Internal nanostructure and structure-processing relationship of injection molded poly (butylene adipate-co-terephthalate) studied by SAXS-CT

Abstract

Exploring the micro structure is of great benefit to the manufacture and application of polymers. Small angle X-ray scattering computed tomography (SAXS-CT), a novel method with ability of nondestructive spatial-resolved, is used to characterize injection molded Poly (butylene adipate-co-terephthalate) (PBAT). The three-dimensional distribution of long period, lamella thickness, amorphous layer thickness and orientation in PBAT made by injection molding have been successfully extracted using the reconstructed voxel scattering. According to the uncovered structure, the bulk PBAT can be clearly divided into three parts as skin, interlayer and core. The lamella thickness shares a distribution in “U" shape while long period, amorphous layer thickness and orientation share a “Swing” shape. More interestingly, a vortex ring inside the PBAT caused by the secondary flow during packing stage in injection molding can be observed via the reconstructed orientation distribution. Here, the internal microstructure and morphology revealed by SAXS-CT can shed a light on the relationship between processing and structure of PBAT.