Blending biopolymers is a valuable method with industrial applications for tuning and improving their properties and performance, as single biopolymers often do not exhibit the appropriate properties for numerous durable applications. Furthermore, the properties of biopolymers can be modified by introducing unmodified and modified metal oxides, such as zinc oxide, titanium oxide, copper oxide and silver oxide.

This work involves adding two different blends of biopolymers, either compatible (such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) or incompatible (such as PLA and polyamide 11 (PA11)), with unmodified and modified zinc oxide and titanium oxide, via melt mixing. The zinc oxide has undergone chemical modification involving the introduction of stearic acid molecules (f-ZnO). Titanium oxide particles were treated with ultrasound to modify them (us-TiO2). Additionally, an acrylate copolymer (EVA-g-AA) has been added in small amounts to improve system compatibility. All the materials have been characterised for their rheological (oscillatory test), morphological (SEM), mechanical (tensile test) and thermal (DSC) behaviour, as well as for their photoxidation resistance (UVB exposure).

Unmodified metal oxides have a reinforcing effect on compatible PLA/PBAT blends, but a less pronounced beneficial effect on incompatible PLA/PA11 blends. The presence of particles significantly influences the blends' rheological and morphological behaviour, acting as a physical compatibiliser. Chemical modification of ZnO and ultrasound treatment of TiO₂ favour the formulation of more compatible blends due to their pronounced compatibilising action. Compatibility is further improved by the presence of the acrylate copolymer. Both unmodified and modified metal oxides promote the photooxidative degradation of blends, as do the more modified oxides.