ZDDP Chemistry

[FormulatorUn]

As I understand it, ZDDP anti-wear/anti-oxidant performance is dependent upon its constituent alkyl chains (I am ignoring aryl chains). I have been trying to purchase a ZDDP additive for research purposes but so far find that manufactures do not detail the exact ZDDP or mixture of ZDDPs present in their product.

My questions:
How drastically does the chain structure alter the additive's performance?
Are there specific ZDDPs that are commonly used?
In a ZDDP mixture, how does one decide upon the ratios of the components?

 

[drwebb]

You can find a discussion of ZDDP chemistry in "Chemistry and Technology of Lubricants" edited by R. M. Mortier, Malcolm F. Fox, S. T. Orszulik. Alkyl structure mainly controls thermal activation temperature and thereby at what point the AW chemistry is most active. So that's the balance the formulator is targeting in adjusting primary or secondary alcohol ligand ratios.