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(ε-caprolactone)-b-poly(ethylene glycol)-b-poly(ε-caprolactone), PCL-PEG-PCL triblock copolymer with poly(ε-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 Tg 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 (Ea) 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.

► Synthesis of layered silicate/poly (PHB/PCL-PEG-PCL)urethanes nanocomposites.
► Enhancement of nanocomposites' thermal stability with increasing Mt-PCL content.
► Enhancement of crystallization rate of PHB and PCL-PEG-PCL segments.
► Increase of Tg of PCL-PEG-PCL soft segments in polyurethane/nanocomposites with increasing organoclay content.