Succinic or glutaric anhydride modified linear unsaturated (epoxy) polyesters |
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Authors: | Marta Worzakowska |
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Institution: | 1.College of Chemistry and Chemical Engineering,Central South University,Changsha,People’s Republic of China |
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Abstract: | A series of N-alkyl-N-alkyl′-pyrrolidinium-bis(trifluoromethanesulfonyl) imide (TFSI−) room temperature ionic liquids (RTILs) has been investigated by means of thermogravimetric analysis (TG), differential scanning
calorimetry, FT-IR spectroscopy, and X-ray diffraction analysis. These compounds exhibit a thermal stability up to 548–573 K.
The mass loss starting temperature, T
ml, falls in a narrow range of temperatures: 578–594 K. FT-IR spectra, performed before and after 24 h isothermal experiments
at 553 and 573 K, have confirmed their great thermal stability. Below the ambient temperature, these compounds exhibit a complex
behavior. N-methyl-N-propyl-pyrrolidinium-TFSI is the sole liquid which crystallizes without forming any amorphous phase even after quenching
in liquid nitrogen. Its crystalline phase has a melting point, T
m, of 283 ± 1 K. When the amorphous solid is heated, the N-butyl-N-ethyl-pyrrolidinium-TFSI presents a glass transition temperature, T
g, at 186 K followed by a cold crystallization, T
cc, at 225 K, and a final T
m at 262 K. The N-butyl-N-methyl-pyrrolidinium-TFSI exhibits a T
g between 186 and 181 K, its cold crystallization leading to two different solid phases. Solid phase I has a melting point
T
I,m = 252 K and phase II, T
II,m = 262 K. When the amorphous phase is obtained at a cooling rate of 10 K/min, its T
cc is 204 K, and a metastable solid phase (III) is obtained which transforms into the phase II at 226 K. However, when the sample
is quenched, the amorphous phase transforms into phase II at T
cc = 217 K and phase I at 239 K. P15-TFSI exhibits the most complicated pattern as, on cooling, it leads to both a crystallized phase at 237 K and an amorphous
phase at 191 K. On heating, after a T
g at 186 K and a T
cc at 217 K, two solid–solid phase transitions are observed at 239 K and 270 K, the final T
m being 279 K. |
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Keywords: | |
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