Abstract:Starch/polyhydroxyalkanoate (PHA) composite films were prepared using the blown film extrusion method with hydroxypropylated crosslinked tapioca starch and PHA as the film-forming substrate, glycerol (GLY) as the primary plasticizer, polyethylene glycol 200 (PEG200) as the secondary plasticizer, and organically modified montmorillonite (OMMT) as the enhancer. The effect of weight ratios of PEG200/GLY on the properties of the composite films was evaluated. The structure, microstructure, and molecular interactions of the films were analyzed by X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy, respectively. The water vapor barrier properties, mechanical properties, light transmittance, and color of the films were also measured. The results showed that the primary plasticizer GLY had a good plasticizing effect on the starch/PHA blend systems. Moreover, the addition of PEG200 facilitated the formation of intercalated nanostructures between starch, PHA, and OMMT, and increased the light transmittance and whiteness values of the composite films. Additionally, the surface of the composite films became flat and smooth. When the weight ratio of PEG200/GLY was 8/92, the composite films showed good moisture barrier properties and high elongation at break. When the weight ratio of PEG200/GLY was 12/88, the composite films showed a high tensile strength and good light transmittance. The addition of the secondary plasticizer PEG200 enhanced intermolecular interactions. During the preparation of starch/PHA composite films, PEG200 was a preferable compatibilizer and plasticizer, and the weight ratio of PEG200/GLY should be less than 12/88.
