국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Long Term Degradation of Polymide Composites
저자	Kaustubh A. Patekar and Hugh L. McManus
Keyword	Polymers; Polymide; Composites; Durability; Modeling; Thermal stability
URL	http://gltrs.grc.nasa.gov/reports/1998/CR-1998-208675.pdf
보고서번호	NASA CR-1998-208675
발행년도	1998
출처	NASA Glenn Research Center
ABSTRACT	The durability of polymer matrix composites exposed to harsh environments is a major concern. Surface degradation and damage are observed in polyimide composites used in air at 125300 캜. It is believed that diffusion of oxygen into the material and oxidative chemical reactions are responsible. Previous work has characterized and modeled diffusion behavior, and thermogravimetric analyses (TGAs) have been carried out in nitrogen, air, and oxygen to provide quantitative information on thermal and oxidative reactions. However, the model developed using these data did not successfully extrapolate TGA data down to conditions seen in service. A test program that focuses on lower temperatures and makes use of isothermal tests was undertaken to achieve a better understanding of the degradation reactions under use conditions. A new, lowcost technique was developed to collect chemical degradation data for isothermal tests lasting over 200 hours in the temperature range 125300 캜. Results indicate complex behavior not captured by the previous model, including the presence of weightadding reactions. Weight gain reactions dominated in the 125225 캜 temperature range, while weight loss reactions dominated beyond 225 캜. The data obtained from isothermal tests and earlier TGAs is used to develop an advanced model of the material behavior.