Partially miscible polymer blends of ethyl cellulose and hydroxyl terminated polybutadiene

Abstract

The phase behavior of the recently developed blend of ethyl cellulose (EC) and hydroxyl terminated polybutadiene (HTPB) for oxygen scavenging applications was investigated using thermal and thermomechanical analysis as well as morphological and topographical images. The complexity in the phase structure of this system is most probably related to the presence of special hydrogen bonding interactions between the blend's components verified by FTIR-ATR measurements, which led us to expect some degree of miscibility in our blends. The presence of partial miscibility was predicted using the miscibility guideline by Coleman and Painter. Scanning electron microscopy (SEM) revealed well dispersed trapped microdomains in the matrix that may have been related to the HTPB rich phase. Moreover, atomic force microscopy (AFM) images showed different contrasts, which was translated to the presence of partial miscibility and conjugated phases in the system. In addition, DSC analysis was performed to verify this concept in conjunction with DMTA measurements. Although glass transition temperatures were not well pronounced by DSC measurements, DMTA curves obviously depicted turning glass transition temperatures from one at the lowest HTPB composition into two and three transitions at two higher HTPB compositions which confirmed the presence of partial miscibility in our blends. Oxygen absorption measurements demonstrated a proper oxygen scavenging efficiency for the blend in comparison with pure EC.