Green Plasticizers from Dimer Acids Selected Esters Classified Through the Nile Red [E(NR)] Polarity Scale

Dimer and trimer acids are interesting viscous liquids produced from fatty acids derived from renewable sources. The chemical structures of dimer and trimer acids are known and quite complex and are presented here and discussed and further elucidated through the electronic absorption spectroscopy, FT-IR and Raman spectroscopy. Dimer and trimer acids find a number of applications as such or under the form of derivatives. In the present study, a series of esters of dimer and trimer acids with alcohols from renewable sources have been synthesized with the purpose to be used as plasticizers for rubber and plastics. The polarity of dimer and trimer acids as well as their esters with alcohols from renewable sources (dimerates and trimerates) were systematically studied using the Nile Red solvatochromic probe. The resulting E(NR) values were compared and discussed with the E(NR) values of the most common rubber and plastics. The compatibility and other physical properties expected from the E(NR) scale was studied and successfully confirmed in tire tread rubber compounds formulations and in nitrile rubber and PVC matrices, confirming once again the sensitivity and the validity of the Nile Red solvatochromic polarity scale for the development of new plasticizers.