含氟苯乙炔苯胺封端聚酰亚胺的合成与性能研究

SYNTHESIS AND CHARACTERIZATION OF POLYIMIDE END-CAPPED WITH FLUORINATED PHENYLETHYNYLANILINE

设计并合成了一种含氟苯乙炔苯胺封端剂4-苯乙炔基-3-三氟甲基苯胺(3FPA),使用3FPA与4,4′-(六氟异丙基)双邻苯二甲酸二酐(6FDA)和对苯二胺(p-PDA)制备了计算分子量为5000的聚酰亚胺树脂3FPA-PI-50,并对树脂溶液、树脂模塑粉和树脂模压件的制备与性能进行了研究,实验结果表明3FPA-PI-50树脂溶液具有良好的储存稳定性,成型后树脂具有优异的热性能和热氧化稳定性,后固化后树脂玻璃化转变温度为404℃,5%热失重温度大于530℃.此外树脂具有低的介电常数和吸水率.

A novel end cap 3-trifluoromethyl-4-（phenylethynyl）aniline （3FPA） was obtained by reduction of the corresponding nitro-compound which was synthesized by coupling of 2-trifluoromethyl-4-nitro-l-bromobenzene with ethynylbenzene. Polyimide monomer solutions were prepared by classic PMR process using p-phenylenediamine （p- PDA）, the diethyl ester of 4, 4＇-hexafluoroisopropylidene-bisphthalic acid （6FDE） and 3-trifluoromethyl-4- （phenylethynyl） aniline as endcap. The monomer solution has high solid contents of about 40% - 45%, low viscosity of about 28 - 36 mPa· s and show high stability at room temperature in two months. The polyimide molding powders were produced by thermally curing the monomer solutions at 200 ℃, and the imidization degree of powders increased with increasing the curing temperature. The thermosetted polyimides were produced by thermal curing the polyimide molding powders at 370℃ under pressure of 1 - 2 MPa. The postcured polyimide showed a 5% weight loss temperature of 536 ℃ and Tg about 404 ℃ （DMA）. The thermo-oxidative stability of the thermosetted polyimides 3FPA-PI-50 and PMR- Ⅱ resins at elevated temperature （370℃） were determined by isothermally aging the samples in flowing air atmosphere, and the weight loss of 3FPA-PI-50 was about 6.78 wt% after 300 h isothermal aging which was lower than that of PMR- Ⅱ （7.15 % ）.