Structural characterization and high‐temperature compressive creep of PTFE‐based composites filled with inorganic nanoparticles

The PTFE‐based nanocomposites with various contents of inorganic nanoparticles (n‐AlN and n‐Si3N4) were prepared by cold compaction followed by free sintering. The results of scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction show that PTFE spherulite formed in the nanocomposites. When 2 wt% inorganic nanoparticles were added into the PTFE matrix, the crystallinity increased from 34.3% to 42.1% and 43.2%, respectively. Moreover, the interplanar distances for each crystal plane were enlarged and the grain sizes were smaller than that of pure PTFE. In addition, the mechanical and high‐temperature compressive creep properties were investigated. The results indicate that the introduction of inorganic nanoparticles largely increased the high‐temperature compressive creep resistance, and the maximal reduction of percentage of creep strain was up to 68%. The tensile strengths of the nanocomposites increased with increasing filler content when it was no more than 2%, and then decreased with the further increase of the filler content, whereas the elongations at break showed a reverse tendency.