Sustainable, Low Flammability, Mechanically-Strong Poly(vinyl alcohol) Aerogels

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Poly(vinyl alcohol) (PVA) aerogels are known for their versatility but often lack mechanical strength and flame resistance.
• Developing advanced aerogel materials with improved properties is crucial for various industrial applications.

Purpose of the Study:

• To prepare mechanically robust and low-flammability aerogels using poly(vinyl alcohol) (PVA), tannic acid (TA), and sodium hydroxide (NaOH).
• To investigate the structural, mechanical, and thermal properties of the resulting PVA/TA/NaOH aerogels.

Main Methods:

• Environmentally-friendly freeze-drying method.
• Preparation of aerogels using PVA, TA, and NaOH.
• Characterization using compressive testing, thermogravimetric analysis (TGA), and cone calorimetry.

Main Results:

• PVA/TA/NaOH aerogels exhibited a compressive modulus of 12.7 MPa, 20 times higher than control PVA aerogels, due to strong hydrogen bonding between TA and PVA.
• NaOH disrupted the conventional aerogel microstructure, while TA promoted a stereoscopic uniform structure.
• Aerogels showed decreased decomposition onset temperature but reduced decomposition rate after char formation.
• Peak heat release rate and total heat release decreased by 69% and 54%, respectively, indicating enhanced flame retardancy.

Conclusions:

• The combination of PVA, TA, and NaOH via freeze-drying yields aerogels with significantly enhanced mechanical strength and reduced flammability.
• The developed aerogels offer a promising pathway for creating high-performance, safer materials.