Form III to form II phase transition of polybutene‐1

Abstract

Abstract The Form III to Form II transition of crystalline potybutene‐1 at elevated temperature has been observed by differential thermal analysis (DTA), dilatometry, x‐ray diffraction, and photomicrography. DTA thermograma of polybutene‐1 in Form III were found to exhibit endotherms at 94°C., and 110°C, corresponding to the transformation of Form III and melting of Form II, respectively. The origin of an exothermic peak observed at 90°C, is not entirely resolved at the present time. The transition of poly‐biitene‐1 in the Form III modification was also studied by x‐ray diffraction methods. It was shown that the intensity of the peak at 2θ = 12.1°, corresponding to the Form III crystalline phase, begins to decrease in sine at 88°C, while simultaneously the peak at 2θ = 11.7°, corresponding to the Form II modification, starts to grow. The transformation is complete at 98°C. The nature of the Form III to Form II transition of polybutene‐1 is discussed in the paper; two alternative mechanisms are deemed possible: a solid‐solid transition or a transition involving a short‐lived intermediate molten state.