摘要
CPMG(Carr-Purcell-Meiboom-Gill)回波法是测量橡胶交联密度[常用交联点之间的分子量(Mc)表示]的一种常用核磁共振(NMR)技术,但实验发现通过该技术获得的Mc对于CPMG序列中脉冲间隔时间具有较强的依赖性,导致交联密度NMR测量值与橡胶材料硬度的相关性低.为了克服这一缺点,本文对不同脉冲间隔时间下CPMG实验测得的质子横向驰豫曲线进行高斯加权.通过对高斯加权求和后的质子横向驰豫曲线进行处理分析,实现了对橡胶交联密度更加准确地测量,大幅提升了天然橡胶交联密度NMR测量值与材料硬度的相关性.本文方案测量能获得与~1H DQ NMR方法相当,或比之更佳的交联密度-硬度相关性.同时,本文方案比~1H DQ NMR方法更为高效,整体测量时间缩短为~1H DQ NMR实验时间的1/10.
CPMG sequence is widely used to measure crosslink density of rubber. However, the crosslink density obtained by this technique has a strong dependence on the interval times between the pulses in CPMG sequence, and the results measured have only a weak correlation with rubber hardness. To overcome this shortcoming, we proposed in this work to construct a ^1H T2 relaxation curve by summing Gaussian-weighted CPMG relaxation curves acquired at by varying the interval time between the pulses in CPMG sequence. Using the multi-echo Gaussian-weighted relaxation curve to calculate the crosslink density gave results that had greatly improved correlation with the rubber hardness. The new method was also fast and efficient, as it took only one-tenth of the experimental time required for the conventional ^1H double quantum NMR （^1H DQ NMR） experiment.
出处
《波谱学杂志》
CAS
CSCD
北大核心
2018年第1期60-74,共15页
Chinese Journal of Magnetic Resonance
基金
国家自然科学基金资助项目(21574043,41572103)
国家重点基础研究发展计划(“973计划”)资助项目(2013CB921801)
上海市科委资助项目(15142200500)
华东师范大学科研创新基金资助项目.
关键词
^1H
CPMG
高斯加权求和
^1H
DQ
NMR
交联密度
橡胶
^1H CPMG, Gaussian-weighted summation, 1H double quantum NMR （1H DQ NMR）, crosslink density, rubber
