The characteristics of poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) (PEN), and blends with 30, 40, 50, 60, and 70 wt % PEN prepared by melt-blending were analyzed using Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, solid-state nuclear magnetic resonance (NMR), and Xray photoelectron spectroscopy. The spectroscopic analyses provide no direct evidence for the occurrence of transesterification reactions occurring during melt-processing of the blends under the conditions that were used. The improved mechanical properties of the PBT/PEN blends are attributed to physical interactions occurring over a large interfacial area. X-ray diffraction and high-resolution solid-state carbon-13 (C-13) NMR confirmed the formation of the alpha-PEN phase after annealing samples at 200 degrees C for 19 h. (c) 2007 Wiley Periodicals, Inc.