Films of polypropylene/organically modified montmorillonite (PP/OMMT) nanocomposites were drawn at two different temperatures with various draw ratios. The effect of OMMT on the orientations of the crystalline and amorphous phases was studied using polarized infrared spectroscopy. It is found that OMMT layers always retard the orientation of the crystalline phase. The higher the OMMT loading, the stronger the retardance effect. In contrast, the effect of OMMT layers on the orientation of the amorphous phase depends on draw temperature and OMMT loading. A favorable effect on the orientation of the amorphous phase is observed at low OMMT loading and high draw temperature, but the retardance prevails at high OMMT loading and low draw temperature. The favorable effect on orientation at high draw temperature is attributed to the stabilization effect of OMMT layers on the conformation of amorphous PP chains. Such an effect was further verified by comparing the crystallization behavior and the morphologies of drawn PP and PP/OMMT films crystallized from 180 degrees C. Memory effect is observed for crystallization of drawn PP/OMMT film, but it is not obvious for the drawn film of neat PP. Spherulites are formed for orientated neat PP films cooled from 180 degrees C, but cylindrites are still formed after the drawn PP/OMMT films undergo melting at 180 degrees C and recrystallization. The stabilization effect disappears at higher temperature (230 degrees C). (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 3321-3330, 2012