Thermal properties of biodegradable poly(PHB/PCL-PEG-PCL) urethanes nanocomposites using clay/poly(ε-caprolactone) nanohybrid based masterbatch

Organoclay/polyurethanes nanocomposites (CPNs) based on bacterial poly(3-hydroxybutyrate), PHB and poly(epsilon-caprolactone)-b-poly(ethylene glycol)-b-poly(epsilon-caprolactone), PCL-PEG-PCL triblock copolymer with poly(epsilon-caprolactone) grafted montmorillonite, Mt-PCL, were prepared by dispersion intercalation method. The microstructure of the CPNs with different content of Mt-PCL was investigated with wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) revealed good dispersion of Mt-PCL within the polyurethane matrix. The thermal properties of the prepared CPNs were investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC data revealed the increase in T-g and crystallization rate of both the PHB and PCL-PEG-PCL segments upon incorporation of Mt-PCL The thermal stability of the nanocomposites was enhanced with increase of the Mt-PCL content. Activation energy (E-alpha)was evaluated applying both Flynn-Wall-Ozawa and Kissinger methods. The CPNs were found to exhibit a lower activation energy compared with pure polyurethanes, indicating that the presence of Mt-PCL possesses an accelerating effect on the thermal decomposition of polyurethanes. (C) 2012 Elsevier B.V. All rights reserved.