3D Analysis of the progressive modification of the cellular architecture in polyurethane nanocomposite foams via X-ray microtomography

This paper presents a detailed characterization of the cellular architecture of rigid polyurethane (PU) nanocomposite foams with increasing contents of nanoadditives (nanoclays) by X-ray computed micro-tomography. The comparative study also includes the unfilled PU foam. Based on this technique and using 3D image analysis, a complete study on the evolution of the most typically analysed cellular descriptors (cell size distribution, cell size and anisotropy ratio) is provided. Furthermore, non-conventional descriptors such the cell-coordination number, strut volumetric fraction (fs) and cell wall thickness are studied. Results confirm that nanoclays addition modifies the mean cell size and cell size distribution. In addition, it is also proved that the pore orientation, cell-coordination number and strut volume fraction are clearly influenced by nanoclays presence. The presented methodology allows obtaining a better understanding of the effects of nanoparticles during the foaming process and is important to gain knowledge on the structure–property relationships for these materials.