High Thermo-Mechanical Stability in Polybenzoxazine Aerogels


Aerogels are three-dimensional networks of nanoparticles with high specific surface area and high porosity. Following the significant improvement on the mechanical strengths and ductility of traditional aerogels with polymer cross-linking (i.e., X-aerogels), the emergence of pure polymeric aerogels has enabled unprecedented aerogel applications such as ballistic armor protection, which is quite surprising for such low-density materials. However, generally low glass transition temperatures (Tg) of polymeric aerogels hinder their structural applicability at service temperatures above their Tg temperatures. Thereby, developing novel polymeric aerogels with high Tg temperatures is crucial for high-temperature structural applications. As phenolic resins, polybenzoxazines are heat-resistant and mechanically strong with high glass transition temperatures. In this study, polybenzoxazine aerogels have been successfully synthesized, and their mechanical properties at different densities and elevated temperatures have been investigated. High thermo-mechanical stability has been observed over the entire temperature range of interest (i.e., below 250 °C) for their quasi-static compressive properties such as Young's modulus and compressive strength. Moreover, the storage and loss moduli in shear of the aerogels have been studied at different temperatures and frequencies. The strong mechanical performance of these aerogels at elevated temperatures makes them an important, inexpensive, and advanced material for high-temperature applications, competitive with significantly more expensive polyimides.

Meeting Name

ASME 2019 International Mechanical Engineering Congress and Exposition, IMECE 2019 (2019: Nov. 11-14, Salt Lake City, UT)




The support by AFOSR FA9550-14-1-0227, NSF CMMI-1661246, CMMI-1636306, and CMMI-1726435, and Nashi New Materials in China is acknowledged. N. L. and C. S.-L. thank the Army Research Office for financial support under W911NF-14-1-0369 and NSF under CMMI-1530603.

Keywords and Phrases

Compressive strength; Crosslinking; Glass; Glass transition; High temperature applications; Mechanical stability; Phenolic resins; Polymer blends; Temperature, High specific surface area; High temperature structural applications; High-glass transition temperatures; Low glass transition temperatures; Polybenzoxazine aerogels; Storage and loss modulus; Thermomechanical stability; Three-dimensional networks, Aerogels

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Document Type

Article - Conference proceedings

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© 2019 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Nov 2019