Characterization of the polymorphic transformation of poly(1-butene) based on FTIR and mechanical properties

The polymorphic transformations (from form II to form I) of three kinds of isotactic poly(1-butene) were characterized by FTIR and by changes in their macroscopic physical and mechanical properties, including density and tensile characteristics. The kinetics of the form II to form I transformation were followed by performing FTIR measurements in real time. At 25 °C, as the crystallization time increased, the characteristic FTIR peak of form I of the poly(1-butene) increased, while that of form II diminished and finally disappeared. The polymorphic transformation from form II to form I of the poly(1-butene) obtained by the solution method (S-PB) occurred the most rapidly, followed by the corresponding transformation for the poly(1-butene) obtained from Mitsui Chemicals (M-PB) and then that for the poly(1-butene) produced using the high-pressure bulk polymerization method (B-PB). This transformation behavior is due to the higher isotacticity of the S-PB, as also demonstrated by the results of the density and tensile tests. The density of S-PB is higher than the densities of M-PB and B-PB due to its greater crystallinity.