Transformation by the Action of Heat and Oxygen of the Sulfur Bonds Which Compose a Vulcanization Network

1956 ◽  
Vol 29 (4) ◽  
pp. 1276-1283 ◽  
Author(s):  
T. G. Degteva ◽  
A. S. Kuzminskiĭ
Keyword(s):  
Oxidation Reaction ◽  
Sodium Sulfite ◽  
Equilibrium Concentration ◽  
Reverse Effect ◽  
Forming Process ◽  
Alcoholic Alkali ◽  
Decomposition Products ◽  
Tetramethylthiuram Disulfide ◽  
Different Types ◽  
Swollen Vulcanizates

Abstract 1. A study of the effect of combined sulfur on the oxidation of swollen and unswollen polybutadiene vulcanizates shows that stocks vulcanized with different types of accelerators (tetramethylthiuram disulfide, diphenylguanidine, and zinc ethylphenyldithiocarbamate) form sulfur bonds which differ in their content of long polysulfide groups. 2. It is shown that sulfur liberated by the polysulfide bonds in vulcanizates reduces the speed of the oxidation reaction and the equilibrium concentration of stable peroxides. The sulfur content also governs the structure-forming process which develops when a raw polymer containing sulfur is oxidized at 90° C. The decomposition products of the polysulfide groups likewise lower the speed of oxidation in swollen vulcanizates at 150°. 3. When swollen vulcanizates are heated in the absence of oxygen at 150°, only the polysulfide bonds decompose. Heating unswollen vulcanizates under the same conditions, however, brings about the reverse effect, viz., structure formation. 4. Sodium sulfite and alcoholic alkali do not remove completely the polysulfide sulfur from vulcanizates. 5. In the process of vulcanization a rearrangement of the sulfur bonds takes place, and this is accompanied by a reduction of the polysulfide content.

scholarly journals Physico-technical approach to design of composites from mineral and polymer technogenic resources

2015 ◽  
Vol 1 ◽  
pp. 162 ◽  
Author(s):  
Gotfrīds Noviks
Keyword(s):  
Composite Materials ◽  
Experimental Studies ◽  
Process Efficiency ◽  
Operating Characteristics ◽  
Forming Process ◽  
Polymer Waste ◽  
Composite Forming ◽  
Different Types ◽  
Low Levels

<p class="R-AbstractKeywords"><span lang="EN-US">Artificial composite materials are currently being produced in large quantities, they are diverse and they are widely used in the economy. There have been extensive theoretical and experimental studies of different types of components, developed the calculation methods of composites production with predefined properties.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">At the same time industry produces a lot of mineral and polymer waste, which are practically technogenic resources, but their use is currently at quite low levels. The paper examines the possibilities to use technogenic resources- mineral (such as ash and clay) and organic (polymers -PET containers) for producing qualitative composite materials. For this purpose theoretical analysis and calculations of the physical properties of components and process parameters that determine the operating characteristics of the composite material were carried out.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">Composite-forming process efficiency determinative parameters were analysed: adhesion, the specific surface energy, specific free surface, adsorption capacity and the degree of dispersion of the particles.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">The role of external factors in processing of composite were examined – temperature, concentration of components.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">The characteristics of prepared samples of composites showed the possibility to use these waste for the development of qualitative products for different purposes.</span></p>

scholarly journals EFFECTS OF ADMIXTURES ON THE CRYSTALLISATION RATE OF GYPSUM A BATCH CRYSTALLISATION STUDY

REAKTOR ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 85
Author(s):  
S. Muryanto ◽  
H. M. Ang
Keyword(s):  
Equilibrium Concentration ◽  
Crystallization Rate ◽  
Supersaturated Solution ◽  
Different Types ◽  
Different Temperatures ◽  
Copper Zinc ◽  
Time Required ◽  
Crystallisation Rate ◽  
Zinc Concentrate ◽  
Concentrate Production

This paper descripbes a study on the effects of admixtures on the crystallization rate of gypsum. Two different types of biodegradable admixtures commonly used as flotation agent in copper/zinc concentrate production, namely, sodium isopropyl xanthate (=SIPX) and isopropyl thionocarbamate were investigated in this study. A laboratory batch crystallizer was used in this study, and the experiments were run using seeded method. The rate of desupersaturation or the time required to reach the equilibrium concentration was  compared for varying admixture oncentrations. It was discovered that the added seed crystals started growing imediately upon addition into the supersaturated solution, i.e. there  was no induction time.Results of this batch crystallizationstudy suggest that addition of admixtures individually or in combination, significantly affects the crystallization kinetics and in particular, reduces the rate of crystallization of gypsum. Activation energies were determined using three different temperatures, and the values obtained  mostly agreed with other published values, i.e. 60.00 ± 3.00, 57.39 ± 2.87, and 37.65 ±1.88 kj/mol, for pure gypsum, isopropyl yhionocarbamate, and SIPX, respectively.Keywords : activation energy; admixtures; CaSO4.2H2O; crystallization, gypsum; reaction rate

Development of Parametric Simulation Models for Metal Forming Processes of Plate Structures

2018 ◽  
Author(s):  
Tom Wurzler ◽  
Thomas Lindemann ◽  
Josefine Kistner ◽  
Patrick Kaeding
Keyword(s):  
Metal Forming ◽  
Simulation Models ◽  
Metal Plate ◽  
The Finite Element Method ◽  
Forming Process ◽  
Common Procedure ◽  
Plate Structures ◽  
Metal Plates ◽  
Die Structure ◽  
Different Types

During the process of workpiece productions in metal forming industries, it is necessary to control the results of the reshaped piece to ensure its quality. A common procedure of metal plate forming processes is given by the application of an upper and lower die. Therefore, ribbed die configurations can be used. To simulate the forming process of metal workpieces, the Finite Element Method (FEM) is a feasible tool. In this paper, a parametric model of a ribbed die structure is developed with the specification that only small imperfections on the workpiece surfaces will appear after the forming process. The workpieces in this paper are plates with thickness values equal and greater than 20mm. Furthermore, the springback behaviour of the different workpieces will be in the main focus of the proposed analyses. The results of the simulations are used to developed different types of holder configurations instead of the lower die. This concept might further reduce the costs of forming processes of large metal plates.

Thermal Decomposition of Dolomite Containing Phosphorus

2011 ◽  
Vol 492 ◽  
pp. 337-340
Author(s):  
Hong Wei Zhang ◽  
Qin Fang Fang ◽  
Ying Guo
Keyword(s):  
Thermal Decomposition ◽  
Oxidation Reaction ◽  
Spherical Shape ◽  
Bubble Shape ◽  
Final Temperature ◽  
Decomposition Products ◽  
Standard Atmosphere ◽  
Dolomite Sample ◽  
Shape Structure ◽  
Thermal Decomposition Products

In this paper,DTA-TG and TEM are used to investigate dolomite containing phosphorus. The investigations suggest that the thermal decomposition of dolomite containing a little bit of phosphorus powder has only one reaction while that of dolomite has two reactions, and the final temperature of the reaction reduces by about 18°C. The oxidation reaction of the phosphorus in dolomite begins at about 500°C, which is 140°C higher than that of the oxidation reaction of phosphorus in standard atmosphere condition. Round-bubble-shape structure gradually appears on the surface of the dolomite sample when observed using TEM. Furthermore, the number and size of this structure increased with the rising of the temperature. Finally, the round-bubble-shape structure breaks to small hollows, showing as teared-shape, and forms a series of protruding and intensive larger hollows and spherical shape. Therefore, the temperature of thermal decomposition of thermal decomposition of dolomite is decreased and the components of thermal decomposition products of dolomite containing phosphorus are almost the same as that of dolomite.

scholarly journals RESISTANCE TO ANTIBIOTICS AND THEIR UTILIZATION BY MICROORGANISMS

2021 ◽  
Vol 14 (3) ◽  
pp. 22-29
Author(s):  
N.B. Golub ◽  
Keyword(s):  
Natural Environment ◽  
Heterotrophic Bacteria ◽  
Negative Impact ◽  
Antibiotic Resistance Genes ◽  
Environmental Safety ◽  
Decomposition Products ◽  
Biochemical Processes ◽  
Physico Chemical ◽  
Different Types ◽  
Negative Effect

With the development of antibiotics application, their spread in the natural environment increases dramatically. The presence of antibiotics in the environment changes microorganism and other living beings ratio and composition, which causes a negative impact on biochemical processes that take place in the environment. The spread of antibiotic resistance genes in environmental microorganisms is a growing problem of environmental safety and human health. Aim. The objective of the work was to analyze the adaptation mechanisms of microorganisms to the influence of antibiotics and methods for antibiotics utilization. Results. The mechanisms of microorganisms’ adaptation to antibiotics are shown. The conditions for utilization of different antibiotics classes by microorganisms are provided. Conclusions. Methods of antibiotics destruction depend on its structure and physicochemical properties. Physico-chemical methods are used for local waste purification and are not suitable for antibiotics disposal in the natural environment. The decomposition products can also have a negative effect on the microorganisms’ cells. Depending on the class of antibiotics, their biodegradation occurs by different types of microorganisms. It has been shown that sulfonamides and amphinecoles are easily destroyed by many heterotrophic bacteria; biodegradation of aminoglycosides occurs by a strain of Pseudomonas spp.; tetracyclines - mushrooms; β-lactams - through the microorganisms’ association including: Burkholderiales, Pseudomonadales, Enterobacteriales, Actinomycetales, Rhizobiales, Sphingobacteriales. A consortium of destructors must be created to dispose of a specific classes of antibiotics.

Photocatalytic Partial Oxidation of 5-hydroxymethyl-2-furfural Under UV and Natural Solar Irradiation in Aqueous Suspension of K Containing C3N4

2020 ◽  
Vol 1 (1) ◽  
pp. 16-29
Author(s):  
Elisa I. García-López ◽  
Giuseppe Marcì ◽  
Marina Ilkaeva ◽  
Filippo Saiano ◽  
Leonardo Palmisano
Keyword(s):  
Partial Oxidation ◽  
Oxidation Reaction ◽  
Carbon Nitride ◽  
Aqueous Suspension ◽  
The Other ◽  
Added Value ◽  
Solar Irradiation ◽  
Oxidative Conversion ◽  
Partial Oxidation Reaction ◽  
Different Types

Background: The influence of the potassium metal cation on the graphitic carbon nitride (g-C3N4) photocatalyst has been studied in the partial oxidation of 5-hydroxymethyl-2-furfural (HMF) to 2,5-furandicarboxaldehyde (FDC). Objective: The aim of this study was to understand if the presence of K in C3N4 could increase the oxidative conversion of HMF to high added value species. Methods: Two sets of photocatalysts were prepared by following two different methodologies. In both series of the materials, the precursor of C3N4 was melamine with different types of the K containing species including KCl and KOH in one case and KNO3 alone in the other case. However, for both series of photocatalysts, materials were prepared with different amounts of potassium. Results: The results obtained by using materials prepared by the two different methodologies indicate that in both cases the presence of K was almost irrelevant at least for the lower amounts of potassium content. On the contrary, its presence was beneficial for the activity versus the photocatalytic partial oxidation reaction of the alcohol for the highest K content. Conclusion: Some of the prepared K containing g-C3N4 materials showed increased photocatalytic activity for the partial oxidation reaction of HMF in water, particularly by using natural solar light as the irradiation source.

Simulation and Experimental study on IMS (Injection Molded Solder) bumping with expanded resist patterning for reinforcement of fine-pitch capability

2020 ◽  
Vol 2020 (1) ◽  
pp. 000119-000124
Author(s):  
Risa Miyazawa ◽  
Eiji Nakamura ◽  
Chinami Marushima ◽  
Toyohiro Aoki ◽  
Takashi Hisada
Keyword(s):  
Solder Bump ◽  
Lower Layer ◽  
Injection Pressure ◽  
Design Experiment ◽  
The Novel ◽  
Forming Process ◽  
Fine Pitch ◽  
Different Types ◽  
Wetting Property ◽  
Injection Molded

Abstract Injection Molded Solder (IMS) process has been developed as one of the advanced micro-bumps forming techniques. This paper presents a novel IMS process utilizing a double-layer resist patterning with expanded opening for the reduction of required injection pressure. It consists of upper resist layer with larger opening diameter than lower resist opening. With this configuration, necessary injection pressure is adjusted to upper resist size, while lower layer determines the position and the size of fabricated bump. Furthermore, two different types of resist opening shape, an isolated opening and connected opening are proposed and evaluated in this study from both simulation and experimental perspective. For simulation, CFD analysis is performed to demonstrate the behavior of liquid molten solder flow and its bump forming process. It is revealed that solder bump was successfully formed in accordance with theoretical bump size in both designs. However, the result indicates that insufficient non-wetting property of resist material could lead solder bridging between adjacent bumps in connected design. Experiment is also conducted using the novel resist structure with the dimension correlated to the simulation model which has lower resist diameter of 10 μm, upper resist diameter of 15 μm, and the pitch of 20 μm. IMS is operated and it is confirmed that the uniform bumps can be favorably formed without any defects.

New Joining Concepts for Self-Pierce Riveting

2021 ◽  
Vol 883 ◽  
pp. 119-126
Author(s):  
Luis M. Alves ◽  
Rafael M. Afonso ◽  
Paulo A.F. Martins
Keyword(s):  
Lap Joints ◽  
Common Element ◽  
Tube Sheet ◽  
Structural Elements ◽  
Forming Process ◽  
Steel Tubes ◽  
Aluminum Sheets ◽  
Different Types ◽  
Deformation Mechanics ◽  
The Common

This paper is focused on innovative self-pierce riveting concepts to produce invisible joints in sheet-sheet and tube-sheet connections. The common element to these two different types of joints is the use of tubular rivets with chamfered ends, which are accessories in the case of sheet-sheet joints and constitutive (structural) elements in the case of tube-sheet joints. The presentation draws from the deformation mechanics of double-sided self-pierce riveting for producing lap joints in overlapped sheets to the development of self-pierce riveting of tubes to sheets, which is a new joining by forming process capable of attaching a sheet to the end of a tube, at room temperature. Aluminum sheets, carbon and stainless-steel tubes are utilized to demonstrate the effectiveness of the new self-pierce riveting concepts and finite element modelling using an in-house computer program gives support to the overall presentation. Destructive tests are carried out to evaluate the destructive strength that the joints are capable to withstand without failure.

Mechanism of the Action of Accelerators of Vulcanization. Vulcanization of Rubber by a Sulfur Radioisotope

1954 ◽  
Vol 27 (4) ◽  
pp. 974-976 ◽  
Author(s):  
G. A. Blokh
Keyword(s):  
Bond Energy ◽  
Disulfide Bonds ◽  
Sodium Sulfite ◽  
Butadiene Rubber ◽  
Exchange Reactions ◽  
Cent Solution ◽  
Tetramethylthiuram Disulfide ◽  
Cold Acetone ◽  
Rubber Accelerators

Abstract The problem of the mechanism of the action of accelerators and vulcanizing agents during the vulcanization of rubber has been studied in earlier works. It was shown that, during the vulcanization of natural and sodium-butadiene rubber, accelerators of the type of mercaptobenzothiazole and tetramethylthiuram disulfide enter into exchange reactions with the vulcanizing agent, sulfur. However, the role of the chemically combined sulfur, that is, the so-called bridge sulfur, in the exchange reactions with the accelerators remained unexplained. As Dogadkin and Tarasova show, in the case of sulfur vulcanizates, the following kinds of bonds between the rubber chains can occur : (1) —C—C—, formed as a result of polymerization or condensation processes (bond energy 62.7 kcal. per mole); (2) —C—S—C—, monosulfide bonds, formed during thiuram vulcanization (bond energy 54.5 kcal. per mole) ; (3) —C—S—S—C—, disulfide bonds; (4) —C—Sn—C—, polysulfides, formed during vulcanization with elemental sulfur in the absence of accelerators containing sulfur (bond energy 27.5 kcal. per mole). These authors established the presence of polysulfide bonds by extracting sulfur from vulcanizates, already extracted with cold acetone, by heating the extracted vulcanizate in a 10 per cent solution of sodium sulfite. Ten to twenty per cent of the total amount of combined sulfur was thus extracted as polysulfide, whereas rubber vulcanized with thiuram contained no sulfur at all which could be extracted by sodium sulfite. In order to study the exchange reactions between accelerators containing sulfur and chemically combined or bridge sulfur, the present investigation was made.

Numerical Analysis and Simulation of Drawpiece Forming Process by Finite Element Method

2014 ◽  
Vol 474 ◽  
pp. 153-158 ◽  
Author(s):  
Pawel Kaldunski ◽  
Leon Kukielka
Keyword(s):  
Drawing Process ◽  
Forming Process ◽  
Material Models ◽  
Punch Force ◽  
Plastic Model ◽  
Elastic Plastic ◽  
Current State ◽  
Different Types ◽  
The Subject ◽  
Unconventional Methods

This paper shows the application of an incremental modelling and numerical solution of the contact problem between movable elastic or rigid tool and elastic/visco-plastic bodies developed in [ to the numerical simulation of drawpiece forming process for the case of rigid tool (punch and die block) and elastic-plastic body (drawpiece). Also the current state of knowledge of the subject matter of the drawing process, modelling and simulation of this process is discussed. The latest and unconventional methods of drawpiece forming have been presented. The important factors determining the proper formation of drawpiece and the ways of their determination have been described. Three types of material models have been used: elastic-plastic model with the linear hardening, elastic-plastic model with the power-law hardening and Frederic's Barlat model which takes into account the anisotropy in three main directions and three tangents. For an example of selected simulations, dependence of punch force from its displacement for different types of die blocks has been presented.

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