New Vulcanizing Agents for Ethylene-Propylene Elastomers. II

1962 ◽  
Vol 35 (4) ◽  
pp. 1091-1100
Author(s):  
Peter E. Wei ◽  
John Rehner
Keyword(s):  
Zinc Oxide ◽  
Iron Oxide ◽  
Carbon Black ◽  
Periodic System ◽  
Chemical Diversity ◽  
Complex Behavior ◽  
Iron Compounds ◽  
Ethylene Propylene ◽  
Ethylene Propylene Rubber

Abstract In searching for new vulcanizing systems for ethylene-propylene elastomers, we have found several more classes of active agents, heretofore undisclosed. They are: (a) perhaloalkanes and some polyhaloalkanes; (b) polyhalocycloalkenes; and (c) poly-N-halobenzoguanamines. Specific examples are: hexachloroethane, octachloropropane, octachlorocyclopentene, perchlorofulvalene, and N,N,N′,N′-tetrachlorobenzoguanamine. These agents are all effective in ethylene-propylene rubber, and some are capable of vulcanizing polyethylene, polypropylene, polyisobutylene, butyl, and highly unsaturated rubbers and their blends. The agents are most effective in the presence of sulfur. All are active in carbon black stocks, and at least some are active in mineral-filled and oil-extended stocks. Some of the vulcanizing agents can be accelerated by certain oxides and salts of metals widely distributed over the periodic system. Among the most active accelerators are iron compounds, such as iron tallate, stearate, naphthenate, octoate, and oxalate, and corresponding combinations of iron oxide and the free acids. These accelerators are antagonized by the presence of zinc oxide. The chemical diversity of these classes of vulcanizing agents and the complex behavior of the accelerators mentioned preclude an explanation of the vulcanization chemistry at this time.

Electrical Conductivity of Polystyrene-Rubber Blends Loaded with Carbon Black

1997 ◽  
Vol 70 (1) ◽  
pp. 60-70 ◽  
Author(s):  
B. G. Soares ◽  
F. Gubbels ◽  
R. Jéro^me ◽  
E. Vanlathem ◽  
R. Deltour
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Chemical Structure ◽  
Two Phase ◽  
Ethylene Propylene ◽  
Rubber Blends ◽  
Ethylene Propylene Rubber

Abstract Polystyrene/rubber blends have been loaded with carbon black (CB) and the filler localization in the two-phase polyblends has been studied in relation to the chemical structure of the rubber. The CB localization and the electrical conductivity are greatly influenced by the substitution of the rubber chains. In polystyrene/polybutadiene blends, the filler is localized within the polybutadiene phase. In contrast, in polystyrene/polyisoprene and polystyrene/ethylene—propylene rubber (EPM) blends, CB is mainly localized at the interface, so that the CB percolation threshold in cocontinuous two-phase polyblends is dramatically decreased.

Study of Sulfur Vulcanization of Brominated Ethylene-Propylene Rubber

1971 ◽  
Vol 44 (3) ◽  
pp. 721-727 ◽  
Author(s):  
A. A. Dontsov ◽  
S. P. Novitskaya ◽  
B. A. Dogadkin
Keyword(s):  
Zinc Oxide ◽  
Nucleophilic Substitution ◽  
Polymer Chains ◽  
Substitution Reactions ◽  
Ethylene Propylene ◽  
Nucleophilic Substitution Reactions ◽  
Sulfur Vulcanization ◽  
Ethylene Propylene Rubber ◽  
Increased Strength

Abstract (1) It is shown that when BEPR is heated at 130–190 ° with various components of a sulfur vulcanizing system, the latter take part in nucleophilic substitution reactions with the combined bromine, and promote dehydrobromination of the polymer chains and crosslinking of the elastomer. (2) The effect of the components of the vulcanizing system on dehydrobromination is dependent on the acidity of the component, and their effect on vulcanization is dependent on the extent to which they activate the reaction of sulfur with the polymer. (3) Zinc oxide is itself a vulcanizing agent. In reacting with BEPR it forms ether crosslinks. (4) When BEPR is vulcanized by sulfur together with sulfur vulcanization accelerators and activators two types of crosslink are formed, namely strong C-C and C-O-C bonds and weaker sulfur bonds. This combination of bonds gives vulcanizates of increased strength.

Evaluation of Crosslinking Coagents in Ethylene-Propylene Rubber

1964 ◽  
Vol 37 (1) ◽  
pp. 229-245 ◽  
Author(s):  
L. P. Lenas
Keyword(s):  
Carbon Black ◽  
Ethylene Propylene ◽  
Cure Cycle ◽  
Reactive Chemicals ◽  
Ethylene Propylene Rubber ◽  
Ethylene Dimethacrylate ◽  
Filler Particles ◽  
Mineral Fillers ◽  
Highly Loaded ◽  
Sulfur Curing

Abstract Ethylene-propylene rubber (EPR), a saturated elastomer, is usually vulcanized by a peroxide-sulfur curing system. However, several disadvantages associated with this system—undesirable odor for some applications, narrow curing range, and poor strength obtained with mineral fillers—emphasize the need for other reactive chemicals as crosslinking coagents for EPR. Certain polyfunctional monomers such as ethylene dimethacrylate, and polyfunctional polymers such as 1,2-polybutadiene were promising crosslinking coagents for EPR. When used in place of sulfur, they decrease peroxide requirements of moderately filled EPR compounds. They also impart higher states of cure, improve the cure cycle, and decrease odor. The coagents are much superior to sulfur in mineral-filled EPR compounds where, in addition to increasing the crosslinking efficiency, they also improve the wetting of the filler particles by the rubber. However, in highly loaded (carbon black and oil) EPR formulations, the superiority of the peroxide-coagent system is mainly due to the ability to replace sulfur and, consequently, to improve odor.

Preparation and Thermal-Resistant Performance of Silicon Rubber

2014 ◽  
Vol 1033-1034 ◽  
pp. 1207-1212
Author(s):  
Qin Fang Lu ◽  
Xiao Bing Li ◽  
Hua Lu Zhang ◽  
Bao Hua Xie ◽  
Xiao Yu Zhang
Keyword(s):  
Zinc Oxide ◽  
Iron Oxide ◽  
Carbon Black ◽  
Benzoyl Peroxide ◽  
Process Conditions ◽  
Silicon Rubber ◽  
Vinyl Group ◽  
Optimal Formula

Heat vulcanized silicon rubber was prepared by mixing technology. The influences of factors on silicon rubber performance were investigated such as raw rubber dosage, thermal-resistant additive dosage and process conditions. The results show that the optimal formula is as follows: 28.8phr raw rubber containing 0.23 vinyl group, 0.4phr white carbon black dispersant, 10phr vapor white carbon black, 0.5phr iron oxide, 0.7phr zinc oxide, 0.99phr thermal-resistant additive, 0.4phr accelerator DM and 0.6phr benzoyl peroxide. After placed for 24h, the mixture underwent two-step vulcanization (127°C×10.0MPa×6min and 200°C×4h). The thermal-resistant performance of silicon rubber was dramatically improved by thermal-resistant additive.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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