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Improvement of the Impact Damage Resistance of BMI/Graphite Laminates by the Ex-situ Method
Institute of Polymer Composites, Zhejiang University, Hangzhou 310027, People's Republic of China
National Key Laboratory of Advanced Composites/BIAM, P.O. Box 81, Beijing 100095, People's Republic of China
National Key Laboratory of Advanced Composites/BIAM, P.O. Box 81, Beijing 100095, People's Republic of China; xiaosu.yi{at}biam.ac.cn High-performance bismaleimide (BMI) matrix composites reinforced with graphite fibers were prepared and toughened with a thermoplastic component (PEK-C) by using different toughening methods. Four experimental options were conducted using the neat BMI matrix, toughened BMI matrix with PEKC, BMI laminates periodically interleaved with neat PEK-C films (Ex-situ concept 1) and BMI laminates periodically interleaved with BMI/PEK-C blend films (Ex-situ concept 2), respectively. The laminates were tested for compression strength after impact using an impact energy of 2 J mm-1. The highest impact damage resistance was obtained for the laminates toughened using the Ex-situ concept 2, especially, when PEK-C/BMI two-component films, cast from a mixture of PEK-C: BMI = 60: 40 were interleaved between the BMI laminate plies. Interleaving the pure thermoplastic film also gave good results (Ex-situ concept 1). There were two peak temperatures evident in the dynamic mechanical thermal analyses of the ex-situ toughened laminates implying that phase separation had occurred. The glass transition temperature of the toughened BMI laminates was slightly reduced due to the lower glass transition temperature of PEK-C. Morphological investigations revealed that a granular structure was present in the interply region presumably due to spinodal decomposition and coarsening. The results of this study are presented herein.
Key Words: Compression after impact toughened BMI interlaminar morphology
This version was published on December
1, 2006 High Performance Polymers, Vol. 18, No. 6,
907-917 (2006) |
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