Cold-Pressing Processing of a Fluoropolymer-Based Composite Material

• Published in: Theoretical foundations of chemical engineering Vol. 57; no. 1; pp. 112 - 118
• Main Authors: Stolin, A. M., Stelmakh, L. S., Stelmakh, E. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-02-2023; Springer Nature B.V
• Subjects: Additives; Carbon fibers; Carbon nanotubes; Chemistry; Chemistry and Materials Science; Cold pressing; Compacts; Composite materials; Density; Exact solutions; External pressure; Fluoropolymers; Industrial Chemistry/Chemical Engineering; Inhomogeneity; Kaolinite; Polymer matrix composites; Silicon dioxide; Lagrangian coordinates; cold pressing; density inhomogeneity; friction; fluoropolymer
• ISSN: 0040-5795; 1608-3431
• DOI: 10.1134/S0040579523010141

External friction–assisted single-action cold pressing is theoretically analyzed as applied to powder polymer composite materials based on a fluoropolymer with small contents of additives (<5%), such as silicon dioxide SiO
2
, kaolinite Al
4
[Si
4
O
10
](OH)
8
, carbon nanotubes, and carbon fiber. Analytical solutions are obtained in the form of formulas that make it possible to analyze how the compaction of the materials is affected by the applied pressure, the coefficient of external friction, the geometric sizes of the compacts, and the properties of the material, including its porosity. A simplified system of the initial equations in Lagrangian variables after averaging over the radius is used to numerically calculate the development of the density inhomogeneity over the volume of the material as a function of time, which is brought about by the difference between the compaction rates of the lower and upper layers. New clear concepts of the kinetics of compaction of fluoropolymer-based powder materials are determined, and the qualitative features of various stages of development of the density inhomogeneity are identified. Answers are found to the practically important questions related to the experimental determination of the time of the pressing process to obtain a high-quality blank.