Improvement of the impact damage resistance of BMI/graphite laminates by the ex-situ method

Qunfeng Cheng, Zhengping Fang, Yahong Xu, Xiao Su Yi

Research output: Journal PublicationArticlepeer-review

21 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)907-917
Number of pages11
JournalHigh Performance Polymers
Issue number6
Publication statusPublished - Dec 2006
Externally publishedYes


  • Compression after impact
  • Interlaminar morphology
  • Toughened BMI

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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