Streak and blister cell defects pose extensive surface problems for rigid polyurethane foams. In this study, these morphological anomalies were visually inspected using 2D optical techniques, and the cell microstructural coefficients including degree of anisotropy cell circumdiameter, and the volumetric isoperimetric quotient were calculated from the observations. A geometric regular polyhedron approximation method was developed based on relative density equations, in order to characterize the packing structures of both normal and anomalous cells. The reversely calculated cell volume constant, Cc, from polyhedron geometric voxels was compared with the empirical polyhedron cell volume value, Ch. The geometric relationship between actual cells and approximated polyhedrons was characterized by the defined volumetric isoperimetric quotient. Binary packing structures were derived from deviation comparisons between the two cell volume constants, and the assumed partial relative density ratios of the two individual packing polyhedrons. The modelling results show that normal cells have a similar packing to the Weaire-Phelan model, while anomalous cells have a dodecahedron/icosidodecahedron binary packing.

中文翻译：

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硬质聚氨酯泡沫缺陷的微观结构测量和微观几何填充表征

条纹和泡孔缺陷会给硬质聚氨酯泡沫带来广泛的表面问题。在这项研究中，使用二维光学技术对这些形态异常进行目视检查，并根据观察结果计算细胞微观结构系数，包括各向异性细胞外径的程度和体积等周商。基于相对密度方程开发了一种几何规则多面体近似方法，以表征正常和异常细胞的堆积结构。从多面体几何体素反向计算的单元体积常数 Cc 与经验多面体单元体积值 Ch 进行比较。实际单元格和近似多面体之间的几何关系由定义的体积等周商数表征。二元堆积结构源自两个单元体积常数之间的偏差比较，以及两个单独堆积多面体的假定部分相对密度比。建模结果表明，正常细胞具有与 Weaire-Phelan 模型相似的堆积，而异常细胞具有十二面体/二十面体二元堆积。