A nacre-mimetic superstructure of poly(butylene succinate) structured by using an intense shear flow and ramie fiber as a promising strategy for simultaneous reinforcement and toughening

Structuring nacre-mimetic superstructures during polymer melt processing could be a promising route to high performance structural materials with exceptional strength and toughness. A nacre-mimetic superstructure characterized with aligned lamellae (stiff phase) glued by amorphous polymer chains (soft and tough phase) was fabricated from a biodegradable polymer of poly(butylene succinate) (PBS) with favorable kinetics of crystallization by using an intense shear flow and promoted by natural ramie fiber. The well-aligned layered structure with a thickness of similar to 90 nm for the stiff phase and similar to 100 nm for the soft phase was identified with field-emission scanning electron microscopy, and the nacre-mimetic superstructure was quantitatively characterized by space-resolved small angle X-ray scattering. The thicknesses of crystalline lamellae and the amorphous phase layer between crystalline lamellae in the aligned layers were quantitatively assessed to be 3-4 nm and 4-6 nm respectively, indicating that multilayered crystal stacks are formed in the stiff phase. The nacre-mimetic superstructure leads to highly effective load transfer between the stiff phase and soft phase. Thus, the nacre-mimetic superstructure in PBS and the PBS/ramie fiber biocomposite shows simultaneous enhancement in strength and toughness in comparison to common materials without aligned layered structures. Our findings highlight the significance of nacre-mimetic superstructures in polymeric materials and provide novel prospects for the structuring of polymeric materials during melt processing.