Rubber Chemicals from Cyclic Amines. IV. Thiocarbamyl Amine Disulfide Curing Agents

1971 ◽  
Vol 44 (4) ◽  
pp. 881-888 ◽  
Author(s):  
E. Morita ◽  
J. J. D'Amico
Keyword(s):  
Crosslink Density ◽  
Cure Rate ◽  
Cyclic Amines ◽  
Curing Agents

Abstract The cure properties of thiocarbamyl amine disulfide (I) as vulcanizing agents are influenced by the ionic and steric nature of both R and R′. The relative effects of various R and R′ are analogous to those of R and R′ in thiuram disulfides and dithioamines, respectively. However, the cure properties of I are dominated by the type of R rather than R′. Among the types of R investigated relatively longer scorch delay, slower cure rate and lower crosslink density are obtained, when R is morpholino or 3-azabicyclo(3.2.2)non-3-yl.

Rubber Chemicals from Cyclic Amines. II Dithioamines and Sulfenamides as Accelerators and Curing Agents

1968 ◽  
Vol 41 (3) ◽  
pp. 721-735 ◽  
Author(s):  
Eiichi Morita ◽  
John J. D'Amico ◽  
Evan J. Young
Keyword(s):  
Thermal Analyses ◽  
Empirical Relation ◽  
Basic Structure ◽  
Cure Rate ◽  
Structural Variations ◽  
Cyclic Amine ◽  
Cure Characteristics ◽  
Cyclic Amines ◽  
Curing Agents ◽  
Derivatives Of

Abstract Dithioamines and sulfenamides derived from various cyclic amines were evaluated as accelerators and vulcanizing agents. Structural variations of these compounds are correlated with their scorch delaying properties, accelerating activity and vulcanization efficiency, employing the Mooney Viscometer and the Monsanto Oscillating Disk Rheometer. The relative cure characteristics differed with changes in the basic structure of the compounds, and with the size and type of the cyclic amine moiety. However, the piperidine derivatives consistently showed longer scorch delay and slower mean cure rate than the corresponding derivatives of pyrrolidine, hexamethylenimine or heptamethylenimine. In the case of the thiazolyl sulfenamides, the type of substitution in the thiazolyl group also influenced scorch delay. An empirical relation was observed between the effect of concentration of the thiazolyl sulfenamides on scorch delay and the results of differential thermal analyses of sulfenamide and sulfur blends.

Effect of Accelerator Type on Brass-Rubber Adhesion

1983 ◽  
Vol 56 (2) ◽  
pp. 450-464 ◽  
Author(s):  
G. R. Hamed ◽  
T. Donatelli
Keyword(s):  
Copper Sulfide ◽  
Crosslink Density ◽  
Direct Interaction ◽  
Cure Rate ◽  
Tetramethylthiuram Disulfide ◽  
Sulfide Layer ◽  
Pull Out ◽  
The Poor ◽  
Copper And Zinc ◽  
Poor Adhesion

Abstract A natural rubber compound accelerated with tetramethylthiuram disulfide (TMTD) was studied and compared to an N-oxydiethylene-2-benzothiazolesulfenamide (MBS) accelerated compound in order to determine the factors resulting in the poor adhesion to brass of the former. Adhesion to brass-plated steel cord was measured by using the TCAT pull-out test. Vulcanization time and temperature were varied. Also, both compounds were analyzed for crosslink density and type at different states of cure by selective cleavage of the crosslinks with thiol reagents. The poor adhesion to brass of the TMTD compound was not accounted for by cure rate or crosslink density or crosslink type. Synchronization of the rubber cure rate with the sulfidation rate of the brass surface appeared to be unimportant in determining the brass adhesion characteristics of that compound. This was investigated by testing the adhesion of the TMTD compound to brass plated steel cords of different reactivities. Cords were analyzed for copper sulfide formation by an energy dispersive x-ray (EDX) technique after pull-out and also after immersion in squalene solutions containing each accelerator with and without added free sulfur. This analysis showed that there is significant sulfidation of brass in the presence of TMTD accelerator. Atomic absorption analyses of the squalene solutions, after the cord immersions, showed relatively large amounts of copper and zinc present in the TMTD solutions as compared to the MBS solutions. This indicates that TMTD corrodes brass to a much greater extent than the MBS accelerator. From the data presented, the following conclusions can be drawn: (1) The poor adhesion to brass of TMTD accelerated compounds is not related to: (a) their rapid cure rates, (b) a lack of synchronization between cure rate and sulfidation rate, or (c) crosslink density or type. This implies that a deficiency of physical entanglements of rubber crosslinks within the copper sulfide layer is not a reason for the poor adhesion to brass of these compounds. (2) Considerable sulfidation of brass occurs in squalene solutions with TMTD indicating that lack of sulfur availability for brass sulfidation is not a valid explanation for the poor brass adhesion of TMTD compounds. Contrarily, in fact, the data suggest that excessive sulfidation of brass occurs in the presence of TMTD. (3) The corrosive nature of TMTD toward brass has been documented for cords dipped in TMTD/squalene solutions. This characteristic of TMTD likely results in a copper sulfide layer on the brass which is porous and mechanically weak. It is proposed that this direct interaction of TMTD with brass provides an explanation for the poor adhesion to brass of TMTD accelerated compounds. The mechanism by which the TMTD causes the very rapid removal of the brass into solution is not known at this time. Perhaps the TMTD or its decomposition fragments form relatively stable complexes with copper and zinc such that their removal is favored.

The Influence of Accelerators on EPDM Vulcanizate Structure

1972 ◽  
Vol 45 (5) ◽  
pp. 1348-1365 ◽  
Author(s):  
F. P. Baldwin
Keyword(s):  
Low Temperature ◽  
Crosslink Density ◽  
Low Rank ◽  
Type Synthesis ◽  
Cure Rate ◽  
High Concentration ◽  
Other Information ◽  
The Stability ◽  
Low Sulfur ◽  
Vulcanization Process

Abstract This study of vulcanization has revealed that in low unsaturation EPDM elastomers prepared with ethylidenenorbornene— 1. Stearic acid can be a useful additive for vulcanization. Increasing concentration in the range 0-4 phr leads to faster curing and reduced polysulfidic crosslink concentration at a given crosslink density. 2. Low sulfur and low sulfur/accelerator ratio and/or prolonged curing times are required to generate vulcanizates containing low percentages of polysulfidic crosslinks. 3. At identical crosslink densities, high temperature cures display a lower level of polysulfidic crosslinks than low temperature cures. However, olefin utilization in crosslinking is generally better with low temperature curing. 4. At high sulfur levels, variations in crosslink type distribution resulting from accelerator changes tend to disappear. 5. Mixed acceleration—a dialkylthiocarbamic acid derivative and an accelerator having the benzothiazolylthio radical—appear best suited for the combination of maximizing cure rate and producing stable (lower sulfur rank) crosslinks. Taken together with other information, the results of this study lead to the suggestion that: 6. The stability of the basic accelerator nucleus is influential both on cure rate and on the ability to generate stable crosslinks. 7. The exact structure and concentration of the olefinic moieties present in the polymer have at least as much bearing on the detailed outcome of the vulcanization process as do changes in accelerator. 8. A useful accelerator for these rubbers resulting in the production of vulcanizates containing a high concentration of low rank sulfur crosslink might derive from a MBT type synthesis based on a properly ringalkylated aniline. 9. Some effort devoted to the study of chemicals which may not accelerate crosslinking but could participate in the crosslink shortening process would appear worthwhile.

scholarly journals The Blending of EPDM/NR with Maleic Anhydride as Compatibilizer: Comparing the Effect of Accelerators on Cure Characteristic and Mechanical Properties

2019 ◽  
Vol 19 (1) ◽  
pp. 106
Author(s):  
Hesty Eka Mayasari ◽  
Ike Setyorini ◽  
Arum Yuniari
Keyword(s):  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Crosslink Density ◽  
Testing Machine ◽  
Cure Rate ◽  
Tensile Testing Machine ◽  
Aging Resistance ◽  
Sem Micrograph ◽  
Cure Characteristic ◽  
Accelerator System

The blending of ethylene propylene diene monomer/natural rubber (EPDM/NR) needs much attention because of their incompatibility. In this work, the influence of accelerator type on cure characteristics and mechanical properties of 60/40 EPDM/NR blend was investigated. The compounds were prepared by controlling the migration of curative and using maleic anhydride as the compatibilizer. Three types of accelerators were studied: 2,2-dithiobis(benzothiazole) (MBTS), the combination of MBTS and tetramethyl thiuram disulfide (TMTD), and n-tert-butyl-2-benzothiazolesulfenamide (TBBS). The cure characteristic, mechanical properties, and morphology of the composites had been investigated by rheometer, tensile testing machine, hardness durometer and scanning electron microscope (SEM). Blending of EPDM/NR with various accelerator gave different composite characteristics. MBTS, used in single or binary accelerator system, provided good mechanical properties. TBBS gave the longest scorch time, the lowest crosslink density and poor mechanical properties, except tear strength. Binary accelerator, MBTS/TMTD, provided the lowest processing time and the highest cure rate, but not significantly different from MBTS. Binary accelerator gives the best aging resistance and compatibility blend. These results correspond well with SEM micrograph. From the study, it can be concluded that binary accelerator system was the proper accelerator for EPDM/NR blend.

Enhancement of the crosslink density, glass transition temperature, and strength of epoxy resin by using functionalized graphene oxide co-curing agents

2016 ◽  
Vol 7 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Jin Won Yu ◽  
Jin Jung ◽  
Yong-Mun Choi ◽  
Jae Hun Choi ◽  
Jaesang Yu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Graphene Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Crosslink Density ◽  
Functionalized Graphene ◽  
Functionalized Graphene Oxide ◽  
Curing Agents

Epoxy nanocomposites are fabricated by using diamine-functionalized GO and exhibit high Tg, tensile strength, and crosslink density.

N-(Aminothio)imide Cure Modifiers

1976 ◽  
Vol 49 (2) ◽  
pp. 333-340 ◽  
Author(s):  
J. P. Lawrence
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Crosslink Density ◽  
Electronic Effects ◽  
Cure Rate ◽  
Cure Characteristics ◽  
Free Amine ◽  
Diene Rubbers ◽  
Thermal Stability Of

Abstract N-(Aminothio)imides have been found to influence the cure characteristics of diene rubbers accelerated by conventional vulcanization accelerators. In this respect, they generally act both as scorch inhibitors and activators to increase the cure rate and crosslink density. The ability of these compounds to act as scorch inhibitors is believed to be attributable to trapping of MBT with resultant formation of the corresponding free imide and 2-(aminodithio)benzothiazole. The latter is an active vulcanization agent and may lead directly to the formation of pendent accelerator groups and free amine, likely the source of the cure activation. As precursors to crosslink formation, the pendent accelerator groups carry an atom of sulfur derived from the cure modifier and thus lead to higher crosslink density. The relative scorch inhibiting characteristics are influenced by the basicity of the parent amine and thermal stability of the cure modifier. The compounds derived from amines of weaker basicity are better retarders and less subject to thermal degradation which would lead to nonretarding products. The relative cure activating effects are apparently influenced by both steric and electronic effects of the parent amine. Cure activation increases as the steric bulk decreases and basicity increases. As expected, the nature of the imide substituent played a relative insignificant role in influencing the cure characteristics, aside from a possible stabilization against thermal degradation.

Rubber Chemicals from Cyclic Amines. III. Iminocarbodithioates as Accelerators and Curing Agents

1968 ◽  
Vol 41 (3) ◽  
pp. 736-751
Author(s):  
Eiichi Mortia ◽  
John J. D'Amico ◽  
Evan J. Young
Keyword(s):  
Chemical Structure ◽  
Ring Size ◽  
Cure Characteristics ◽  
Cyclic Amines ◽  
Curing Agents ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract Evaluations of cyclic iminocarbodithioates as accelerators and vulcanizing agents are described. The starting amines include morpholine and 3-azabicyclo-[3.2.2]nonane and vary in ring size from tetra- to octamethylenimine. The chemical structure of these compounds is correlated with their cure characteristics and the kinetics of vulcanization. Basicity and ring size of the amine moiety govern the activity of the iminocarbodithioates.

scholarly journals Influence of n-ZnO Morphology on Sulfur Crosslinking and Properties of Styrene-Butadiene Rubber Vulcanizates

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1040
Author(s):  
Dariusz M. Bieliński ◽  
Katarzyna Klajn ◽  
Tomasz Gozdek ◽  
Rafał Kruszyński ◽  
Marcin Świątkowski
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Zinc Oxide Nanoparticles ◽  
Crosslink Density ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Cure Rate ◽  
Styrene Butadiene ◽  
Scanning Electron ◽  
Bet Equation

This paper examines the influence of the morphology of zinc oxide nanoparticles (n-ZnO) on the activation energy, vulcanization parameters, crosslink density, crosslink structure, and mechanical properties in the extension of the sulfur vulcanizates of styrene-butadiene rubber (SBR). Scanning electron microscopy was used to determine the particle size distribution and morphology, whereas the specific surface area (SSA) and squalene wettability of the n-ZnO nanoparticles were adequately evaluated using the Brunauer–Emmet–Teller (BET) equation and tensiometry. The n-ZnO were then added to the SBR in conventional (CV) or efficient (EV) vulcanization systems. The vulcametric curves were plotted, from which the cure rate index (CRI) rate of the vulcanization and the activation energy were calculated. The influence on the mechanical properties of the SBR vulcanizates was stronger in the case of the EV curing system than when the CV curing system was used. Of the vulcanizates produced in the EV curing system, the best performance was detected for n-ZnO particles with a hybrid morphology (flat-ended rod-like particles on a “cauliflower” base) and high SSA. Vulcanizates produced using the CV curing system showed slightly better mechanical properties after the addition of nanoparticles with a “cauliflower” morphology than when the rod-like type were used, irrespective of their SSA. In general, nanoparticles with a rod-like structure reduced the activation energy and increased the speed of vulcanization, whereas the cauliflower type slowed the rate of the process and the vulcanizates required a higher activation energy, especially when using the EV system. The crosslink structures were also more clearly modified, as manifested by a reduction in the polysulfidic crosslink content, especially when n-ZnO activators with a rod-like morphology were applied.

The Influence of Zinc Dimethacrylate on Crosslink Density, Physical Properties and Heat Aging Resistance of Sulfur Vulcanized Styrene Butadiene Rubber

2013 ◽  
Vol 844 ◽  
pp. 45-48
Author(s):  
Weerawut Naebpetch ◽  
Banja Junhasavasdikul ◽  
Anuwat Saetung ◽  
Tulyapong Tulyapitak ◽  
Nattapong Nithi-Uthai
Keyword(s):  
Physical Properties ◽  
Crosslink Density ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Cure Rate ◽  
Elongation At Break ◽  
Roll Mill ◽  
Aging Resistance ◽  
Equilibrium Swelling ◽  
Styrene Butadiene

In this work, to study the utilization of zinc dimethacrylate (ZDMA) in sulfur vulcanized styrene butadiene rubber (SBR). The compounds were prepared by two roll mill mixer. Crosslink density and crosslink types were determined with an equilibrium swelling method. Physical properties and heat aging resistance were studied. The results shows that increase of ZDMA will decrease cure rate index and crosslink density which lead to decreased in 300% modulus and hardness. However, the addition of ZDMA can improve tensile strength, tear strength, elongation at break and heat aging resistance.

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