PTFE Material is highly resistant to heat, as well as attack from most chemicals. The electrical properties are excellent. Though it has high impact strength, its resistance to wear, durability, and creep resistance are low as compared to alternative engineering-grade thermoplastics. Like many other plastics, its properties are often improved by adding fillers like glass fibre, carbon, and/or graphite.
25% Glass filled PTFE is used to improve the creep resistance of PTFE over all temperature ranges, while still allowing some compression required for sealing in both gaskets and valves. Improved wear behaviour is exhibited, while there is little effect on the electrical properties, as glass fibre is an insulator. 25% Glass has an exceptional resistance to water. Still giving excellent chemical stability, PTFE +25% GF has better thermal conductivity and coefficient of friction when combined with MoS2 or graphite. (Information from Plastim Ltd)
PTFE carbon filled has better creep and wear resistance compared to standard PTFE Sheet. These properties are improved with the addition of a carbon filler. This filler improves dimensional stability, raises the heat deflection temperature, improves creep resistance, and enhances dynamic bearing performance. This grade provides 3½ times higher thermal conductivity than non-reinforced PTFE — dissipating heat from the bearing surface faster. Carbon-filled PTFE is black in colour. (Information from Plastim Ltd)