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.

Study of diamond adhesion behavior on chromium and titanium for obtaining adherent diamond coatings on steel

2000 ◽  
Vol 15 (11) ◽  
pp. 2330-2335 ◽  
Author(s):  
Q. H. Fan ◽  
J. Grácio ◽  
E. Pereira ◽  
N. Ali ◽  
W. Ahmed
Keyword(s):  
Diamond Films ◽  
Film Stress ◽  
Diamond Coatings ◽  
Micro Raman Spectroscopy ◽  
The Poor ◽  
Adhesion Behavior ◽  
Indentation Tests ◽  
Pure Chromium ◽  
Film Form ◽  
Poor Adhesion

It is known that diamond films display poor adhesion on metals such as copper and steel. One solution to overcome the poor adhesion is to use interlayer materials. In this study we report results of an investigation of the adhesion behavior of diamond on pure chromium (Cr) and titanium (Ti) substrates. Cr and Ti are promising interlayer materials for adhering diamond to stainless steel. The coating adhesion was studied using indentation tests combined with acoustic emission signals during loading. It was found that a 105-N load indentation caused the film to delaminate from the Cr substrate, while the diamond film remained attached to the titanium even after the indentation at 180 N. Micro-Raman spectroscopy was used to monitor the film stress. The diamond films grown on Ti substrates were found to be less stressed than the films grown on Cr substrates. Therefore, Ti was used in thin-film form to obtain adherent diamond coatings on steel.

Low Sulfur-Sulfenamide Accelerator Combinations for Injection Molding of Cis-1,4-Poly(Isoprene)

1972 ◽  
Vol 45 (5) ◽  
pp. 1403-1411 ◽  
Author(s):  
J. F. O'Mahoney
Keyword(s):  
Carbon Black ◽  
Injection Molding ◽  
Sulfur Concentration ◽  
Cure Rate ◽  
Tetramethylthiuram Disulfide ◽  
Excellent Method ◽  
Injection Molded ◽  
Low Levels ◽  
Low Sulfur ◽  
Made In

Abstract Earlier work with cis-l,4-poly(isoprene) suggested that low levels of sulfur and high levels of sulfenamide accelerator with high levels of secondary accelerator was an excellent method for curing injection molded stocks. However, subsequent experience showed that despite the benefits of reduced sulfur concentrations on reversion, increased sulfur, increased sulfenamide, and reduced secondary accelerator concentrations were necessary for adequate cure and safety. From that experience we explored further and found that, if the sulfenamide concentration is held constant at a higher level and the secondary accelerator concentration is increased as sulfur concentration is decreased, nearly equivalent hardness and modulus can be maintained throughout most cure conditions with no loss in safety and cure rate and much improvement in reversion resistance. Studies were made in a carbon black filled stock with N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N-oxodiethylene-2-benzothiazole sulfenamide (DBS), and N-morpholinyl-2-benzothiazolyl disulfide (MBD) as primary accelerators and tetramethylthiuram monosulfide (TMTM) and tetramethylthiuram disulfide (TMTD) as secondary accelerators.

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.

Study of Rubber-Brass Adhesion Mechanism by Secondary Ion Mass Spectrometry

2002 ◽  
Vol 75 (2) ◽  
pp. 199-214 ◽  
Author(s):  
Jong Myoung Kim ◽  
Wim J. van Ooij
Keyword(s):  
Mass Spectrometry ◽  
Copper Sulfide ◽  
Secondary Ion Mass Spectrometry ◽  
Cluster Formation ◽  
Copper Sulfides ◽  
Sulfide Layer ◽  
Tof Sims ◽  
Sulfide Film ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Abstract The sulfidization reaction of brass was studied in a squalene model system by Time-of-Flight Secondary Ion Mass Spectrometry, TOF-SIMS. Fragments of the accelerator were observed on the surface of the brass and their concentration changed with reaction time. Copper sulfide formation in the brass panels was confirmed from the TOF-SIMS spectra. The composition of the brass panels could be studied by varying the analysis depth. TOF-SIMS spectra of copper sulfide layer showed a pattern of cluster formation. Cobalt was observed to exist in the sulfide film partly in combination with carbon. Evidence was found of covalent bonding between copper sulfides and squalene.

scholarly journals Recycling of WEEE Plastics Waste in Mortar: The Effects on Mechanical Properties

Recycling ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 70
Author(s):  
Alessandra Merlo ◽  
Luca Lavagna ◽  
Daniel Suarez-Riera ◽  
Matteo Pavese
Keyword(s):  
Mechanical Properties ◽  
Natural Resources ◽  
Mechanical Performance ◽  
Plastic Waste ◽  
Partial Replacement ◽  
Porosity Formation ◽  
Mineral Aggregate ◽  
The Poor ◽  
Structural Applications ◽  
Poor Adhesion

This work focused on the recycling of WEEE plastic waste as a partial substitute for aggregate in light mortars. The plastic mix, provided by the IREN group, was used as a replacement of aggregate in 15, 30, 45, 60, 75, and 90%vol in mortars. Worsening of the mechanical performance of around 50% was detected already at only 15%vol of mineral aggregate substituted with plastic waste. The explanation of this phenomenon was found in both the scarce mechanical properties of the used plastic and in the poor adhesion between matrix and plastics that resulted in extra-porosity formation, as also demonstrated by comparing the results with several models in the literature. However, the use of plastic waste as a partial replacement of natural aggregate contributes to the preservation of natural resources and, in any case, does not limit the application of these materials in non-structural applications.

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.

scholarly journals EFFECT OF POLYMER CHAIN MODIFICATIONS ON ELASTOMER PROPERTIES

2019 ◽  
Vol 92 (1) ◽  
pp. 69-89 ◽  
Author(s):  
Katarzyna S. Bandzierz ◽  
Louis A. E. M. Reuvekamp ◽  
Jerzy Dryzek ◽  
Wilma K. Dierkes ◽  
Anke Blume ◽  
...  
Keyword(s):  
Polymer Chain ◽  
Crosslink Density ◽  
Mechanical Performance ◽  
Transition Process ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Tetramethylthiuram Disulfide

ABSTRACT Considerable attention is paid to the influence of crosslink density and crosslink structures on the behavior of polymer chains and properties of elastomers. However, a very important parameter seems to be underestimated: the modifications to the polymer chains by curatives, formed by sulfur and fragments of accelerators. We draw attention to this important contribution to performance of spatial networks. The emulsion styrene–butadiene rubber samples, cured with tetramethylthiuram disulfide and sulfur (TMTD/S8) and zinc dialkyl dithiophosphate with sulfur (ZDT/S8), were studied. They were characterized in detail in terms of crosslink density and crosslink structures. Microscale techniques were used to obtain information about the behavior of the polymer chains: positron annihilation lifetime spectroscopy (PALS) to study the free volume structure and differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to monitor the glass transition process. Properties such as static mechanical performance and thermo-oxidative stability were also evaluated. All of the investigated characteristics were influenced by a combination of crosslink density, crosslink structures, and, to a large extent, by the modifications of the polymer chains. The effect of the modifications is dependent on the amount and the structure of the curatives' molecules. On the basis of the obtained results, the usefulness of the “phr” unit used for calculation of the curatives' amount has been queried. Furthermore, it has been demonstrated that DSC, DMA, and PALS techniques can provide evidence for the presence of the modifications on the polymer chain by curatives.

Efficiency of TMTD Vulcanization

1958 ◽  
Vol 31 (3) ◽  
pp. 559-561
Author(s):  
E. M. Bevilacqua
Keyword(s):  
Zinc Oxide ◽  
Recent Work ◽  
Crosslink Density ◽  
Tetramethylthiuram Disulfide ◽  
Wide Range ◽  
Series Of Experiments

Abstract Tetramethylthiuram disulfide (TMTD), together with a sufficient amount of zinc oxide, is the simplest and most efficient vulcanizing agent known for introduction of sulfur crosslinks into rubber. No other combination approaches it in efficiency over a wide range of temperatures, although under limited conditions sulfur cures can be obtained with approximately as high a crosslink density per mole of vulcanizing agent. The stoichiometry of vulcanization with this curative has been explored in some detail in recent work of Scheele and coworkers. They have confirmed the observation by Jarrijon that during vulcanization dithiocarbamate is formed equivalent to close to two-thirds of the TMTD taken. The generality of this result was established in an exhaustive series of experiments, covering a range of structures of thiuram disulfide and of polyolefin, of temperature, and of concentration of reactants.

scholarly journals SYNTHESIS OF EVAgMA AND ITS EFFECTS ON TENSILE PROPERTIES AND MORPHOLOGY OF ETHYLENE VINYL ACETATE COPOLYMER/BAMBOO FLOUR AND POLYPROPYLENE/ BAMBOO FLOUR COMPOSITES

2018 ◽  
Vol 56 (3B) ◽  
pp. 199
Author(s):  
Mai Duc Huynh ◽  
Do Quang Tham ◽  
Do Van Cong ◽  
Tran Huu Trung ◽  
Nguyen Vu Giang
Keyword(s):  
Tensile Properties ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Thermoplastic Composites ◽  
The Poor ◽  
Bamboo Flour ◽  
Natural Additive ◽  
Poor Adhesion ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

Thermoplastic composites reinforced with natural fillers (WPCs) have being attracted many attentions in recent years. The biggest challenges for WPCs production have to face is the poor adhesion and interaction between the components in the composites. This study investigates the technique to overcome these challenges without the treatment and surface modification of natural additive fillers. The obtained experimental results showed that using maleic anhydride grafted ethylene vinyl acetate copolymer (EVAgMA) with 1.16 wt.% of MA could enhance the adhesion and interaction of bamboo flour (BF) with EVA and polypropylene (PP) matrices. These expressed through the improvement of tensile properties and mophological structure of EVA/BF composite and PP/BF composite with the presence of EVAgMA. Tensile strength of EVA/BF and PP/BF composites at the same 50 wt% of BF, increased 67 and 12%, respectively when EVAgMA was introduced.

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.

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