The continuous depolymerization of filled polytetrafluoroethylene with a continuous process

24 May 2010

A new method for beneficiating unfilled as well as filled polytetrafluoroethylene (PTFE) waste has been developed. This process does not use any carrier gas while forming the depolymerization products. It enables polymer manufacturers and end‐users to reuse and adds value to filled fluorocarbon polymer waste. The filler material was qualified by means of scanning electron microscopy and thermogravimetric analysis and the success of the depolymerization process inside a rotating kiln was proved by visual observation. The PTFE was depolymerized inside a kiln‐type reactor declined at a 5° angle, with a central rotating paddle screw to scrape the inner wall of the reactor, which was able to operate within the temperature range of 600–800°C and pressure range of 10–90 kPa. Different ratios of the useful products tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and octafluorocyclobutane (OFCB) were produced. The optimum conditions for TFE production are 600°C and 10–30 kPa, for HFP production it was 800°C and 10 kPa, and for OFCB production 600°C and 90 kPa. Temperatures of 700°C should be avoided as this leads to considerable amounts of undesirable HFE and OFP as well as the very toxic PFIB