Adsorption of a Synthetic Rubber onto a White Carbon Surface

Abstract

Adsorption of a synthetic rubber, polybutadiene onto a white carbon surface, i.e., nonporous silica (Aerosil 130), from cyclohexane solutions at 35°C was studied by IR spectroscopy and differential refractometry. The observed infrared frequency shifts of the silanol groups for 1,7-octadiene and for a mixture of cis- and trans-2-octene, which are the monomeric analogues of polybutadiene, and also for polybutadiene, are attributed to the interaction between the silanol groups of the Aerosil 130 silica and the double bonds of these compounds. Adsorbance (A) was determined using a differential refractometer, while both the fraction of the surface sites occupied (θ) and the fraction of the adsorbed segments per polymer chain (p) were determined by IR spectroscopy. The experimental values of A, θ, and p observed in the plateau region of the adsorption isotherms were independent of molecular weight. The data were compared with the theory of Roe formulated for a lattice model. There was qualitative agreement between the observed data and Roe’s theory.