Modificação de microfibrilas de celulose e sua aplicação com látex de borracha natural no recobrimento de papel kraftliner

Abstract

The accumulation of plastic waste, especially from packaging, has driven the search for sustainable alternatives. In this context, the pulp and paper sector stands out, although it still faces limitations such as high hydrophilicity and low gas resistance. This study aimed to evaluate the effect of the chemical modification of cellulose microfibrils (MFCs) with fatty acids derived from carnauba wax, in combination with natural rubber latex, on the coating of kraftliner paper. The microfibrils were subjected to solvent exchange and subsequently modified with carnauba wax under acidic conditions, and then incorporated into formulations containing natural rubber latex. The coatings were applied using a coating machine, resulting in papers composed of two coating layers with a total basis weight of 15 g/m². The modified MFCs were characterized by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), while the coating suspensions were evaluated for solids content, pH, viscosity, and rheology. The coated papers were subjected to analyses including basis weight, scanning electron microscopy (SEM), oil resistance, pencil hardness, water absorption capacity (Cobb 120), water vapor transmission rate (WVTR), water vapor permeability (WVP), and contact angle/wettability. The results indicated that the modification of MFCs, combined with the incorporation of natural rubber latex, improved the physicalmechanical properties and barrier performance against moisture, gases, and oil of kraftliner paper. Therefore, the combination of modified cellulose microfibrils and natural rubber latex proved to be a promising strategy for the development of sustainable coatings, with potential application in replacing plastic materials in packaging.