Chain Order and Cross-Link Density of Elastomers As Investigated by Proton Multiple-Quantum NMR
Chain Order and Cross-Link Density of Elastomers As Investigated by Proton Multiple-Quantum NMR
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DOI：
10.1021/ma051238g
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发表时间：
2005-10
期刊：
影响因子：
5.5
通讯作者：
K. Saalwächter;B. Herrero;M. López-Manchado
中科院分区：
文献类型：
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作者：
K. Saalwächter;B. Herrero;M. López-Manchado
我们提出了一个定量研究的本地链段顺序硫化天然橡胶和丁二烯橡胶远高于玻璃化转变。网络链的顺序是依赖于交联的密度，并在这里来自质子homomethyl剩余偶极耦合测量静态多量子NMR光谱在低场。基于一个合理的局部链结构和快速，单轴对称的局部运动模型，自旋动力学模拟被用来调查实验确定的残余耦合和聚合物主链的序参数之间的关系。该模型进行了验证，在高场的内部和内部共振残余耦合的现场解决的测定。对于这两种类型的橡胶，它被发现，链序参数的分布是相当窄的，在所有情况下很好地解释了本地耦合拓扑结构，从而排除了分布的端到端的分离或网络链长度的重要来源的扩大。这...
We present a quantitative study of local segmental order in vulcanized natural and butadiene rubber far above the glass transition. Network chain order is dependent on the density of cross-links and is here derived from proton homonuclear residual dipolar couplings measured by static multiple-quantum NMR spectroscopy at low field. On the basis of a reasonable model of local chain structure and fast, uniaxially symmetric local motions, spin dynamics simulations are used to investigate the relationship between the experimentally determined residual coupling and the order parameter of the polymer backbone. The model is verified by site-resolved determinations of inter- and intraresonance residual couplings at high field. For both types of rubber, it is found that the distributions of the chain order parameter are rather narrow and in all cases well explained by the local coupling topology, thus excluding distributions of end-to-end separations or network chains lengths as important sources of broadening. Thi...