Thermoplastic phenolphthalein poly(ether ether ketone) (PEK‐C) /epoxy composite foams were prepared by free foaming process (Fre‐foams) and limited foaming process (Lim‐foams), respectively, and the effects of PEK‐C content and foaming methods on the cell structures, phase morphologies, and impact strength of epoxy foams were investigated. The results showed that the gas pressure in the bubbles promoted the resin curing process and polymerization‐induced phase separation process (PIPS) during the free foaming process, while the resin curing process and PIPS were highly constrained in Lim‐foams. The incorporation of PEK‐C in the Fre‐foams showed superior improvement in impact strength compared with the PEK‐C/epoxy Lim‐foams. By adding 12 wt% PEK‐C, the specific impact strength of Fre‐foams could be enhanced by 72%, and the improved specific impact strength was because the phase‐inverted structures could prevent crack initiation and propagation, and moreover the presence of PEK‐C led to significantly refine cell structure and reduce foam density. Interestingly, the impact strength of Lim‐foams was nearly independent on the PEK‐C content, it was attributed to the obviously increased cell size with increasing PEK‐C content, and also that the phase separation process was not carried out.

中文翻译：

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酚酞聚醚醚酮/环氧复合泡沫的孔结构，相形态和冲击韧性

热塑性酚酞聚醚醚酮（PEK-C）/环氧复合泡沫分别通过自由发泡工艺（Fre-foams）和有限发泡工艺（Lim-foams）以及PEK-C含量和发泡的影响而制备研究了有关环氧泡沫的泡孔结构，相形态和冲击强度的方法。结果表明，气泡中的气体压力在自由发泡过程中促进了树脂固化过程和聚合诱导的相分离过程（PIPS），而树脂固化过程和PIPS则在Lim-泡沫中受到了很大的限制。与PEK-C /环氧Lim泡沫相比，PEK-C在Fre-foam泡沫中的掺入显示出优异的抗冲击强度。通过添加12 wt％的PEK‐C，Fre-foams的比冲击强度可以提高72％，比抗冲击强度的提高是因为相变结构可以防止裂纹的产生和扩展，此外，PEK-C的存在可显着改善泡孔结构并降低泡沫密度。有趣的是，Lim-foams的冲击强度几乎与PEK-C含量无关，这归因于随着PEK-C含量的增加，泡孔尺寸明显增加，并且没有进行相分离过程。