# Enhanced Fire Safety of Energy-Saving Foam by Self-Cleavage CO2 Pre-Combustion and Phosphorus Release Post-Combustion

## TL;DR

This paper introduces a new method to improve fire safety in energy-saving foam by delaying ignition and reducing flame spread using potassium salts and a flame retardant.

## Contribution

The novel approach combines potassium salts and a reactive flame retardant to enhance fire safety without affecting foam performance.

## Key findings

- Potassium salts promote CO2 release, delaying ignition by reducing local oxygen concentration.
- DFD releases phosphorus-oxygen radicals, disrupting combustion chain reactions and reducing flame spread.
- The combined method increases LOI and reduces PHRR and THR without compromising foam properties.

## Abstract

Rigid polyurethane foam (RPUF) is widely utilized in construction and rail transportation due to its lightweight properties and low thermal conductivity, contributing to energy conservation and emission reduction. However, the inherent flammability of RPUF presents significant challenges. Delaying the time to ignition and preventing flame spread post-combustion is crucial for ensuring sufficient evacuation time in the event of a fire. Based on this principle, this study explores the efficacy of using potassium salts as a catalyst to promote the self-cleavage of RPUF, generating substantial amounts of CO2, thereby reducing the local oxygen concentration and delaying ignition. Additionally, the inclusion of a reactive flame retardant (DFD) facilitates the release of phosphorus-oxygen free radicals during combustion, disrupting the combustion chain reaction and thus mitigating flame propagation. Moreover, potassium salt-induced catalytic carbonization and phosphorus derivative cross-linking enhance the condensed phase flame retardancy. Consequently, the combined application of potassium salts and DFD increases the limiting oxygen index (LOI) and reduces both peak heat release rate (PHRR) and total heat release (THR). Importantly, the incorporation of these additives does not compromise the compressive strength or thermal insulation performance of RPUF. This integrated approach offers a new and effective strategy for the development of flame retardant RPUF.