Polymer-ceramic multilayer composites with high fracture toughness

两个小组在这个研究项目中合作，目的是开发和理解由聚合物和陶瓷层组成的坚韧层状复合材料的性能-结构-关系。为此，将制备粘接陶瓷箔的层状复合材料。创新的复合材料应具有与应用的高性能陶瓷相似的刚度和强度，但具有更高的机械可靠性和韧性。复合材料的性能在很大程度上取决于所用胶粘剂的强度和断裂伸长率，而强度和断裂伸长率是系统变化的。此外，胶粘剂的用量应尽可能低。粘合剂将以阳离子固化环氧树脂为基础。在我们之前的工作中，我们发现用部分结晶聚酯多元醇（主要基于聚己内酯）改性环氧树脂，可以显著提高断裂强度和断裂伸长率。虽然我们的材料没有系统的配方，但这种组合比高端商用粘合剂更好。有迹象表明，优异的性能主要是由聚合粘合剂的异质形态引起的，尽管它们在宏观层面上似乎是均匀的。聚（己内酯）的结构将因此系统地变化，然后这些化合物将用于粘合剂制备。所选择的聚合物体系是最充分的基本检查，因为它的性质可以调整只有最小的变化组成。如果在不同的温度下进行光化学固化，即使在相同的成分下，均质性也会发生变化。这允许单独检查形态和组成对粘合剂性能的影响。为了研究不同厚度的陶瓷箔和胶粘剂层对复合材料力学性能的影响，研究了胶粘剂和陶瓷材料以及层状复合材料堆结构对复合材料力学性能的影响。为了实现这一目标，将开展广泛的工作计划，包括陶瓷材料的物理和机械特性，新开发的热固性粘合剂聚合物和制备的层状复合材料。期望对结构变化与所得聚合物以及复合材料性能之间的关系有深入的了解。除了实验研究外，还将生成具体的材料模型并应用于数值模拟。数值计算的重点是聚合物陶瓷界面的裂纹扩展。在此基础上，制备了具有优化性能的层状复合材料。将实验确定的层状复合材料的性能与有限元计算结果进行比较，将有助于验证所建立的结构性能模型。

Two groups are working together in this research project and it is the aim to develop and understand the property-structure-relationships of tough layered composites consisting of polymer and ceramic layers. For this purpose, layered composites of adhesively bonded ceramic foils will be prepared. The innovative composites should have a stiffness and a strength on a similar level like the applied high-perfotmance ceramic but higher mechanical reliability and toughness. The composite properties should highly depend on strength and elongation at break of the used adhesives which will be varied systematically. Furthermore, the adhesives amount should be kept as low as possible. The adhesives will be based on cationically curing epoxy resins. In our previous work we found that the modification of epoxy resins with partially crystalline polyesterpolyols, mainly based on poly(caprolactone), improves fracture strength and elongation at break strongly. The combination is better than that of high end commercial adhesives although our materials are not systematically formulated. There are indications that the outstanding properties are mainly caused by a heterogeneous morphology of the polymerised adhesive, although they seem to be homogeneous on the macroscopic level. The structure of the poly(caprolactone) will be varied therefore systematically and these compounds will be applied then for the adhesives preparation. The selected polymer system is most sufficient for basic examinations as its properties can be adjusted by only minimal changes of the composition. If photochemical curing is applied at different temperatures, heterogeneity can be varied even with identical composition. This allows the separate examination of the influence of morphology and composition on the adhesives properties. Different layer thicknesses of the ceramic foils and adhesive layers will be examined in order to work out the influence of the adhesives and the ceramics materials as well as of the construction of the layered composite stacks on the composites mechanical properties. For this goal an extensive work program will be carried out covering the physical and mechanical characterisation of the ceramic materials, the newly developed thermosetting adhesive polymers and the prepared layered composites. A deep understanding of the relationship between the structural variations and the resulting polymer as well as properties of the composites is expected. Beside the experimental investigation specific material models will be generated and applied for numerical simulation. The crack growth at the polymer ceramics interphase will be in the special focus of the numerical calculations. Based on the numerical results, layered composites with optimised properties will be prepared. Comparison between the experimentally determined properties of the layered composites and the results of the FEM calculations will contribute to the verification of the developed structure property models.