Synthesis and characterization of AlCl3-chitosan composite aerogels incorporating polyvinyl alcohol and bentonite clay

In this work, AlCl 3 -chitosan composite aerogels incorporating polyvinyl alcohol (PVA) and bentonite clay were synthesized by a freeze-drying technique based on the chemical cross-linking between AlCl 3 and chitosan and physical interaction among chitosan, PVA and bentonite. The microstructure, mechanical and thermal properties of the as-prepared AlCl 3 -chitosan/PVA/bentonite (ACP-B) composite aerogels were systematically studied. The results indicated that the AlCl 3 -chitosan network was reinforced by PVA at molecular level and bentonite was evenly dispersed in the polymeric matrix. The effects of bentonite clay on the mechanical and thermal performance were investigated by adjusting the content of bentonite. The obtained ACP-B composite aerogels showed high specific modulus of 78.6–81.6 m 2 s −2 and low thermal conductivity of 46.6 – 52.0 mW m −1 K −1 . Additionally, the presence of bentonite proved beneficial to the thermal stability and fire resistance of the composite aerogel. Combustion experimentation manifested that ACP-B composite aerogels displayed self-extinguishing behavior and high limited-oxygen-index (LOI) values of 32.1–33.3%. Graphical abstract Highlights AlCl 3 -chitosan/PVA/bentonite composite aerogels were synthesized by freeze drying. The aerogels showed low density and high compressive modulus of 7.02–7.59 MPa. The aerogels exhibited low thermal conductivity of 46.6–52.0 mW·m −1 ·K −1 . The aerogels had high LOI value of 32.1%–33.3% and self-distinguishing behavior.