Biodegradable polymers have become a topic of great scientific and industrial interest due to their environmentally friendly nature. For the benefit of the market economy and environment, biodegradable materials should play a more critical role in packaging materials, which currently account for more than 50% of plastic products. However, various challenges remain for biodegradable polymers for practical packaging applications. Particularly pertaining to the poor oxygen/moisture barrier issues, which greatly limit the application of current biodegradable polymers in food packaging. In this review, various strategies for barrier property improvement are summarized, such as chain architecture and crystallinity tailoring, melt blending, multi-layer co-extrusion, surface coating, and nanotechnology. These strategies have also been considered effective ways for overcoming the poor oxygen or water vapor barrier properties of representative biodegradable polymers in mainstream research.

Degradable and high-barrier plastic packaging materials draw more attention with the development of a social economy and the demands of environmental protection. In this study, poly(propylene carbonate phthalate) (PPC-P) and poly(butylene adipate-co-terephthalate) (PBAT) blends with different ratios were designed and prepared, marked as PPC-P/PBAT. Chain extenders were introduced into the blends, and the mechanical properties, thermal properties, and barrier properties of the composites were studied. The 75PPC-P/PBAT with 2% extenders represent the best performance. The addition of the chain extender has significantly improved the thermal stability and tensile elongation of PPC-P/PBAT. On this basis, the PPC-P/PBAT composite film was coated with PVA and borax using the dipping and pulling method. The oxygen barrier properties have been further improved for the composite film with a coating layer. Considering the characteristics of biodegradability and a high-barrier property, the 75PPC-P/PBAT/2MDI@Gly blend coated with 2 wt% PVA and 3 wt% borax exhibits potential as a superior food/pharmaceutical plastic packaging material with excellent tensile and barrier properties.