Reactions between Compounding Ingredients during Vulcanization of Rubber

1941 ◽  
Vol 14 (1) ◽  
pp. 45-51
Author(s):  
E. C. B. Bott
Keyword(s):  
Zinc Oxide ◽  
Free Energy ◽  
Hydrogen Sulfide ◽  
Zinc Sulfide ◽  
Accelerated Aging ◽  
Lead Sulfate ◽  
Large Decrease ◽  
The Right

Abstract The calculations indicate that reactions (1), (3), and (5) can take place and proceed to virtual completion, whereas reactions (2) and (4) are not possible. They indicate also that the addition of extra sulfur to mixes containing litharge is necessary, and is in accordance with a custom long established empirically. It is evident that oxygen or nascent oxygen is not formed by any of these reactions; therefore no accelerated aging can take place by reactions between sulfur and litharge or zinc oxide. One peculiarity is that, although sulfur will react with litharge according to reaction (1), it appears that no oxygen is evolved by reaction (2), one possible reason being that the formation of lead sulfate takes place with a large decrease in free energy and is therefore readily formed. A possible explanation of the reaction between litharge and sulfur is that reaction (2), a possible first stage in reaction (1), is made to proceed to the right by the readiness with which lead sulfate can be formed. With respect to the reactions of zinc oxide, the assumption that zinc sulfide is formed by the action of hydrogen sulfide appears to be true.

The Nature of Vulcanization Part IV

1929 ◽  
Vol 2 (3) ◽  
pp. 421-430
Author(s):  
H. P. Stevens ◽  
W. H. Stevens
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Hydrochloric Acid ◽  
Zinc Sulfide ◽  
Low Temperatures ◽  
Sulfur Compounds ◽  
Zinc Salt ◽  
Acetone Vapor ◽  
Volatile Sulfur Compounds ◽  
Ether Mixture

Abstract (1) At low temperatures by means of accelerators it is possible to produce vulcanites containing “combined sulfur” considerably in excess of that required for the formula C5H8S. Such vulcanites may be obtained by vulcanizing at 100° with a variety of ultra-accelerators with and without zinc oxide as an activator. If zinc oxide or a zinc salt is used the excess coefficient cannot be explained by the presence of the zinc sulfide in the vulcanite. (2) The amount of sulfur combined with the rubber, given sufficient heating and presence of accelerator, is mainly dependent on the excess of sulfur present. (3) Extraction of the vulcanite with hydrochloric acid-ether mixture removes a part of the “combined” sulfur. A considerable amount is removed when the amount of combined sulfur is very large, but even then the amount of sulfur remaining is considerably in excess of that required by the formula C5H8S. (4) Vulcanization at low temperatures in solution in accordance with Whitby's procedure with the aid of accelerators also yields vulcanites with coefficients in excess of that required for the formula C5H8S. (5) The result of vulcanization at low temperatures is approximately the same, whether the rubber contains all the protein and serum ingredients, the usual proportion, or very little. (6) Extraction of sulfur from vulcanite with hot acetone vapor is not complete after 1210 hrs. (7) Having regard to the hydrogen sulfide and other volatile sulfur compounds evolved in appreciable quantities during vulcanization, it is evident that part of the combined sulfur results from substitution of hydrogen by sulfur. This substituted product is decomposed by the hydrochloric acid-ether mixture. It may not be possible to decompose the whole in this manner. Consequently, any “combined” sulfur in excess of that required by the formula C5H8S may result from substitution in the molecule.

Organic Sulfides and Polysulfides. VI. Reactions of Metallic Oxides with Polysulfide Rubbers

1958 ◽  
Vol 31 (3) ◽  
pp. 624-630
Author(s):  
Yuji Minoura
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Zinc Sulfide ◽  
Lead Sulfide ◽  
Lead Oxide ◽  
High Polymer ◽  
Metallic Oxide ◽  
Metallic Oxides ◽  
Organic Sulfides

Abstract 1. Both mercaptides and disulfides were obtained by the reactions between benzyl mercaptan or tolyl mercaptan with zinc oxide or lead oxide. Qualitatively, mercaptides were formed from benzyl mercaptan easier than from tolyl mercaptan, and lead oxide reacted with mercaptan easier than zinc oxide with mercaptan. From the fact that no metallic sulfide was present, disulfides were likely formed from the oxidation of mercaptans by air. 2. The mono- or disulfides of the benzyl and tolyl series did not react with zinc oxide or lead oxide. 3. Neither tolyl tri- nor tetrasulfide reacted with zinc oxide, but benzyl tri- and tetrasulfide reacted with zinc oxide to give zinc sulfide. In the case of benzyl trisulfide, hydrogen sulfide, stilbene and benzaldehyde were formed, and in the case of tetrasulfide, we found the formation of hydrogen sulfide, stilbene, benzaldehyde and sulfur. 4. The tri- and tetrasulfide of both the benzyl and tolyl series reacted with lead oxide and they gave lead sulfide and organic disulfide. That is, they were desulfurized by lead oxide. In these reactions the benzyl series was more reactive than the tolyl series and the tetrasulfide was more reactive than trisulfide in the same series. 5. Lead oxide reacted with polysulfide easier than zinc oxide. 6. From the results of reactions between metallic oxide with mercaptan or other sulfide, it was concluded that the vulcanization mechanism of polysulfide rubber by metallic oxide is the reaction represented by Equations (1) to (4), the products being converted to high polymer without formation of a network of polysulfides.

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

In situ sulfur K-edge X-ray absorption spectroscopy of the reaction of zinc oxide with hydrogen sulfide

1996 ◽  
pp. 1431 ◽  
Author(s):  
John Evans ◽  
Judith M. Corker ◽  
Clive E. Hayter ◽  
Richard J. Oldman ◽  
B. Peter Williams
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Absorption Spectroscopy ◽  
X Ray ◽  
X Ray Absorption

In-situ prevention of hydrogen sulfide formation during anaerobic digestion using zinc oxide nanowires

2018 ◽  
Vol 6 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Robert Lupitskyy ◽  
Dania Alvarez-Fonseca ◽  
Zachary D. Herde ◽  
Jagannadh Satyavolu
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Anaerobic Digestion ◽  
Zinc Oxide Nanowires ◽  
Oxide Nanowires

scholarly journals Diffusion of Sulfur on the Crystallization of Zinc Sulfide in Atmosphere of Hydrogen Sulfide

RADIOISOTOPES ◽  
1965 ◽  
Vol 14 (6) ◽  
pp. 439-444
Author(s):  
Masakazu SAKAGUCHI ◽  
Katsuhide MANABE
Keyword(s):  
Hydrogen Sulfide ◽  
Zinc Sulfide

Scorch Control of Carboxylic Elastomers

1973 ◽  
Vol 46 (1) ◽  
pp. 78-95 ◽  
Author(s):  
V. L. Hallenbeck
Keyword(s):  
Zinc Oxide ◽  
Physical Properties ◽  
Shelf Life ◽  
Zinc Sulfide ◽  
Zinc Phosphate ◽  
Carboxyl Groups ◽  
Carboxyl Group ◽  
Phosphate Coating ◽  
Ionic Bond ◽  
Cure Temperature

Abstract Carboxylic elastomers can be cured by standard compounding recipes utilizing sulfur and zinc oxide. The zinc oxide, besides aiding the sulfur cure, also gives a secondary cure through an ionic bond with the carboxyl groups. However, because of the affinity of the zinc oxide for the carboxyl group, the stocks tend to have an excessive scorch and a short shelf life. To prevent this excessive scorch the zinc oxide must be isolated from the carboxyl group until the desired cure temperature is reached. Three materials may be used to isolate the zinc oxide : 1) zinc sulfide coated zinc oxide, 2) zinc phosphate coated zinc oxide and 3) metallic alkoxide combined with the zinc oxide. The use of any of these gives scorch control without affecting final physical properties. The amount of zinc sulfide coating, zinc phosphate coating, and metallic alkoxide varies with the type of carboxylic elastomer.

scholarly journals A Comparative study to measure the horizontal condylar guidance obtained by protrusive interocclusal records and panoramic radiographic images in completely edentulous patients

2018 ◽  
Vol 14 (1) ◽  
pp. 21-27
Author(s):  
Arjun Bhandari ◽  
Archana Manandhar ◽  
Raj Kumar Singh ◽  
Pramita Suwal ◽  
Prakash Kumar Parajuli
Keyword(s):  
Zinc Oxide ◽  
Horizontal Plane ◽  
Significant Positive Correlation ◽  
Panoramic Radiograph ◽  
Articular Eminence ◽  
Radiographic Images ◽  
The Mean ◽  
Edentulous Patients ◽  
The Right ◽  
Interocclusal Records

Background & Objectives:The study was conducted with objective to compare the horizontal condylar guidance (HCG) obtained by protrusive interocclusal records and panoramic radiographic images in completely edentulous patients.Materials & Methods:The horizontal condylar guidance was measured in 25 completely edentulous patients by protrusive interocclusal records using zinc oxide eugenol paste through a face bow transfer (HanauTM Spring bow, Whip Mix Corporation, USA) to a semi-adjustable articulator (HanauTM Wide-Vue Articulator, Whip Mix Corporation, USA).  In the same patients, HCG was traced in the panoramic radiograph. The angles formed by the intersection of two lines: Frankfurt’s horizontal plane and posterior slope of articular eminence was measured using protractor to represent the horizontal condylar guidance angle on each side.Results:The mean difference between the horizontal condylar guidance angles values obtained using protrusive interocclusal record and panoramic radiograph was 2.68 degrees and 3.40 degrees for the right and the left side respectively, with the panoramic radiograph values being higher. This difference between the values was found to be highly significant between the two methods for the right side (t = 2.70, p = 0.012) and left side (t = 3.69, p = 0.001). A significant positive correlation was found between the horizontal condylar guidance obtained from protrusive interocclusal record and panoramic radiograph for the right (r = 0.643, p = 0.001) and left sides (r = 0.622, p = 0.001) separately.Conclusion:The panoramic radiographic tracing can be used to calculate the mean horizontal condylar guidance in the completely edentulous patients and these values can be used to programme semi-adjustable articulators avoiding the cumbersome process of obtaining protrusive interocclusal records.

Ellipsometric evaluation and morphology of mixed zinc sulfide/zinc oxide and zinc oxide nanostructures synthesized at various temperatures

2020 ◽  
Vol 98 (7) ◽  
pp. 689-694
Author(s):  
Mohammed S. Alqahtani ◽  
S.H. Mohamed ◽  
Z.A. Alrowaili ◽  
N.M.A. Hadia
Keyword(s):  
Zinc Oxide ◽  
Zinc Sulfide ◽  
Optical Constants ◽  
Calculated Data ◽  
Synthesis Temperature ◽  
Vapor Transport ◽  
Zinc Oxide Nanostructures ◽  
Oxide Nanostructures ◽  
Lower Oxygen ◽  
Device Applications

The aim of this work was to carry out systematic studies of how synthesis temperatures affect the morphology and properties of mixed zinc sulfide/zinc oxide (ZnSxOy and ZnO) nanostructures, and to get reliable data on optical constants of ZnSxOy and ZnO nanowires/nanobelts (NW/NB) for the use in device applications. ZnSxOy and ZnO NWs/NBs were fabricated using vapor transport in an open-end tube. Mixed ZnS0.47O0.62NWs was obtained at the synthesis temperature of 850 °C. The sulfur content disappeared as the temperature increased to 950 °C and 1050 °C and the morphology changed to a mixture of NW/NB. The NW prepared at 850 °C were indexed as mixed phases of hexagonal ZnS and hexagonal ZnO structures. The NW/NB prepared at 950 °C and 1050 °C were indexed as pure hexagonal ZnO structures. The thickness, surface roughness, and optical constants of the synthesized nanostructured samples were extracted from measurements of spectroscopic ellipsometry. A two-layers model was proposed to fit the calculated data to the measured ellipsometric spectra. The estimated band gap values of the prepared nanostructures lay 0.66–0.79 eV below the bulk ZnO value due to the lower oxygen content present in the samples and the stresses built in the samples during preparation.

Sign in / Sign up

Export Citation Format

Share Document