Simulation of the development of the microstructure of injection-moulded semi-crystalline thermoplastics by means of a multi-scale approach under consideration of shear-induced crystal forms (alpha and beta)

在考虑剪切诱导晶型（α 和 β）的情况下，通过多尺度方法模拟注塑半结晶热塑性塑料的微观结构的发展

• 批准号: 408012354
• 负责人: Professor Dr.-Ing. Christian Hopmann
• 金额: --
• 依托单位: Institut für Kunststoffverarbeitung (IKV) in Industrie und Handwerk an der RWTH Aachen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/408012354?language=en
• 关键词: Simulation; development; microstructure; injection; moulded

Semicrystalline thermoplastics have partially spherical spherulitic microstructure. Despite the geometrical similarity of all spherulites, there are three distinct forms (α-, β- and γ-form) that arise from unique unit cells. This results in different local mechanical, thermal and optical component properties. The α-form represents the predominant crystal modification. In general, the lamellae are formed in the form of folded chains in the crystallization of semi-crystalline homopolymers in a quiescent melt. Isotactic polypropylene (iPP) in the α-form shows the unique phenomenon that lamellae are arranged in a so-called "cross-hatched" structure. The β-form has a lower degree of order compared to the α-form, which results inter alia in a higher degree of crystallization and a lower melting point. The formation of the crystalline regions of the β-form can be promoted by the addition of nucleating agents, by the choice of thermal conditions as well as by shear stress. The formation of crystallites of the γ-form occurs relatively rarely in industrially produced components and only in small proportions. It should be noted that the developed model at IKV for describing the crystallization process can not distinguish between different crystal forms. Which means all spherulites are considered the same and in the α-form, which does not correspond to reality, since the influence of β-spherulites are neglected. In the scientific literature, no work or approach is known which simulates the crystallization process in an injection-moulded component made of semicrystalline thermoplastics taking into account the different crystal forms.The aim of this project is the simulation of microstructure formation taking into account the shear-induced crystallization and consequently two dominating crystal forms (α and β) to calculate realistic microstructures and thus to precisely predict the component properties. To this end, the developed model at the IKV will be adapted so that unique nucleation and growth models for each crystal form will be derived and the calibrated using experimental experiments. These models are then implemented in the software SphäroSim, developed at IKV. The boundary conditions for the microstructure simulation come from filling simulation results based on a self-developed approach that describes the boundary conditions with a high resolution. The simulated microstructure will be then compared with the components, which will be produced under the same injection moulding process, and verified.

半晶体热塑料具有部分球形球形。尽管所有球形岩都具有几何相似性，但仍有三种不同的形式（α-，β-和γ形式）由独特的单位细胞产生。这导致不同的局部机械，热和光学组件特性。 α形式代表主要的晶体修饰。通常，在静态熔体中半晶均聚物的结晶中以折叠链的形式形成薄片。 α-形式中的同骨聚丙烯（IPP）显示了薄片以所谓的“交叉唱片”结构排列的独特现象。与α形式相比，β形式具有较低的级数，这在较高程度的结晶程度和较低的熔点。可以通过选择热条件和剪切应力来促进β形式的晶体区域的形成。 γ形式的结晶石的形成相对较少发生在工业生产的组件中，仅以小比例为单位。应该注意的是，IKV的开发模型描述了结晶过程，无法区分不同的晶体形式。这意味着所有球形岩都被认为是相同的，并且在α-形式中，这与现实无关，因为β-透明质的影响被忽略了。在科学文献中，尚无任何工作或方法，它可以在注射型的成分中模拟结晶过程，这些成分由半结晶的热塑料制成，考虑到不同的晶体形式。该项目的目的是模拟微观结构形成的模拟，同时考虑了剪切诱导的结晶，从而考虑了剪切的晶体形式，从而计算了两种均匀的晶体形式（从而实现了crystructy（实际上）（α），以实现（实际上）。 特性。为此，将对IKV的开发模型进行调整，以便将得出每种晶体形式的独特成核和生长模型，并使用实验实验进行校准。然后在IKV开发的软件Sphärosim中实现了这些模型。微观结构模拟的边界条件来自基于一种自我开发的方法来填充模拟结果，该方法描述了用高分辨率描述边界条件。然后将将模拟的微观结构与组件进行比较，该组件将在相同的注射成型过程中生成并进行验证。