Ductility potential of brittle epoxies: Thermomechanical behaviour of plastically-deformed fully-cured composite resins
Ductility potential of brittle epoxies: Thermomechanical behaviour of plastically-deformed fully-cured composite resins
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DOI：
10.1016/j.polymer.2017.05.052
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发表时间：
2017-06
期刊：
影响因子：
4.6
通讯作者：
Mark A. Turk;I. Hamerton;D. Ivanov
中科院分区：
文献类型：
--
作者：
Mark A. Turk;I. Hamerton;D. Ivanov
通常用于结构复合材料的热固性矩阵通常以其极高的脆性、对缺陷的敏感性以及在复杂应变状态下的较差性能而闻名。这些特征阻碍了对它们行为的全面的材料特征和理解。然而，将依赖于规模和缺陷的失效与环氧树脂的整体材料性能分开是至关重要的，以实现延展性的显著改善。本文提出了一种新的实验方法，用于研究脆性环氧树脂的塑性极限，并积累大量塑性变形的环氧树脂，这是研究固化热固性树脂屈服后的物理和力学性能所必需的。结果表明，完全固化、高密度交联的环氧树脂可以承受至少50%的等效塑性应变，而不会损失硬度，内部结构也不会出现明显的退化。研究还表明，变形的环氧树脂改变了它们的热粘弹性行为。对普通环氧树脂和增韧环氧树脂的比较研究表明，前者比大量填充热塑性塑料的体系具有更高的延展性潜力。这意味着，为了改善热固性延展性，可能需要修订环氧改性的概念。
The thermoset matrices that are typically used in structural composites are generally well known for extreme brittleness, sensitivity to defects, and poor performance at complex strain states. These features impede a full material characterisation and an understanding of their behaviour. It is, however, of fundamental importance to separate the scale-dependent and defect-imposed failure from the bulk material performance of epoxies, to enable significant improvements in ductility to be realised. The current paper suggests a new experimental routine for investigating the ductility limits of brittle epoxies and accumulating the large macro-scale volumes of plastically deformed epoxies, necessary to study physical and mechanical properties of cured thermosets following yield. It has been shown that a fully cured, densely cross-linked epoxy can undergo at least 50% of the equivalent plastic strain without loss in stiffness and with no detectable degradation of internal architecture. It has also been shown that the deformed epoxies change their thermo-visco-elastic behaviour. A comparative study of plain and toughened epoxies has shown that the former have higher ductility potential than the systems heavily loaded with thermoplastics. This implies that in order to achieve improvements in thermoset ductility, a revised concept of epoxy modification may be required.