What are the detriments of V. Improvers?

[Dad2leia]

I guess then that there are just too many variables in the picture to accurately plot a chart of this so to speak. Just reinforces just why we all are so anal about oil, right there G-man?

 

[bruce381]

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Good read there buster, now a question on that read. Given that we know VII's will eventually shear permanently, do we have the ability to predict just how many shears, or how long of in service "tugging" (for lack of a better word) that they will last before being chemically changed into the shorter molecules?

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Not chemicaly changed but physicaly changed as in molecule is broke in pieces, Also shear stability of VII is mesured and reported as a a SSI or shear stability index the lower the better the number such as say 35 means that 35% of the vis increase from the VII is lost in this test most PCMOs use 35-50 VII's tho there are lower ones to just cost more used in gear oils.
bruce

 

[Shannow]

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Not chemicaly changed but physicaly changed as in molecule is broke in pieces,
bruce

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bruce,
I might be grabbing the wrong end of the bull here.

When a molecule, such as a VII is chopped, what happens to the "loose ends" ?

What do they pick up to make up for the free bonds, or is that why they are nasty sludge precursors as the next available reactant is oxygen or CO, or some sulfur compound ?

 

[bruce381]

they just loose "bulk" or some/all of the vis increase they do as they "swell' or exspand with heat since the molecule is now shorter in lenght it can not increase vis as much if at all, SSI is used by formulators to predict how well a oil may last.
bruce

 

[Shannow]

I still don't get it.

I understand that they are smaller, and don't bulk up and interact with each other as much.

Just wondering what happens to the sheared ends (e.g. a hydrocarbon chain, chopped off must have something attach itself to the reactive end).

I think

 

[G-MAN]

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I still don't get it.

I understand that they are smaller, and don't bulk up and interact with each other as much.

Just wondering what happens to the sheared ends (e.g. a hydrocarbon chain, chopped off must have something attach itself to the reactive end).

I think

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I think you're confusing atoms and molecules. Shearing doesn't break apart the VI improvers at the atomic level. It cuts up the molecules which limits their ability to alter the high temp vis characteristics of the host fluid.

 

[Merkava_4]

Let's talk about protons, neutrons, and electrons while we're at it.

 

[oilyriser]

Exactly. The chopped molecule has an unpaired electron, which can react with any of the other radicals floating around.

 

[Dad2leia]

I prefer to talk about the quarks of the protons, neutrons, and electrons, in the molecular chains of hydrocarbons, neatly arranged to make the things that they go between very very slippery...

 

[Shannow]

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Exactly. The chopped molecule has an unpaired electron, which can react with any of the other radicals floating around.

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thankyou