Viscosity Index Improvers:PhysicalState?

[Cyclops]

What is the physical state of VII's? I'm assuming they are dispersed particles in the oil but then how do they prevent being captured by the oil filter? Is the size at a submicron level that allows unimpeded flow through the filter or are they fully dissolved in the oil?

Doug

 

[MolaKule]

Check out:

https://bobistheoilguy.com/forums/threads/additives-xii-multifunctional-additives.41173/


Quote:
Viscosity Index Improver or Viscosity Modifier (Performance Additive): Olefin copolymers (OCP's), hydrogentated styrene-diene copolymers, styrene esters, polymetharylates (PMA's), mixed alkyl methacrylate-vinyl-pyrrolidines, aminated ethylene propylene, mixed alkylmethacrylate ethylene/propylenes; reduces viscosity change with temperature. Increases viscosity of base oil as temperature rises when base oil tends to thin. Some VII's may also act as dispersants by incorporating dispersant compounds.


VII's are just large polymer molecules.

Some internet infO;

http://www.machinerylubrication.com/Read/1327/viscosity-index-improvers

 

[unDummy]

Physical state?
I was under the impression that Lucas snot was either brightstock or PIB.

http://www.mitsuichemicals.com/PerformanceComparisonofLucant.pdf
http://www.lubrizol.com/AstericViscosityModifiers/Presentation.pdf

 

[Cyclops]

Thanks guys, those are some great links. What has caused my curiosity was reading an older article about viscosity change in a motorcycle application where the tester centrifuged samples prior to measuring viscosity to prevent data skewing from possible contaminant particles. However, I'm not sure about the state of vii's, are they soluble in oil or are they small colloidal particles that would be influenced by centrifugation?

Doug

 

[MolaKule]

Quote:
However, I'm not sure about the state of vii's, are they soluble in oil or are they small colloidal particles that would be influenced by centrifugation?



They may have been centifuging to get the insolubles and solids down to the bottom of the test tube so they could pour off the top fluid without any solid contaminants.

VII's are oil soluble polymers and not colloids.

 

[Torino]

Most (if not all) of those EARLY VII's were polydiobutylenes. They were especially prone to shearing. The sheared molecules would then 'glom' onto whatever was present and create a 'sludge'. They worked but the downside was noticeable. John--Las Vegas.

 

[Cyclops]

Thanks guys! And yes, the centrifuged supernate was used.

Doug