Damping and adhesive properties of carboxyl-terminated butadiene-nitrile rubber/epoxy polymer blends - The effect of acrylonitrile content

The damping properties and the adhesive properties of carboxyl-terminated butadiene acrylonitrile rubber (CTBN)/epoxy (diglycidyl ether of bisphenol-A: DGEBA) polymer blends, including 60 wt% CTBN, were evaluated. In cases when the acrylonitrile (AN) contents in CTBN were 10-18 mol%, the blend resins showed micro-phase separated morphologies with rubber-rich continuous phases and epoxy-rich dispersed phases. The composite loss factors (eta) for steel laminates, which consisted of two steel plates with the resin layer in between, depended strongly on the environmental temperature and the resonant frequencies. Moreover, in the case that the acrylonitrile (AN) content in CTBN was 26 mol%, the compatibility in the blend was enhanced and the resin did not indicate clear micro-phase separation in nanoscale. The temperature dependence of the tan delta of the resin was small, which resulted in the high loss factor (eta > 0.1) for the steel laminate over a broad temperature range, with several resonant frequencies. The resin also indicated high adhesive strength values in both shear mode and peel mode. The temperature dependence of eta and the order of eta among resin formulations could be explained according to the mode proposed by Ross, Unger, and Kerwin.