Abstract Polyurethane foams attract great attentions in various applications due to their superior materials properties. Foam structure is strongly related to the initial reaction rate of polymerization process. The effects of isocyanate (NCO) ratios between aromatic and aliphatic types on acoustic and mechanical properties were investigated. Highly electrophilic carbon atoms and less sterically hindered planar structure in aromatic NCO groups showed higher reactivity than in aliphatic nonplanar structure, and consequently the pore size and numbers decreased with increasing aliphatic contents from reduced pore formations due to high asymmetry molecular arrangements. The highest acoustic activity was also achieved at optimum aliphatic content.

中文翻译：

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异佛尔酮二异氰酸酯在聚氨酯泡沫制造中的反应性以改善声学和机械性能

摘要 聚氨酯泡沫由于其优异的材料性能而在各种应用中受到广泛关注。泡沫结构与聚合过程的初始反应速率密切相关。研究了芳香族和脂肪族类型之间异氰酸酯 (NCO) 比率对声学和机械性能的影响。芳香族 NCO 基团中的高度亲电碳原子和空间位阻较小的平面结构显示出比脂肪族非平面结构更高的反应性，因此孔径和数量随着脂肪族含量的增加而减少，因为高度不对称的分子排列减少了孔的形成。在最佳脂肪族含量下也实现了最高的声学活性。