Vulcanization of Rubber. By Organic Peroxides or by Ammonium Persulphate

1930 ◽  
Vol 3 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Iwan Ostromislensky
Keyword(s):  
Benzoyl Peroxide ◽  
Organic Peroxides ◽  
Ammonium Persulphate ◽  
Aluminium Powder ◽  
Metallic Oxides ◽  
Vulcanized Rubber ◽  
Viscous Mass ◽  
Metallic Aluminium ◽  
Short Time ◽  
Rubber Product

Abstract 1. Organic peroxides vulcanize rubber not only in the absence of sulphur but likewise without any foreign substances such as metallic oxides or accelerators of any kind. 2. Rubber vulcanized by means of an adequate amount of benzoyl peroxide (10 to 30 per cent.) gives a soft rubber product which does not differ in point of physical properties from products cured with sulphur, or rather with sulphur chloride. 3. The process of vulcanizing rubber with benzoyl Superoxide is completed in a relatively short time even at a fairly low temperature, sometimes even in two minutes at 119° C., corresponding to 13 pounds pressure. 4. Vulcanization of rubber by means of peroxides may lead to the formation of a soft, transparent and elastic product, which is almost entirely colorless. 5. The products in question vulcanized by means of various peroxides are gradually converted to a very sticky and viscous mass. 6. Sulphur protects the vulcanizates in question from such decomposition or oxidation. However, the products obtained in vulcanization of rubber with organic peroxides in the presence of sulphur are opaque. 7. As distinguished from sulphur, selenium, tellurium, their sulphides, metal oxides (in particular, lead oxide) as well as amines (aniline), tannic acid, and metallic aluminium powder not only do not protect the peroxide vulcanized rubber products from decomposition or oxidation but, on the contrary, they accelerate such processes quite considerably. 8. Benzoyl peroxide is the active vulcanizing agent in the process of heating rubber with a mixture of sulphur and benzoyl peroxide. 9. When rubber is subjected to the action of a mixture of some nitrobenzenes and benzoyl peroxides, vulcanization is effected exclusively by the nitrobenzenes, and the benzoyl peroxide remains altogether passive. 10. Ammonium persulphate vulcanizes rubber completely, resulting in a porous product which, generally speaking, is of small practical value.

Production of Aluminium Based MMCs by Short-Time Ammonia Gas Flow Milling

2018 ◽  
Vol 772 ◽  
pp. 18-22
Author(s):  
Eduardo Sanchez Caballero ◽  
Raquel Astacio ◽  
F.J.V. Reina ◽  
Juan Manuel Montes ◽  
Jesus Cintas
Keyword(s):  
Gas Flow ◽  
Good Control ◽  
Milling Process ◽  
Matrix Composites ◽  
Ammonia Gas ◽  
Aluminium Powder ◽  
Long Time ◽  
Second Phases ◽  
Cold Pressed ◽  
Short Time

In order to produce metal matrix composites (MMCs), aluminium powder was milled for a total time of 5 hours. Aluminium nitride was the ceramic reinforcement chosen to improve the mechanical behaviour of the aluminium matrix. In order to form it in situ, an ammonia gas flow was incorporated during a certain period of the milling process. Two different conditions of NH3 flow during milling were studied: short time (5 min) and long time (3 h). In both cases, milling started with a 2 h period of mechanical alloy in vacuum (5 Pa). Then, NH3 was incorporated during the stipulated time (5 min or 3 h), after which the milling process continued under vacuum to complete 5 hours. The powders were cold pressed and vacuum sintered to produce compacts. The results showed that compacts with better mechanical properties are obtained when short duration ammonia gas flow is used. The use of short flows provides good control of the amount of ceramic second phases formed. This allows the produced compacts to reach ultimate tensile strength higher than 400 MPa.

scholarly journals Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

2017 ◽  
Vol 62 (2) ◽  
pp. 987-992 ◽  
Author(s):  
T. Pieczonka
Keyword(s):  
Thermal Analyses ◽  
Metal Contacts ◽  
Alumina Layer ◽  
Sintering Atmosphere ◽  
Aluminium Powder ◽  
Mechanical Disruption ◽  
Chemically Induced ◽  
Metal Metal ◽  
Metallic Aluminium ◽  
Alloyed Aluminium

AbstractAluminium oxide layer on aluminium particles cannot be avoided. However, to make the metal-metal contacts possible, this sintering barrier has to be overcome in some way, necessarily to form sintering necks and their development. It is postulated that the disruption of alumina layer under sintering conditions may originate physically and chemically. Additionally, to sinter successfully non alloyed aluminium powder in nitrogen, the operation of both types mechanism is required. It is to be noted that metallic aluminium surface has to be available to initiate reactions between aluminium and the sintering atmosphere, i.e. mechanical disruption of alumina film precedes the chemical reactions, and only then chemically induced mechanisms may develop. Dilatometry, gravimetric and differential thermal analyses, and microstructure investigations were used to study the sintering response of aluminium at 620°C in nitrogen, which is the only sintering atmosphere producing shrinkage.

scholarly journals Sintesis dan karakterisasi polimer superabsorban dari akrilamida

2018 ◽  
Vol 11 (2) ◽  
pp. 84
Author(s):  
A. Zainal Abidin ◽  
G Susanto ◽  
N.M.T. Sastra ◽  
T Puspasari
Keyword(s):  
Absorption Capacity ◽  
Synthesis And Characterization ◽  
Superabsorbent Polymer ◽  
Ammonium Persulphate ◽  
Surface Contact Area ◽  
Acrylamide Monomer ◽  
Cross Linker ◽  
Short Time ◽  
High Absorption

Synthesis and Characterization of Superabsorbent from Acrylamide Superabsorbent polymer (SAP) is a material that can absorb water in a large amount in a short time. In this research, the polymer has been synthesized from acrylamide monomer (Am) using N,N methylene bisacrylamide (MBA)as a cross-linker and ammonium persulphate (APS) as an initiator. Effects of MBA and APS on the SAP characteristic were studied by varying composition of MBA and APS each of 0.1%-wt, 0.2 %-wt, 0.6 %-wt and 1.0 %-wt. SAP was characterized by measuring its absorption capacity to distilled water. Based on the experiment, the highest absorption capacity for 1 gram SAP is 14.5 gram water. The highest absorption is produced by SAP with APS 0.2 %-wt and MBA 0.6 %-wt. Further studies by using SEM showed that SAP which had high absorption capacity contained a lot of pores with the waving surface. Therefore, the surface contact area between SAP and water is high. Keywords: acrylamide, absorption capacity, superabsorbent polymerAbstrakSuperabsorbent Polymer (SAP) merupakan polimer yang dapat menyerap air dalam jumlah yang sangat banyak. Dalam penelitian ini, polimer tersebut disintesis dari monomer akrilamida menggunakan crosslinker N,N-metilene bisakrilamide (MBA) dan inisiator amonium persulfat (APS). Pengaruh crosslinker dan inisiator terhadap karakteristik SAP dipelajari dengan melakukan variasi komposisi APS dan (MBA) masing-masing sebesar 0,1 %-b, 0,2 %-b, 0,6 %-b, dan 1 %-b. Karakteristik produk SAP dipelajari dengan FTIR untuk menganalisis gugus fungsi yang terbentuk untuk menunjukkan bahwa polimerisasi betul terjadi dan produknya berupa SAP. Pengukuran kemampuan absorpsi SAP terhadap air destilasi menunjukkan bahwa kapasitas absorpsi terbesar yang dihasilkan oleh superabsorbent polymer dari penelitian ini sebesar 14,5 gram air dalam 1 gram produk SAP yang dibuat. Kapasitas terbesar ini dimiliki oleh SAP dengan 0,2 %-b APS dan 0,6 %-b MBA. Studi lebih lanjut dengan SEM menunjukkan bahwa SAP yang memiliki kapasitas absorpsi tertinggi itu mempunyai morfologi permukaan yang berombak dan jumlah pori yang tertinggi sehingga luas permukaan kontak antara SAP dan air juga tertinggi. Kata kunci: akrilamida, kapasitas absorpsi, superabsorbent polymer

Chemical Unsaturation of Rubbers Vulcanized with Polynitro Compounds and Benzoyl Peroxide, and Its Possible Bearing on Vulcanization

1928 ◽  
Vol 1 (1) ◽  
pp. 101-105
Author(s):  
Harry L. Fisher ◽  
A. E. Gray
Keyword(s):  
Benzoyl Peroxide ◽  
Vulcanized Rubber ◽  
Chemical Combination ◽  
Sulfur Vulcanization

Abstract STUDIES on the chemical unsaturation of ordinary vulcanized rubber show that vulcanization has caused no change in the unsaturation of the rubber hydrocarbon beyond that which can satisfactorily be accounted for by the chemical combination of sulfur on the basis of one atomic equivalent of sulfur to a C5H8 group. If such is the case with sulfur vulcanization, it becomes very desirable to know whether there is any change in the unsaturation when rubber is vulcanized with substances other than sulfur, namely, polynitro compounds and benzoyl peroxide.

Weathering of Soft Vulcanized Rubber

1946 ◽  
Vol 19 (3) ◽  
pp. 712-752 ◽  
Author(s):  
James Crabtree ◽  
A. R. Kemp
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Nitrogen Oxides ◽  
Considerable Extent ◽  
Organic Peroxides ◽  
Mineral Salts ◽  
Vulcanized Rubber ◽  
Helium Neon ◽  
Ultimate Condition ◽  
Selection Of

Abstract When rubber goods are exposed to the agencies which constitute “weather”, they undergo profound changes. The rubber may lose elasticity, it may split or crack, or the surface may take on a crinkled appearance in a wide variety of designs. Figure 1 shows a small selection of such weathered rubbers. The course of deterioration, or the ultimate condition of any particular rubber specimen, moreover, is not always the same, but depends to a considerable extent on the kind of weather encountered which, in turn, depends on geography, topography, and season. The components of weather are air, heat, water, and sunlight, each varying in quantity and quality so that infinite combinations are possible. Among the major (nitrogen and oxygen), minor (carbon dioxide, argon, helium, neon, krypton, xenon), and trace (ozone, nitrogen oxides, ammonia, sulfur dioxide, sulfuric acid, hydrogen sulfide, carbon monoxide, hydrocarbons, hydrogen, mineral salts, hydrogen peroxide, organic peroxides) components of the atmosphere, only oxygen, ozone, and nitrogen oxides are capable of reacting with rubber. Trial shows steadily that, of these, only oxygen and ozone produce any perceptible effect at the concentrations in which they are present.

High chemiluminescence activity of an FeIII–TAML activator in aqueous–organic media and its use in the determination of organic peroxides

The Analyst ◽  
2015 ◽  
Vol 140 (9) ◽  
pp. 2964-2968 ◽  
Author(s):  
Alexandra S. Demiyanova ◽  
Ivan Yu. Sakharov
Keyword(s):  
Benzoyl Peroxide ◽  
Organic Solvents ◽  
Organic Media ◽  
Organic Peroxides ◽  
Peroxidase Mimic ◽  
Butyl Hydroperoxide ◽  
Highly Active

Using FeIII–TAML, highly active peroxidase mimic, the sensitive chemiluminescence assays for the determination of benzoyl peroxide and tert-butyl hydroperoxide in the presence of organic solvents were developed.

Studies of Hard Rubber Reactions. VI. Liberation of So-Called Free Sulfur and Changes in the Acetone Extract of Vulcanized Rubber by Repeated Extraction and Heating

1940 ◽  
Vol 13 (3) ◽  
pp. 598-603 ◽  
Author(s):  
Seiiti Numaziri
Keyword(s):  
Sulfur Compound ◽  
Acetone Extract ◽  
Acetone Extraction ◽  
Vulcanized Rubber ◽  
Rubber Product ◽  
Free Sulfur

Abstract 1. True Free Sulfur.—In the case of the pure rubber-sulfur compound, as shown in the graph, the quantity of true free sulfur liberated from the thermally active hard rubber product by 120 minutes' cure was generally a little greater than that from the thermally nonactive sample with 300 minutes' cure. During the whole course of the extraction and heating, there occurs a lowest point in the true free sulfur curve, which increases again. In view of this fact, liberation of free sulfur can not be attributed to the insufficiency of the acetone extraction but is probably attributable to depolymerization of the vulcanizate or the like. 2. Acetone Extract.—Although purified rubber was used, the corrected acetone extract due to the formation of resinous substances from the depolymerized or aged hard rubber product showed relatively high values at the beginning of extraction and heating. To some extent, the change in acetone followed a course similar to that of the true free sulfur.

Properties of turpentine relative to the effects on fowl plasma in vitro. II. The separation of peroxide components of turpentine by thin-layer chromatography

1968 ◽  
Vol 46 (5) ◽  
pp. 509-510
Author(s):  
C. le Q. Darcel
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Benzoyl Peroxide ◽  
Styrene Oxide ◽  
Cumene Hydroperoxide ◽  
Organic Peroxides ◽  
Experimental Pathology ◽  
Layer Chromatography

Thin-layer chromatograms were made of some turpentines, organic peroxides, and epoxides, and sprayed to detect peroxides. Benzoyl peroxide, cumene hydroperoxide, and painters' turpentine gave the most prominent spots. Only one of the three epoxides tested, styrene oxide, showed peroxide. Many more peroxides were present in "aged" turpentine than in freshly prepared samples. As aged turpentine has most effect on fowl plasma α-lipoprotein, chemical differences between samples should be considered when turpentines are used in experimental pathology.

The Vulcanization of Rubber by Diazoamino Compounds

1937 ◽  
Vol 10 (3) ◽  
pp. 471-473
Author(s):  
T. G. Levi
Keyword(s):  
Sulfur Dioxide ◽  
Hypochlorous Acid ◽  
Ammonium Persulfate ◽  
Nitro Compounds ◽  
Organic Peroxides ◽  
Oxygenated Compounds ◽  
Metallic Oxides ◽  
Perbenzoic Acid ◽  
Sulfur Chloride ◽  
Derivatives Of

Abstract Vulcanizing agents for rubber can be classified in the following six types: (1) Sulfur, including α-sulfur, β-sulfur, γ-sulfur, precipitated sulfur, and nascent δ-sulfur. (2) compounds containing sulfur, e. g., sulfur chloride, sulfur iodide, sulfur dioxide, phosphorous sulfides, hydrogen persulfides, nitrogen sulfide, and alkaline polysulfides. (3) elements of the sulfur group and their compounds, e. g., selenium, tellurium, selenium sulfur chloride, and selenium diethyldithiocarbamate. (4) halogens and halogenated compounds, e. g., chlorine, bromine, iodine, hypochlorous acid, hypochlorites, and benzoquinone dichloride. (5) oxygenated compounds capable of liberating nascent oxygen at vulcanizing temperatures, e. g., persulfates (such as ammonium persulfate), peracids (such as perbenzoic acid), nitro compounds (such as 1,3,5-trinitrobenzene, tetranitronaphthalene, and nitrocyclohexane in the presence of metallic oxides), and organic peroxides (such as benzoyl peroxide). (6) derivatives of rubber, e. g., rubber ozonide, chlorinated rubber, brominated rubber, and rubber hydrochloride.

Sign in / Sign up

Export Citation Format

Share Document