Predictive Tools to Assist the Development of Flame Retarded Phosphorus‐Free Polypropylene and Identify Synergy between Flame Retardants

Abstract

Abstract The development of flame‐retarded polypropylene is carried out with the ultimate goal of obtaining a UL94‐V0 not only halogen‐ but also phosphorus‐free formulation because phosphate rocks, precursors of phosphorus‐based flame retardants, are recognized as critical raw materials within Europe. Different flame retardants (FRs) (melamine, phosphate ester, and radical generator) are used. A statistical approach is applied to predict UL94 behavior and develop optimized formulations in terms of cost, filler or phosphorus content. Models for most common “nondripping” as well as “nonflaming dripping” UL94‐V0 behavior are proposed. The experimental validation has shown the reliability of the models proposed and their usefulness to assist and speed up the development of optimized formulations. The use of the models also gives insight into the interactions between flame retardants, thus suggesting if potential synergies take place, before studying the FRs system in details. Indeed, synergies between melamine and phosphate ester as well as melamine and radical generator are discovered. Thanks to these synergies that V0 rating can be achieved. A UL94‐V0 formulation, comprising melamine and radical generator, is identified as the optimal halogen‐ and phosphorus‐free formulation with a reduced filler content.

Keywords

• flame retardants
• melamine
• N‐alkoxy hindered amine
• polypropylene
• predictive models
• radical generators