An in situ stretching instrument combined with low field nuclear magnetic resonance (NMR): Rheo-Spin NMR.
An in situ stretching instrument combined with low field nuclear magnetic resonance (NMR): Rheo-Spin NMR.
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DOI：
10.1063/5.0080767
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Zhijie Xia;Yusong Wang;Ke Gong;Wei Chen
中科院分区：
文献类型：
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作者：
Zhijie Xia;Yusong Wang;Ke Gong;Wei Chen
设计并研制了一种与低场核磁共振（LF-NMR）相结合的原位拉伸仪器，即Rheo-Spin NMR。可以同时获得时间分辨的应力-应变曲线和相应的NMR信号。Rheo-Spin NMR包含功能模块，包括（1）原位拉伸模块，（2）NMR信号采集模块，和（3）NMR定位模块的腔体。由于NMR探头内空间有限，采用样品独特的环状形状来代替传统的哑铃状样品，整个环状样品在单轴拉伸过程中会发生变形，避免了未变形样品产生干扰信号。设计制作了氧化锆陶瓷拉伸组件，对环形试样进行了匹配拉伸。应变速率在10-5 ~ 10- 2s-1范围内可调，最大拉伸比λmax为3.8。采用LF-NMR结合原位拉伸实验，成功地对不同炭黑含量的天然橡胶进行了拉伸实验。采用时间分辨T2弛豫技术研究了单轴变形过程中的链段弛豫，首次提供了直接的、原位的分子动力学信息。流变自旋核磁共振有望为聚合物产品在真实的使用条件下的结构和动力学演变提供更深入的见解。
An in situ stretching instrument combined with low field nuclear magnetic resonance (LF-NMR) was designed and developed, namely, Rheo-Spin NMR. The time resolved stress-strain curve together with the corresponding NMR signal can be simultaneously obtained. The Rheo-Spin NMR contains the functional modules, including (1) the in situ stretching module, (2) the NMR signal acquisition module, and (3) the cavity of the NMR positioning module. The unique ring-like shape of the sample is used to replace the traditional dumbbell sample due to limited space in the NMR probe, and the whole ring-like sample will be deformed during the uniaxial stretching process, which avoids the generation of interference signals from the undeformed sample. The designed stretching assembly made by zirconia ceramics is manufactured to match and stretch the ring-like samples. The strain rate can be tuned within the range of 10-5-10-2 s-1 with the maximum stretching ratio λmax of ∼3.8. The in situ stretching experiments combined with LF-NMR were carried out successfully with natural rubber of different fractions of carbon black. The time-resolved T2 relaxometry was adopted to evaluate segmental relaxation during uniaxial deformation which, for the first time, provides the direct and in situ molecular dynamics information. The Rheo-Spin NMR is promising to provide more in-depth insights into the structure and dynamics evolution of polymer products under real service conditions.