Masterbatch efficiency system for rubbers

Abstract

The quest to develop more eco-friendly and sustainable rubber products requires the use of lightweight fillers made from renewable feedstock and that have suitable mechanical and functional properties. Cellulose nanocrystals (CNCs) are among the most promising candidates for such applications due to their sustainability, abundance, high surface area, and excellent mechanical properties. To achieve a good reinforcing performance from CNCs in rubber, a high level of dispersion is needed. We have studied here the co-coagulation of natural rubber (NR) latex and CNC dispersions, which is possible because of the aqueous colloidal stability of both the CNC dispersion and NR latex. The coagulants used in this study are acetic acid, formic acid, and a combination of these acids with CaCl2 salt. While all the coagulants provided good coagulation, as seen by an excellent integration of the CNC into the rubber matrix, a combination of the acids with CaCl2 produced an undesirable CNC aggregation likely through the formation of CNC-cation-CNC bridges. Formic acid provides optimal co-coagulation and CNC dispersion as observed from scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) evaluations.