Preparation of pampas grass (Cortaderia selloana) cellulose nanofibers (CNF) and its potential as a reinforcing material in polyvinyl acetate (PVAc) nanocomposites

Renewable natural sources have been recently used to produce nanocellulose for the mechanical reinforcement of polymers. Cortaderia selloana (a.k.a. pampas grass) is a worldwide spread grass species, being able to grow even at extreme climatic situations, like high temperatures, arid soil and sunny regions. Although it is capable of offering a relatively abundant quantity of lignocellulosic material, it was not considered before its utilization for technological ends. This study proposes a protocol of chemical and mechanical treatments that allowed the production of nanocellulose from this source and performed characterization techniques that evaluate the influence of these treatments on its morphological (width in the nanoscale), chemical, rheological and physical characteristics, allowing its further application. The obtained cellulose nanofiber (CNF) was used to improve characteristics of a well-known but underused polymer, the polyvinyl acetate (PVAc) commercial emulsion. The nanocomposites (PVAc-CNF) showed an improvement of the thermal and mechanical properties, and an addition of just 1.25% of CNF resulted in an increase of the tensile strength from ˜42 to ˜78 MPa and enhanced the thermal stability. The results obtained suggests an effect of defibrillation intensity on the rheological behavior and crystallinity index of the CNF, as well over the performance as a nanofiber for the PVAc matrix, where less defibrillated material showed a high viscosity and crystallinity index but was less effective on the mechanical reinforcement of the polymer. Suggesting that for each botanical species that could be considered for nanocellulose production it is important to evaluate the impact of the processing on the overall quality of the material and how it will implicate its application.