Effect of Halloysite nanotubes on properties of biodegradable PBAT/PHBV blend

Fully biodegradable composites based on a commercial PBAT/PHBV blend with varying concentrations of neat or silanized Halloysite nanotubes (HNTs) 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. On the contrary, crystallization behaviour of the PBAT phase was not affected by the nanotubes. X-ray diffraction analysis (XRD) indicated that the process of film blowing enables the formation of more perfect crystals and favors the orientation of the included nanotubes. Mechanical tests demonstrated that strength and modulus of nanocomposite systems significantly increase with addition of halloysites without significant loss of ductility. Functionalization of HNTs resulted in further improvement in mechanical properties owing to a better interfacial adhesion. Rheological investigations revealed that the inclusion of halloysites resulted in increases of both the elastic modulus and the complex viscosity even if no percolating phenomena seems to occur on the filler loading range considered. Finally, the filler did not significantly alter the extrudability of the hosting matrix.