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首页> 外文期刊>Journal of Applied Polymer Science >N,N '-pentamethylenethiuram disulfide- and N,N '-pentamethylenethiuram hexasulfide-accelerated sulfur vulcanization. I. Interaction of curatives in the absence of rubber
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N,N '-pentamethylenethiuram disulfide- and N,N '-pentamethylenethiuram hexasulfide-accelerated sulfur vulcanization. I. Interaction of curatives in the absence of rubber

机译：N，N′-五亚甲基秋兰姆二硫化物和N，N′-五亚甲基秋兰姆六硫化物促进的硫磺硫化。 I.在没有橡胶的情况下固化剂的相互作用

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N,N'-pentamethylenethiuram disulfide (CPTD), CPTD/sulfur, and N,N'-pentamethylenethiuram hexasulfide (CPTP6) were heated in a DSC at a programmed heating rate and isothermally at 140 degrees C. Residual reactants and reaction products were analyzed by HPLC at various temperatures or reaction times. CPTD rapidly formed N,N'-pentamethylenethiuram monosulfide (CPTM) and N,N'-pentamethylenethiuram polysulfides (CPTP) of different sulfur rank, CPTP of higher sulfur rank forming sequentially, as reported earlier for tetramethylthiuram disulfide (TMTD). As with TMTD, the high concentration of the accelerator monosulfide that develops is attributed to an exchange between CPTD and sulfenyl radicals, produced on homolysis of CPTD. However, a different mechanism for CPTP formation to that suggested for TMTD is proposed. It is suggested that disulfenyl radicals, resulting from CPTM formation, exchange with CPTD and/or CPTP already formed, to give CPTP of higher sulfur rank. CPTD/sulfur and CPTP6 very rapidly form a similar product spectrum with CPTP of sulfur rank 1-14 being detectable. Unlike with TMTD/sulfur, polysulfides of high sulfur rank did not form sequentially when sulfur was present, CPTP of all sulfur rank being detected after 30 s. It is proposed that sulfur adds directly to thiuram sulfenyl radicals. Recombination with sulfenyl radicals, which would be the most plentiful in the system, would result in highly sulfurated unstable CPTP. CPTP of higher sulfur rank are less stable than are disulfides as persulfenyl radicals are stabilized by cyclization, and the rapid random dissociation of the highly sulfurated CPTP, followed by the rapid random recombination of the radicals, would result in the observed product spectrum. CPTP is thermally less stable than is TMTD and at 140 degrees C decomposed rapidly to N,N'-pentamethylenethiourea (CPTU), sulfur, and CS2. At 120 degrees C, little degradation was observed. The zinc complex, zinc bis(pentamethylenedithiocarbamate), did not form at vulcanization temperatures, although limited formation was observed above 170 degrees C. ZnO inhibits degradation of CPTD to CPTU. (C) 2000 John Wiley & Sons, Inc. [References: 40]
机译：N，N'-五亚甲基秋兰姆二硫化物（CPTD），CPTD /硫和N，N'-五亚甲基秋兰姆六硫化物（CPTP6）在DSC中以程序升温速率加热，并在140℃下等温加热。分析了残留的反应物和反应产物通过HPLC在各种温度或反应时间进行。 CPTD迅速形成了不同硫等级的N，N'-戊亚甲基秋兰姆单硫化物（CPTM）和N，N'-戊亚甲基秋兰姆多硫化物（CPTP），高硫等级的CPTP依次形成，如先前关于四甲基秋兰姆二硫化物（TMTD）的报道。与TMTD一样，产生的高浓度促进剂一硫化物归因于CPTD与均质CPTD产生的亚硫基​​之间的交换。但是，提出了一种不同于TMTD建议的CPTP形成机制。建议由CPTM形成产生的二硫烯基与已经形成的CPTD和/或CPTP交换，从而得到更高硫级的CPTP。 CPTD /硫和CPTP6很快形成了相似的产物谱，可检测到1-14级硫的CPTP。与TMTD /硫不同，高硫等级的多硫化物在存在硫时不会顺序形成，所有硫等级的CPTP在30 s后都被检测到。建议将硫直接加到秋兰姆亚磺酰基基团上。与亚磺酰基基团的重组是系统中最丰富的，会导致高度硫化的不稳定CPTP。较高硫级的CPTP不如二硫化物稳定，因为过环亚砜基通过环化作用得以稳定，并且高度硫化的CPTP的快速随机解离，然后自由基的快速随机重组，将导致观察到的产物光谱。 CPTP的热稳定性不如TMTD稳定，并且在140摄氏度时迅速分解为N，N'-五亚甲基硫脲（CPTU），硫和CS2。在120℃下，几乎观察不到降解。锌配合物双（五亚甲基二硫代氨基甲酸锌）在硫化温度下没有形成，尽管在170摄氏度以上观察到有限的形成。ZnO抑制了CPTD降解为CPTU。 （C）2000 John Wiley＆Sons，Inc. [参考：40]

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