Rheology of Highly Filled Polymer Compositions—Limits of Filling, Structure, and Transport Phenomena

Abstract

The current state of the rheology of various polymeric and other materials containing a high concentration of spherical solid filler is considered. The physics of the critical points on the concentration scale are discussed in detail. These points determine the features of the rheological behavior of the highly filled materials corresponding to transitions from a liquid to a yielding medium, elastic–plastic state, and finally to an elastic solid-like state of suspensions. Theoretical and experimental data are summarized, showing the limits of the most dense packing of solid particles, which is of key importance for applications and obtaining high-quality products. The results of model and fine structural studies of physical phenomena that occur when approaching the point of filling the volume, including the occurrence of instabilities, are considered. The occurrence of heterogeneity in the form of individual clusters is also described. These heterogeneous objects begin to move as a whole that leads to the appearance of discontinuities in the suspension volume or wall slip. Understanding these phenomena is a key for particle technology and multiphase processing.

Rheological Behavior Features of Feedstocks with a Two-Component Wax–Polyolefin Binder Compared to Analogs Based on Polyoxymethylene

“…Currently, many papers regularly publish study results on the rheological properties of feedstocks and polymers used in them [8][9][10]. New reviews and articles devoted to the issues of modeling the molding process based on rheological data continue to appear [11][12][13].…”

“…Among the recent studies that analyze the rheological properties of feedstocks qualitatively rather than quantitatively, it is necessary to note several ones. Previous studies [8][9][10] presented a generalized diagram of the rheological states of suspensions with polymer matrices. For the first time, these studies discovered and described the presence of the elastic-plastic state region of suspensions, which may increase the fluidity of feedstocks at the maximum concentration of solid phase in powder casting.…”

A New Approach to Carbon Nanotube Filament Nanostructuring for Additive Manufacturing

“…Carbon nanotubes (CNTs) have recently been actively used as fillers [30,31] in creating conductive polymer-based compositions. The stability of CNTfilled filament and corresponding product properties is provided by the homogeneity of the filler spatial distribution over the polymer matrix volume [32]. Uneven distribution leads to void formation (misprinting) and 3D-printed layer displacement (smearing).…”