Velásquez Eliezer, López de Dicastillo Carol, Patiño Vidal Cristian, Copello Guillermo, Reyes Cristopher, Guarda Abel, Galotto María José
Packaging Innovation Center (LABEN-Chile), University of Santiago of Chile (USACH), Santiago 9170201, Chile.
Center for the Development of Nanoscience and Nanotechnology (CEDENNA), University of Santiago of Chile, Santiago 9170124, Chile.
Polymers (Basel). 2023 Feb 21;15(5):1081. doi: 10.3390/polym15051081.
The food industry has a current challenge of increasing the recycling of post-consumer plastics to reduce plastic waste towards a circular economy, especially flexible polypropylene, which is highly demanded in food packaging. However, recycling post-consumer plastics is limited because service life and reprocessing degrade their physical-mechanical properties and modify the migration of components from the recycled material to the food. This research evaluated the feasibility of valorization of post-consumer recycled flexible polypropylene (PCPP) by incorporating fumed nanosilica (NS). For this purpose, the effect of concentration and type (hydrophilic and hydrophobic) of NS on the morphological, mechanical, sealing, barrier and overall migration properties of PCPP films was studied. Incorporating NS improved Young's modulus and, more significantly, tensile strength at 0.5 wt% and 1 wt%, where a better particle dispersion was confirmed by EDS-SEM, but it diminished elongation at breakage of the films. Interestingly, NS tended to increase the seal strength of PCPP nanocomposite films more significantly at higher NS content, showing a seal failure of the adhesive peel type which is preferred for flexible packaging. NS at 1 wt% did not affect the water vapor and oxygen permeabilities of the films. Overall migration of PCPP and nanocomposites exceeded the limit value of 10 mg dm allowed by European legislation at the studied concentrations of 1% and 4 wt%. Nonetheless, NS reduced the overall migration of PCPP from 17.3 to 15 mg dm in all nanocomposites. In conclusion, PCPP with 1 wt% of hydrophobic NS presented an improved overall performance of the studied packaging properties.
食品行业目前面临一项挑战，即增加消费后塑料的回收利用，以减少塑料垃圾，朝着循环经济发展，尤其是食品包装中需求量很大的软质聚丙烯。然而，消费后塑料的回收利用受到限制，因为使用寿命和再加工会降低其物理机械性能，并改变回收材料中成分向食品中的迁移。本研究评估了通过添加气相纳米二氧化硅（NS）使消费后回收软质聚丙烯（PCPP）增值的可行性。为此，研究了NS的浓度和类型（亲水性和疏水性）对PCPP薄膜的形态、机械、密封、阻隔和总体迁移性能的影响。添加NS提高了杨氏模量，更显著的是，在0.5 wt%和1 wt%时提高了拉伸强度，EDS-SEM证实此时颗粒分散性更好，但降低了薄膜的断裂伸长率。有趣的是，在较高NS含量下，NS更显著地提高了PCPP纳米复合薄膜的密封强度，呈现出柔性包装首选的粘合剂剥离型密封失效。1 wt%的NS不影响薄膜的水蒸气和氧气透过率。在1%和4 wt%的研究浓度下，PCPP及其纳米复合材料的总体迁移量超过了欧洲法规允许的10 mg/dm²的限值。尽管如此，NS使所有纳米复合材料中PCPP的总体迁移量从17.3降至15 mg/dm²。总之，含有1 wt%疏水性NS的PCPP在所研究的包装性能方面呈现出改善的总体性能。
