A Strategy to Achieve the Inherently Flame-retardant PA56 by Copolymerization with DDP

As a bio-based polyamide, polypentamethylene adipate (PA56) is restricted in many fields due to its flammability. In this research, flame-retardant PA56 copolymers (FRPA56s) were designed and successfully synthesized with the introduction of 9,10-dihydro-10-[2,3-di(hydroxy carbonyl)propyl]-10-phosphaphenanthrene-10-oxide (DDP) unit. The thermal properties, degradation flame behavior resultant copolymer investigated by DSC, TGA, LOI, UL-94 cone calorimeter tests, respectively. Compared PA56, peak value heat release rate total FRPA56 containing 1.2 mol% DDP decrease 35% 19%, respectively, indicating high efficiency DDP. It also found that only 1.0 passes V-0 grade test while performance almost same as homopolymer PA56. pyrolysis products both condensed gas phases further systematically analyzed SEM, Raman, FTIR, X-ray photoelectron spectroscopy TGA-GC/MS. mechanism was proposed for FRPA56s.