文献类型：期刊文献

英文题名：CO2-induced phase transition of isotactic poly-1-butene with form III upon heating

作者：Li, Lei[1]; Liu, Tao[1]; Zhao, Ling[1]; Yuan, Wei-Kang[1]

机构：[1] State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China

年份：2011

卷号：44

期号：12

起止页码：4836

外文期刊名：Macromolecules

收录：EI(收录号：20112614091064)

语种：英文

外文关键词：Differential scanning calorimetry - X ray diffraction - Fourier transform infrared spectroscopy - Carbon dioxide - Butenes - Indium compounds - Recrystallization (metallurgy) - Heating

摘要：This work is aimed at studying the effect of CO2 on the phase transition of isotactic poly-1-butene (iPB-1) with form III upon heating. The melting behaviors of form III under atmospheric N2 and compressed CO2 at different heating rates ranging from 1 to 20 °C/min were investigated using high-pressure differential scanning calorimetry (DSC). The results showed that the plasticization effect of CO2 promoted melting of form III and inhibited the phase transition of form III to II as a whole. By analyzing the melting parameters obtained from the DSC measurements, we deduced that the phase transition of form III to II might comprise another transition process besides the melt-recrystallization mechanism. In-situ wide-angle X-ray diffraction (WAXD) measurement on form III under atmospheric N2 at a heating rate of 0.25 °C/min verified that the phase transition of form III to II passed through the solid-solid phase transition before melt-recrystallization. In-situ high-pressure Fourier transform infrared (FTIR) was then used to detect the phase transition of form III under atmospheric N2 and compressed CO2 at the heating rate of 1 °C/min. It was also shown that the phase transition of form III to II passed through the solid-solid phase transition and melt-recrystallization under atmospheric N2, 1 and 2 MPa CO2. However, form II formed completely through the melt-recrystallization under 3 MPa CO2 and could not generate with further increasing CO2 pressure to 4 MPa. Moreover, more form I′ generated during heating through the solid-solid phase transition with increasing CO2 pressure. Besides carbon tetrachloride solution prepared form III, the other two solutions, i.e., dilute toluene and o-xylene, cast form III also exhibited the similar generation processes of form II upon heating under atmospheric N2 and compressed CO2 as measured by in-situ high-pressure FTIR. ? 2011 American Chemical Society.