Stabilizing nanocellulose-nonionic surfactant composite foams by delayed Ca-induced gelation

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• 作者：Korneliya S. Gordeyeva^a ; ^{korneliya.gordeyeva@mmk.su.se" class="auth_mail" title="E-mail the corresponding author} ; Andreas B. Fall^a ; ^{andreas.fall@mmk.su.se" class="auth_mail" title="E-mail the corresponding author} ; Stephen Hall^b ; ^{stephen.hall@solid.lth.se" class="auth_mail" title="E-mail the corresponding author} ; Bernd Wicklein^a ; ¹ ; ^{bernd@icmm.csic.es" class="auth_mail" title="E-mail the corresponding author} ; Lennart Bergströ ; m^a ; ^{lennart.bergstrom@mmk.su.se" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Nanocellulose ; Foams ; Surfactant ; Gelation ; Multivalent-ion ; Strength ; X-ray tomography
• 刊名：Journal of Colloid and Interface Science
• 出版年：2016
• 出版时间：15 June 2016
• 年：2016
• 卷：472
• 期：Complete
• 页码：44-51
• 全文大小：2478 K

文摘

Aggregation of dispersed rod-like particles like nanocellulose can improve the strength and rigidity of percolated networks but may also have a detrimental effect on the foamability. However, it should be possible to improve the strength of nanocellulose foams by multivalent ion-induced aggregation if the aggregation occurs after the foam has been formed. Lightweight and highly porous foams based on TEMPO-mediated oxidized cellulose nanofibrils (CNF) were formulated with the addition of a non-ionic surfactant, pluronic P123, and CaCO₃ nanoparticles. Foam volume measurements show that addition of the non-ionic surfactant generates wet CNF/P123 foams with a high foamability. Foam bubble size studies show that delayed Ca-induced aggregation of CNF by gluconic acid-triggered dissolution of the CaCO₃ nanoparticles significantly improves the long-term stability of the wet composite foams. Drying the Ca-reinforced foam at 60 °C results in a moderate shrinkage and electron microscopy and X-ray tomography studies show that the pores became slightly oblate after drying but the overall microstructure and pore/foam bubble size distribution is preserved after drying. The elastic modulus (0.9–1.4 MPa) of Ca-reinforced composite foams with a density of 9–15 kg/m³ is significantly higher than commercially available polyurethane foams used for thermal insulation.