Morphological Characteristics and Properties of PLA/PA12/EGMA Ternary Blends Under Shear and Elongational Flow Fields

This study explores the influence of shear‐dominated and elongational flow fields on the morphology and properties of PLA/PA12 polymer blends, using ethylene–glycidyl methacrylate–methyl acrylate (EGMA) terpolymer as a compatibilizer. The ternary blends were fabricated via melt blending using a twin‐screw extruder (TSE) and an eccentric rotor extruder (ERE), respectively. Morphological observations and FTIR analysis confirmed that EGMA significantly improved interfacial compatibility between PLA and PA12, resulting in a more homogeneous and finer phase morphology. SEM analysis revealed that the samples prepared via TSE exhibited a droplet–matrix structure, whereas ERE‐prepared samples exhibited highly oriented fibrous morphologies along the flow direction. The extent of orientation increased with the content of the dispersed phase, indicating enhanced mixing efficiency under elongational flow. Rheological results indicated that the blends exhibited longer relaxation times than neat PLA, especially those processed under elongational flow. Crystallization studies showed that shear flow had limited influence, while elongational flow promoted molecular chain alignment and accelerated crystallization, evidenced by a lower‐temperature cold crystallization peak. Mechanical testing demonstrated that ERE‐processed blends possessed significantly higher yield strength and elongation at break across all blend ratios. These findings highlight the advantages of elongational flow fields in improving the structure–property relationship of polymer blends.