Transformation from form II to form I accelerated by oriented lamellae in Polybutene-1

Abstract

Promoting the transformation from Form II to Form I in polybutene-1 (PB-1) is deemed to be crucial and demanded for commercial applications. The mechanism of phase transition is previously described in terms of thermal or mechanical stress applied between the crystalline and amorphous regions. Here, we find that the structural feature of lamellae, such as lamellar orientation, can also be a vital factor to facilitate the transition process. In-situ X-ray measurement allows us to observe a power-law decrease of the induction time of Form I, ti, with increasing the degree of orientation of (200) plane of initial Form II crystallites, f(200): ti ~ f(200)−1. By comparison with the randomly oriented lamellae, the well-defined oriented lamellae perpendicular to the flow direction are in favor of shortening the ti. The acceleration of this phase transition may be due to more tie molecules distributed in the oriented lamellae increasing the probability of the formation of Form I nuclei.