Influence of different synthesis processes on the rheology of PVAc–MMT–DOAB exfoliated nano-composite

It is very helpful to guide design production and processing conditions for polymer-based inorganic or organic nano-composites by investigating their rheology. In this study, an intercalated nano-composite of montmorillonite (MMT)-dioctadecyl dimethyl ammonium bromide (DOAB) was added and reacted with vinyl acetate (VAc) to form the exfoliated nano-composite of polyvinyl acetate (PVAc)–MMT–DOAB through five different synthesis processes. The MMT–DOAB was exfoliated into nano-particles of layers or sheets and dispersed randomly in PVAc matrix. The different synthesis processes affected the dispersion and apparent viscosity of PVAc and PVAc–MMT–DOAB. With the polymerization time shortening and the water decreasing, the dispersion got bad and the apparent viscosity increased. PVAc and PVAc–MMT–DOAB were pseudo-plastic non-Newtonian fluids and both possessed the normal stress effect (Weissenberg effect) that is also called the pole-climbing phenomenon. By the help of the apparent viscosity analyzed using the power-law function equation, Newtonian fluid flow equation and Cross-Williamson model viscous equation, the different synthesis processes and MMT–DOAB had a certain effect on the rheology of PVAc and PVAc–MMT–DOAB. With the change of different synthesis processes and the increase of MMT–DOAB content in the synthesis system, the estimated molecular weight of PVAc–MMT–DOAB was also increased accordingly.