Flame Retardancy Index (FRI) for Polymer Materials Ranking.

Area of Science:

• Materials Science and Engineering
• Polymer Science
• Fire Safety Engineering

Background:

• The Flame Retardancy Index (FRI) was introduced in 2019 as a universal, dimensionless metric for classifying flame-retardant polymer materials.
• FRI utilizes cone calorimetry data, specifically peak Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (t_i), to quantify flame retardancy relative to a reference polymer.
• The index categorizes materials as Poor (FRI < 10⁰), Good (10⁰ ≤ FRI < 10¹), or Excellent (FRI ≥ 10¹) and has demonstrated reliability for both thermoplastic and thermoset composites.

Purpose of the Study:

• To investigate whether incorporating additional cone calorimetry parameters, such as the time to pHRR (t_p), enhances the predictive capability of the Flame Retardancy Index (FRI).
• To define and evaluate new FRI variants for assessing classification capability and variation intervals.
• To introduce the Flammability Index (FI) derived from Pyrolysis Combustion Flow Calorimetry (PCFC) data and explore its relationship with FRI for a deeper understanding of flame retardancy mechanisms.

Main Methods:

• Analysis of existing cone calorimetry datasets to evaluate the impact of additional parameters on FRI classification.
• Development and application of new FRI variants to assess classification robustness and variability.
• Definition of the Flammability Index (FI) using Pyrolysis Combustion Flow Calorimetry (PCFC) data.

Main Results:

• The study confirms the established reliability of FRI for ranking polymer flame retardancy performance across various material types.
• Exploration of new FRI variants and their classification capabilities is presented.
• Introduction of the FI metric based on PCFC data to facilitate comparative analysis with FRI.

Conclusions:

• The Flame Retardancy Index (FRI) remains a valuable and reliable tool for the rapid classification of polymer flame retardancy.
• Further research into FRI variants and the correlation between FRI and FI may provide deeper insights into flame retardancy mechanisms.
• The study encourages further investigation into the relationship between condensed-phase (FRI) and gas-phase (FI) flame retardancy metrics.