Preheating between the temperatures of 200 and 280 degrees C is done to a film-structured poly(vinyl chloride) (PVC) sample, which has a gelation temperature similar to 250 degrees C. After this preheat, the PVC's thermomechanical and thermal differences, at temperatures before and after thermal gelation, are observed. Consequently, when some thermomechanical and thermal parameters, obtained at temperatures before and after gelation, are compared, it can be said that this is an easier method to determine the gelation temperature of a polymer. (c) 2005 Wiley Periodicals, Inc.