A phosphorus-containing PET ionomer: from ionic aggregates to flame retardance and restricted melt-dripping

Abstract

In this study, a novel phosphorus-containing ionic monomer, named sodium salt of 10H-phenoxaphosphine-2,8-dicarboxylic acid,10-hydroxy-,2,8-dihydroxyethyl ester,10-oxide (DHPPO-Na), was synthesized, characterized, and then copolymerized to prepare poly(ethylene terephthalate)based ionomers. The chemical structure of the resulting ionomers was confirmed by 1 H, 13 C, and 31 P NMR spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to investigate the thermal properties of the ionomers. Compared with that of neat PET, the initial decomposition temperature of PETIs decreased in a nitrogen atmosphere while it increased in air. The crystallinity of PETIs was enhanced firstly and then destroyed with the ionic group increase. The limiting oxygen index (LOI) test and cone calorimeter were used to characterize the flame-retardant properties of the ionomers. The results showed that the introduction of DHPPO-Na could endow an expected flame-retardant performance, meanwhile it considerably restricted the melt-dripping behavior and suppressed the smoke release. The rheology test confirmed that the ionic groups increased the melt viscosity via ionic aggregation during heating, which was a benefit for the flame-retardant property of the copolyester.

Properties regulation of poly(butylene succinate) ionomers through their ionic group distribution

“…It is well known that the ionic groups are prone to form phase-separated ionic aggregates due to the incompatibility of hydrophilic ionic groups with hydrophobic polymer matrix. The ionic aggregates serve as physical crosslinking points to improve the melt viscosity [1e3], crystallization properties [4,5], mechanical strength [6e8], and toughness [3] of polymer matrix significantly. Therefore, the introduction of ionic group into polymer chains has become one of the important strategies to modify the properties of polymers.…”

PET-based copolyesters with bisphenol A or bisphenol F structural units: Their distinct differences in pyrolysis behaviours and flame-retardant performances

“…However, most phosphorus-containing copolyesters will drip seriously in the fire, leading to secondary damage and scald for human body [7,8]. Recently, our research group copolymerized thermo-cross-linkable monomers or ionic monomer into PET, which can promote the carbonization reactions of copolyester during combustion [9][10][11]. Via chemical cross-linking or ionic aggregation, the char residue was enhanced, and the release of volatile products was decreased, as well as the melt dripping was inhibited.…”

A novel oligomer containing DOPO and ferrocene groups: Synthesis, characterization, and its application in fire retardant epoxy resin

“…As an important halogen-free flame retardant, phosphorus flame retardants (PFRs) [7,8] have attracted extensive attention [9][10][11] for their high efficiency. Most of the PFRs not only play flame retardant effects through a protective char layer caused by the catalyzation of phosphoric acid [12,13], but also play flame retardant role in the gas phase through the radical trapping by PO and PO2 fragments [14,15].…”