ELECTRON-PARAMAGNETIC-RESONANCE SPECTROSCOPIC STUDIES OF THERMALLY GENERATED FREE-RADICALS IN PMR-15 POLYIMIDE RESINS

被引：16

作者：

AHN, MK ^{[1
]}

STRINGFELLOW, TC ^{[1
]}

FASANO, M ^{[1
]}

BOWLES, KJ ^{[1
]}

MEADOR, MA ^{[1
]}

机构：

[1] NASA,LEWIS RES CTR,CLEVELAND,OH 44135

来源：

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS | 1993年 / 31卷 / 07期

关键词：

POLYIMIDE; EPR; FREE RADICALS;

D O I：

10.1002/polb.1993.090310711

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

PMR-15 is a high-performance thermoset polyimide resin that is used in many high-temperature applications. Postcured PMR-15 produces room-temperature electron paramagnetic resonance (EPR) spectra from stable free-radical species that are formed during the postcuring stages. The variable-temperature EPR spectral intensities show a minimum at T(min). in the range -60 to -40-degrees=C, and a maximum at T(max) in the range 80-120-degrees-C. The EPR intensities follow the inverse temperature dependence of Curie's law below T(min) and are due to a stable free radical. The intensities then increase with increasing temperature between T(min) and T(max). The free radical with such temperature dependence is not present below T(min) and is undetectable by EPR at temperatures above T(max). These free radicals are generated during the postcuring process at elevated temperature above 310-degrees-C. The thermo-oxidative degradation involves free radicals generated during the postcuring process in the presence of oxygen gas.

引用

页码：831 / 841

页数：11