Processing Analysis of Nanoparticle Filled PTFE: Restrictions and Limitations of High Temperature Production

In this research work, unfilled and monofilled polytetrafluoroethylene (PTFE) were investigated. The applied fillers were graphene, alumina (Al(2)O(3)), boehmite alumina (BA80) and hydrotalcite (MG70). Graphene and Al(2)O(3) are already known in the literature as potential fillers of PTFE, while BA80 and MG70 are novel fillers in PTFE. Materials were produced by room temperature pressing—free sintering method with a maximum sintering temperature of 370 °C. The mass loss and decomposition analyses were carried out by thermogravimetric analysis (TGA) in two different ways. The first was a sensitivity analysis to gain a better view into the sintering process at 370 °C maximal temperature. The second was a heating from 50 °C up to 1000 °C for a full-scale decomposition analysis. BA80 is a suitable filler for PTFE, as most of its functional groups still existed after the sintering process. Both PTFE and Al(2)O(3) had high thermal stability. However, when Al(2)O(3) was incorporated in PTFE, a remarkable mass loss was observed during the sintering process, which indicated that the decomposition of PTFE was catalysed by the Al(2)O(3) filler. The observed mass loss of the Al(2)O(3)-filled PTFE was increased, as the Al(2)O(3) content or the applied dwelling time at a 370 °C sintering temperature increased.