Fractal-Percolation Approach for Determination of Structural and Mechanical Properties of Metal-Filled Polyurethane Auxetics

Abstract

The use of fractal and percolation approaches to the metal-filled polymer systems enables to analyze processes of their structure formation. The main aim of research paper is to define structural parameters and mechanical properties of metal-filled polyurethane systems based on results of ultrasonic study using fractal analysis and percolation approach. Polyurethanes auxetics filled with particles of iron (Fe), molybdenum (Mo) and wolfram (W) with radius between 0.3-1.0 µm are investigated. Polyurethane composites with polymer matrix are made of thermoplastic polyurethane synthesized from 4.4′-Methylen diphenyl diisocyanate, 1.4-Butanediol and Poly(tetramethylene ether)glycol with molecular weight 1500. Metal-filled polymer systems are obtained with the help of hot-pressing in T-p mode just after the components were all mixed. The results of acoustic research of investigated metal-filled thermoplastic polyurethane systems with 52% vol. Fe, 48% vol. W, 43% vol. Mo have proven to be with negative Poisson's constant. Based on percolation cluster model of metal-filled polyurethane auxetics their fractal dimensions and percolation indexes are distinguished. Usage of fractal-percolation ap

Viscoelastic Properties of Filled Polyurethane Auxetics

“…Filled polymer systems were obtained with the help of hot pressing in T-p mode just after the components were all mixed. Volume filler's density for TPU systems was critical to the system, so respectively for Mo, Fe, W it was 48, 43 and 52 % [27,28].…”

Percolation characteristics of filled polyurethane auxetics

“…Among such materials a special place belongs to polymer auxetics [4][5][6], which find prospects for application in various fields of science, technology, production [7,8]. Various models are used to analyze the structural features of polymer systems with a negative Poisson's ratio and their auxetic behavior [9,10].…”