Isothermal crystallization and mechanical properties of poly(butylene succinate)/layered double hydroxide nanocomposites

Biodegradable poly(butylene succinate) (PBS) and layered double hydroxide (LDH) nanocomposites were prepared via melt blending in a twin-screw extruder. Isothermal crystallization and subsequent melting behavior, thermal stability, crystal structure, spherulitic morphology and mechanical properties of PBS and its nanocomposites were studied by DSC, TGA, WAXD, POM and DMA in detail. The crystallization rate of PBS in its nanocomposites was accelerated by the addition of LDH, due to its heterogeneous nucleation effect. The Avrami equation successfully described the isothermal crystallization kinetics of the nanocomposites. The melting profile of PBS/LDH composites and pure PBS showed the very similar T-c-dependent DSC traces. The TGA analysis revealed that the catalyst effect of Mg and/or Al metals reduced the thermal decomposition temperature of PBS. The spherulite size of PBS/LDH nanocomposites decreased and the spherulite density increased remarkably with an increase of LDH, however, the crystalline structure was not influenced by the presence of LDH, as evidenced by the same diffraction peaks from WAXD patterns. The DMA results indicated that a significant enhancement of the modulus of the nanocomposites was achieved.