Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of rad...Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of radiation dose was discussed.An obviously chain scission was found near the branch carbons, and the ~ 13 C-NMR spectra of the corresponding gels confirmed the result.Linewidths of irradiated POE samples of various absorbed doses were observed to which were related to the molecular mobility of the radiation-crosslinked polymer.展开更多
The solubility of poly(phenyl glycidyl ether)s (PPGEs) depends on the stereoregularity.Different solvents and temperatures (CDCl 3/300 K or TCE d 2/350 K)were used in 13 C\|NMR characterization of these polymers.It wa...The solubility of poly(phenyl glycidyl ether)s (PPGEs) depends on the stereoregularity.Different solvents and temperatures (CDCl 3/300 K or TCE d 2/350 K)were used in 13 C\|NMR characterization of these polymers.It was necessary to investigate first the effect of temperature on the 13 C\|NMR spectra of PPGEs.It was found that all the 13 C NMR signals of PPGE were shifted to the lower magnetic field with the increase of the temperature.The temperature sensitivity of the 13 C NMR chemical shifts for different carbon atoms was different.The pendent CH 2 group was most sensitive to the temperature.The change of the 13 C\|NMR chemical shift for the pendent CH 2 group was mainly caused by the temperature change,and the effects of the solvent kind and the stereoregularity of the polymer were of minor importance.The change of temperature did not make any significant influence on the result of the stereoregularity calculation according to the 13 C\|NMR spectra for PPGEs.Utilizing the different temperature sensitivity of 13 C\|NMR signals for different groups,it is possible to separate the overlapped signals by choosing an appropriate temperature.This method was found especially useful in the 13 C\|NMR characterization of complex polymer samples.展开更多
文摘Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of radiation dose was discussed.An obviously chain scission was found near the branch carbons, and the ~ 13 C-NMR spectra of the corresponding gels confirmed the result.Linewidths of irradiated POE samples of various absorbed doses were observed to which were related to the molecular mobility of the radiation-crosslinked polymer.
文摘The solubility of poly(phenyl glycidyl ether)s (PPGEs) depends on the stereoregularity.Different solvents and temperatures (CDCl 3/300 K or TCE d 2/350 K)were used in 13 C\|NMR characterization of these polymers.It was necessary to investigate first the effect of temperature on the 13 C\|NMR spectra of PPGEs.It was found that all the 13 C NMR signals of PPGE were shifted to the lower magnetic field with the increase of the temperature.The temperature sensitivity of the 13 C NMR chemical shifts for different carbon atoms was different.The pendent CH 2 group was most sensitive to the temperature.The change of the 13 C\|NMR chemical shift for the pendent CH 2 group was mainly caused by the temperature change,and the effects of the solvent kind and the stereoregularity of the polymer were of minor importance.The change of temperature did not make any significant influence on the result of the stereoregularity calculation according to the 13 C\|NMR spectra for PPGEs.Utilizing the different temperature sensitivity of 13 C\|NMR signals for different groups,it is possible to separate the overlapped signals by choosing an appropriate temperature.This method was found especially useful in the 13 C\|NMR characterization of complex polymer samples.
