STUDY ON THE VISCOELASTOPLASTIC PROPERTIES OF POLYTETRAFLUOROETHYLENE AND NANOCOMPOSITES WITH INCREASED WEAR RESISTANCE BASED ON IT. PART 1. MATERIALS, TEST PROGRAMS AND BASIC PROPERTIES

Abstract

This is the first (introductory) article in a series of articles devoted to a comprehensive experimental study and modeling of the viscoelastoplastic properties of polytetrafluoroethylene and a number of composites with increased wear resistance based on it, obtained in recent years in the laboratories “Technology of Polymer Nanocomposites” and “Polymer Composites for the North” of the Ammosov North-Eastern Federal University by introducing layered silicates (mechanically activated kaolin and serpentine, magnesium spinel) and short basalt or carbon fibers as fillers. Data from quasi-static tensile tests of these materials under different loading programs are presented: a family of stress-strain curves (until failure) at different strain rates, loading and unloading curves at different strain rates, creep and recovery curves for different stress levels, etc. The basic scalar characteristics of materials are determined (instantaneous modulus, yield strength, stress and strain at failure depending on the loading rate, etc.), the influence of the composition and proportion of fillers on them, and their strain rate sensitivity are analyzed. After mechanical tests, changes in the microstructure of PTFE and composites with different filler contents in the destruction zones of the samples were studied using a scanning electron microscope. An initial analysis of the volume of test data accumulated over 2 years revealed high deformability of materials, pronounced hereditary properties, the ability of materials to creep (flow) under constant load and accumulate irreversible (plastic) deformation, very high strain rate sensitivity, a strong influence of small amounts of fillers on the structure and mechanical properties. A more detailed presentation of the entire volume of test data and effects found, a systematic study of the viscoelastoplastic properties of these materials with different filler contents and their detailed comparative analysis as well as detection of connection with wear resistance are the topics of subsequent articles in the series in 2023-2025.