Beverte Ilze, Cabulis Ugis, Andersons Janis, Kirpluks Mikelis, Skruls Vilis, Cabulis Peteris
Institute for Mechanics of Materials, University of Latvia, 3 Jelgavas St., LV-1004 Riga, Latvia.
Latvian State Institute of Wood Chemistry, 27 Dzerbenes St., LV-1006 Riga, Latvia.
Polymers (Basel). 2023 Jun 5;15(11):2582. doi: 10.3390/polym15112582.
Medium-density rigid polyurethane (PU) foams are often produced in sealed molds; therefore, the processes inside the mold and structure of the produced foam blocks need to be understood. The structural and mechanical anisotropy is shown to be the third variable along with (1) concentration of the nanoclay filler and (2) density, to determine the mechanical properties of the filled PU foam composites produced in a sealed mold. The varying anisotropy of the specimens hinders the accurate evaluation of the filling effect. The methodology for the estimation of the anisotropy characteristics of specimens from different locations within the nanoclay filled PU foam blocks is elaborated. A criterion, based on analysis of Poisson's ratios, is formulated for the selection of specimens with similar anisotropy characteristics. The shear and bulk moduli are estimated theoretically, dependent on the filler's concentration, using the experimentally determined constants.
中密度硬质聚氨酯（PU）泡沫通常在密封模具中生产；因此，需要了解模具内部的过程以及所生产泡沫块的结构。结构和机械各向异性被证明是与（1）纳米粘土填料浓度和（2）密度一起决定在密封模具中生产的填充PU泡沫复合材料机械性能的第三个变量。试样变化的各向异性阻碍了对填充效果的准确评估。阐述了从纳米粘土填充PU泡沫块内不同位置估计试样各向异性特征的方法。基于泊松比分析制定了一个标准，用于选择具有相似各向异性特征的试样。根据实验确定的常数，理论上估计了取决于填料浓度的剪切模量和体积模量。
