An Efficient Halogen-free Flame Retardant for Polyethylene：Piperazine-modified Ammonium Polyphosphates with Different Structures

• Published in: 高分子科学：英文版 2016-11 (11), p.1339-1353
• Main Author: Shi-fu Liao Cong Deng Sheng-chao Huang Jing-yu Cao Yu-zhong Wang
• Format: Article
• Language: English
• Subjects: ICP-AES; 傅里叶变换红外光谱; 哌嗪; 层次结构; 改性; 无卤阻燃聚乙烯; 电感耦合等离子体原子发射光谱; 聚磷酸铵
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-016-1855-8

In this study, piperazine-modified ammonium polyphosphates（PA-APPs） with hierarchical structure were synthesized through ion exchange reaction. ^1H nuclear magnetic resonance（^1H-NMR）, Fourier transform infrared spectra（FTIR）, elemental analysis（EA）, and inductively coupled plasma atomic emission spectroscopy（ICP-AES） confirmed that the PA-APPs with different structures were prepared successfully. Then these flame retardants were used alone as monocomponent intumescent flame retardant for low-density polyethylene（LDPE）. Combustion tests demonstrated that the flameretardant efficiency of PA-APP containing about 7 wt% carbon（PA-APP_7） was significantly higher than that of the other PAAPPs with more or less carbon. The flame-retarded LDPE system with 30 wt% PA-APP_7 passed the UL-94 V-0 rating, and had the oxygen index（LOI） of 33.0%. Thermal analysis illustrated that the thermal decomposition behavior of PA-APP changed with incorporating different contents of PA. For all these PA-APPs, PA-APP_7 showed higher thermal stability than the other PA-APP flame retardants. All the experimental results proved that PA-APP_7 could reach the balance of an acid source, a blowing source, and a charring source as a mono-component intumescent flame retardant for LDPE. Further, it led to the formation of a compact intumescent char layer containing the structures of rich P―O―P, P―N―C, C=C, etc. during burning which in turn resulted in the excellent flame-retardant efficiency of PA-APP7.