Flame‐retardant performance and mechanism of epoxy thermosets modified with a novel reactive flame retardant containing phosphorus, nitrogen, and sulfur

Abstract

A novel phosphorus‐containing, nitrogen‐containing, and sulfur‐containing reactive flame retardant (BPD) was successfully synthesized by 1‐pot reaction. The intrinsic flame‐retardant epoxy resins were prepared by blending different content of BPD with diglycidyl ether of bisphenol‐A (DGEBA). Thermal stability, flame‐retardant properties, and combustion behaviors of EP/BPD thermosets were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The flame‐retardant mechanism of BPD was studied by TGA/infrared spectrometry (TGA‐FTIR), pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), morphology, and chemical component analysis of the char residues. The results demonstrated that EP/BPD thermosets not only exhibited outstanding flame retardancy but also kept high glass transition temperature. EP/BPD‐1.0 thermoset achieved LOI value of 39.1% and UL94 V‐0 rating. In comparison to pure epoxy thermoset, the average of heat release rate (av‐HRR), total heat release (THR), and total smoke release (TSR) of EP/BPD‐1.0 thermoset were decreased by 35.8%, 36.5% and 16.5%, respectively. Although the phosphorus content of EP/BPD‐0.75 thermoset was lower than that of EP/DOPO thermoset, EP/BPD‐0.75 thermoset exhibited better flame retardancy than EP/DOPO thermoset. The significant improvement of flame retardancy of EP/BPD thermosets was ascribed to the blocking effect of phosphorus‐rich intumescent char in condensed phase, and the quenching and diluting effects of abundant phosphorus‐containing free radicals and nitrogen/sulfur‐containing inert gases in gaseous phase. There was flame‐retardant synergism between phosphorus, nitrogen, and sulfur of BPD.

The Preparation, Thermal Properties, and Fire Property of a Phosphorus-Containing Flame-Retardant Styrene Copolymer

“…It may be easily modified, due to the P-H bond, to generate a series of derivatives that may be used to improve polymer thermal stability and fire behavior [18,19]. In addition, DOPO derivatives have been modified to contain different flame retardancy elements, such as P-N [20][21][22], P-Si [23][24][25], and P-N-S [26,27].…”

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

“…The absorption peaks at 930, 1160, and 1597 cm −1 were ascribed to the stretching vibrations for POPh, PO, and PPh, confirming the introduction of phosphaphenanthrene in FRD. Moreover, the characteristic absorption peak of PH bond at 2434 cm −1 disappeared in the FTIR spectrum of FRD, which confirmed that the conjugation of the component of DOPO into FRD . Furthermore, the peaks at 3415 and 1658 cm −1 belonged to the vibration for OH, and the intensity of OH vibration from FRD was significantly reduced compared with BHAPE, affirming the existence of BHAPE in FRD …”

Synthesis of DOPO‐g‐GPTS modified wood fiber and its effects on the properties of composite phenolic foams

“…TG and DTG of wood fiber were shown in Figure . Compared with WF, initial decomposition temperatures ( T i ) and the temperature of maximum weight loss rate ( T max) of DGMWF were increased by 26.6 and 33.2 °C respectively. However the carbon residue (800 °C) was slightly reduced.…”