ISSN:
0308-0501
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Architecture, Civil Engineering, Surveying
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Ammonium polyphosphate is shown to be an effective flame retardant for homopolymeric and selected fibre-forming copolymers of acrylonitrile. Compared with other phosphates and phosphorus-containing species, it significantly increases both limiting oxygen index and char levels. The mechanism of retardancy is shown to be both physical and chemical in character. When heated to 300°C, the polyphosphate melts and converts to polyphosphoric acid which acts as a physical barrier to surface polymer oxidation and promotes nucleophilic oligomerization of pendant, adjacent nitrile groups. A reduction in the activation energy of this first stage of acrylic polymer degradation suggests that the favoured decomposition route gives rise via oligomerization to char-promoting precursors. Char analyses indicate an empirical formula of C30H13N7P2, which compares favourably with that of a proposed phosphorylated, polynuclear, aromatic heterocyclic structure.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/fam.810180506
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