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，例如一般的隔热，轻质结构，特别是汽车部件。聚合物泡沫的泡孔结构，以及因此它们对特定应用的适用性，主要由技术工艺参数和聚合物的分子性质或聚合物熔体的所得流变性质的相互作用决定。文献中的大多数研究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，它们通常基于未知拓扑结构的工业样品，或者没有将相关效应与拓扑结构和结晶度分开。到目前为止，还不可能对拓扑学的影响作出明确的区分。因此，本申请的首要目标是理解三种关键分子聚合物性质与泡孔结构的相关性以及所得聚合物泡沫的所得应用性质，例如密度、机械固态性质和绝热能力。定制的无定形模型聚合物将使我们能够分别研究各个参数的影响，重点放在三个不同的方面：1）拓扑结构决定了聚合物熔体的剪切和拉伸流变性能，从而决定了膨胀过程。通过系统地改变拓扑结构，我们将研究流变性能的影响，如剪切粘度，拉伸粘度和应变硬化行为。2)固定：泡沫稳定性取决于聚合物的流动性和发泡剂的类型和比例。将使用具有不同玻璃化转变温度Tg但相同发泡剂溶解度的特殊合成的均聚物来分离不同的影响。3)成核：相分离嵌段共聚物表现出上级均聚物的内在成核。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不均匀性的影响和相边界对链流动性的限制。所产生的泡沫将通过固态机械性能和成像方法来表征。所获得的知识将被纳入到一个循环过程中的模型系统的分子特性，直到最好的可能的理解的相关性的分子特性与泡沫的蜂窝结构和应用性能的实现。在应用中获得的知识应该能够直接确定泡沫的计划特定应用的最佳可能的聚合物特性，从而显著简化制造工艺的特定应用适应性。

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.