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graebot t1_j2rcrr5 wrote

Reply to comment by Duros001 in Molecularly, what make pine pitch sticky? by orangegore

So would tar be less sticky in a vacuum?

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Indemnity4 t1_j2usq4x wrote

The properties of tar will not change in a vacuum (depending on how strong is the vacuum).

Some glues are air drying, but pine tar is not. The adhesion and cohesion properties do not change with oxygen or gravity.

However, pine tar is a mixture of hydrocarbons, acids and bases. At low vapour pressure some of those will evaporate / outgas. All the volatile stuff is acting as a solvent for the non-volatile stuff. Too strong a vacuum or too long in vacuum and the pine tar will become hard and brittle.

Problems exist in space because of the vacuum but also it's really cold. Many adhesives are only active above the glass transition temperature or melting point.

There are test standards for minimal outgassing required for adhesives used in space craft. It must not lose too much mass, and that lost mass should not recondense in a harmful way.

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Triairius t1_j2ugj9b wrote

I am actually unsure, but I suspect it might be the same amount of sticky, as there is still no air getting in to regulate the pressure. However, the tar itself might react to a vacuum somehow.

These are just my thoughts, since your question intrigued me. Someone else will hopefully provide an informed answer.

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graebot t1_j30yk7p wrote

If there's no atmosphere, then there's no pressure to press things together. Suction cups, for instance, do not work in a vacuum. They require atmospheric pressure to press the cup to the surface. If part of tar's stickiness comes from the suction effect in an atmosphere, then at least some of that "stickiness" must disappear

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[deleted] t1_j2renk4 wrote

[deleted]

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l4mbch0ps t1_j2s9oua wrote

Nah, it would be less sticky in a vacuum because you wouldn't have air pressure working to close the vacuum bubbles formed in the stretching material. Suction doesn't work without air pressure.

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