Effect of foaming on mechanical properties of microfibrillated cellulose-based porous solids

Wemmer, Judith; Gossweiler, Elias; Fischer, Peter; Windhab, Erich J.

doi:10.1007/s10570-018-02228-5

Cited by 6 publications

(4 citation statements)

References 35 publications

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“…The networked-CNF xerogels were, however, mechanically strong despite their high SSA. The combination of these two aspects was likely achieved by the inter-CNF cross-linking in the networked structure . The same argument holds for the comparison with silica and organosilicon-based aerogels, which typically possess bulk densities, elastic moduli, SSA values of 0.01–0.2 g cm –3 , 1–10 MPa, and 500–600 m 2 g –1 , respectively. ,, …”

Section: Results and Discussionmentioning

confidence: 76%

“…Figure shows Ashby plots of the porous CNF structures for displaying their compressive properties. ,,− ,− All the aerogels in the plots possessed a networked-CNF structure, and the cryogels included both foam-like and networked CNF structures. It should be noted that the term “cryogel” is used to refer to porous structures obtained via freeze-drying of CNF dispersions or wet gels.…”

Section: Results and Discussionmentioning

confidence: 99%

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Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction

et al. 2021

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Scalability is a common challenge in the structuring of nanoscale particle dispersions, particularly in the drying of these dispersions for producing functional, porous structures such as aerogels. Aerogel production relies on supercritical drying, which exhibits poor scalability. A solution to this scalability limitation is the use of evaporative drying under ambient pressure. However, the evaporative drying of wet gels comprising nanoscale particles is accompanied by a strong capillary force. Therefore, it is challenging to produce evaporative-dried gels or "xerogels" that possess the specific structural profiles of aerogels such as mesoscale pores, high porosity, and high specific surface area (SSA). Herein, we demonstrate a structure of mesoporous xerogels with high porosity (∼80%) and high SSA (>400 m 2 g −1 ) achieved by exploiting cellulose nanofibers (CNFs) as the building blocks with tunable interparticle interactions. CNFs are sustainable, wood-derived materials with high strength. In this study, the few-nanometer-wide CNFs bearing carboxy groups were structured into a stable network via ionic inter-CNF interaction. The outline of the resulting xerogels was then tailored into a regular, millimeter-thick, board-like structure. Several characterization techniques highlighted the multifunctionality of the CNF xerogels combining outstanding strength (compression E = 170 MPa, σ = 10 MPa; tension E = 290 MPa, σ = 8 MPa), moderate light permeability, thermal insulation (0.06−0.07 W m −1 K −1 ), and flame self-extinction. As a potential application of the xerogels, daylighting yet insulating, load-bearing wall members can be thus proposed.

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Section: Results and Discussionmentioning

confidence: 76%

Section: Results and Discussionmentioning

confidence: 99%

Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction

et al. 2021

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“…The common method to transfer nanocelluloses into foams is by the removal of solvent from nanocellulose suspension, which leads to the formation of a porous fibril network (Ganesan et al, 2018). Foaming of nanocelluloses can also be realized by incorporating a foaming agent in the suspension and is followed with freezedrying (Wemmer et al, 2019). However, the nanocelluloses are more commonly known for stabilizing emulsions than foams (Fujisawa et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

N2O–Assisted Siphon Foaming of Modified Galactoglucomannans With Cellulose Nanofibers

Nypelö¹,

Fredriksson²,

Arumughan³

et al. 2021

Front. Chem. Eng.

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Foaming of most bio-based polymers is challenged by low pore formation and foam stability. At the same time, the developing utilization of bio-based materials for the circular economy is placing new demands for easily processable, low-density materials from renewable raw materials. In this work, we investigate cellulose nanofiber (CNF) foams in which foaming is facilitated with wood-based hemicelluloses, galactoglucomannans (GGMs). Interfacial activity of the GGM is modulated via modification of the molecule’s amphiphilicity, where the surface tension is decreased from approximately 70 to 30 mN m−1 for unmodified and modified GGM, respectively. The chemical modification of GGMs by substitution with butyl glycidyl ether increased the molecule’s hydrophobicity and interaction with the nanocellulose component. The highest specific foam volume using 1 wt% CNF was achieved when modified GGM was added (3.1 ml g−1), compared to unmodified GGM with CNF (2.1 ml g−1). An amount of 96 and 98% of the GGM and GGM-BGE foams were lost after 15 min of foaming while the GGM and GGM-BGE with cellulose nanofibers lost only 33 and 28% of the foam respectively. In the case of GGM-BGE, the foam stability increased with increasing nanofiber concentration. This suggests that the altered hydrophobicity facilitated increased foam formation when the additive was incorporated in the CNF suspension and foamed with nitrous oxide (N2O). Thus, the hydrophobic character of the modified GGM was a necessity for foam formation and stability while the CNFs were needed for generating a self-standing foam structure.

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“…Cellulose nanocrystals alone do not decrease the surface tension and thus do not produce foams, but the stability of methyl cellulose foams can be increased with CNC (Hu et al 2016). Wemmer et al (2019) used methyl cellulose as a foaming agent when studying the effect of replacing MFC with methyl cellulose on the mechanical properties and structure of the foam.…”

Section: Introductionmentioning

confidence: 99%

Film formation and foamability of cellulose derivatives: Influence of co-binders and substrate properties on coating holdout

Lyytikäinen

Ovaska

Heiskanen

et al. 2020

BioRes

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Foams were prepared from hydrophobically modified ethyl(hydroxyethyl) cellulose (EHEC), methyl nanocellulose, and native microfibrillated cellulose (MFC). Their film- and foam-forming abilities, stabilities, and suitabilities for foam coating on different substrates were investigated. The role of EHEC as a polymeric stabilizing agent was also studied. The EHEC-MFC foams showed greater stability and water-holding ability under pressurized dewatering than MFC foams prepared in the presence of a surfactant. A foam could be created with methyl nanocellulose without any foaming agent. Selected nanocellulose gels and foam formulations were used to coat various substrates. The surface was efficiently closed by gel and foam coatings prepared from the methyl nanocellulose and EHEC solutions, which was ascribed to good coating holdout. Coatings on papers with different levels of smoothness/density and hydrophobicity/ hydrophilicity confirmed that foam-substrate interactions affected the coat quality. The air permeance was reduced by 99% and 64% with a methyl nanocellulose coating and an EHEC-MFC coating, respectively. An EHEC-MFC coating created a hydrophobic surface on a hydrophilic substrate, and methyl nanocellulose improved the oil resistance even at a low coat weight.

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Effect of foaming on mechanical properties of microfibrillated cellulose-based porous solids

Cited by 6 publications

References 35 publications

Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction

Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction

N2O–Assisted Siphon Foaming of Modified Galactoglucomannans With Cellulose Nanofibers

Film formation and foamability of cellulose derivatives: Influence of co-binders and substrate properties on coating holdout

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