Fluoroelastomers, comparison

Figure 10 Comparison of hardness 3 sigma variability ratings fluoroelastomer compound.

Figure 5 Comparison of HNBR with fluoroelastomer (FPM), NBR and XNBR in Sour Crude Oil (sour gas = 20% H2S + 65% CH4 + 15% CO2). Source Bayer AG, Germany.

In all these comparisons, the overall properties must be taken into account. Although fluoroelastomers have excellent compression set properties, the other poor physical properties and cost also must be considered. 

Fluoropolymers are thermoplastic and nonrigid materials while fluoroelastomers have elastomeric properties. See Tables 2.1 and 2.2 for a comparison of physical and mechanical properties of select plastics and elastomers including fluorinated materials. 

Fluoroelastomers Product Information Manual (1997), Product Comparison Guide (1999), Dyneon LLC, A 3M-Hoechst Enterprise, Oakdale, Minnesota, 1997. 

Fig. 4.8. Failure envelopes from rubber vulcanizates. (a) Schematic representation of the dependence of tensile stress-strain curves for an amorphous rubber on strain rate and temperature (b) failure points for a resin-cured butyl rubber gum vulcanizate tested at various rates and temperatures, = stress at break, b = elongation at break (c) comparison of vulcanizates (Viton B is a fluoroelastomer). Ab = relative extension at break, Ec = equilibrium modulus. (From Smith, 1962.)...

Comparison of NBR with Fluoroelastomers A paper by Du Pont published in 1984 compared nitrile elastomer with various fluoroelastomers. The results compared soft and hard seals at 150°C and 200°C, in various oil well fluids. 

Table 19 shows this effect, in comparison with the same data obtained for fluoroelastomer, which is obviously superior. 

Two demanding environments are considered explosive decompression and hydrogen sulphide exposure. A brief review of previous data is given for the former, comparing different polymer types. An attempt is also made to establish a compounding baseline to optimise HNBR performance by examining formulation variables and their effects. For the latter, a comparison of HNBR with NBR, FKM fluoroelastomer and TFE/P is made, as well as a brief look at the effect of ACN (acrylonitrile) content on performance. 4 refs. CANADA... 

Diamines were the first materials used to cross-link polyacrylates and fluorocarbon polymers. They provide excellent compression set and aging characteristics, but require an oven post-cure after molding to develop optimum properties. These curatives are also corrosive to mild steel molds. See Table 13.10 for a comparison of two diamines and a bisphenol curative in a fluoroelastomer. 

A comparison is made of standard kneading elements with tapered kneaders nsing results from several case studies. These case studies relate to the compounding of foamable, carbon black filled EPDM automotive weather stripping, an EPDM roofing compound and fluoroelastomer based compounds. 

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