Phosphorus Polyester - an Alternative to Low-Molecular-Weight Flame Retardants in Poly(Butylene Terephthalate)?

• Published in: Macromolecular chemistry and physics Vol. 213; no. 22; pp. 2386 - 2397
• Main Authors: Brehme, Sven, Köppl, Thomas, Schartel, Bernhard, Fischer, Oliver, Altstädt, Volker, Pospiech, Doris, Döring, Manfred
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 23.11.2012; WILEY‐VCH Verlag
• Subjects: 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide; aluminium phosphinate; blends; flame retardance; polyesters
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201200072

Pyrolysis, fire behaviour and mechanical properties of a blend of poly(butylene terephthalate) (PBT) with a phosphorus polyester (PET‐P‐DOPO) are investigated and compared with PBT/aluminium diethylphosphinate (AlPi‐Et) composites. The PBT/PET‐P‐DOPO is immiscible and exhibits gas‐phase and condensed‐phase activity, whereas AlPi‐Et in PBT results mainly in flame inhibition. Only higher loadings of AlPi‐Et yield significant condensed‐phase activity. Using the same phosphorus content, PBT/PET‐P‐DOPO and PBT/AlPi‐Et exhibit similar reductions in fire load (22%) and flame spread (17% assessed by fire growth rate, FIGRA), compared with PBT. In contrast to AlPi‐Et, the addition of PET‐P‐DOPO does not decrease the tensile strength of PBT. Thus, PET‐P‐DOPO is an interesting alternative to low‐molecular‐weight flame retardants. The phosphorus polyester PET‐P‐DOPO is an interesting alternative to low‐molecular‐ weight additives for the flame retardancy of poly(butylene terephthalate) (PBT). In comparison to a common additive, PET‐P‐DOPO causes a similar reduction in fire risk of PBT without decreasing the tensile strength of PBT, which is an advantage over most low‐molecular‐weight flame retardant additives.