BIOCOMPOSITE REINFORCED WITH MICROFIBRILLATED CELLULOSE (MFC) FOR PAPER PACKAGING COATING
Biocomposites are materials in which the matrix is generally made by a polymeric material and the dispersed phase materials from natural origin, such as fibers. In recent decades, due to the need of sustainable alternatives to petroleum-derived polymers, this type of material has been studied as coating for paper packaging (cellulose). This coating aims to improve barrier properties in relation to water, oils and gases, while maintaining sustainability aspects such as biodegradation, compostability, use of renewable materials and paper repulpability. The objective of this study was the development of a biocomposite with dispersed phase of microfibrillated cellulose (MFC) that will be applied in packaging or paper artifacts normally used in the food industry. Two polymers of renewable origin and biodegradable were evaluated for the matrix, namely the poly(lactic) acid (PLA) and the poly(hydroxybutyrate) (PHB). The thermal behaviour and crystallinity of the polymers were analyzed by differential scanning calorimetry, the barrier properties through water vapor transmission rate and melt flow index tests. The biocomposites were prepared by extrusion using high (MFC-A) and low (MFC-B) refining MFC and the coating step on the paper by pressing was simulated in the film press. The biocomposite coated on the paper was based on PLLA 4043D, which presented the best results among the polymers analyzed, and thermal, rheological, migration and permeability analyzes of this material were carried out. It was shown that the composite with high-refining fiber had good interaction with the lighter paper grammage, in addition to a lower degree of crystallinity. In turn, the low-refined fiber showed a higher degree of crystallinity and better interaction with the heavier paper grammage. In general, composite materials showed better results than the raw polymer.