Highly effective flame‐retarded polyester diol with synergistic effects for waterborne polyurethane application

Abstract

In this article, a novel bi-reactive flame retardant (FRD) was successfully synthesized for waterborne polyurethane (WPU). The chemical structures of FRD were characterized by Fourier-transform infrared spectra and 1 H and 31 P nuclear magnetic resonance. Then, the FRD was incorporated into polyurethane backbone to prepare a series of flame-retarded WPU (FRWPU). The flammability characteristics of FRWPU were measured by limited oxygen index (LOI), UL-94, and cone calorimeter (CCT) tests. The FRPWU-7 had a high LOI value of 30.5% with UL94 V-0 rating. Moreover, the CCT values indicated that FRD induced the gaseous phase quenching effect of phosphoruscontaining free radicals derived from the decomposed phosphaphenanthrene group on the gas-phase flame retardancy. Scanning electron micrographs and Raman spectra exhibited that FRD promoted the charring formation of phosphorus-rich char layer with graphitized surface and honeycomb-like intumescent structure in WPU matrix during burning. This study provides a new way to design a novel reactive P-P flame retardant consisted of the phosphaphenanthrene group and intumescent flame retardant for WPU application.

Phosphorus esters of1‐dopyl‐1,2‐(4‐hydroxyphenyl)ethene as effective flame retardants for polymeric materials

“…All are stable to temperatures approaching 350°C. As might be expected, the presence of BDE‐DPP containing two phosphate groups promotes char formation (22%‐24%) to a greater extent than does the DOPO derivative (12%‐15%) 34‐37 . The thermal properties for all the blends are summarized in Table 1.…”

“…Further, DOPO should undergo decomposition to release PO radical to the gas phase to scavange combustion propagating radicals 32,33 . One of them, BDE‐DPP, contains both phosphate groups which should promote char formation and a dopyl unit to contribute to gas‐phase activity 34‐37 …”

Multi‐element heterocyclic compound derived from DOPO and thiadiazole toward flame‐retardant epoxy resin with satisfactory mechanical properties

“…29 It is caused by that phosphaphenanthrene structure in VAP produced phosphoric acid compounds during combustion, and the existence of phosphoric acid compounds was conducive to the formation of char layer. 42,43 The decomposition products containing phosphorus took part in the stage of matrix melting into char, resulting in a stable char layer containing phosphorus. 44 Correspondingly, through EDX analysis, it was found that there was phosphorus element in the char residue of EP-10, which was consistent with the results of infrared spectrum.…”

Halogen-free instinct flame-retardant waterborne polyurethanes: composition, performance, and application

“…The innovative IFWPU is modied at the molecular level, which overcomes interfacial incompatibility (e.g., volatilization, dissolution, migration, and exudation) and provides durable high ame-retardance. [22][23][24][25] According to the differently modied PU molecular segments, the modications of IFWPU are classied as so-, hard-, and so-co-hard segment modications. [26][27][28][29][30][31][32][33] Besides, the compositions of IFWPU are classied as one-component, twocomponent, and hyperbranched based on different components.…”