The mechanically as well as the thermally induced chain conformational transformations in syndiotactic polypropylene (sPP) were monitored using both Raman and FT-IR spectroscopic techniques. Samples of syndiotactic polypropylene of helical crystalline conformations were elongated at different elongations up to 600%, while Raman and infrared spectra were simultaneously recorded. Quantitative analysis of these spectra using the ratio of helical to trans-planar content known as the 'Transformation Index' calculated from both Raman and infrared methods revealed that the relative proportion of the helical to the trans-planar conformation dramatically alters when the 100% elongation is reached, while any residual helical proportion has vanished above 500% elongation. Furthermore, we report for the first time an overall comprehensive Raman study of the helical to the trans-planar transformation of sPP during elongation up to 600% and consequent relaxation. In addition, a study of the thermal treatment of an sPP sample in the trans-planar conformation also took place. Furthermore, molecular orientation studies with the use of polarized infrared spectroscopy have been performed in order to monitor the changes in the orientation of the molecular chains during the application of stress. Both Raman and infrared experiments have demonstrated that when the tension is removed, a mixed stage of conformations is observed. Finally, the use of the above-mentioned techniques allows the monitoring of the thermally induced phase transformation from trans-planar configurations to helical in the temperature range between 60 and 90 degreesC. These spectroscopic findings are in agreement with differential scanning calorimetry thermal studies, which also confirm the thermally induced phase transformation. (C) 2004 Elsevier Ltd. All rights reserved.