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Depolymerization of clean unfilled PTFE waste in a continuous process

Authors

  • I. J. Van Der Walt,

    Corresponding author
    1. South African Nuclear Energy Corporation, Church Street Extension, Pelindaba, Pretoria 0216, South Africa
    • South African Nuclear Energy Corporation, Church Street Extension, Pelindaba, Pretoria 0216, South Africa
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  • O. S. L. Bruinsma

    1. School of Chemical and Minerals Engineering, North-West University, Hoffmanstraat, Potchefstroom 2531, South Africa
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Abstract

A continuous process is described whereby waste PTFE was converted into tetrafluoroethylene (C2F4, TFE), hexafluoroethane (C2F6, HFE), hexafluoropropylene (C3F6, HFP), and octafluorocyclobutane (c-C4F8, OFCB). The waste PTFE was depolymerized inside a reactor that was heated by a radiofrequency induction generator. The reactor was capable of operating at various temperatures (600–900°C) as well as various reduced pressures (5–80 kPa). The depolymerization reaction conditions could be changed while the reactor was in operation in order to manipulate the reaction product composition. Under certain conditions, high yields of TFE (> 94%) and low concentrations of by-products were formed. The PTFE was fed vertically downward from the hopper, with the screw feeder, into the reactor where the depolymerization process took place. The hot intermediate products were continuously evacuated through a self-cleaning quench probe, where it was quenched to form the final products. The depolymerized products were analyzed with a gas chromatograph. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2752–2759, 2006

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