The effect of temperature on the characteristic of Fourier Transform Infrared(FTIR),the dependence of the average molecular weight and the polydispersity on the annealing temperature and the relationship between linea...The effect of temperature on the characteristic of Fourier Transform Infrared(FTIR),the dependence of the average molecular weight and the polydispersity on the annealing temperature and the relationship between linear expansion coefficients and temperature of poly(propylene carbonate) end-capped with maleic anhydride(MA-PPC) were investigated.The vibration peak of hydroxyl group at 1714?cm -1 in the FTIR spectra,which belongs to the carboxyl end-group in MA-PPC,decreases with increasing the temperature of the sample and it disappeared totally when the sample was heated over 70℃.The average molecular weight of MA-PPC almost doubled when the sample was annealed at 110～150℃ for 30 min,however the polydispersity was maintained roughly.A new relaxation transition at about 80℃ was detected on the curve of the linear expansion coefficient versus temperature that is the characteristic of macromolecular coupling or crosslinking reaction.These results confirmed that the macromolecular coupling reaction was carried out between the end carboxyl groups of MA-PPC when the sample was heated over 70℃.展开更多
Poly（lactic acid）/montmorillonite nanocomposites were prepared by the melt inter calation method. Their structures and thermal properties were investigated by WA XD, DSC and TGA techniques. The WAXD results show tha...Poly（lactic acid）/montmorillonite nanocomposites were prepared by the melt inter calation method. Their structures and thermal properties were investigated by WA XD, DSC and TGA techniques. The WAXD results show that the interlayer spacin g of montmorillonite in the nanocomposites was increased after melt intercalat ion, indicating that the molecular chains of poly（lactic acid） had been interc alated into the montmo-rillonite layers. The thermal stability of poly（lact ic acid） was obviously improved after intercalation with montmorillonite. Compar ed with that of pure poly（lactic acid）, the thermal decomposition temperatures o f the nanocomposites were increased by about 22.5 ℃ in air and 14 ℃ in N2 , respectively.展开更多
The synthesis and properties of a novel room-temperature ionic liquid hexaalkylguanidium salts 4 and 5 were reported. The reaction of 1,3-dimethyl-2-imidazolidinon with POCl 3 and n-BuNH 2 afforded to pentaalkyl-guani...The synthesis and properties of a novel room-temperature ionic liquid hexaalkylguanidium salts 4 and 5 were reported. The reaction of 1,3-dimethyl-2-imidazolidinon with POCl 3 and n-BuNH 2 afforded to pentaalkyl-guanidine(2), which reacted with CH 3I, generated hexaalkylguanidium(3). The hexaalkylguanidium salts 4 and 5 were synthesized by the reaction of hexaalkylguanidium(3) with KPF 6, AgBF 4 respectively. The results showed that both compounds 4 and 5 were room-temperature ionic liquids. The structures of these compounds were determined by 1H NMR, 13C NMR, IR and MS spectra data. Compounds 4 and 5 were found to have better solublities in organic solvents and better thermal stabilities.展开更多
文摘The effect of temperature on the characteristic of Fourier Transform Infrared(FTIR),the dependence of the average molecular weight and the polydispersity on the annealing temperature and the relationship between linear expansion coefficients and temperature of poly(propylene carbonate) end-capped with maleic anhydride(MA-PPC) were investigated.The vibration peak of hydroxyl group at 1714?cm -1 in the FTIR spectra,which belongs to the carboxyl end-group in MA-PPC,decreases with increasing the temperature of the sample and it disappeared totally when the sample was heated over 70℃.The average molecular weight of MA-PPC almost doubled when the sample was annealed at 110～150℃ for 30 min,however the polydispersity was maintained roughly.A new relaxation transition at about 80℃ was detected on the curve of the linear expansion coefficient versus temperature that is the characteristic of macromolecular coupling or crosslinking reaction.These results confirmed that the macromolecular coupling reaction was carried out between the end carboxyl groups of MA-PPC when the sample was heated over 70℃.
文摘Poly（lactic acid）/montmorillonite nanocomposites were prepared by the melt inter calation method. Their structures and thermal properties were investigated by WA XD, DSC and TGA techniques. The WAXD results show that the interlayer spacin g of montmorillonite in the nanocomposites was increased after melt intercalat ion, indicating that the molecular chains of poly（lactic acid） had been interc alated into the montmo-rillonite layers. The thermal stability of poly（lact ic acid） was obviously improved after intercalation with montmorillonite. Compar ed with that of pure poly（lactic acid）, the thermal decomposition temperatures o f the nanocomposites were increased by about 22.5 ℃ in air and 14 ℃ in N2 , respectively.
文摘The synthesis and properties of a novel room-temperature ionic liquid hexaalkylguanidium salts 4 and 5 were reported. The reaction of 1,3-dimethyl-2-imidazolidinon with POCl 3 and n-BuNH 2 afforded to pentaalkyl-guanidine(2), which reacted with CH 3I, generated hexaalkylguanidium(3). The hexaalkylguanidium salts 4 and 5 were synthesized by the reaction of hexaalkylguanidium(3) with KPF 6, AgBF 4 respectively. The results showed that both compounds 4 and 5 were room-temperature ionic liquids. The structures of these compounds were determined by 1H NMR, 13C NMR, IR and MS spectra data. Compounds 4 and 5 were found to have better solublities in organic solvents and better thermal stabilities.
