Development of experimental procedures for application of digital image correlation during PTFE sintering

• Grant number: 18/02179-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2018
• End date: July 31, 2019
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Rodrigo Bresciani Canto
• Grantee: Matheus Freire Garcia
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 18/22811-4 - Identification of elastic properties of PTFE at different temperatures via digital image correlation, BE.EP.IC

Abstract

PTFE (polytetrafluoroethylene) is a polymer with excellent strength and mechanical properties even when submitted to high work temperatures (up to 260 °C). This material presents high dynamic viscosity in the molten state which makes unfeasible its processing by extrusion or injection molding. Instead, the PTFE granules (form in which the material is commercialized) are processed by techniques as cold pressing followed by sintering. Thus, the main disadvantages of the use of PTFE in the industry are the relatively high costs of the raw material and of the processing. Bulky PTFE parts can be submitted to severe thermal gradients capable of damage the material during the sintering. In order to enrich the understanding and contribute to the planning of the sintering during this project, a thermal chamber with windows will be developed for the application of the Digital Image Correlation (DIC) in green PTFE compacts submitted to thermal gradients (H 100 °C between the base and the top of the green compact). In this apparatus, the isostatically pressed PTFE green compacts will be instrumented with thermocouples for temperature measurement in different regions. As results, maps of strain and displacement isovalues will be obtained by DIC and presented with emphasis to the interface between the regions that passed the melting temperature and those that did not. This interface can be a source of damage in PTFE parts during the sintering. In conclusion, to obtain the strain fields in the compact submitted to considerable thermal gradients is the main contribution of the equipment to be developed.