Polychlorotrifluoroethylene shear

Figure 6.5 Shear modulus Gi and logarithmic decrement A of polychlorotrifluoroethylene (PCTFE) and polyvinyl fluoride (PVF) as a function of temperature at 3 Hz. (Reproduced with permission from Schmieder and Wolf, Kolloidzeitschrift, 134,149 (1953))...

A number of commercial polychlorotrifluoroethylene products such as Fluorolube and Kel-F (oils, grease and powders) when used for machining aluminium yield explosive reactions under high shear loads. This kind of reactivity is rarely observed with pure fluorocarbons. Thus, it is assumed that the high reactivity stems from the chlorine connected to the polymer that is more easily abstracted than fluorine. In addition, thermal reaction between A1 and Kel-F oil has been observed at temperatures as low as 218 °C, whereas a fully fluorinated grease does not react until about 648°C [13]. Tribochemical-induced reaction between fluorocarbons and certain metals has been confirmed by Electron Spectroscopy for Chemical Analysis (ESCA) investigations on PTFE samples filled with both aluminium and zinc [14, 15]. 

Epoxy-polyamide and epoxy-polysulfide adhesives have been used successfully for bonding properly treated polychlorotrifluoroethylene (PCTFE). An epoxy-polyamide adhesive (Epon 828/Versamid 125 60 40 ratio) cured for 16 h at room temperature followed by 4 h at 74°C has given tensile-shear strengths of 19.6—20.8 MPa for various grades of PCTFE resins treated with sodium naphthalene etch solutions and also abraded [28,29]. 

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