NMR microscopy has received great attention from various fields of research, especially material science by its possibility to study materials directly without destruction. Although this technique is almost limited to...NMR microscopy has received great attention from various fields of research, especially material science by its possibility to study materials directly without destruction. Although this technique is almost limited to the detection of fluids constricted in solid samples, such as water in biological systems, solvent diffused in a polymer material^1 and liquid saturated rock systems^2, the mechanical defects of high elastic rubbers have also been detected^3 We are extending this technique to the direct study of the effect of y-irradiation on cis 1, 4-polybutadiene (PB). This article deals with the investigation of radiation induced crosslinking of PB by NMR microscopy.展开更多
In this work, the effect of the fullerene（C_（60）） weight fraction and PB-C_（60） interaction on the glass transition temperature（T_g） of polymer chains has been systemically investigated by adopting the united ...In this work, the effect of the fullerene（C_（60）） weight fraction and PB-C_（60） interaction on the glass transition temperature（T_g） of polymer chains has been systemically investigated by adopting the united atom model of cis-1,4-poly（butadiene）（cis-PB）. Various chain dynamics properties, such as atom translational mobility, bond/segment reorientation dynamics, torsional dynamics, conformational transition rate and dynamic heterogeneity of the cis-PB chains, are analyzed in detail. It is found that T_g could be affected by the C_（60） weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, T_g is different, which depends on different dynamics scales. Among the chain dynamics properties, T_g is the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, T_g can be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C_（60） weight fraction compared with others. For pure cis-PB chains, T_g and the activation energy in this work can be compared with those of other polymers. In addition, the temperature dependence of the dynamic properties has different Arrhenius behaviors above and below T_g. The activation energy below T_g is lower than that above T_g. This work can help to understand the effect of the C_（60） on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.展开更多
文摘NMR microscopy has received great attention from various fields of research, especially material science by its possibility to study materials directly without destruction. Although this technique is almost limited to the detection of fluids constricted in solid samples, such as water in biological systems, solvent diffused in a polymer material^1 and liquid saturated rock systems^2, the mechanical defects of high elastic rubbers have also been detected^3 We are extending this technique to the direct study of the effect of y-irradiation on cis 1, 4-polybutadiene (PB). This article deals with the investigation of radiation induced crosslinking of PB by NMR microscopy.
基金financial supports from the start-up funding of Beijing University of Chemical Technology(BUCT)for excellent introduced talentsthe Fundamental Research Funds for the Central Universities(JD1711)
文摘In this work, the effect of the fullerene（C_（60）） weight fraction and PB-C_（60） interaction on the glass transition temperature（T_g） of polymer chains has been systemically investigated by adopting the united atom model of cis-1,4-poly（butadiene）（cis-PB）. Various chain dynamics properties, such as atom translational mobility, bond/segment reorientation dynamics, torsional dynamics, conformational transition rate and dynamic heterogeneity of the cis-PB chains, are analyzed in detail. It is found that T_g could be affected by the C_（60） weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, T_g is different, which depends on different dynamics scales. Among the chain dynamics properties, T_g is the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, T_g can be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C_（60） weight fraction compared with others. For pure cis-PB chains, T_g and the activation energy in this work can be compared with those of other polymers. In addition, the temperature dependence of the dynamic properties has different Arrhenius behaviors above and below T_g. The activation energy below T_g is lower than that above T_g. This work can help to understand the effect of the C_（60） on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.
