Poly(ethylene naphthalene-2,6-dicarboxylate) has been uniaxially stretched at different draw ratios and at two different temperatures below and above its glass transition (T-g similar to 120 degrees C) respectively, at 100 and 160 degrees C. Crystallinity has been evaluated from calorimetric analyses and compared to the values deduced by FTIR spectroscopic data. As expected, the obtained results are quite similar and show that films stretched at lower temperature (100 degrees C) are more crystalline than those stretched at 160 degrees C. Optical anisotropy associated with orientation has been evaluated by birefringence and show that films stretched at 100 degrees C are more birefringent than those stretched at 160 degrees C as a result of a higher chain relaxation above T-g. Polarized FTIR was also performed to evaluate the individual orientation of amorphous and crystalline phases by calculating dichroic ratios R and orientation functions < P-2(cos theta)> and also show that amorphous and crystalline phases are more oriented in the case of films stretched below T-g. Nevertheless, the orientation of the amorphous phase is always weaker than that of the crystalline phase. Films stretched at 100 degrees C show a rapid increase in orientation (and crystallinity) with draw ratio and < P-2(cos theta)> reaches a limit value when draw ratio becomes higher than 3.5. Films drawn at 160 degrees C are less oriented and their orientation is increasing progressively with draw ratio without showing a plateau. A careful measurement of the IR absorbance was necessary to evaluate the structural angles of the transition moments to the molecular chain axis. (c) 2007 Wiley Periodicals, Inc.