Does a substances friction increase with increased heat?

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SUMMARY

The coefficient of friction (CoF) is defined for a pair of surfaces and primarily depends on surface texture rather than bulk properties like density. While generally, temperature does not affect the CoF for most solids, specific materials, such as rubber used in NASCAR tires, exhibit increased CoF when heated due to softening. This softening enhances traction, demonstrating that temperature can influence friction in certain cases, particularly with polymeric materials. However, a universal relationship between temperature and CoF cannot be established for all materials.

PREREQUISITES
  • Understanding of coefficient of friction (CoF) concepts
  • Knowledge of material properties, especially in polymers
  • Familiarity with surface texture effects on friction
  • Basic principles of thermodynamics related to solids
NEXT STEPS
  • Research the effects of temperature on rubber properties in automotive applications
  • Study the relationship between surface texture and friction in engineering materials
  • Explore the mechanics of polymeric materials under varying thermal conditions
  • Investigate recrystallization effects on friction in high-temperature scenarios
USEFUL FOR

Mechanical engineers, materials scientists, automotive engineers, and anyone interested in the dynamics of friction and material performance under varying temperatures.

wasteofo2
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Assuming it stays a solid, if something gets colder, it seems, it's molecules become more tightly compressed and less able to drag on things and vice versa. Is that assumption correct?
 
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In general, no. The coefficient of friction is dot defined on a single material, but for a pair of surfaces. It only depends on the surface texture - the bulk properties like density (which is what you are describing) have no effect on the coefficient of friction.
 
Gokul43201 said:
In general, no. The coefficient of friction is dot defined on a single material, but for a pair of surfaces. It only depends on the surface texture - the bulk properties like density (which is what you are describing) have no effect on the coefficient of friction.

So then why does NASCAR heat their tires prior to installation during a pitstop. Are you saying hot and cold tires have the same COF when running on the same track?
 
No, I'm not. You are right that hot tires have better traction.

My explanation was for a general solid which does not undergo (inter)molecular rearrangement upon heating. In the case of tires, the heat softens the rubber and as a result increases its coefficient of friction.

So there are cases where the temperature affects the coefficient of friction (such are in polymeric materials like rubber), but you can not draw up a generic relation between temperature and friction coefficient.

Most other common solids, don't behave this way, unless you get really hot, at which point there are recrystallization effects that may lead to a change in the CoF through plastic flow/creep.
 

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