Comparison between cellulose nanocrystal and microfibrillated cellulose as reinforcement of poly(vinyl acetate) composites obtained by either in situ emulsion polymerization or a simple mixing technique

Abstract

Nanocellulose is abundant, renewable, biocompatible, and a good candidate as reinforcement agent in nanocomposites; however, its hydrophilicity leads to poor dispersion in hydrophobic polymers. Recently, both in situ polymerization and cellulose surface modification have been used to improve dispersion, but emulsion polymerization is rarely adopted, and when it is, the reinforcement agent is usually cellulose nanocrystal (CNC), with gain in mechanical properties being the main focus of the research. Therefore, this work aims to explore the influence of adding either CNC or microfibrillated cellulose (MFC), both without surface modification, on the mechanical resistance, thermal degradation, and water vapor permeability of poly(vinyl acetate) composites obtained by either in situ emulsion polymerization or mixing. The results showed that despite having similar impacts on thermal and barrier properties, MFC and CNC affect the mechanical properties of their composites differently. Both cause decrease of the thermal degradation rate and do not have a significant impact on water vapor permeability. However, the addition of CNC during synthesis increased composite mechanical resistance significantly while the addition of MFC did not show improvement. Mechanical resistance is also strongly dependent on the procedure used to produce the composites.