Novel Analytical Toolkit Concept for the Characterization and Development of Halogen Free Flame Retardants (HFFR): A case study with P and P-N based Flame Retardants.

This study presents a novel toolkit concept for the characterization and development of halogen-free flame-retardant (HFFR) specially based on P and P-N flame retardant systems, aimed at understanding and predicting the influence of flame-retardant additives in polymers especially polyolefins. The development of this toolkit concept is based on the existing research on flame-retardant mechanisms. From a comprehensive literature survey, we identified several key parameters that control the flammability of materials. This toolkit concept includes several analytical techniques to quantitatively measure these parameters. The primary parameters influencing the flammability of polymer materials are found to be the surface ignition temperature, thermal degradation kinetics, total amount of volatiles produced during combustion, chemical composition of the volatiles, and the presence of flame retardants, particularly phosphorus and phosphorus-nitrogen-based derivatives (PFR), in the gas phase, condensed phase, or in both. This paper presents our findings on surface ignition temperature (Tign) and kinetic degradation parameters such as Arrhenius activation energy (Ea) and frequency factor (A) from Thermo-Gravimetric Analysis (TGA)/SDTA) measurements. Additionally, we report the Total Volatile Organic Compounds (TVOC) produced during combustion, determined using Thermal Desorption (TD)/Gas Chromatography (GC)/Mass Spectrometry (MS) techniques, and the chemical composition of the volatiles identified through MS analysis of GC chromatograms for several model HFFR polypropylene (PP) formulations containing phosphorus (P) or phosphorus-nitrogen (P-N) based derivatives (PFR). The presence of flame retardants in the gas or condensed phase, and their activity in either phase or both, was determined using Inductively Coupled Plasma (ICP) and Surface Focussed Mass Spectrometer (SFMS). In this report, the validity of the analytical results from this toolkit concept is also presented for several model formulations by comparing the analytical results with fire retarding properties of these model formulations with standard UL-94V fire tests. Applicability of this toolkit was demonstrated by investigating the influence for a proprietary additive, Paxymer® in these HFFR systems.