Development of bioplastic composite films with improved antimicrobial properties: a comparative study between blown film extrusion, doctor blading and spray coating

Abstract

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) is a bioplastic that has gained attention as a potential alternative to petroleum-based plastics in film packaging due to its good barrier properties and thermal stability. However, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) has no outstanding properties. Therefore, the researcher added lignin powder to improve its antimicrobial properties, another essential property of the packaging film. This work successfully prepared a composite bioplastic film between poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and lignin powder by forming through a blown film extrusion, doctor blading, and spray coating. In order to give the film a high surface energy and enable it to adhere to the lignin solution on the surface, the film's surface underwent corona treatment before the spray coating process. The composite films were studied with analytical instruments for morphological, mechanical, contact angle, barrier, anti-UV, and antimicrobial properties. The effect of added lignin greatly improves the oxygen and water vapor permeability properties of the film. Regarding anti-UV properties, lignin exhibited UV blocking in the wavelength range of 300 to 400 nm. When studying the antimicrobial property, it was found that the composite film was able to inhibit gram-positive bacteria well. Compared to gram-negative bacteria, which cannot show very good antimicrobial properties. Corresponding to the overall properties, the bioplastic composite film formed by blown film extrusion showed excellent properties as a packaging film compared to the doctor blading and spray coating.