| 摘要 |
Polybismaleimides prepared by delayed curing of bis-imides having the formula <IMAGE> wherein R1 and R2 each independently is H, C1-4-alkyl, C1-4-alkoxy, Cl or Br, or R1 and R2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R1 and R2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the -(CH2)n- group, optionally, is substituted by 1-3 methyl groups or by fluorine.
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