Polytetrafluoroethylene ---- mechanical properties

The coefficient of friction of PTFE is extremely small, only 1/5 of that of polyethylene, which is an important characteristic of perfluorocarbon surfaces. And because of the fluorine-carbon chain intermolecular force is very low, so polytetrafluoroethylene has non-stick.

PTFE in -196 ~ 260 ℃ in a wide range of temperature are to maintain excellent mechanical properties, one of the characteristics of perfluorocarbon polymer is not brittle at low temperatures.

PTFE density is large, 2. 14 a 2. 20g/cm3, almost non-absorbent, equilibrium water absorption rate of less than 0. 01%.

PTFE is a typical soft and weak polymer, the mutual gravitational force between macromolecules is small, stiffness, hardness, strength are small, in the long-term role of stress will be deformed.

PTFE is a typical plastic with cold flow when loaded, and creep varies with compressive stress, temperature and crystallinity, the higher the temperature, the greater the creep. The crystallinity of PTFE is between 55% and 80%, creep does not exceed 2%; when the crystallinity is below 55% and above 80%, creep increases rapidly.

The excellent mechanical properties of PTFE is a small friction factor, between 0. 01 and 0. 10, the smallest among existing plastic materials, and even all engineering materials.

PTFE friction factor increases with the increase in sliding rate, when the linear velocity reaches 0. 5 a. 1. 0m / s or more tends to stabilize; and static friction factor is less than the dynamic friction factor, this characteristic will be used in bearing manufacturing, can reduce its starting resistance, so that it is very smooth from the start to operation. PTFE friction factor decreases with the increase in load, when the load reaches 0. 8 MPa or more tends to Constant. At high speed and high load, the friction factor of PTFE is less than 0.01. From ultra-low temperature to the melting point of PTFE, the friction factor is almost constant, and only when the surface temperature is higher than the melting point, the friction factor increases sharply.

Due to the low intermolecular gravitational force, the hardness of PTFE is low and easily worn by other materials. However, as long as the surface roughness of the abrasive material is suitable, the amount of wear of PTFE can be reduced to a considerable extent.

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