Morphology and thermal properties relationship in poly(p-dioxanone)/layered double hydroxides nanocomposites

Abstract

Nanocomposites of poly(p-dioxanone) (PPDO) with unmodified and organically modified layered double hydroxide (LDH) have been prepared by melt extrusion method. Dodecyl sulfate was used as organic modifier. The morphology of nanocomposites was analyzed by X-ray diffraction and transmission electron microscopy and their thermal properties by differential scanning calorimetry and thermogravimetric analysis. It has been found that the organic modifier decisively influences the nanocomposite morphology, resulting in a higher level of exfoliation. In addition, the glass transition temperature of nanocomposites was slightly higher than in case of unfilled PPDO. Moreover, the crystallization was delayed by LDH incorporation. The above behavior was ascribed to interactions between carbonyl groups of polymer matrix and hydroxyl groups of LDH, as supported by Fourier transformed infrared analysis. Interestingly, two different crystallization processes have been observed in the nanocomposite of PPDO and organically modified LDH. Unmodified and organo-modified LDH, practically did not alter the final melting point of PPDO. However, the thermal decomposition behavior was clearly influenced by the morphology exhibited by nanocomposites.