Paper number 467


Bronwyn Fox1, Jonathan Hodgkin2, Ben Jar1, Adrian Lowe1, Trevor Morton2 and Zbigniew Stachurski1

1Department of Engineering, Faculty of Engineering and Information Technology,
Australian National University, Canberra, ACT, 0200, Australia
2CSIRO Division of Molecular Science,
Private Bag 10, Clayton South MDC, VIC, 3169, Australia

Summary Preliminary results from isothermal aging at 250C of high temperature carbon fibre reinforced composites are presented. Composites made from two different thermosetting polyimide resin systems have been compared: one the novel CBR 320/328 resin developed by CSIRO and the other the commercial Matrimid? 5292 A/B system. The two materials were found to behave quite differently after being aged at this temperature for periods of up to six weeks. The mode I interlaminar fracture toughness of the commercial system decreased substantially after four weeks of aging due to matrix embrittlement. This coincided with significant chemical changes (as detected by Raman and Fourier Transform Infrared Spectroscopy) and the loss of a measurable glass tranisiton temperature. None of these observations were noted in the CSIRO composites which showed only surface degradation after four weeks at 250C. Contrary to this, the thermal stability evaluated on the basis of weight loss data over the same period of time, indicated that the commercial composite (12% weight loss) was more stable than the CSIRO composite (16%).
Keywords thermosetting polyimide, aging, interlaminar fracture toughness, FTIR, Raman, DMTA.

Theme : Durability and Ageing

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