The effects of functional nanofillers on the reaction kinetics, microstructure, thermal and mechanical properties of water blown rigid polyurethane foams

Santiago‐Calvo, Mercedes; Tirado‐Mediavilla, Josías; Ruiz‐Herrero, J.L.; Rodríguez‐Pérez, Miguel Ángel; Villafañe, Fernando

doi:10.1016/j.polymer.2018.07.029

Cited by 51 publications

(62 citation statements)

References 52 publications

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“…Such changes in thermal conductivity are mostly related to changes in closed-cells content and the size of cells. A possible explanation may be also found in different polarities of fibers and polymer, which results in poor compatibility and weak ability of the structure's cells to encapsulate blowing gas [28,90]. This dependence is more prominent for foams modified with non-treated fibers.…”

Section: Thermal Conductivity Of Polyurethane Foamsmentioning

confidence: 99%

Effects of Chemically Treated Eucalyptus Fibers on Mechanical, Thermal and Insulating Properties of Polyurethane Composite Foams

et al. 2020

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In this work, rigid polyurethane (PUR) foams were prepared by incorporating 2 wt% of eucalyptus fibers. The eucalyptus fibers were surface-modified by maleic anhydride, alkali, and silane (triphenylsilanol) treatment. The impact of the modified eucalyptus fibers on the mechanical, thermal, and fire performances of polyurethane foams was analyzed. It was observed that the addition of eucalyptus fibers showed improved mechanical and thermal properties and the best properties were shown by silane-treated fibers with a compressive strength of 312 kPa and a flexural strength of 432 kPa. Moreover, the thermal stability values showed the lowest decline for polyurethane foams modified with the silane-treated fibers, due to the better thermal stability of such modified fibers. Furthermore, the flame resistance of polyurethane foams modified with the silane-treated fibers was also the best among the studied composites. A cone calorimetry test showed a decrease in the peak of heat release from 245 to 110 kW∙m−2 by the incorporation of silane-treated fibers. Furthermore, total heat release and total smoke release were also found to decrease remarkably upon the incorporation of silane-treated fibers. The value of limiting oxygen index was increased from 20.2% to 22.1%. Char residue was also found to be increased from 24.4% to 28.3%. It can be concluded that the application of chemically modified eucalyptus fibers has great potential as an additive to incorporate good mechanical, thermal, and fire properties in rigid polyurethane foams.

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Section: Thermal Conductivity Of Polyurethane Foamsmentioning

confidence: 99%

Effects of Chemically Treated Eucalyptus Fibers on Mechanical, Thermal and Insulating Properties of Polyurethane Composite Foams

et al. 2020

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“…It has been reported 30 that the nanocomposite foams with hydrophilic SNP have higher density compared to the reference foam. The density can be controlled by the competitive process of cell nucleation, growth, and cell coalescence during the foaming reaction 18 .…”

Section: Resultsmentioning

confidence: 97%

Evaluation of microstructure, thermal, and mechanical properties of the green lignin‐based polyurethane/hydrophobic silica nanocomposite foam

Mohammadpour

Sadeghi

2020

J of Applied Polymer Sci

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In the present study, lignin‐based polyurethane foam (LPUF) and hydrophobic silica LPUF (SLPUF) were synthesized using different concentrations of silica nanoparticles (SNP). The effect of SNP on the structure and properties of SLPUF samples was investigated and compared with LPUF through the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), and compressive tests. The FT‐IR results showed changes in the H bonding interactions between the structures of SLPUF samples. Moreover, the SEM results indicated a decrease in the cell size of SLPUF samples. Incorporation of SNP improved the thermal stability of SLPUF samples while the compressive strength of SLPUF samples decreased in comparison with LPUF. Furthermore, the DMTA results revealed a decrease in the glass transition temperature from 90°C (LPUF) to around 52°C (SLPUF samples). This means that applying the hydrophobic SNP changes the foam type from a rigid foam to soft one. Therefore, significant changes were observed in the physical–chemical properties of the SLPUF samples compared to the LPUF.

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“…Thus, the use of blowing agents with low thermal conductivities is one of the key strategies to improve the thermal properties of RPU foams. Moreover, the addition of fillers to the RPU matrix may also decrease the cell size and/or block infrared radiation, reducing the radiation contribution to the thermal conductivity …”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the addition of fillers to the RPU matrix may also decrease the cell size and/or block infrared radiation, reducing the radiation contribution to the thermal conductivity. 5,10,11 Another important aspect to consider is the aging of the RPU foam, since the thermal conductivity values always increase with time. This aging phenomenon occurs because the blowing agents slowly diffuse out of the cells, being replaced by atmospheric air which diffuses into them.…”

Section: Introductionmentioning

confidence: 99%

“…The use of fillers is of great interest in the field of RPU foams because their addition can improve the thermal insulation of these materials. 10,11,[20][21][22] In this work we report the effect of different types of particles (talc (T), diatomaceous earth (DE) and non-porous silica (NPS)) on the long-term thermal conductivity of RPU foams containing CP and water as blowing agents. In addition, another aim of this work was to establish, for the first time, a correlation between the effect of the fillers during foaming and the aging performance.…”

Section: Introductionmentioning

confidence: 99%

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Long‐term thermal conductivity of cyclopentane–water blown rigid polyurethane foams reinforced with different types of fillers

Santiago‐Calvo

Tirado‐Mediavilla

Ruiz‐Herrero

et al. 2019

Polymer International

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An understanding of the long‐term thermal conductivity of rigid polyurethane (RPU) foams presents great interest in the building field considering the conservation of energy efficiency. In this study, the effect of different types of particles (talc, diatomaceous earth and non‐porous silica) on the thermal conductivity of RPU foams blown with cyclopentane and water as blowing agents was investigated during 3 years of aging. The characterization of the cellular structure shows how the addition of particles causes a cell size reduction of the foams, and consequently an enhancement of the thermal properties just after production. However, this initial reduction is not maintained, because each foam shows a different thermal conductivity evolution with time. We have found, for the first time, a relationship between the slope of the thermal conductivity versus time at the first measurements and the internal temperature reached during the foaming process. The evolution of the RPU foams in which higher internal temperatures were reached is more pronounced than in those RPU foams where lower foaming temperatures were observed. This effect is related to the kinetics of the diffusion of the gas occluded inside the cells and imposes a new criterion for the selection of particles to reduce the thermal conductivity of RPU foams; these additives should ideally decrease the temperature reached during the foaming process. Moreover, the effect of aging on the thermal conductivity is explained by using theoretical models. © 2019 Society of Chemical Industry

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The effects of functional nanofillers on the reaction kinetics, microstructure, thermal and mechanical properties of water blown rigid polyurethane foams

Cited by 51 publications

References 52 publications

Effects of Chemically Treated Eucalyptus Fibers on Mechanical, Thermal and Insulating Properties of Polyurethane Composite Foams

Effects of Chemically Treated Eucalyptus Fibers on Mechanical, Thermal and Insulating Properties of Polyurethane Composite Foams

Evaluation of microstructure, thermal, and mechanical properties of the green lignin‐based polyurethane/hydrophobic silica nanocomposite foam

Long‐term thermal conductivity of cyclopentane–water blown rigid polyurethane foams reinforced with different types of fillers

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