Synthesis and characterization of a cyclic 9,9-bis(4-hydroxyphenyl)fluorine (phenylene phosphonate) oligomer and its flame retardancy application?

RSC Advances Pub Date: 2015-09-11 DOI: 10.1039/C5RA15404A

Abstract

A novel solid flame retardant cyclic 9,9-bis(4-hydroxyphenyl)fluorine (phenylene phosphonate) (CPFP) oligomer was synthesized in high yields by the reaction of phenylphosphonic dichloride with 9,9-bis(4-hydroxyphenyl)fluorine under pseudo-high-dilution conditions via polycondensation. Detailed structural characterizations of this oligomer were conducted by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), 1H NMR, 31P NMR and FTIR. Furthermore, the flame-retardant efficiency of this oligomer in polybutylene terephthalate (PBT) was studied using limiting oxygen index (LOI) and UL-94 tests. After the addition of CPFP, the LOI increased and the UL-94 V-0 rating was achieved. The occurrence of an interaction between CPFP and PBT was elucidated by thermogravimetric analysis (TGA), FTIR and pyrolysis/GC/MS. The results showed that the CPFP oligomer could change the degradation path of PBT and improves the char formation of the PBT/CPFP system. The residual morphologies of residues of the PBT/CPFP25% system were investigated by scanning electron microscopy (SEM). SEM investigations revealed that the residual chars contained polyphosphoric or phosphoric acid, which plays an important role in the process of carbonization.

Graphical abstract: Synthesis and characterization of a cyclic 9,9-bis(4-hydroxyphenyl)fluorine (phenylene phosphonate) oligomer and its flame retardancy application
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