Deformation-induced crystal-crystal transition of polybutene-1: an in situ FTIR imaging study

Crystal-crystal transition of polybutene-1 from forms II to I inside and outside a large hedrite or spherulite during deformation is investigated with in situ Fourier transform infrared sepectroscopic imaging technique and miniature tensile tester. Three stages have been observed for both of samples. In the first stage (strain epsilon < 0.2), form I crystal formed slowly under the effect of deformation. When entering the second stage II (0.2 < epsilon < 1.2), the crystal-crystal transition was accelerated significantly. In the third stage, form II translates into form I almost completely. It was also found that the transition rate inside large hedrite and spherulite is slightly faster than the surrounding initially, especially for the hedrite. However, the difference inside and outside becomes negligible when epsilon > 0.8. We proposed that the difference in crystal-crystal transformation between spherulite and hedrite is attributed to the different alignment of lamellar stacks in two samples. The results demonstrate the effect of different morphologies on the crystal-crystal transition during deformation.