linseed oils are highly unsaturated and are oily. Moreover, as
double bonds are more sensitive to oxidative attack,
unsaturated TGs are less stable than saturated ones, and may
degrade or polymerize more easily (tendency to go rancid or to
harden). That means in terms of oxidation stability, that a
higher grade of saturation of the molecules corresponds to
higher oxidation stability. But on the other side such high
saturated TGs have high pour points and viscosity.
All these chemical considerations are useful to make
informed choice of the best natural esters for electrotechnical
applications. And numerous trial tests have shown that the
oxidation stability of natural ester formulations can be adequate
for use in transformers.