Degradable polyoctamethylene suberate/clay nanocomposites. Crystallization studies by DSC and simultaneous SAXS/WAXD synchrotron radiation

Several organo-modified montmorillonites were studied to prepare nanocomposites of polyoctamethylene suberate, a biodegradable polyester. Mixtures were analyzed by conventional powder X-ray diffraction and transmission electron microscopy techniques. C30B clay was effective in rendering an intercalated structure with rather variable silicate layer spacing. The hydroxyl groups of the organo-modifier may allow the establishment of good interactions with the polar carbonyl groups of the studied polyester. A slight decrease in thermal stability was detected when the modified clay was incorporated into the polymer matrix. Isothermal and nonisothermal crystallization kinetics were studied by DSC and results compared with those for the neat polyester. The overall crystallization rate determined by calorimetric methods depends on the nucleation density and the crystal growth rate, which were independently evaluated by means of optical microscopy. Crystallization and morphological features were also analyzed by simultaneous SAXS/WAXD measurements made at a selected crystallization temperature and cooling rate under both isothermal and nonisothermal conditions, respectively.