Identification of elastic properties of PTFE at different temperatures via digital image correlation

• Grant number: 18/22811-4
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: December 15, 2018
• End date: March 14, 2019
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Rodrigo Bresciani Canto
• Grantee: Matheus Freire Garcia
• Supervisor: Nicolas Pierre Schmitt
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: École Normale Supérieure, Cachan (ENS), France
• Associated to the scholarship: 18/02179-1 - Development of experimental procedures for application of digital image correlation during PTFE sintering, BP.IC

Abstract

PTFE (polytetrafluoroethylene) is a polymer with distinguished properties, commonly used in applications when high working temperatures (up to 260°C) and chemical stability are needed. This material exhibits high viscosity even above the melting temperature Tm(H327°C, for first melting), thus, to form PTFE parts, polymer granules are cold-pressed and sintered. The costs of this manufacturing process and of producing the raw material are the main disadvantage of PTFE uses in the industry. During the sintering process, due to the low thermal conductivity of PTFE, the parts are exposed to temperature gradients and consequently self equilibrated internal stresses occur that may damage the finished part. If the sintering process is numerically simulated, the risk of damage of parts can be diminished and the sintering step de optimized, increasing production. For an accurate modelling of the process, material properties should be well known. With the objective of enriching the simulation of PTFE sintering, this Research Internship Abroad (BEPE) project proposes running simple compression tests to measure the elastic isotropic properties (Young's Modulus, E, and the Poison's ratio, ½) of PTFE parts at different temperatures, using specimens obtained by isostatic pressing. The proposed tests will be carried out in a universal testing machine equipped with an oven and windows for image capture. The windows enable the execution of Digital Image Correlation (DIC), which provides displacement field measurements without contact with the specimen. The main expected results are the elastic parameters, E(T) and ½(T), of PTFE at different temperatures (30, 100, 170, 240, 300, 320, 340, 360, 375 and 390°C). The results will be verified via a comparison with literature data and will be compiled to compose a scientific publication. (AU)