Azoalkanes: A Novel Class of Flame Retardants

Abstract

Summary: The synthesis of azoalkanes such as azocyclohexane (1) and 4,4′‐bis(cyclohexylazocyclohexyl)methane (2) and their use as flame retardants in polymeric substrates is reported. For the first time it is demonstrated that azoalkanes alone can effectively provide flame retardancy and self‐extinguishing properties to poly(propylene) films at a very low concentration of 0.25 to 0.5 wt.‐%. All the poly(propylene) formulations passed DIN 4102‐1/B2 standards and the instant azoalkane‐containing poly(propylene) blends show no discoloration.

Design and Utilization of Nitrogen Containing Flame Retardants Based on N-Alkoxyamines, Azoalkanes and Related Compounds

“…the role of alkyl radicals on flame retardancy of polypropylene. Azoalkanes were selected as the cleanest and most convenient source of alkyl free radicals [44] ( Figure 6). As in the case of N-alkoxy hindered amines, the thermal stability of azoalkanes is very closely related to their chemical structure.…”

Development of a Halogen Free Flame Retardant Masterbatch for Polypropylene Fibers

“…Another possibility is the synthesis or the formulation of multifunctional flame retardants, such as Flamestab ® Nor 116 (BASF, Basel, Switzerland) which is mainly used for polypropylene fibers or films [6]. In this context, Roth and coworkers have developed new nitrogen based flame retardant compounds that exhibit self-extinguishing properties for polypropylene compounds [5,[7][8][9].…”

Disulfides – Effective radical generators for flame retardancy of polypropylene

“…From the viewpoint of flame retardancy of polymers mainly radical generators triggered by thermolysis or redox systems have been successfully used to suppress and retard the fire response of polymeric materials [21,22]. In the past it has been demonstrated that certain peroxides can be used as synergists to enhance the action of brominated flame retardants (BFR) [23][24][25][26][27][28][29], whereas azo compounds [30] and alkoxyamines [12,31] have been shown to provide self-extinguishing properties to polymers even by themselves. Thus, it has been established that radical precursors that are capable of generating various carbon (e.g.…”