Tetramethylthiuram disulfide vulcanization of extracted rubber. IV. Behavior of rubber as an acid

Craig, D. P.; Juve, A. E.; Davidson, W.

doi:10.1002/pol.1951.120060103

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…When a ZnO/TMTM mixture was heated until mass loss discontinued, requiring 38 h at 140°C, the sample was shown to contain as much as 30% of ZDMC, relative to the initial amount of TMTM present. This contradicts earlier statements that ZnO and TMTM do not react, 26,27 but, in view of the long reaction times, it is not excluded that degradation of TMTM would have furnished the required elemental sulfur to produce reactive TMTD. Irrespective of the course of action, the ability of TMTM to yield ZDMC in the presence of ZnO should not be ruled out.…”

Section: Reactivities Of Zns and Tmtmcontrasting

confidence: 82%

The limiting value of ZDMC formation: new insight into the reaction of ZNO and TMTD

Nieuwenhuizen

Duin

Haasnoot

et al. 1999

J. Appl. Polym. Sci.

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The reaction of ZnO and tetramethylthiuram disulfide (TMTD) was reinvestigated in detail. Under conditions where evaporation of volatiles is possible, TMTD and an excess of ZnO are found to produce bis(dimethyldithiocarbamato)zinc(II) (ZDMC) in limiting amounts close to 60 mol %, irrespective of the ratio between ZnO and TMTD. This result points to the operation of more than one route toward ZDMC. When ZnO and TMTD are reacted in closed vessels in inert atmosphere, a nucleophilic reaction of ZnO with TMTD was confirmed by GC-mass spectroscopy (MS) detection of COS and NMR observation of tetramethylthiourea (TMTU). This route is found to account for about 70 mol % of the total amount of ZDMC formed. A previously unrecognized redox reaction between ZnO, sulfur, and TMTD, furnishing ZnSO 4 and ZDMC, is responsible for approximately 15 mol % of the amount of ZDMC. Other products that were detected are CO 2 , CS 2 , and tetramethylurea, whereas ZnSO 3 , ZnS, and dioxygen were absent. Based on the latter observation, the operation of a mechanism constituting radical reduction of water by TMTD, yielding dioxygen, was excluded.

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Section: Reactivities Of Zns and Tmtmcontrasting

confidence: 82%

The limiting value of ZDMC formation: new insight into the reaction of ZNO and TMTD

Nieuwenhuizen

Duin

Haasnoot

et al. 1999

J. Appl. Polym. Sci.

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“…Numerous authors have reported on the interaction of TMTD and ZnO to form zinc dimethyldithiocarbamate (ZDMC) 3, 6–8. Kruger and McGill5 obtained very little or no reaction with ZnO, and the presence of ZDMC in rubber was attributed to it being a byproduct of the crosslinking reaction in rubber.…”

Section: Introductionmentioning

confidence: 99%

“…Kruger and McGill5 obtained very little or no reaction with ZnO, and the presence of ZDMC in rubber was attributed to it being a byproduct of the crosslinking reaction in rubber. Craig et al6 heated radio‐sulfur labeled TMTD with ZnO and produced randomly radioactive ZDMC and radioactive sulfur in high yield. Jarrijon9 obtained a 60 mol % conversion of TMTD to ZDMC when TMTD (three parts) was heated with ZnO (two parts) for 2 h at 147°C, in the absence of a solvent.…”

Section: Introductionmentioning

confidence: 99%

Comparison of tetraethyl‐ and tetramethylthiuram disulfide vulcanization. I. Reactions in the absence of rubber

Gradwell¹,

Grooff²

2001

J of Applied Polymer Sci

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ABSTRACT:The reactions of tetraethylthiuram di-and monosulfide (TETD and TETM, respectively) were investigated in the absence of rubber and compared with those reported previously for tetramethylthiuram compounds. The reactions of TETM, TETD, and zinc diethyldithiocarbamic acid with zinc oxide and sulfur were investigated by differential scanning calorimetry, and the reaction products analyzed by high performance liquid chromatography. TETM was shown to be more stable at vulcanization temperatures (Ϯ150°C), but also less reactive with sulfur than tetramethylthiuram disulfide (TMTD). The reactions of TETD are very similar to those of TMTD, the TETD reacting slower than the TMTD to form analogous products. In the presence of zinc oxide, the formation of the zinc compound of TETD, zinc diethyldithiocarbamic acid, occurred readily. TMTD does not react readily with zinc oxide. The reaction of TETD with sulfur lead to the formation of polysulfidic accelerator species, although the concentrations formed in the absence of rubber were considerably less than that formed by the corresponding TMTD system. These differences in reactivity would affect the vulcanization reactions that take place in the rubber.

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“…Aliphatic acids, notably stearic acid, are commonly used in accelerated sulfur vulcanization formulations. Its retarding effect on vulcanization, as well as the activating effect of acids on certain accelerators, is well recognized 1, 2. Stearic acid melts below compounding temperatures, and already at this stage will readily react with ZnO.…”

Section: Introductionmentioning

confidence: 99%

“…Kruger and McGill17 reported that sulfur and stearic acid were immiscible and that stearic acid delayed the MBTS/sulfur interaction, while TG and DSC studies13 of TMTD and stearic acid indicated decomposition of TMTD above 146°C, 90% of the TMTD decomposing by 180°C. Craig et al18 found that TMTD reacted slowly with palmitic acid at 130–140°C.…”

Section: Introductionmentioning

confidence: 99%

Effect of carboxylic acids on 2-bisbenzothiazole-2,2?- disulfide- and tetramethylthiuram disulfide-accelerated sulfur vulcanization. I. Reaction between the acids and accelerators

McGill

Shelver

1999

J. Appl. Polym. Sci.

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Benzoic and stearic acids are shown to react with 2-bisbenzothiazole-2,2Ј-disulfide (MBTS) and its polysulfides (MBTP) at vulcanization temperatures to form acid-accelerator complexes 2-benzoylthiobenzothiazole (BzM) and stearicthiobenzothiazole (StM), respectively. At higher temperatures MBTS, MBTP, BzM, and StM are decomposed by the acids. Analogous reactions are observed with tetramethylthiuram disulfide (TMTD) and its polysulfides (TMTP). Lesser amounts of acid-accelerator complexes 2-benzoyldimethyldithiocambamate and stearicdimethyldithiocarbamate are formed, but TMTP are more susceptable to decomposition at higher temperatures. The destruction of MBTP and TMTP by carboxylic acids will reduce the concentration of accelerator polysulfides available in compounds, and should impact negatively on vulcanization.

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Tetramethylthiuram disulfide vulcanization of extracted rubber. IV. Behavior of rubber as an acid

Cited by 10 publications

References 6 publications

The limiting value of ZDMC formation: new insight into the reaction of ZNO and TMTD

The limiting value of ZDMC formation: new insight into the reaction of ZNO and TMTD

Comparison of tetraethyl‐ and tetramethylthiuram disulfide vulcanization. I. Reactions in the absence of rubber

Effect of carboxylic acids on 2-bisbenzothiazole-2,2?- disulfide- and tetramethylthiuram disulfide-accelerated sulfur vulcanization. I. Reaction between the acids and accelerators

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