Effect of ethyl‐bridged diphenylphosphine oxide on flame retardancy and thermal properties of epoxy resin

Abstract

Three commercialized flame retardants, 1,2-bis(diphenylphosphinoyl)ethane (EDPO), 6,6-(1,2-phenethyl)bis-6H-dibenz[c,e][1,2]oxaphosphorin-6,6-dioxide (HTP-6123), and hexa-phenoxy-cyclotriphosphazene (HPCTP), were used to prepare the flame retardant diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP) under the same experimental conditions. The effects of T g , thermal stability, and water absorption properties of EP caused by the three flame retardants were investigated and compared, together with their flame retardant efficiency. Results showed that the introduction of the three flame retardants improved the flame retardant performance of EP but led to decreases in T g and decomposition temperature. EDPO showed higher flame retardant efficiency than the other two flame retardants. EP/EDPO showed higher thermal stability, better flame retardant performance, higher T g value, and lower water absorption than EP/HTP-6123 and EP/HPCTP. The study discovered that EDPO and HTP-6123 primarily act through the gas phase flame retardant mechanism, while HPCTP is primarily driven by the condensed phase mechanism. K E Y W O R D S diphenylphosphine oxide, DOPO, epoxy resin, flame retardant, hexa-phenoxycyclotriphosphazene

A (4‐fluorophenyl)(phenyl)phosphine oxide‐modified epoxy resin with improved flame‐retardancy, hydrophobicity, and dielectric properties

“…Scanning electron microscopy (SEM) and digital images of the residues after the cone calorimeter test. The morphology of EP‐0 residue was reported in our previous study 36 [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Limiting oxygen index (LOI), UL‐94, cone calorimeter tests, thermalgravimetric analysis/infrared (TGIR) spectrometry, microstructure of the char residues, and water absorption were performed as described in our previous work, 28,36 more details are provided in the supporting information.…”

A phosphaphenanthrene‐based derivative for simultaneously improving flame retardant and smoke suppression of epoxy resin composites

“…The average effective heat combustion (av‐EHC), which was usually equal to the ratio of HRR to mass loss rate, corresponded to the combustion degree of volatile gas, of EP/PBO‐1.0 was lower than that of EP, showing the incomplete combustion in gaseous phase. It was mainly attributed to free radicals trapping effect of phosphorus containing groups 27,33,36 . Moreover, av‐COY/av‐CO 2 Y value of EP/PBO‐1.0 raised to a certain extent compared to EP, further suggested that PBO could exert gaseous phase activity.…”

“…It was mainly attributed to free radicals trapping effect of phosphorus containing groups. 27,33,36 Moreover, av-COY/av-CO 2 Y value of EP/PBO-1.0 raised to a certain extent compared to EP, further suggested that PBO could exert gaseous phase activity. Based on the above results, EP modified with PBO possessed excellent flame retardancy, lower heat, and smoke release product.…”

Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins

“…Phosphorus-containing flame retardants have gained increased attention after movements by jurisdictions around the world, such as European Union, to either ban or phase out halogenated flame retardants due to their toxicity and negative impacts on the environment . Among the various organophosphorus flame retardants, diphenyl phosphine oxide (DPO) has been successfully commercialized and used in epoxy resins due to its high flame-retardant efficiency and acceptable price. , Usually, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is directly added as a flame retardant in prepolymers of epoxy resin, and it was then covalently functionalized into an epoxy resin by reacting with the oxirane ring to form an addition product . However, there are some major drawbacks for DOPO-modified epoxy resins: (1) high dosage of DOPO needed, (2) decreased T g of the cured epoxy polymer, (3) poor humidity resistance property, and (4) decreased thermal decomposing temperature .…”