Mixing additives into polymers carbon black

To improve the properties of the raw polymer (wear resistance, creep resistance, thermal and electrical conductivity), various fillers, such as glass fibers, powdered metals, and graphite, are combined with all three types of PTFE polymers, mostly by intimate mixing. Filled fine powders are produced mostly by adding fillers into a dispersion and then coagulating the mixture. Aqueous dispersions can also be modified by the addition of certain fillers, pigments, heat resistant dyes, carbon blacks, and powdered metals, especially when processed into films (see Chapter 6). 

Fig. 2.2. Simplified flow chart of the Phillips process (solution phase polymerisation) (Elias 1992). The solvent (for example isobutane), ethylene, co-monomers and the catalyst are fed into the reactor. The polymer solution is de sed (flashed) from the reactor through a gas separator after a certain reaction time. In a cleaning nnit (centrifuge, washing device, drier) the polymer is separated out and ethylene and solvent residues are processed. The polymer emerges in the drier in the form of snow white flakes. Flakes, carbon black, stabiliser and further additives, for example Ca-stearate, are mixed in a mixer and this mix is fed into an ex-tmder at an adequate mix raho with the polymer flakes. Here the mix is melted, homogenised and finally granulated. The black pellets are then transported to the storage facihties...

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