I know only of classical equations, such as a Fox equation for predicting Tg-s of mixtures, which can be extended to plasticized systems. Another way is to treat plasticized epoxies as concentrated solutions and to use the Flory equation. This does not apply to active diluents, however.

Thanks a lot Gyorgy. I will check the relation you mentioned.

Fox equation related to plasticization:

http://144.206.159.178/ft/862/27646/13381874.pdf

http://www.ncbi.nlm.nih.gov/pubmed/20085370

http://books.google.hu/books?id=JDFT4k8yYAEC&pg=PA91&lpg=PA91&dq=Fox+equation+plasticization+water&source=bl&ots=WJCdXRYHdC&sig=HRweJeS228rCjt2s4--5O2rCKE0&hl=hu&sa=X&ei=HEo7UaGwCcyFtQaNsYCYAw&ved=0CEkQ6AEwAg#v=onepage&q=Fox%20equation%20plasticization%20water&f=false

http://repositorium.sdum.uminho.pt/bitstream/1822/11398/1/Torres_Carbohydrate%20Polymers.pdf

http://144.206.159.178/ft/352/605905/12570098.pdf

Flory relation: (in your context)

http://mae.ucdavis.edu/vlasaponara/moisture_paper.pdf

http://144.206.159.178/ft/862/11615/234930.pdf

http://144.206.159.178/ft/862/79441/1354765.pdf

http://www.mendeley.com/catalog/water-sorption-diffusion-studies-epoxy-resin-system/

http://foodchem.net/publication/files/2002-03-06.pdf

http://www.google.hu/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CIgBEBYwCA&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.151.5235%26rep%3Drep1%26type%3Dpdf&ei=xko7UYHCIcbhtQbov4C4Aw&usg=AFQjCNEmCTEWLC15v1QsHo3M7lxv4EdRfw&sig2=lUk_gR0TMDqWaTlq2La8Yg&bvm=bv.43287494,d.Yms

Probably there are many others ... good luck

Many thanks Georgy for your time and attention. l will check them and send you my feedback.