Synergistic enhancement of melt strength, crystallization and foaming properties for poly (lactic acid)/bacterial...

To improve melt strength and crystallization rate of poly (lactic acid) (PLA) for its foaming application, bacterial cellulose (BC) was selected as filler to improve the foaming performance of PLA. PLA was melt-blended with BC, and azodicarbonamide (ADC) was selected as the foaming agent for compression molding to prepare PLA/BC composite foams. Freeze-dried BC (FDBC) with oriented structure was prepared using a directional freeze-templating method to enhance its barrier effect as a reinforcing agent. The addition of oriented BC not only improved the crystallization behavior and increased the crystallinity of the system, but also, owing to its oriented network structure, reduced the flow rate while enhancing the complex viscosity, storage modulus and melt strength. The resulting foamed materials exhibited well-defined cell structure, high cell density, uniform cell size, and significantly improved compressive and impact strength, along with excellent thermal insulation properties. This paper provides valuable insights into enhancing the melt strength and foaming performance of PLA, offering a promising approach for developing high-performance biodegradable foamed materials.