Novel Spirocyclic Phosphazene-Based Epoxy Resin for Halogen-Free Fire Resistance: Synthesis, Curing Behaviors, and Flammability Characteristics
详细信息 查看全文
- 作者：Jian Sun ; Xiaodong Wang ; Dezhen Wu
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2012
- 出版时间：August 22, 2012
- 年：2012
- 卷：4
- 期：8
- 页码：4047-4061
- 全文大小：800K
- 年卷期：v.4,no.8(August 22, 2012)
- ISSN：1944-8252
文摘
A novel halogen-free fire resistant epoxy resin with pendent spiro-cyclotriphosphazene groups was designed and synthesized via a three-step synthetic pathway. The chemical structures and compositions of spiro-cyclotriphosphazene precursors and final product were confirmed by 1H, 13C, and 31P NMR spectroscopy, mass spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy. The thermal curing behaviors of the synthesized epoxy resin with 4,4鈥?diamino-diphenylmethane, 4,4鈥?diamino-diphenyl sulfone, and novolac as hardeners were investigated by differential scanning calorimetry (DSC), and the curing kinetics were also studied under a nonisothermal condition. The evaluation of the thermal properties demonstrated that these thermosets achieved a good thermal resistance due to their high glass transition temperatures more than 150 掳C, and also gained high thermal stabilities with high char yields. The flammability characteristics of the spirocyclic phosphazene-based epoxy thermosets cured with these three hardeners were investigated on the basis of the results obtained from the limiting oxygen index (LOI) and UL鈥?4 vertical burning experiments as well as the analysis of the residual chars collected from the vertical burning tests. The high LOI values and UL鈥?4 V鈥? classification of these epoxy thermosets indicated that the incorporation of phosphazene rings into the backbone chain imparts nonflammability to the epoxy resin owing to the unique combination of phosphorus and nitrogen following by a synergistic effect on flame retardancy. The epoxy resin obtained in this study is a green functional polymer and will become a potential candidate for fire- and heat-resistant applications in electronic and microelectronic fields with more safety and excellent performance.