Thermal Transition Behavior, Thermal Stability, and Flame Retardancy of Low-Melting-Temperature Copolyester: Comonomer Effect

Abstract

Phosphorus-containing poly(ethylene terephthalate-co-diethylene terephthalate) (PEDT) with a low melting temperature was synthesized through esterification and copolycondensation of terephthalic acid, ethylene glycol, diethylene glycol (DEG), and 3-(hydroxyphenylphosphinyl)propionic acid (HPPPA). DSC results showed that PEDTs still were crystallizable and that the lowest melting temperature of the PEDTs was reduced to 118.0 °C although the chain regularity was destroyed by the incorporation of comonomers. It was found that the addition of HPPPA can improve the thermal oxidative stability of copolyesters. The results of the limiting oxygen index (LOI) test, the UL-94 vertical test, and the cone calorimeter test indicated that HPPPA endowed PEDT with good flame-retardant properties. The LOI values of the PEDTs were increased to 30.5−34.8, the UL-94 ratings of vertical burning were improved to V-0, and both the peak heat release rate (pHRR) and the total heat release (THR) obviously decreased.

Intrinsic Flame Retardant Triboelectric Nanogenerators Based on Liquid-Crystalline Copolyesters

“…In order to endow triboelectric materials (such as PET) of TENGs with flame retardant properties, tremendous efforts have been devoted. The chemical incorporation of phosphorus into the main chain of PET is one of the most efficient methods. , Nevertheless, most phosphorus-containing PETs will drip severely when in contact with flames, causing secondary damage and scalding. − Some polymers with unique aromatic chemical structures also exhibit outstanding flame retardancy and antidripping properties . For example, liquid-crystalline polyarylate (LCP) exhibits excellent thermal stability due to the highly stable aromatic backbone, such as 4-hydroxybenzoic acid (HBA) or 2-hydroxy-6-naphthoic acid (HNA) .…”

“…The chemical incorporation of phosphorus into the main chain of PET is one of the most efficient methods. 22,23 Nevertheless, most phosphorus-containing PETs will drip severely when in contact with flames, causing secondary damage and scalding. 24−27 Some polymers with unique aromatic chemical structures also exhibit outstanding flame retardancy and antidripping properties.…”

Design and Synthesis of PET‐Based Copolyesters with Flame‐Retardant and Antidripping Performance

“…Compared with phosphorus‐containing flame retardants, some halogenated flame retardants pose environmental problems associated with toxicity, bioaccumulation, and recycling, and thus have been banned in many countries . Considering the spinnability, durability, environmental sustainability, and mechanical property, copolymerizing phosphorus‐containing flame retardants into PET skeleton has been one of the most efficient flame‐retardant methods …”

Preparation and Properties of Copolyesters Fiber with Flame Retardant and Anti-Droplet by <i>In Situ</i> Polymerization

“…Some of these methods are, for example: adding flame retardants into PET by blending, incorporating flame-retardant monomers into PET chains via polymerization, or finishing the fabrics/textile in a solution containing flame retardants [5][6][7][8]. Among these methods, introducing phosphorus-containing monomers into the PET backbone is an efficient way for improving PET flame retardance, as it avoids poor durability and compatibility problems caused by the other methods [9][10][11][12]. These phosphorus-containing PET copolyesters usually achieve flame retardancy through removing heat from the burning surface, which enhances the melt-dripping of PET [13].…”