Correlation of molecular polymer properties with application properties of closed-cell foams based on self-synthesized model systems

聚合物泡沫具有独特的物理、机械和热性能。因此，应用领域非常多样化，例如隔热，一般的轻量化结构，特别是汽车零部件。聚合物泡沫的细胞结构，以及它们对特定应用的适用性，主要是由技术工艺参数和聚合物的分子特性或聚合物熔体的流变性能的相互作用决定的。文献中的研究大多涉及发泡技术和工艺条件。只有少数研究涉及聚合物分子性质的影响。然而，它们通常是基于未知拓扑结构的工业样品，或者没有将拓扑结构和结晶度的相关效应分开。到目前为止，还不可能明确区分拓扑的影响。因此，本应用程序的首要目标是了解三个关键分子聚合物特性与细胞结构的相关性，以及由此产生的聚合物泡沫的应用特性，例如密度、机械固体特性和隔热能力。定制的非晶聚合物模型将使我们能够分别研究单个参数的影响，重点关注三个不同的方面：1)拓扑结构决定了聚合物熔体的剪切和拉伸流变特性，从而决定了膨胀过程。通过系统地改变拓扑结构，我们将研究流变特性的影响，如剪切粘度、拉伸粘度和应变硬化行为。2)固定：泡沫稳定性是由聚合物的流动性和发泡剂的种类和比例决定的。采用不同玻璃化转变温度Tg但发泡剂溶解度相同的特殊合成均聚物来分离不同的影响。3)成核：相分离嵌段共聚物的本征成核性优于均聚物。通过系统地合成不同的嵌段共聚物，我们将研究发泡剂溶解度的非均质性和相界对链迁移率的限制。所生产的泡沫将通过固态力学性能和成像方法进行表征。在循环过程中，所获得的知识将被纳入模型系统的分子特性中，直到实现对分子特性与细胞结构和泡沫应用特性之间的相关性的最佳理解。在应用中获得的知识应该可以直接确定计划的特定泡沫应用的最佳聚合物性能，从而显着简化特定应用的制造过程。

Polymer foams exhibit unique physical, mechanical and thermal properties. Therefore, the areas of application are very diverse, such as in thermal insulation, lightweight construction in general, and automotive parts in particular. The cell structure of polymeric foams, and thus their suitability for a specific application, is primarily determined by the interaction of technical process parameters and the molecular properties of the polymers or the resulting rheological properties of the polymer melt. Most studies in the literature refer to foaming techniques and process conditions. Only a few studies address the influence of polymer molecular properties. However, they are often based on industrial samples of an unknown topology or do not separate correlated effects from topology and crystallinity. A clear differentiation of the impact of topology has not been possible so far. Therefore, the overarching goal of this application is to understand the correlation of three key molecular polymer properties on the cellular structure and the resulting application properties of the resulting polymer foam, e.g. density, mechanical solid state properties, and thermal insulation capability. Tailor-made amorphous model polymers will allow us to study the influence of individual parameters separately, focusing on three different aspects: 1) Topology determines the shear and extensional rheological properties of the polymer melt and, thus, the expansion process. By systematically varying the topology, we will study the influence of rheological properties such as shear viscosity, extensional viscosity, and strain hardening behavior. 2) Fixation: Foam stabilization is determined by the mobility of the polymers and the type and proportion of the blowing agent. Specially synthesized homopolymers with varying glass transition temperature Tg but identical blowing agent solubility will be used to separate different influences. 3) Nucleation: phase-separating block copolymers exhibit intrinsic nucleation superior to homopolymers. By synthesizing systematically varied block copolymers, we will study the effect of heterogeneity of blowing agent solubility and the limitation of chain mobility by phase boundaries. The foams produced will be characterized by solid-state mechanical properties and imaging methods. The obtained knowledge will be incorporated into the molecular properties of the model systems in a circular process until the best possible understanding of the correlation of the molecular properties with the cellular structure and the application properties of the foams are achieved. The knowledge gained in the application should make it possible to directly determine the best possible polymer properties for a planned specific application of the foam, thus significantly simplifying the application-specific adaptation of the manufacturing process.