Polyimides (PI) are known for their extremely high thermal stability and lack of a glass transition temperature below their decomposition point. Therefore, they are frequently used in high-demanding tribological applications. The tribological characteristics of sintered polyimide (SP-1) are presently investigated as a function of the sliding temperature that is artificially varied between 60 degrees C and 260 degrees C under fixed load in counterformal contact with a steel plate. For obtaining low friction and wear, a transfer film needs to develop onto the sliding counterface, induced by viscous polymer flow. As surface plastification is more difficult for high-performance materials, for example, polyimide, a transition towards low friction and stabilized wear rates is observed at temperatures higher than 180 degrees C in accordance with the occurrence of plate-like transfer particles, while high friction and no transfer was observed at lower temperatures. This transition is correlated to a peak value in both friction and wear at 180 degrees C and is further explained by Raman spectroscopy performed on the worn polymer surfaces and temperature-modulated differential scanning calorimetry. It is concluded that the intensity of C-N-C related absorption bands is minimal at 180 degrees C and is complementary to the intensity of the C=C phenylene structure that is maximal at 180 degrees C. The orientation of the C-O-C structure slightly decreases relative to the sliding surface at higher bulk temperatures. The amount of C=O functional groups is the lowest at 140 degrees C, while its orientation progressively enhances at higher bulk temperatures. At 140 degrees C also, the lowest wear rates were measured. The 180 degrees C transition temperature with a peak value in both friction and wear corresponds to a secondary transition measured in the specific complex heat capacity, pointing out that the overall bulk temperature is presently more important than local flash temperatures for causing transitions in tribological behavior. (c) 2006 Wiley Periodicals, Inc.