Starch/clay aerogel reinforced by cellulose nanofibrils for thermal insulation

• Published in: Cellulose (London) Vol. 28; no. 6; pp. 3505 - 3513
• Main Authors: Zhao, Yan-Wen, Tian, Mao-Zhang, Huang, Pei
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.04.2021; Springer Nature B.V
• Subjects: Addition polymerization; Aerogels; Bioorganic Chemistry; Cellulose; Ceramics; Chemistry; Chemistry and Materials Science; Clay; Composites; Compressive strength; Crack propagation; Density; Fire resistance; Freeze drying; Freezing; Glass; Heat conductivity; Heat transfer; High aspect ratio; Hydroxyl groups; Insulation; Integrity; Moisture resistance; Natural Materials; Organic Chemistry; Original Research; Physical Chemistry; Polymer Sciences; Sustainable Development; Thermal conductivity; Thermal insulation; Thermal resistance; Thermal stability; Aerogel; Cellulose nanofibril; Freeze-drying; Thermal insulation; Crack
• ISSN: 0969-0239; 1572-882X
• DOI: 10.1007/s10570-021-03750-9

Characterized by low cost, flame resistance and mild processing procedure, freeze-dried clay aerogel is an ideal alternative for thermal insulation in building sector. However, the negatively charged surface of clay platelet and high freezing rate require the addition of a high amount of polymer to ensure the integrity of aerogel during freezing stage, which inevitably increases the density as well as the thermal conductivity of aerogel. Herein, we reported a green and versatile strategy to fabricate crack-free yet thermal insulative aerogel by introducing cellulose nanofibrils (CNFs) into starch/clay system. Owing to the abundant hydroxyl groups, high aspect ratio and excellent mechanical strength of CNFs, the CNF/starch/clay aerogels prepared exhibit enhanced crack resistance and compressive strength, enabling the reduction of starch content from 4 to 2% while maintaining the integrity of aerogel in the process of freezing. As a result, the density and thermal conductivity of aerogel significantly decrease from 0.12 to 0.05 g/cm 3 and 48.3 to 41.5 mW/mK respectively. Further crosslinked by glutaraldehyde, the CNF/starch/clay aerogels display improved moisture resistance, shape recovery and thermal stability. Being versatile and cost-effective, the present approach is thought-provoking for the up-scale production of freeze-dried clay aerogel for thermal insulation. Graphical abstract