Polar Association in Polyethylacrylate Observed at Small Shear and Large Elongation: Effect of Concentration of Polar Solvent*

Polyethylacrylate is a polar rubber that exhibits strain-induced association in elongation, a behavior quite similar to strain-induced crystallization of crystallizable rubbers. Two questions are considered: whether or not strain-induced association is suppressed when the polymer is diluted with polar solvents and whether or not some extent of polar association is present even in the quiescent state and can be detected under small shear deformation. Dynamic mechanical measurements were performed in shear in the linear region of viscoelastic properties for a “gel-free” rubber plasticized with dibutyl-phthalate (DBP). The elongational data were linearized according to a previously developed linearization scheme. The linearized elongation modulus–time curve was in good agreement with the shear modulus–time curve, with a factor of 3, for 15% and 20% DBP. This is similar to the case for nonpolar elastomers. Therefore, at these concentrations, there is no polar association. For 0% and 10% DBP, the elongational ...