Abstract
Flame retardants for polypropylene (PP) and their potential suitability for use in fibre applications are reviewed. Five principal types of generic flame retardant systems for inclusion in polypropylene fibres have been identified as phosphorus-containing, halogen-containing, silicon-containing, metal hydrate and oxide and the more recently developed nanocomposite flame retardant formulations.
The most effective to date comprise halogen–antimony and phosphorus–bromine combinations, which while having limited performance also are falling environmental pressures. Alternatives are discussed as well as means of enhancing the effectiveness and hence usefulness of phosphorus–nitrogen formulations normally used at concentrations too high for fibre inclusion. Of special interest is the potential for inclusion of functionalised nanoclays and recent observations that certain hindered amine stabilisers are effective at concentrations of 1% or so.