| Abstract
| - Isothermal crystallizations from the melt of samples of syndiotactic polypropylene havingdifferent degrees of syndiotacticity have been performed. The thermal behavior and the structural featuresof the melt-crystallized samples have been analyzed by differential scanning calorimetry and X-raydiffraction. According to this analysis, less stereoregular samples, crystallized in disordered modificationsof form I with defects implying local arrangements of the chains such as in form II, present recrystallizationphenomena during heating. For most stereoregular samples relevant recrystallization phenomena areabsent. Extrapolation to the equilibrium melting temperature of syndiotactic polypropylene was attemptedby using the Hoffmann−Weeks method, taking into account the occurrence of recrystallization andsuperheating phenomena. A value of nearly 182 °C has been obtained for the equilibrium meltingtemperature of the fully syndiotactic polypropylene.
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