Micro‐ CT Characterization of the Domain and Flaw Morphology of Immiscible Blends: Application to a Liquid Crystalline Polymer/Polycarbonate System Processed With Layer Multiplying Elements

ABSTRACT

Immiscible polymer blends suffer mechanical weakening due to segregation into large, weakly bonded domains. Micro‐computed tomography (micro‐CT) enables nondestructive characterization of heterogeneous structures, but its application to polymer blends is limited by low density contrast between components. We present a segmentation method to identify material domains and voids in micro‐CT images of polymer blends, assuming known blend ratios. The method is validated on coextruded polycarbonate (PC) and liquid‐crystalline polymer (LCP) blends with zero, one, or two layer multiplying elements (LMEs). Dynamic mechanical analysis (DMA) characterizes effects of LMEs and blend ratio on mechanical properties, and a micromechanical model based on Euler‐Bernoulli beam theory estimates flexural modulus from micro‐CT cross‐sections to link morphology and properties. For the 50/50 PC/LCP blend, one and two LMEs increase storage modulus at 40°C by 122% and 196% versus no LMEs. For the 25/75 PC/LCP blend, the trend is non‐monotonic: one LME increases the modulus by 50%, while two LMEs decrease it by 24%. Micro‐CT analysis confirms LMEs shift materials from central to peripheral regions, improving mixing and dispersion, but also redistributes and introduces voids. The micromechanical model captures many experimental trends, qualitatively validating segmentation and illustrating how domain and void morphologies influence elastic properties.