Assessing the effect of compaction pressure on the mechanical properties of polytetrafluoroethylene elaborated by field assisted sintering technique

Abstract

We study the effect of compaction pressure on the mechanical properties of polytetrafluoroethylene (PTFE) synthesized by the field-assisted sintering technique (FAST). PTFE is a commonly polymer use material with various technological applications in the automotive, aerospace, and chemical industries. While the manufacture of PTFE is problematic due to its high molecular weight and hence a very high melt viscosity, FAST is an adequate process which can fix this problem by offering rapid densification (a few minutes). In this context, we explore the mechanical behavior of sintered PTFE produced with different compaction pressures, all other operating parameters being held constant. The stress-strain curves of PTFE investigated by uniaxial tension tests show a significant dependence of the compaction pressure on the elastic and plastic mechanical characteristics. An attempt is made to correlate the applied pressure during the sintering process to microstructural changes according to the de Gennes creep model. For plastic deformation, the stress-strain curves are compared to the predictive Hollomon's and Haward and Thackray's models and discussed in physical terms. We conclude that a better mechanical behavior of sintered PTFE materials can be achieved by using an optimum value of compaction pressure which is not necessary found above the yield flow. • PTFE samples produced by the field-assisted sintering technique are characterized. • Stress-strain curves show significant dependence on compaction pressure. • Hollomon's and HT analysis allow us to characterize the strain hardening behavior. • Optimal properties correspond to sintered samples at pressure less than 5 MPa.