Paper Coating with Biodegradable Polymer for Food Packaging

Commodity plastics are widely used for food packaging. However, their slow degradation andpredicted exhaustion of the world petroleum reserves have become worldwide major environmentalconcerns. Therefore, it is necessary to quickly replace them with biodegradable polymers that candegrade in a short period when exposed to a biologically active environment. The possibility for theuse of biopolymers, such as poly-3-hydroxybutyrate (PHB) and polylactide (PLA), in paper coatingfor food packaging has been investigated in this study. Dip coating process has the potential ofproviding an easy and economical way to form PHB and PLA coated layers on paper. The effects ofdip coating operating parameters such as initial concentrations of polymer solution, types of solvent,types of paper and dipping periods have been investigated in this study. The dip-coated PHB and PLApapers were analyzed by gravimetric analysis and ATR-FTIR spectroscopy. The results showed thatthe polymer film weight also increased, as the polymer initial concentration and dipping periodincreased, and then reached the equilibrium state at the polymer initial concentration of 4%w/v andthe dipping period of 5 minutes. By varying types of solvent, chloroform and dichloromethane gavealmost the same satisfactory result for PHB dip coating while ethyl acetate provided the optimal resultfor PLA. By using different types of paper, the commercial bleached bagasse paper (Beermat )showed the most satisfactory results with the maximum adsorbed capacity of 122.9 and 99.3 mg/g forPHB and PLA coated paper, respectively. Generally, most coated papers showed better barrierproperties against air, water, and oil than the non-coated paper. However, the PHB coated papershowed higher water resistance but lower oil resistance than PLA coated paper.