Compatibility of poly(ethylene 2,6‐naphthalate) and poly(butylene 2,6‐naphthalate) blends

Blends prepared from poly(ethylene 2,6‐naphthalate) (PEN) and poly(butylene 2,6‐naphthalate) (PBN) show only partial miscibility judged from their glass transition temperatures. Two distinct mechanical behaviors are observed: brittle for the blends < 20 wt% of PBN, while ductile > 20 wt% of PBN. The experimental modulus and strength values of the blends are within the predicted values according to Kleiner and Paul models, respectively. This means that PEN/PBN blends are somewhat compatible based on their tensile properties. Especially for 20 wt% of PBN blend, the high modulus and strength are observed. The viscosity of the blend is high, which may imply a somewhat entangled morphology in the amorphous state.