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 (Al₂O₃), boehmite alumina (BA80) and hydrotalcite (MG70). Graphene and Al₂O₃ 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 Al₂O₃ had high thermal stability. However, when Al₂O₃ 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 Al₂O₃ filler. The observed mass loss of the Al₂O₃-filled PTFE was increased, as the Al₂O₃ content or the applied dwelling time at a 370 °C sintering temperature increased.