplifications and estimate the FFV f v in the following way. We assume that the relative intensity I oPs is proportional to the volume concentration of holes and the spherical cavity represents the average free volume of the real local free volume v h , then 16) where cI oPs corresponds to the number of voids per volume unit. If the value of the proportionality factor c for the given material is not known, eq 16 can be used for estimation of the relative free volume fraction…”

Section: Polymer Permeabilitymentioning

confidence: 99%

“…−150 °C. 16 As an example, thermal strain ε of a PU polymer, determined with respect to specimen length at T 0 = 20 °C, as a function of temperature is shown in Figure 9a. It is seen that reduction of temperature to ca.…”

Section: Polymer Permeabilitymentioning

confidence: 99%

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Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Kirpļuks

Godiņa

Švajdlenková

et al. 2023

ACS Appl. Polym. Mater.

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Gradual replacement of the traditional raw materials in polyurethane (PU) synthesis by bio-based ones and introduction of environmentally friendly physical blowing agents (PBAs) motivate the analysis of thermal aging of bio-based foams in order to optimize the chemical structure of the PU matrix so that its permeability to PBA is minimized. With the aim of elucidating the effect of the PU chemical structure on thermal aging of foams, rigid low-density closed-cell PU foams were produced solely from bio-based polyols. The effective diffusivities of PBA and atmospheric gasses were evaluated based on the measured thermal conductivity aging of foams and validated by gas chromatography measurements of gas composition in foam cells. Gas permeability of the PU polymer was estimated based on effective diffusivity in foams and foam morphology and found to decrease with increasing crosslink density, apparently due to reduction in the fractional free volume in the polymers.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Polymer Permeabilitymentioning

confidence: 99%

Section: Polymer Permeabilitymentioning

confidence: 99%

See 3 more Smart Citations

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Kirpļuks

Godiņa

Švajdlenková

et al. 2023

ACS Appl. Polym. Mater.

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Microstructure and performances of rigid polyurethane foam prepared using double‐effect baking powder as a foaming agent

Cheng,

Zhang,

Liu

et al. 2024

Polymer Engineering & Sci

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The preparation of rigid polyurethane foam with uniform pore size is extremely challenging. In this work, double‐effect baking powder was used as foaming agent, and rigid polyurethane foam with regular morphology was successfully prepared through semi‐prepolymerization. The rigid polyurethane foam apertures with regular morphology were controlled by the secondary release of CO2 when the content of baking powder is 0.30 part. Combined with theoretical calculation and experimental test, it is found that the particle size distribution, wall thickness, and hole shape are uniform, regular, thin, polygonal, and few broken holes. The compression strength, contact angle, and surface energy of the rigid polyurethane foam are 33.36 kPa, 109.6°, and 21.8 mJ/m2 after adding 0.20 part of double‐effect baking powder, respectively. By adjusting the amount of double‐acting baking powder, the porosity, mechanical properties and foam rate of the polyurethane foams could be significantly improved. Due to the molecular solvation effect, rigid polyurethane foams will deform in the water and oil due phase, but it can remain stable for a long time at room temperature without solvent. It provides a new method for the preparation of rigid polyurethane foam, which is expected to be widely used in transportation and other fields.Highlights Baking powder was firstly used as a foaming modifier for rigid polyurethane. Baking powder releases CO2 twice to ensure uniform structure of polyurethane cell. Rigid polyurethane foam has long‐term stability and regular, uniform cell holes. The porosity and mechanical properties of foams could be significantly improved. Foaming mechanism of rigid polyurethane using baking powder was firstly revealed.

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Additively manufactured meta-biomaterials: A state-of-the-art review

Vyavahare

Mahesh²,

Mahesh³

et al. 2023

Composite Structures

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Anisotropic thermal expansion of bio-based rigid low-density closed-cell polyurethane foams

Cited by 10 publications

References 38 publications

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Microstructure and performances of rigid polyurethane foam prepared using double‐effect baking powder as a foaming agent

Additively manufactured meta-biomaterials: A state-of-the-art review

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