PTFE (Teflon) Rods have excellent thermal and electrical insulation properties, have low coefficient of friction, but are not suitable for wear application and are difficult to bond with adhesive.
 
Pure PTFE Rods - highly flexible as well as extremely dense, low friction and can withstand huge changes in temperature
Glass-filled PTFE Rods - stronger and more durable
Carbon-filled PTFE Rods - improved compressive strength, reduced deformation under heavy loads, and better wear resistance
Bronze-filled PTFE Rods - has good thermal and electrical conductivity
other fillers may not be readily available