Mechanisms of thermoset plasticity explained on the basis of spectroscopic analysis and atomistic simulations

基于光谱分析和原子模拟解释热固性塑料塑性机理

• 批准号: 525597740
• 负责人: Professor Dr.-Ing. Bodo Fiedler
• 金额: --
• 依托单位: Institut für Kunststoffe und Verbundwerkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/525597740?language=en
• 关键词: Mechanisms; thermoset; plasticity; explained; basis

An unexpected feature of epoxy resins is the increasing ductility with reduced test volume. This has already been demonstrated for different epoxy resin systems in the form of microscopic fibres. Under mechanical load, these did not exhibit brittle failure behaviour typical of the material, but ductile behaviour with pronounced necking. The ductility and elongation at break increased with decreasing test volume. The reproducible production of thin EP films with constant thickness is challenging, but on the other hand it allows the investigation by transmitted light infrared spectroscopy. In the first mechanical investigations of microscopic films (d = 50 µm) made of epoxy resin, these films formed shear bands under load and also necked down. So far, there is no complete explanation for this effect in terms of plasticity. For this reason, the physical, mechanochemical and molecular mechanisms of the associated brittle-ductile transition in the epoxy resin under load are investigated within this project. Epoxy resin films with reproducible, constant and adjustable thicknesses are selected to obtain information about the molecular mechanisms, their interactions and the resulting macroscopic mechanical behaviour. Using infrared spectrometry, it is possible to obtain information about inter- and intramolecular mechanisms acting during in-situ mechanical testing by spectral changes and peak shift under load. Molecular dynamics simulations can then be used to infer explicit molecular vibrations or configurations. This triad of methods, i.e. AI-mediated interpretation of IR spectra using idealised MD simulation models in combination with experiments on thin epoxy films, offers the possibility to understand molecular processes of plasticity in small volumes of epoxies. The AI-mediated simulations, which are based on sufficiently detailed ab initio calculations and also include anharmonic effects, are key to explaining IR peak shifts and more general changes in the spectra that can be attributed to specific molecular interactions, thus providing a link to experimentally obtained spectra from in situ tests on thin epoxy films. With this know-how gained, it will be possible to understand more fundamentally the behaviour of the matrix in intermediate phases (fibre composites), thin coatings and adhesives and to use epoxy in new technical applications. From a materials science perspective, the research proposed here could provide new insights into the structural design of future composites.

环氧树脂的一个意想不到的特征是随着测试体积的减少而增加的延展性。这已经在不同的环氧树脂体系中以微观纤维的形式得到了证明。在机械载荷下，这些材料没有表现出典型的脆性破坏行为，但具有明显颈缩的韧性行为。随着试验体积的减小，材料的延展性和断裂伸长率增加。具有恒定厚度的薄EP膜的可重复生产具有挑战性，但另一方面，它允许通过透射光红外光谱进行调查。在对环氧树脂制成的微观薄膜（d = 50 µm）进行的第一次力学研究中，这些薄膜在载荷下形成剪切带，并发生颈缩。到目前为止，还没有从可塑性方面对这种效应做出完整的解释。基于此，本计画将探讨环氧树脂在负载下脆韧转变的物理、机械化学及分子机制。选择具有可再现的、恒定的和可调节的厚度的环氧树脂膜，以获得关于分子机制、它们的相互作用和所得到的宏观机械行为的信息。使用红外光谱法，可以通过载荷下的光谱变化和峰位移获得关于在原位机械测试期间作用的分子间和分子内机制的信息。分子动力学模拟可以用来推断明确的分子振动或配置。这三种方法，即AI介导的解释红外光谱使用理想化的MD模拟模型结合实验薄环氧树脂膜，提供了可能性，以了解小体积的环氧树脂的可塑性的分子过程。人工智能介导的模拟，这是基于足够详细的从头计算，也包括非谐效应，是关键解释红外峰位移和更一般的光谱变化，可以归因于特定的分子相互作用，从而提供了一个链接到实验获得的光谱从现场测试薄环氧树脂膜。有了这些技术诀窍，就有可能从根本上了解中间相（纤维复合材料）、薄涂层和粘合剂中基质的行为，并在新的技术应用中使用环氧树脂。从材料科学的角度来看，这里提出的研究可以为未来复合材料的结构设计提供新的见解。