Isotactic polybutene‐1: Modification 3 and its transformations

Abstract Modification 3 of isotactic polybutene‐1, prepared by crystallization from a solution at room temperature, was studied by dilatometric and X‐ray examinations at different temperatures. At high degrees of crystallinity, its specific volume is intermediate between that of modification 1 and 2. By rapid heating its melting can be observed at about 102°C., while by a sufficiently slow heating it can even be totally converted into modification 1 before melting, by a solid‐solid transformation. Modification 1 obtained in this way melts surprisingly low, at 109°C., probably because of morphological memory. During the melting of modification 3, or modification 1 originated by modification 3, crystallization of available liquid phase usually takes place, giving modification 2, which happens to be the most highly melting polymorph under these particular conditions.