Kinetics of zinc oxide formation from zinc sulfide by reaction with lime in the presence of water vapor

1987 ◽  
Vol 18 (4) ◽  
pp. 727-732 ◽  
Author(s):  
H. Y. Sohn ◽  
Daesoo Kim
Keyword(s):  
Zinc Oxide ◽  
Water Vapor ◽  
Zinc Sulfide ◽  
Oxide Formation ◽  
Kinetics Of

The Influence of Activators on the Vulcanization Process. II. The Influence of Zinc Oxide on the Structure of Vulcanizates

1959 ◽  
Vol 32 (3) ◽  
pp. 780-784 ◽  
Author(s):  
J. Beniska ◽  
B. Dogadkin
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Zinc Sulfide ◽  
Network Formation ◽  
Marked Influence ◽  
Sh Groups ◽  
The Individual ◽  
Kinetics Of ◽  
Vulcanization Process ◽  
Kinetics Of Swelling

Abstract The influence of zinc oxide and stearic acid on the structures of vulcanizates was traced in stocks with mercaptobenzothiazole by means of the kinetics of swelling. It was found that zinc oxide in the presence of stearic acid has a marked influence on the rate and degree of crosslinked network formation in vulcanizates. In the formation of crosslinks (sulfur bridges) a number of reactions participate: the direct combination of rubber molecules with biradicals of sulfur, during which polysulfide bonds are mainly formed; the oxidation of rubber mercaptans (-SH groups), which is followed by the formation of mono-sulfide, disulfide and polysulfide links; and the decomposition of polysulfide links, which is followed by the formation of new crosslinks with a smaller number of sulfur atoms per crosslink. Zinc oxide has a varying influence on the individual reactions : the first two are activated by it, and the last one is retarded by it, because it does not react with the polysulfide sulfur to form zinc sulfide.

The Influence of Activators on the Vulcanization Process. I. The Influence of Zinc Oxide on the Rate of Combination of Sulfur with Rubber

1959 ◽  
Vol 32 (3) ◽  
pp. 774-779 ◽  
Author(s):  
J. Beniska ◽  
B. Dogadkin
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Zinc Sulfide ◽  
Kinetics Of ◽  
Vulcanization Process

Abstract In this work the effect of zinc oxide and stearic acid on the kinetics of sulfur combination with rubber was traced, in stocks containing accelerators as well as in stocks without the latter. It was proved that ZnO does not increase the rate of sulfur combination in sodium catalyzed polybutadiene rubbers (SKB-25). On the contrary, in stocks with mercaptobenzothiazole, zinc oxide decreases the rate of sulfur combination. In vulcanizates ZnS is formed in the presence of ZnO. The largest amount of zinc sulfide is formed in stocks with phenyl-2-naphthylamine and with stearic acid.

The Action of Vulcanization Activators

1958 ◽  
Vol 31 (2) ◽  
pp. 329-342 ◽  
Author(s):  
B. Dogadkin ◽  
I. Beniska
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Zinc Sulfide ◽  
Isotope Exchange ◽  
Thiol Group ◽  
Elementary Sulfur ◽  
Crosslinking Reaction ◽  
Butadiene Rubber ◽  
Zinc Compounds ◽  
Kinetics Of

Abstract 1. Zinc oxide and stearic acid do not affect the rate of addition of sulfur to rubber in the vulcanization of pure sodium butadiene rubber in mixtures without accelerators. 2. In mixtures containing diphenylguanidine as accelerator zinc oxide and stearic acid do not affect the rate of addition of sulfur to rubber. 3. In mixtures containing mercaptobenzothiazole zinc oxide retards and stearic acid accelerates the addition of sulfur to rubber. 4. In a similar manner zinc oxide suppresses and stearic acid activates isotope exchange between elementary sulfur and sulfur of the thiol group in mercaptobenzothiazole. 5. Zinc oxide and stearic acid in mixtures with mercaptobenzothiazole increase the rate and degree of crosslinking of the molecular chains of rubber; zinc oxide has the greater influence on the degree, while stearic acid has the greater influence on the rate, of the crosslinking reaction. 6. In mixtures with diphenylguanidine the influence of vulcanization activators on the degree and rate of crosslinking is considerably less pronounced than in mixtures with mercaptobenzothiazole. 7. The kinetics of zinc sulfide formation during vulcanization has been studied and it was established that ZnS is formed as the result of reactions of zinc oxide and zinc compounds with thiol and polysulfide groups in the rubber. Model substances have been used to demonstrate other possible routes for the formation of zinc sulfide during vulcanization. The effect of zinc oxide and stearic acid on the rate and degree of crosslinking is associated with participation of these compounds in such reactions. 8. Isotope exchange between radioactive sulfur in the vulcanizate and elementary sulfur was used to follow the formation and changes in the numbers of polysulfide linkages during the vulcanization process. The amount of sulfur participating in isotope exchange as vulcanization proceeds at first increases, passes through a maximum, and then decreases, which indicates a regrouping of the polysulfide linkages with an increase in their number and a decrease of the average number of sulfur atoms per linkage. Zinc oxide decreases the degree of isotope exchange between the vulcanizate and elementary sulfur at all stages of vulcanization. 9. Vulcanization activators, by favoring a decrease in the number of sulfur atoms in the sulfur bonds, increase the heat stability of the vulcanizates. This effect of the activators was demonstrated by kinetic data on stress relaxation in deformed vulcanizates at 126°. 10. The cleavage and regrouping of polysulfide linkages in the presence of zinc oxide and zinc compounds is accompanied by the combination of part of the sulfur as zinc sulfide, which leads to a decrease in the number of newly formed crosslinks. This effect of zinc oxide is manifested in vulcanization reversion effects and in changes of vulcanizate properties under thermomechanical influences. 11. From the above experimental data the general conclusion may be drawn that the fundamental role of vulcanization activators does not lie in their influence on the kinetics of the addition of sulfur to rubber, but rather in their influence on the nature of the vulcanization structures formed and on changes in them in the course of vulcanization.

Kinetics of Accelerated Vulcanization—III N-Cyclohexyl-Benzothiazole-2-Sulfenamide Accelerated Sulfur Vulcanization of Rubbers

1969 ◽  
Vol 42 (5) ◽  
pp. 1366-1382 ◽  
Author(s):  
S. K. Bhatnagar ◽  
S. Banerjee
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Zinc Sulfide ◽  
Cross Link ◽  
Influence Of Temperature ◽  
Sulfur Vulcanization ◽  
Preliminary Study ◽  
Kinetics Of ◽  
Link Formation ◽  
Insight Into

Abstract Sulfenamide type of accelerators are well known for their outstanding processing safety combined with ultra-strong accelerating activity resulting in superior quality vulcanizates. Sulfenamides derived from different amines afford varying degrees of scorch delay and accelerating activity. Since there is no unanimity on the chemistry involved in this type of accelerated vulcanization, a preliminary study has been carried out to gain some insight into the mechanistic scheme. The present paper contains reports on the effects of varying concentrations of N-cyclohexyl-benzothiazole-2-sulfenamide (CBS) on the rate of free sulfur decrease and cross-link formation as well as zinc sulfide formation—whenever it occurs—both in the absence and presence of zinc oxide and of zinc oxide and stearic acid. The influence of temperature has also been investigated.

Low-Temperature Thermal Expansion of Zinc Oxide. Vibrations in Zinc Oxide and Sphalerite Zinc Sulfide

1971 ◽  
Vol 4 (4) ◽  
pp. 1314-1323 ◽  
Author(s):  
B. Yates ◽  
R. F. Cooper ◽  
M. M. Kreitman
Keyword(s):  
Zinc Oxide ◽  
Thermal Expansion ◽  
Low Temperature ◽  
Zinc Sulfide
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