The properties of poly(tetrafluoroethylene) (PTFE) in compression

Compressive properties of extruded polytetrafluoroethylene

“…In order to determine the degree of crystallinity in the sample, DSC and density measurements were conducted, as described by Rae and Dattelbaum [4]. By employing the same analysis and material constants it is possible to make direct comparisons between the PTFE 9B reported in the current work and the previously reported work on PTFE 7C [4e11].…”

“…The constants are taken directly from Rae and Dattelbaum [4], who in turn took them as the averages of the wide range of reported values from the literature as tabulated by Lehnert [38]. The measured densities, heats of fusion and calculated crystallinities are presented in Table 2 and Fig.…”

“…Dynamic mechanical analysis of annealed PTFE. Table 2 Densities, heat of fusion and calculated crystallinity for as-received and annealed PTFE compared to as-received PTFE 7C [4,11] Density (kg/m 3 )…”

“…Although some studies on the compressive properties of PTFE across a range of strain rates and temperatures have been presented in the literature [1e3], until recently importance was not placed on the processing history of the material prior to testing [4e11]. However, the processing route used to prepare the PTFE can greatly affect the crystallinity of the material, which is known to influence the strength and deformation behavior [4,5].…”

“…While phases II and IV are rigorously crystalline, phase I is sometimes described as mesophase [12]. In addition, the amorphous PTFE undergoes three relaxations, g and a, which are similar to glass transitions and b, which encompasses the crystalline phase transitions between phases II, IV, and I [4,13]. PTFE can be thought of as a two-phase structure, similar to a particulate composite, with a ''rigid'' crystalline phase in a matrix of a ''softer'' amorphous phase.…”