Advantages and disadvantages of PTFE materials
sourceBaidu
publisherTina
time2016/09/14
- Advantages and disadvantages of PTFE materials
Advantage：
1.Resistance to high temperature, the use of the operating temperature of 250 degrees.
2.Resistance to low temperature -- with good mechanical toughness; even if the temperature dropped to -196 degrees Celsius, but also to maintain an elongation of 5%.
3.The corrosion of most chemicals and solvents, showing the inertia, resistance to acid and alkali, water and organic solvents.
4.Weather resistant - there is the best aging life of plastics.
5.High lubrication is the lowest friction coefficient of solid materials.
6.Does not adhere to the minimum surface tension of the solid material, does not adhere to any material.
7.No poison - has the physiological inertia, as artificial blood vessels and organs for long-term implantation in vivo without adverse reactions.
8.Electrical insulation - can resist 1500 volts of high voltage power.
9.PTFE relative molecular mass is larger, low for hundreds of thousands, up to more than ten million
PTFE relative molecular mass is larger, low for hundreds of thousands, as high as ten million or more, generally for millions (degree of polymerization in the 10^4, and polyethylene only in 10^3).The general crystallinity was 90 ~ 95%, and the melting temperature was 327 ~ 342℃.The CF2 unit of PTFE molecules in a zigzag shape arrangement, because the carbon fluorine atom radius is slightly larger, so the CF2 unit can not completely according to the adjacent trans cross orientation, twisted chains, but the formation of a spiral, covering almost the entire surface of fluorine polymer chain.This molecular structure explains the various properties of PTFE.When the temperature is below 19 degrees Celsius, the 13/6 helix is formed; the phase transition occurs at 19℃ and the molecule is slightly loosened to form a 15/7 helix.
Disadvantages:
1.PTFE has a "cold flow".It is the plastic deformation (creep) under the action of long time continuous load, which brings certain limitation to its application.When PTFE used as a sealing pad, seal tight and the bolts are screwed tightly, so that more specific compression stress, the gasket of "cold flow" (creep) and squashed.These shortcomings can be overcome by adding appropriate fillers and improved part structure.
2.PTFE has a prominent non viscous, limiting its industrial applications.It is an excellent anti - adhesive material, which makes it difficult to bond with the surface of other objects.
3.The linear expansion coefficient of 10~20 is PTFE times larger than that of most plastics, and the linear expansion coefficient varies with the change of temperature.
In the application of PTFE, if the performance of this area is not enough attention, it is easy to cause damage.