Yang Kang, Wu Sujun, Guan Juan, Shao Zhengzhong, Ritchie Robert O
Intl. Research Center for Advanced Structural and Biomaterials, School of Materials Science and Engineering, Beihang University, Beijing, 100191, China.
State Key Laboratory of Molecular Engineering of Polymers, Laboratory of Advanced Materials, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
Sci Rep. 2017 Sep 20;7(1):11939. doi: 10.1038/s41598-017-11919-1.
Strong and tough epoxy composites are developed using a less-studied fibre reinforcement, that of natural silk. Two common but structurally distinct silks from the domestic B. mori/Bm and the wild A. pernyi/Ap silkworms are selected in fabric forms. We show that the toughening effects on silk-epoxy composites or SFRPs are dependent on the silk species and the volume fraction of silk. Both silks enhance the room-temperature tensile and flexural mechanical properties of the composite, whereas the more resilient Ap silk shows a more pronounced toughening effect and a lower critical reinforcement volume for the brittle-ductile transition. Specifically, our 60 vol.% Ap-SFRP displays a three-fold elevation in tensile and flexural strength, as compared to pure epoxy resin, with an order of magnitude higher breaking energy via a distinct, ductile failure mode. Importantly, the 60 vol.% Ap-SFRP remains ductile with 7% flexural elongation at lower temperatures (-50 °C). Under impact, these SFRPs show significantly improved energy absorption, and the 60 vol.% Ap-SFRP has an impact strength some eight times that of pure epoxy resin. The findings demonstrate both marked toughening and strengthening effects for epoxy composites from natural silk reinforcements, which presents opportunities for mechanically superior and "green" structural composites.
利用一种研究较少的纤维增强材料——天然蚕丝，开发出了坚固耐用的环氧复合材料。选用了家蚕（B. mori/Bm）和野蚕（A. pernyi/Ap）两种常见但结构不同的丝织物形式。我们发现，蚕丝-环氧复合材料（SFRP）的增韧效果取决于蚕丝种类和蚕丝的体积分数。两种蚕丝都提高了复合材料的室温拉伸和弯曲力学性能，而弹性更强的Ap蚕丝表现出更显著的增韧效果和更低的脆韧转变临界增强体积。具体而言，与纯环氧树脂相比，我们的60体积% Ap-SFRP的拉伸和弯曲强度提高了三倍，通过独特的韧性破坏模式，断裂能高出一个数量级。重要的是，60体积% Ap-SFRP在较低温度（-50°C）下仍具有韧性，弯曲伸长率为7%。在冲击下，这些SFRP显示出显著改善的能量吸收，60体积% Ap-SFRP的冲击强度约为纯环氧树脂的八倍。研究结果表明，天然蚕丝增强的环氧复合材料具有显著的增韧和增强效果，这为机械性能优越的“绿色”结构复合材料提供了机会。
