Influence of Vulcanization on Adhesion to Non-Vulcanizing Polymers

1961 ◽  
Vol 34 (3) ◽  
pp. 879-883 ◽  
Author(s):  
V. G. Raevskiĭ ◽  
S. S. Voyutskiĭ
Keyword(s):  
Initial Period ◽  
Practical Importance ◽  
Chemical Bonds ◽  
Optimum Conditions ◽  
Synthetic Fibers ◽  
Adhesion Joint ◽  
The Difference ◽  
Vulcanization Process ◽  
Mechanisms Of Adhesion ◽  
Butadiene Styrene

Abstract According to contemporary ideas the mechanisms of adhesion and co-vulcanization of rubbers have much in common. The phenomenon of co-vulcanization, like that of adhesion of polymers, includes the diffusion of macromolecules and of segments of them, which is particularly intensive in the initial period of vulcanization, when the crosslinks have not yet formed. The difference between covulcanization and adhesion lies solely in the fact that the process of interpenetration of the molecular chains in the former case is sooner or later broken off by the vulcanization process being superimposed upon it, securing the macromolecules or portions of them by strong chemical bonds. This leads to the formation of an adhesion joint considerably superior in strength to a joint in which the molecules diffusing through are attached only by weak intermolecular bonds. It is important to ascertain what is the influence of the vulcanization of elastomers upon their adhesion to polymers not capable of forming chemical bonds with them. This case is of immense practical importance, since unvulcanized rubbers are very often used in combination with vegetable and synthetic fibers which are not capable of vulcanizing. As adhesives we selected elastomers of varying molecular structure, polarity and degree of molecular mobility: butadiene-acrylonitrile rubber (SKN-26), butadiene-styrene rubber (SKS-30A), butadiene-styrene oil-extended rubber (SKS-30ARM-15) and butyl rubber. Using these rubbers we prepared stocks both containing and not containing vulcanizing groups (in the latter case the components of the vulcanizing groups were replaced by an equal quantity of inert filler—whiting). The amount of vulcanizing group was set at the optimum for each rubber. The substrates used were films containing no plasticizers—cellophane (cellulose hydrate) and Perfol' PK-4 (polycaprolactam). The adhesive was applied to the substrate by coating on a calender at the optimum conditions for each elastomer. The specimens produced in this way were plied up and subjected to vulcanization. Vulcanization was carried out in a Berstorff apparatus for continuous vulcanization at 143° C and a specific pressure ≈ 0.85 kg/sq cm. The time of cure was varied between 0 and 88 min.

Factors controlling N mineralization, nitrification, and nitrogen losses in an Oxisol amended with sewage sludge

Soil Research ◽  
2001 ◽  
Vol 39 (3) ◽  
pp. 519 ◽  
Author(s):  
J. Sierra ◽  
S. Fontaine ◽  
L. Desfontaines
Keyword(s):  
Sewage Sludge ◽  
Field Experiment ◽  
Water Content ◽  
N Mineralization ◽  
Initial Period ◽  
Factorial Experiment ◽  
Net N Mineralization ◽  
N Losses ◽  
Mineral N ◽  
The Difference

Laboratory incubations and a field experiment were carried out to determine the factors controlling N mineralization and nitrification, and to estimate the N losses (leaching and volatilization) in a sewage-sludge-amended Oxisol. Aerobically digested sludge was applied at a rate equivalent to 625 kg N/ha. The incubations were conducted as a factorial experiment of temperature (20˚C, 30˚C, and 40˚C) soil water (–30 kPa and –1500 kPa) sludge type [fresh (FS) water content 6230 g/kg; dry (DS) water content 50 g/kg]. The amount of nitrifiers was determined at the beginning and at the end of the experiment. The incubation lasted 24 weeks. The field study was conducted using bare microplots (4 m) and consisted of a factorial experiment of sludge type (FS and DS) sludge placement (subsurface, I+; surface, I–). Ammonia volatilization and the profile (0–0.90 m) of mineral N concentration were measured during 6 and 29 weeks after sludge application, respectively. After 24 weeks of incubation at 40˚C and –30 kPa, net N mineralization represented 52% (FS) and 71% (DS) of the applied N. The difference between sludges was due to an initial period of N immobilization in FS. Nitrification was more sensitive than N mineralization to changes in water potential and it was fully inhibited at –1500 kPa. The introduction of a large amount of nitrifiers with FS did not modify the rate of nitrification, which was principally limited by soil acidity (pH 4.9). Although N mineralization was greatest at 30˚C, nitrification increased continuously with temperature. Nitrogen mineralization from DS was well described by the double-exponential equation. For FS, the equation was modified to take into account an immobilization-remineralization period. Sludge placement significantly affected the soil NO-3/NH+4 ratio in the field: 16 for I+ and 1.5 for I–, after 11 weeks. In the I– treatment, nitrification of the released NH+4 was limited by soil moisture because of the dry soil mulch formed a few hours after rain. At the end of the field experiment, the estimated losses of N by leaching were 432 kg N/ha for I+ and 356 kg N/ha for I–. Volatilization was not detectable in the I+ microplots and it represented only 0.5% of the applied N in the I– microplots. The results showed that placement of sludge may be a valuable tool to decrease NO-3 leaching by placing the sludge under unfavourable conditions for nitrification.

scholarly journals EXTRACTION OF RUBBER FROM LATEX BY HYBRID COAGULANT BASED ON POLYDIMETHYLDIALLYLAMMONIUM CHLORIDE AND VISCOSE FIBER

2021 ◽  
Vol 64 (6) ◽  
pp. 62-68
Author(s):  
Nadezhda S. Nikulina ◽  
Inna N. Pugacheva ◽  
Vyacheslav M. Misin ◽  
Viktor N. Verezhnikov ◽  
Natalia Yu. Sannikova ◽  
...  
Keyword(s):  
Multicomponent System ◽  
Aggregate Stability ◽  
Physical And Mechanical Properties ◽  
Cationic Polyelectrolyte ◽  
Viscose Fiber ◽  
Emulsion System ◽  
Latex Dispersions ◽  
The Difference ◽  
Styrene Butadiene ◽  
Butadiene Styrene

In the proposed work, the possibility of using a hybrid coagulant based on a polymer cationic electrolyte-VPK – 402 (poly-N,N-dimethyl-N, N-diallylammonium chloride) in combination with viscose fiber in the technological process of separating SKS-30 ark rubber from latex is considered. The influence of the consumption of a hybrid coagulating agent, viscose fiber and its dosage, as well as the process temperature on the reduction of the aggregate stability of styrene-butadiene latex is considered. The influence of viscose fiber on the physical and mechanical properties of vulcanizates is established. At the same time, a number of features were noted consisting in a decrease in the aggregate stability of latex butadiene-styrene rubber during its coagulation with a hybrid coagulant. It was found that the use of a hybrid coagulant can reduce the consumption of cationic polyelectrolyte by up to 30%. It is shown that in the multicomponent system under consideration, several processes can occur simultaneously, which lead to the destabilization of latex dispersions. The use of a hybrid coagulant, including cationic polyelectrolyte, provides a combined effect of the bridging and neutralization mechanisms of violation of the aggregate stability of the dispersion. The presence of viscose fiber in the dispersed phase leads to an additional coagulating effect-adagulation, which is a kind of heterocoagulation. This may be due to the difference in surface potentials between the latex globules and the fiber additive. It is established that the temperature regime of the process of isolation of rubber from latex does not significantly affect the completeness of the extraction of rubber from latex. A decrease in the content of components of the emulsion system in wastewater discharged from the shops producing rubbers by emulsion polymerization was noted. According to the main physical and mechanical parameters, rubbers, rubber mixtures and vulcanizates prepared on their basis meet the requirements.

scholarly journals RECEIVING OIL FROM CLOUDBERRIES FRUITS BY SUPERCRITICAL CARBON DIOXIDE EXTRACTION

2018 ◽  
pp. 91-97
Author(s):  
Artyom Dmitrievich Ivakhnov ◽  
Kristina Sergeevna Sadkova ◽  
Alina Sergeyevna Sobashnikova ◽  
Tat'yana Eduardovna Skrebets ◽  
Mikhail Vladislavovich Bogdanov
Keyword(s):  
Carbon Dioxide ◽  
Fatty Acids ◽  
Supercritical Carbon Dioxide ◽  
Unsaturated Fatty Acids ◽  
Optimum Conditions ◽  
Hexane Extraction ◽  
Rubus Chamaemorus ◽  
The Difference ◽  
Key Indicators ◽  
Supercritical Carbon

Comparative researches of ways of oil extraction from the fulfilled fruits of cloudberries (Rubus chamaemorus) with application of hexane and supercritical carbon dioxide as solvents are executed. Optimization is performed and optimum conditions of supercritical fluid extraction of oil are defined with use of central composite design of 2nd order. Pressure of carbon dioxide of 350 atm, temperature 85 °C, duration of extraction of 80 min are the optimum conditions of carrying out of the process. The yield of oil is 9.0%. Quality key indicators of the received oil were defined. The difference between the oil received by the SKF-CO2 method and the oil received by hexane extraction consists in improvement of organoleptic properties, the raised share of the combined fatty acids at decrease of a share of the free acids and high content of unsaturated fatty acids. It is shown that supercritical carbon dioxide can be an alternative to the hydrocarbons which are traditionally used for these purposes.

Biocatalytic and chemical leaching of a low-grade nickel laterite ore

2018 ◽  
Vol 115 (3) ◽  
pp. 305 ◽  
Author(s):  
Hasan Ciftci ◽  
Suleyman Atik ◽  
Fatma Gurbuz
Keyword(s):  
Sucrose Concentration ◽  
Low Grade ◽  
Optimum Conditions ◽  
Nickel Laterite ◽  
Chemical Leaching ◽  
Solid Ratio ◽  
Metals Recovery ◽  
Nickel Laterite Ore ◽  
The Difference ◽  
Laterite Ore

Nickel and cobalt recovery from a low-grade nickel laterite ore, supplied from Çaldağ deposit (Manisa, Turkey) were investigated by bio and chemical leaching processes. The fungus, Aspergillus niger was used for biocatalytic leaching experiments. The effects of parameters (solid ratio and sucrose concentration) on the biocatalytic leaching of the ore were initially tested in flasks to obtain the optimum conditions for the A. niger. Then chemical leaching was applied as a comparison to bioleaching, using organic acids (citric, oxalic, acetic and gluconic acids) as well as a mixture of acids. According the results, the maximum dissolution yield of nickel, cobalt and iron were detected respectively as 95.3%, 74.3% and 50.0% by biocatalytic processes which containing 25% (w/v) sucrose and 1% (w/v) solids. The increase in the solid ratio adversely influenced the biocatalytic activity of A. niger. Finally, further tests in reactors (v = 1 and 10 L) were performed using the optimum conditions from the flask tests. The difference in metals recovery between biocatalytic and chemical leaching was significantly important. Bioleaching produced higher Ni and Co extractions (34.3–75.6%) than chemical process.

scholarly journals Structure and Dielectric Properties of Electroactive Tetraaniline Grafted Non-Polar Elastomers

2020 ◽  
Vol 4 (1) ◽  
pp. 25
Author(s):  
Christopher Ellingford ◽  
Atcharaporn Pengchaicharoen ◽  
Alan M. Wemyss ◽  
Chaoying Wan
Keyword(s):  
Dielectric Properties ◽  
Relative Permittivity ◽  
Similar Rate ◽  
Chain Structure ◽  
Electrically Conducting ◽  
Styrene Butadiene Styrene ◽  
The Difference ◽  
Actuation Devices ◽  
Styrene Butadiene ◽  
Butadiene Styrene

Intrinsic modification of polybutadiene and block copolymer styrene–butadiene–styrene with the electrically conducting emeraldine salt of tetraaniline (TANI) via a three-step grafting method, is reported in this work. Whilst the TANI oligomer grafted at a similar rate to both polybutadiene and styrene–butadiene–styrene under the same conditions, the resulting elastomers exhibited vastly different properties. 1 mol% TANI-PB exhibited an increased relative permittivity of 5.9, and a high strain at break of 156%, whilst 25 mol% TANI-SBS demonstrated a relative permittivity of 6.2 and a strain at break of 186%. The difference in the behaviour of the two polymers was due to the compatibilisation of TANI by styrene in SBS through π-π stacking, which prevented the formation of a conducting TANI network in SBS at. Without the styrene group, TANI-PB formed a phase separated structure with high levels of TANI grafting. Overall, it was concluded that the polymer chain structure, the morphology of the modified elastomers, and the degree of grafting of TANI, had the greatest effect on the mechanical and dielectric properties of the resultant elastomers. This work paves the way for an alternative approach to the extrinsic incorporation of conducting groups into unsaturated elastomers, and demonstrates dielectric elastomers with enhanced electrical properties for use in actuation devices and energy harvesting applications.

scholarly journals The barratry of the shipmaster in early modern law: the approach of Italian and English law courts

2019 ◽  
Vol 87 (4) ◽  
pp. 504-574
Author(s):  
Guido Rossi
Keyword(s):  
Early Modern ◽  
Common Law ◽  
Practical Importance ◽  
Civil Law ◽  
Case Law ◽  
Legal Framework ◽  
Walk Away ◽  
Long Time ◽  
Law Courts ◽  
The Difference

SummaryFor a long time, the concept of barratry (at least in its maritime meaning) was one and the same on both sides of the Channel. The barratry of the shipmaster was part of the mercantile usages, and it identified the intentionally blameworthy conduct of the master. When law courts began to decide on insurance litigation they were confronted with a notion quite alien to them. Broadly speaking, the shipmaster’s barratry could well be considered a fraud of sort. But in order to decide on its occurrence in a specific case, law courts had to analyse it in legal terms, and so according to the specific legal categories of their own system. The point ceases to be trivially obvious if we think that the different legal framework of civil and common law courts progressively led to very different interpretations of the same thing. Thus, with the shift of insurance litigation from mercantile justice to law courts maritime barratry began to acquire increasingly different features in the two legal systems. Very often, the very same conduct of the shipmaster was considered as negligent by civil law courts and barratrous by common law courts. The difference was of great practical importance, for many policies excluded barratry from the risks insured against. So, depending on the kind of law court, an insurer could be charged with full liability for the mishap or walk away without paying anything. If the beginning of the story was the same, its end could not have been more different.

scholarly journals Comparison of three methods for rendering plant fat transesterification

2013 ◽  
Vol 59 (No. 2) ◽  
pp. 51-55
Author(s):  
A. Prošková ◽  
J. Kučera ◽  
Z. Kopicová ◽  
L. Škarková
Keyword(s):  
Fatty Acids ◽  
Free Acid ◽  
The Other ◽  
Alkaline Media ◽  
Optimum Temperature ◽  
Optimum Conditions ◽  
High Concentration ◽  
Reaction Velocity ◽  
Catalysed Reaction ◽  
The Difference

Three most frequently used methods for fat transesterification were compared using rendering plant fat (RPF) as model. Acid-catalysed transesterification was found to be the most effective (conversion 90%) at optimum conditions (fat: methanol ratio 1:10, sulphuric acid amount of 2% v/v, temperature 95°C). Base-catalysed transesterification of RPF on the other hand, results in much lower conversion (45%) at optimum conditions (fat:methanol ratio 1:20, NaOH amount 8% w/v, optimum temperature 95°C). The difference is done (among others) by the fact that RPF has high concentration of free acid (high acidity number) compared with the fats usually used for transesterification and that free acids are not esterified in alkaline media. Enzyme-(lipase) catalysed reaction could lead to partial esterification of free fatty acids, but with much lower reaction velocity. This fact leads to higher conversion in the case of enzyme-catalysed transesterification of RPF compared with base-catalysed reaction; nevertheless, even in this case the conversion is much lower in comparison with acid-catalysed reaction. The optimum conversion in enzyme-catalysed reaction was 55%.  

“Railway track” module in “master of infrastructure and operation of rapid and high-speed railroads”

2017 ◽  
pp. 119-126
Author(s):  
Ludmila Blazhko ◽  
Andrey Romanov
Keyword(s):  
Educational Program ◽  
High Speed ◽  
Practical Importance ◽  
Railway Track ◽  
Learning Materials ◽  
Engineering Construction ◽  
Republic Of China ◽  
Supplementary Education ◽  
The Difference ◽  
Creative Team

Objective: To report on “Railway track” module which is included in international educational program of supplementary education “Master of infrastructure and operation of rapid and high-speed railroads”. Methods: Methodological foundations of learning materials’ selection were considered, including the conducted survey of home and international experience in engineering, construction and operation of high-speed networks. Moreover, FGBOU VO PGUPS participation in research and training program of OAO “RZhD” high-speed traffic realization was characterized. Results: The experience in project realization was presented by the international creative team, which included organizations and higher educational establishments of Russia, Ukraine and France. The difficulties connected with the difference in the normative base and different methodological approaches of academic schools were analyzed, which occurred in the process of creating educational learning materials by the developers and teachers The emphasis was placed on audience make-up diversity both in the level of audience competence and the scope of specialties. The review of events related to participants’ training in Beijing Transport University of People’s Republic of China was conducted. Practical importance: The conclusion was made on the demand for supplementary educational program among students and experts.

Viscoelastic Behavior of Styrene-Butadiene-Styrene Block Copolymers in Temperature Range of Glass-Rubber Transition of Styrene Block

1996 ◽  
Vol 69 (1) ◽  
pp. 73-80 ◽  
Author(s):  
N. Nakajima
Keyword(s):  
Molecular Weight ◽  
Block Copolymers ◽  
Viscoelastic Behavior ◽  
Shear Mode ◽  
Molecular Weight Polymer ◽  
Styrene Butadiene Styrene ◽  
The Difference ◽  
Tan Δ ◽  
Styrene Butadiene ◽  
Butadiene Styrene

Abstract Dynamic mechanical measurements were performed with styrene-butadiene-styrene (SBS) block copolymers, Kraton D-1101 and D-l 102. Isochronal data were obtained from −130 to 85°C in the tensile mode at 1 Hz and from 60 to 160°C in the shear mode at 1 rad/s. The isothermal measurements were also performed at 60, 90, 120, 140, and 160°C in the frequency range of 0.0316 to 100 rad/s. The results suggest that the two polymers have different morphologies although the styrene content and the diblock content are about the same for both polymers. Kraton D-1101, which has 1.5 times higher molecular weight, has 3–5 times higher rubbery modulus, compared to D-1102. The lower molecular weight polymer, D-1102, appears to have a larger amount of the mixed phase at the boundary. This is suggest by the lower temperature of the “domain disruption”, Tdd and the higher magnitude of tan δ at Tdd. This explains the difference in the rubbery moduli of the two polymers.

Effect of Temperature on Ozone Cracking of Butyl Rubbers

1968 ◽  
Vol 41 (5) ◽  
pp. 1294-1299 ◽  
Author(s):  
A. N. Gent ◽  
H. Hirakawa
Keyword(s):  
Crack Growth ◽  
Ozone Concentration ◽  
Effect Of Temperature ◽  
Segmental Mobility ◽  
Temperature Range ◽  
Styrene Copolymers ◽  
The Difference ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Butadiene Styrene

Abstract Rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20-160° C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate form of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate-controlling step. This is contrasted with the behavior of butadiene styrene copolymers, for which rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.

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