Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates
Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates
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偶氮甲碱基无卤阻燃聚膦酸酯的合成、表征及热降解动力学
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
SC Murugavel
中科院分区：
文献类型：
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作者：
R. Vini;S. Thenmozhi;SC Murugavel
在本研究中，通过在室温下使用三乙胺催化剂，苯基膦二氯化物与各种偶氮甲碱二醇如[4-（4-羟基苯基）亚氨基甲基]苯酚、[（4-（4-羟基-3-甲氧基苯基）亚氨基甲基]苯酚和[4-（4-羟基-3-乙氧基苯基）亚氨基甲基]苯酚的溶液缩聚，合成了偶氮甲碱聚膦酸酯。合成的聚合物的结构通过傅里叶变换红外光谱和1H-，13 C-和31 P-核磁共振光谱技术进行了确认。在氮气气氛下通过热重分析（TGA）和差示扫描量热法研究了聚合物的热性能。热重分析结果表明，合成的聚膦酸酯在600°C时由于磷原子的存在而产生较高的残炭率，因此具有良好的阻燃性能。将一种合成的聚膦酸酯与市售双酚A型二缩水甘油醚（DGEBA）树脂以不同的质量百分比共混，并用市售固化剂三乙烯四胺（TETA）固化。聚膦酸酯共混的环氧热固性材料的拉伸强度在5-41 MPa范围内，断裂伸长率为4-18。结果发现，将聚膦酸酯引入环氧热固性树脂中，使拉伸强度从41 MPa降低到5 MPa，而断裂伸长率值随着聚膦酸酯的重量百分比的增加而增加。通过极限氧指数（LOI）和垂直燃烧（UL-94）测试来检查聚膦酸酯对共混热固性材料的阻燃性的影响，并且发现聚合物样品实现了增加的UL-94等级，并且LOI值在24-26的范围内。采用Broido法和Horowitz-Metzger法研究了其热降解动力学参数。
In this study, azomethine polyphosphonates were synthesized by solution polycondensation of phenylphosphonic dichloride with various azomethine diols such as [4-(4-hydroxy phenyl) iminomethyl] phenol, [(4-(4-hydroxy-3-methoxy phenyl) iminomethyl)] phenol and [4-(4-hydroxy-3-ethoxy phenyl) iminomethyl] phenol using triethylamine catalyst at ambient temperature. The structure of the synthesized polymers was confirmed by Fourier transform infrared and 1H-, 13C- and 31P- nuclear magnetic resonance spectroscopic techniques. Thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. The TGA data showed that the synthesized polyphosphonates produce high char yield at 600°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. One of the synthesized polyphosphonate was blended with commercial diglycidyl ether of bisphenol-A (DGEBA) resin in various weight percentage and cured with commercial curing agent triethylene tetramine (TETA). The polyphosphonates-blended epoxy thermosets have tensile strength in the range of 5–41 MPa and the percentage of elongation at breaks was 4–18. It was found that the incorporation of polyphosphonates into epoxy thermoset decreased the tensile strength from 41 MPa to 5 MPa, whereas the elongation at break value increased with increase in the weight percentage of polyphosphonate. The influence of polyphosphonates on the flame retardancy of blended thermosets was examined by limiting oxygen index (LOI) and vertical burning (UL-94) tests and found that the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 24–26. Broido and Horowitz–Metzger methods have been used to study the thermal degradation kinetic parameters.