Abstract The influence of cryogenic mechanical mil領(lǐng) on the structure and the thermal behavior of isotactic polypropylene was investigated by means of wide-angle X-ray scattering, differential scanning calorimetry and transmission electron microscopy. The results presented show that structural changes caused by mechanical mil領(lǐng) at cryogenic temperatures are only partly reversible. The decrease in the degree of crystallinity as determined by differential scanning calorimetry with increasing mil領(lǐng) time is attributed to a reversible transformation of the initial morphology into a nanostructured morphology, consisting of small fragments of the original isotactic polypropylene lamellae. During recrystallization from the molten state, there still exists an influence of the previous mil領(lǐng) treatment, leading to significantly changed crystallization behavior. The reason for this behavior might be a decrease in the molecular weight or a change in the molecular weight distribution or the formation of long-chain branched polypropylene molecules induced by cryogenic mechanical mil領(lǐng). Keywords Cryogenic mechanical mil領(lǐng) Æ Polypropylene Æ Transmission electron microscopy Æ Nanostructure Æ Differential scanning calorimetry SPEX6770 全自動冷凍研磨機 SPEX6870 全自動冷凍研磨機 SPEX6970EFM 冷凍研磨機