Question

If you had to introduce lubrication to your polymers compound what would you add?

Answer 1

Explanation:

Polymers and polymer-based composites are increasingly becoming preferred materials and coatings for green tribology because of the combination of good mechanical and tribological properties, resistance to corrosion and chemicals, lightweight, reduced noise and maintenance costs. They can be used in dry or lubricated condition to further reduce friction and wear of tribological parts.

Surface Energy (mN/m) and Hardness of Polymers

Table 1

This project investigates the tribological and wetting properties of a range of polymers with different polarities, hardnesses and roughnesses (Table 1).

Lubricant characteristics

Table 2

Polymers were tested dry and lubricated with water/oils using the MTM. Oils were selected to have similar viscosities at the testing temperature but different polarities (Table 2).

Water wettability on high and low Ra polymers

Table 3

Both, polymers and oil lubricants have low surface energies but because their chemistry varies widely they interact differently as shown by the wettability parameters (Table 3) and the CoF values (Fig.1).

Stribeck curves for water on high Ra polymer specimens

Fig 1

The water wettability has been found to increase with the polarity of the polymer while to COF varied oppositely to the wettability.

Table 4 Oils wettability on high and low Ra PTFE; Fig 2 Stribeck curves for oils on high Ra PTFE specimens

Table 4 and Fig 2

The wettability of PTFE is higher with non-polar oils but in general, the variations of both, oil wettability and COF are small (Tab 4 and Fig 2).

Table 4 Oils wettability on high and low Ra PTFE; Fig 2 Stribeck curves for oils on high Ra PTFE specimens.

Through a careful selection of the lubricant-polymer pair it is possible to achieve low levels of friction and wear according to application-specific requirements.