Solid State Carbon-13 NMR Studies of Elastomers. XL N-t-Butyl Benzothiazole Sulfenimide Accelerated Sulfur Vulcanization of cis-Polyisoprene at 75 MHz
Solid State Carbon-13 NMR Studies of Elastomers. XL N-t-Butyl Benzothiazole Sulfenimide Accelerated Sulfur Vulcanization of cis-Polyisoprene at 75 MHz
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弹性体的固态碳 13 NMR 研究。
DOI：
10.5254/1.3538300
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发表时间：
1993
影响因子：
1.5
通讯作者：
J. Koenig
中科院分区：
文献类型：
--
作者：
M. Krejsa;J. Koenig
摘要用C-13固体核磁共振研究了TbSi加速顺式聚异戊二烯硫化的网络结构。最初的交联产物由A1c(顺式)和A2c(顺式)多硫化物组成。随着固化百分数的增加，A1c和A2c结构降级为单硫化物，形成多硫化物B1c(顺式)和b1t(反式)结构。在成熟期，还形成了C1c(Cis)多硫化物结构。硫化百分率与硫磺浓度成正比，而硫化效率(交联度/环结构比)随促进剂含量而变化。在初始硫化阶段，TBSI加速硫化比TBBS加速硫化效率更低(交联度/环结构比更低)。然而，这会导致硫链变短，与硫化硫化过程中的硫化产物相比，硫化硫化物硫化活性降低。
Abstract The network structure of TBSI-accelerated vulcanization of cis-polyisoprene was studied using C-13 solid-state NMR. The initial crosslink products consisted of A1c (cis) and A2c (cis) polysulfides. As the percent cure is increased, the A1c and A2c structures reduce in rank to monosulfides, and polysulfidic B1c (cis) and B1t (trans) structures are formed. During the maturation period C1c (cis) polysulfidic structures are also formed. The percent of sulfurization was shown to vary directly with sulfur concentration, while the efficiency of sulfurization (crosslink/cyclic-structure ratio) was shown to vary with accelerator content. TBSI-accelerated vulcanization was found to be more inefficient (lower crosslink/cyclic-structure ratio) than TBBS-accelerated vulcanization during the initial cure region. However, this results in shorter sulfur chains, which decreases the reactivity of TBSI vulcanizates as compared to TBBS vulcanizates during the reversion regime.