The very thin and lightweight silkworm cocoon has outstanding mechanical properties attributed to its specific composite microstructure. However, the microstructures of the cocoons have not been studied quantitatively, and their anti-puncture performance has not been examined as well. In this study, both domesticated (Bombyx mori) and wild silkworm cocoons (Antheraea pernyi, Antheraea mylitta and Samia canningi) were investigated for their microstructures using fractal theory, and their quasi-static puncture resistance was tested and compared. In addition, the effects of cocoon layers and hot-press treatments on the puncture resistance of two cocoon types (B. mori and A. pernyi) were investigated. The three wild cocoons demonstrated significantly higher fractal dimensions, higher fiber intersectional densities and low porosities, indicating their structures are more optimized. They also displayed better puncture resistance than B. mori. Increased layer numbers could significantly increase the puncture resistance of both cocoon types and A. pernyi showed more remarkable increases. Moreover, the two cocoon types showed optimum puncture resistance after heat treatment with hot-press temperature of 135℃ and pressure of 25 MPa, and A. pernyi showed better puncture resistance after such treatment. Finally, both the maximum puncture force and puncture energy of cocoons displayed a linear increase with the increasing fractal dimensions. The new insights can guide the development of novel protective fiber composites with desirable and predictable anti-puncture performance.

中文翻译：

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家蚕和野生蚕茧的微观结构特征和准静态抗穿刺性研究

由于其特定的复合微观结构，非常薄且重量轻的蚕茧具有出色的机械性能。然而，尚未对茧的微观结构进行定量研究，也未检查其抗穿刺性能。在这项研究中，使用分形理论研究了家蚕（家蚕）和野生蚕茧（柞蚕、白花蚕和桑蚕）的微观结构，并测试和比较了它们的准静态穿刺阻力。此外，研究了茧层和热压处理对两种茧类型（B. mori 和 A. pernyi）的抗穿刺性的影响。三个野生茧表现出明显更高的分形维数、更高的纤维交叉密度和低孔隙率，表明它们的结构更加优化。它们还表现出比 B. mori 更好的抗穿刺性。增加层数可以显着提高两种茧类型的抗穿刺性，柞蚕表现出更显着的增加。此外，两种茧型在热压温度为135℃，压力为25 MPa的热处理后均表现出最佳的抗刺穿性，柞蚕表现出更好的抗刺穿性。最后，茧的最大穿刺力和穿刺能量都随着分形维数的增加呈线性增加。新的见解可以指导具有理想和可预测的抗穿刺性能的新型保护性纤维复合材料的开发。增加层数可以显着提高两种茧类型的抗穿刺性，柞蚕表现出更显着的增加。此外，两种茧型在热压温度为135℃，压力为25 MPa的热处理后均表现出最佳的抗刺穿性，柞蚕表现出更好的抗刺穿性。最后，茧的最大穿刺力和穿刺能量都随着分形维数的增加呈线性增加。新的见解可以指导具有理想和可预测的抗穿刺性能的新型保护性纤维复合材料的开发。增加层数可以显着提高两种茧类型的抗穿刺性，柞蚕表现出更显着的增加。此外，两种茧型在热压温度为135℃，压力为25 MPa的热处理后均表现出最佳的抗刺穿性，柞蚕表现出更好的抗刺穿性。最后，茧的最大穿刺力和穿刺能量都随着分形维数的增加呈线性增加。新的见解可以指导具有理想和可预测的抗穿刺性能的新型保护性纤维复合材料的开发。两种茧型在热压温度135℃、压力25MPa的热处理后均表现出最佳的抗穿刺性，柞蚕表现出较好的抗穿刺性。最后，茧的最大穿刺力和穿刺能量都随着分形维数的增加呈线性增加。新的见解可以指导具有理想和可预测的抗穿刺性能的新型保护性纤维复合材料的开发。两种茧型在热压温度135℃、压力25MPa的热处理后均表现出最佳的抗穿刺性，柞蚕表现出较好的抗穿刺性。最后，茧的最大穿刺力和穿刺能量都随着分形维数的增加呈线性增加。新的见解可以指导具有理想和可预测的抗穿刺性能的新型保护性纤维复合材料的开发。