Thermal and structural characterization of biodegradable blends filled with halloysite nanotubes

Fully biodegradable composites based on a commercial PHBV/PBAT blend with varying concentrations of neat or silanized clay nanotubes were prepared by twin-screw extrusion and filmed by melt blowing process. Thermal analysis suggested the simultaneous occurrence for the PHBV phase of both homogeneous crystallization and heterogeneous nucleation promoted by the included fillers. These phenomena show effects of mutual entities depending on the quality of the filler-matrix interface and the applied cooling rate. On the contrary, for the PBAT phase, although the filler may alter kinetics and mechanisms of crystallizations, no effect is reported in terms of its degree of crystallinity. All these evidences have been supported by structural investigations. Moreover, X-ray diffraction analysis indicated that the process of film blowing enables the formation of more perfect crystals and, as expected, favors the orientation of the included nanotubes of clay.