The mechanical properties of polymeric foams are strongly associated with their cellular structure. However, the relationship between the cellular structure and the mechanical behavior of polymeric foams is complicated by the interdependence of cell size and expansion ratio. Herein, we explored the relationship between cell size and impact strength in poly(lactic acid) (PLA)/rubber blend foams by controlling the cell size while maintaining a constant expansion ratio. Surprisingly, a cell size-induced brittle-to-tough transition was observed at a critical cell size. Foams exhibited brittleness when the cell size exceeded this critical threshold, whereas smaller cell sizes led to improved toughness. The increased toughness was attributed to the robust interaction of stress fields generated by adjacent cells and rubber particles, which could hinder the progression of cell-induced crazes into cracks, resulting in greater energy absorption. This study provides a universal strategy for enhancing the resilience of polymer/rubber blend foams.

中文翻译：

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具有受控泡孔尺寸的 Supertough 聚丙交酯共混泡沫


聚合物泡沫的机械性能与其蜂窝结构密切相关。然而，由于泡孔尺寸和膨胀率的相互依赖性，泡孔结构和聚合物泡沫的机械行为之间的关系变得复杂。在此，我们通过控制泡孔尺寸同时保持恒定的膨胀率，探讨了聚乳酸 （PLA）/橡胶共混泡沫中泡孔尺寸与冲击强度之间的关系。令人惊讶的是，在临界细胞尺寸下观察到细胞大小诱导的脆性到坚韧转变。当泡孔尺寸超过此临界阈值时，泡沫表现出脆性，而较小的泡孔尺寸会导致韧性提高。韧性的增加归因于相邻单元和橡胶颗粒产生的应力场的强烈相互作用，这可能会阻止单元诱导的裂纹发展为裂纹，从而导致更大的能量吸收。本研究为增强聚合物/橡胶共混泡沫的弹性提供了一种通用策略。