动物犄角的强韧化机制解析及其仿生柞蚕丝纤维复合材料的研究

Lightweight, green and toughness are important targets in aviation and automotive industry. Recently, study on natural materials and biomimetic materials with light weight and high toughness have been a great interest of scientists. It was expected to acquire antherea pernyi silk fiber reinforced composites with light weight and high toughness by biomimetic design based on 3D structure of animal horns. Through quantitatively analyzing spatial distribution of keratin fibers, micro-pore in core and microtubule in shell, as well as the “transitional” interfacial layer between core and shell, the 3D structure of animal horns in micro-meso-macro scale would be revealed. Simultaneously, crack propagation behavior of horn was investigated by in situ SEM observation and the design model of biomimetic materials was quantitatively constructed subsequently. Then, through two-step manufacturing strategy of core and shell, antherea pernyi silk fiber reinforced composites with multi-structure features（layered/fiber/gradient/porous） were obtained and the key process parameters and biomimetic structure model were optimized. Finally, a light, green and high toughness biomimetic composite material was successfully achieved. Our research would help to promote the understanding of toughening mechanism in animal horn, and provide new strategy for the material design and preparation in aviation and automotive industry.

“轻量化”、“绿色环保”与“强韧性”等指标的提升是航空与汽车领域追求的重要目标，而一些天然生物材料恰恰具有轻质高韧性的特点，因此，本课题借鉴高韧性动物犄角的跨尺度三维结构，为复合材料的结构设计提供新的思路，在制备中采用轻质高韧性的天然柞蚕丝纤维，实现材料和结构的双重韧化。通过跨尺度三维结构解析和原位断裂行为分析，明晰动物犄角中纤维、芯层微孔、壳层微管等的空间分布规律和“过渡”界面层的形态特征，定量化构建动物犄角的微观-介观-宏观尺度的三维结构模型，揭示动物犄角的强韧化机制，提炼出适合于轻质高韧性仿生材料的设计原则。进而，通过芯、壳层分步成型的策略，获得具有层状/纤维/梯度/多孔多元结构特点的柞蚕丝纤维复合材料，优化关键成型参数和仿生结构的设计，最终获得一种轻质、绿色、高韧性的仿生复合材料。本课题的研究有助于深化动物犄角强韧化机制的理解，为航空与汽车领域的材料设计与制备提供新的思路和方法。

动物犄角在日常战斗中承载各种负荷并且一旦损坏就无法修复，其经过亿万年物种竞争和自然选择后，角鞘具有优异的力学性能。本课题深入研究了不同种类动物犄角的三维结构，构建了三维跨尺度模型，解析了不同载荷下动物犄角的强韧化机制。经研究发现，动物犄角内部的波纹层状结构对于强度和韧性影响较大，尤其是非均质化的波纹层状结构。动物犄角的基底细胞在血管中生长和增殖，然后转化为角质层细胞，以角蛋白细丝聚集和分子间二硫键交联的形成为特征，从表皮细胞到角质形成细胞的细胞分化可能产生不均匀的波纹状薄片，这可能是非均质的波纹结构的形成机制。此外，多孔、微管结构对于动物犄角的韧性提升也有较大作用。基于动物犄角的结构特点，本课题采用柞蚕丝作为原料，设计并制备了“波纹-多孔”仿生复合材料，获得了获得具有层状/纤维/梯度/多孔多元结构特点的柞蚕丝纤维复合材料，完成了工艺参数的优化，冲击强度最高超过150KJ m-2。本课题的研究成果有望为轻质高强韧仿生复合材料的结构设计和性能优化提供积极的指导意义。