Intumescent coatings are a passive fire protection technique commonly applied to steel load-bearing beams for building fire protection. In recent years, the phenolic molecule tannic acid (TA) gained increased attention in fire protection applications based on its bio-availability and char-forming ability. Our lab sought to leverage prior knowledge of bio-based intumescent fire protection to create novel TA-based intumescent composites. There is a need for safety standards and material solutions for package substrate protection. Apart from steel load-bearing beams, can TA composites offer protection to cardboard-based substrates? Here we show a thorough evaluation of a tannic acid-based intumescent composite systems for application as fire-protective coatings on cardboard in package-fire situations. This study investigated overall protective ability and proposed associated structure-property relationships. All results were compared against pentaerythritol (PER), a commonly used char forming agent in commercial intumescent flame protection formulations. We found TA-based composites offered superior cardboard-substrate fire protection via torch testing relative to uncoated and PER composite-coated cardboard. Quantitative analysis via cone calorimetry (CC) testing corroborated the torch testing, showing (relative to PER composites) lower peak heat release rate (211 vs. 108 kW/m2), lower total heat release (37.2 vs. 24.4 MJ/m2), and lower fire growth rates (2.43 vs. 1.27 kW/m2s-1). A char analysis elucidated a condensed-phase fire protection mechanism based on significant char expansion coupled with a larger carbon-content (via XPS), higher crystalline carbon (via Raman), and significantly higher surface area (via BET), all relative to PER-composites. TA-based intumescent composites show promise for application in package fire protection.

Superintumescent coatings based on tannic acid for package fire protection

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.