Papadopoulou Evie L, Paul Uttam C, Tran Thi Nga, Suarato Giulia, Ceseracciu Luca, Marras Sergio, d'Arcy Richard, Athanassiou Athanassia
ACS Appl Mater Interfaces. 2019 Aug 28;11(34):31317-31327. doi: 10.1021/acsami.9b09755. Epub 2019 Aug 15.
Sustainable biocomposites have been developed by solvent mixing of poly(lactic acid) (PLA) with a fine powder of cocoa bean shells (CBS) and subsequent solution casting, using different concentrations of CBS. The inclusion of CBS recovers the crystallinity of the initially amorphous PLA films and improves the physical properties of the composites. Young's modulus increases by 80% with 75 wt % CBS inclusion; however, the composites maintain plasticity. The barrier properties of the hydrophobic composites were characterized, and the water vapor permeability is found to be ca. 3.5 × 10 g·m·day·Pa and independent of the CBS content. On the other hand, oxygen permeability is found to depend on the CBS content, with values as low as 10 000 mL·μm·m·day·atm for 50 wt % CBS. Furthermore, CBS confer antioxidant activity to the composites and improve swelling properties rendering the composites biodegradable in aquatic environments, reaching 70% of the maximum biodegradability in just 30 days. The above, in conjunction with the low level of migration measured in food simulant, make the PLA/CBS composites a highly promising material for active food packaging.
通过将聚乳酸（PLA）与可可豆壳（CBS）细粉进行溶剂混合，随后采用不同浓度的CBS进行溶液浇铸，制备出了可持续生物复合材料。CBS的加入恢复了初始无定形PLA薄膜的结晶度，并改善了复合材料的物理性能。当加入75 wt%的CBS时，杨氏模量提高了80%；然而，复合材料仍保持可塑性。对疏水性复合材料的阻隔性能进行了表征，发现其水蒸气透过率约为3.5×10 g·m·day·Pa，且与CBS含量无关。另一方面，发现氧气透过率取决于CBS含量，对于50 wt%的CBS，其值低至10 000 mL·μm·m·day·atm。此外，CBS赋予复合材料抗氧化活性，并改善其溶胀性能，使复合材料在水生环境中可生物降解，在短短30天内即可达到最大生物降解率的70%。上述特性，再加上在食品模拟物中测得的低迁移水平，使得PLA/CBS复合材料成为一种极具前景的活性食品包装材料。
