Reconstruction of Calorimetric Curves from X-ray Diffraction Data during the Melting-Recrystallization Process of Polymers: Simultaneous Calorimetry/X-ray Diffraction Measurements of Isotactic Poly(1-butene) in Form III

To understand complex phase behaviors of crystalline or semi-crystalline polymers, it is indispensable to clarify the correlation between the thermal and structural change events. Simultaneous calorimetty/X-ray diffraction measurement is one of the powerful methods to clarify, such correlation. Isotactic poly(1-butene) (PB-1) exhibits complex phase transformation among the various crystal forms (Forms I, II, III, etc.). Here, we studied the transformation behavior of PB-1 in Fonts III by means of the simultaneous measurement and developed a new analytic method to reconstruct calorimetric curves from the X-ray diffraction data recorded simultaneously. Considering the recorded enthalpy values, we reconstructed a corresponding calorimetric curve from the temperature dependence of the X-ray diffraction intensity data. The curve almost agreed with the original curve. This analysis revealed the phase transformations of Form HI PB-1 during heating as follows: First, Form HI crystals melt and then Form II crystallization happens before completing the melting of the Form HI. Finally Form II melts.