Hydrophobic properties of cardboard coated with polylactic acid and ethylene scavengers

The corrugated cardboard used in food packaging readily absorbs moisture from the environment, especially when stored under high humidity conditions. In this research, the water barrier of cardboard was modified by changing the wettability of the cardboard surface, applying hydrophobic coatings of polylactic acid (PLA), alone or in combination with other substances that absorb gases (ethylene scavengers) such as clinoptilolite (C), sepiolite (S), and sepiolite permanganate (SP). The water barrier properties tested as water vapor permeability (WVP), water absorptiveness (WA), and water drop contact angle (CA) showed that the water resistance of the resulting cardboard was improved by the coating. The best results of these properties were obtained by using a coating of PLA 2% alone. In addition, PLA 2% with C 1.5% also showed good results, but the WA results were higher. The use of PLA coating produces a greater uniformity and smoothness of the coated cardboard surface due to the best filling of the pores or spaces between cellulose fibers. Our findings and the environmentally friendly nature of PLA strengthen the advantages of using these kinds of coatings on cardboard trays for the packaging, storage, and transport of foods such as fresh fruit and vegetables.