Influence of a novel P/N-containing oligomer on flame retardancy and thermal degradation of intumescent flame-retardant epoxy resin

• Published in: Polymer degradation and stability Vol. 162; pp. 129 - 137
• Main Authors: Zhu, Zong-Min, Wang, Luo-Xin, Dong, Liang-Ping
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.04.2019; Elsevier BV
• Subjects: ammonium polyphosphates; Chemical analysis; Dichlorides; epoxides; Epoxy resin; Epoxy resins; Flame retardancy; Flame retardants; Flame-retardant mechanism; Fourier transform infrared spectroscopy; Fourier transforms; gel chromatography; heat; Heat release rate; Infrared analysis; Infrared spectroscopy; Liquid chromatography; NMR; Nuclear magnetic resonance; nuclear magnetic resonance spectroscopy; P/N-containing oligomer; Photoelectrons; piperazine; polymerization; Scanning electron microscopy; Smoke; Thermal degradation; Thermogravimetric analysis; thermogravimetry; X ray photoelectron spectroscopy; Epoxy resin; Flame retardancy; Flame-retardant mechanism; P/N-containing oligomer
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2019.02.021

In this work, a novel P/N-containing oligomer poly(piperazine phenylphosphamide) (BPOPA) was synthesized via the polymerization reaction of phenylphosphonic dichloride with piperazine. Its structure was characterized by Fourier transformation infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), elemental analysis (EA) and gel permeation chromatography (GPC). It was used to enhance the flame retardancy of epoxy resin/ammonium polyphosphate (APP). As expected, improvement in flame retardancy of EP/APP was observed. In detail, EP containing 10 wt% APP alone possessed a LOI value of 30.2% but UL-94 no rating. When both 7.5 wt% APP and 2.5 wt% BPOPA were added into EP, EP/7.5APP/2.5BPOPA passed a UL-94 V-0 rating with a LOI value of 33.1%. Moreover, EP/7.5APP/2.5BPOPA presented much lower values of the peak of heat release rate (PHRR) and total smoke production (TSP) compared with EP/10APP. The flame-retardant mechanism was analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis/infrared spectrometry (TG-IR). Results illustrated that EP/7.5APP/2.5BPOPA mainly functioned in condensed phase which was associated with the formation of more compact char layer. •A novel P/N-containing oligomer (BPOPA) was synthesized and characterized successfully.•Adding BPOPA significantly improved flame retardancy of EP/APP.•Incorporation of BPOPA improved compactness degree of char for EP/APP during combustion.