FT-IR internal reflection study of migration and surface segregation of carboxylic acids in butadiene-styrene rubber

Migration of low molecular weight additives toward the rubber surface has been studied for a number of years. The subject of our study was kinetics of migration and surface segregation of linear aliphatic carboxylic acids (11-18 C atoms) in butadiene-styrene rubber (SBR). The iteration procedure has been proposed for determination of thickness of acid's surface layer formed as a result of segregation as well as for determination of acid diffusion coefficient. With the aim of determining these kinetic curves of migration FT-IR IRS spectra analyses have been used. Differences in final thickness of surface layer of particular acids (after 24 h) have been explained on the basis of differences in their solubility in SBR at temperature of spectroscopic measurement equal to 23 DGC.