Studies of the Vulcanization of Rubber. III. Kinetics of Change of Tensile Strength of Natural Rubber during Vulcanization

1954 ◽  
Vol 27 (3) ◽  
pp. 615-621 ◽  
Author(s):  
B. Dogadkin ◽  
B. Karmin ◽  
I. Golberg
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Structure Formation ◽  
Linear Function ◽  
General Equation ◽  
Original Material ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Butadiene Styrene

Abstract 1. It is shown that the tensile strength of vulcanized butadiene-styrene rubber is a linear function of the plasticity of the original material. 2. Proceeding from concepts of the presence during vulcanization of a number of opposing processes of structure formation and destruction, both of which influence the molecular weight of the rubber, a general equation is derived which expresses the kinetics of the change of tensile strength of a vulcanizate. 3. Experimental material is offered which proves the applicability of the proposed equation to the representation of the kinetics of vulcanization of mixtures of natural rubber containing relatively small sulfur contents, i.e., up to 3 per cent.

The Kinetics and Occurrence of Optimum Vulcanization

1956 ◽  
Vol 29 (2) ◽  
pp. 555-567
Author(s):  
B. A. Dogadkin
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Structure Formation ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Smooth Curves ◽  
Intermolecular Reaction ◽  
Physical And Chemical ◽  
Kinetics Of ◽  
And Chemical Properties

Abstract The fundamental reaction of vulcanization is the combination of a vulcanizing agent with rubber. The kinetics of this reaction is expressed by smooth curves. Simultaneously with the combining of the vulcanizing agent, in fact as a result of it, changes take place in a number of physical and chemical properties of rubber—solubility, modulus, tensile strength, and other indexes. Unlike the kinetics of combination of the vulcanizing agent, the changes in these properties are most often represented by curves having a maximum or minimum which characterizes the phenomenon of optimum vulcanization. The extreme form which curves of changes of physical and chemical properties of rubber assume during vulcanization can be explained, in our opinion, by the fact that, during vulcanization, there is a competition between opposing reactions, of which one set are reactions of structure formation (i.e., increase of the molecular weight and the intensity of intermolecular reaction), and the others are destruction reactions. Thus, during vulcanization under factory conditions, at least two reactions take place: (1) the reaction between rubber and sulfur, and (2) the reaction between rubber and molecular oxygen introduced into the vulcanization mix by milling with the ingredients. The amount of oxvgen present here in moles approaches the molar concentration of sulfur.

Studies in the Vulcanization of Rubber. III—Kinetics of Vulcanization of Rubber with Sulfur and Selenium

1930 ◽  
Vol 3 (4) ◽  
pp. 650-659
Author(s):  
John T. Blake
Keyword(s):  
Molecular Weight ◽  
Order Reaction ◽  
Order Equation ◽  
Second Order Reaction ◽  
Experimental Conditions ◽  
Mathematical Basis ◽  
First Order ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract A procedure for the determination of combined selenium in rubber has been evolved. The rate of combination of selenium and rubber has been ascertained under certain conditions and shown to follow a first-order equation. A minimum value for the molecular weight of rubber has been estimated. The formation of hard rubber under chosen experimental conditions has been put on a mathematical basis and has been shown to follow a second-order reaction. The soft- and hard-rubber reactions have been shown qualitatively to be successive reactions and the function of accelerators has been discussed. The theory explains the anomalous results obtained by previous investigators.

SERINOL DERIVATIVES FOR THE SUSTAINABLE VULCANIZATION OF DIENE ELASTOMERS

2018 ◽  
Vol 91 (4) ◽  
pp. 701-718 ◽  
Author(s):  
Vincenzina Barbera ◽  
Sara Musto ◽  
Giuseppe Infortuna ◽  
Valeria Cipolletti ◽  
Attilio Citterio ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Building Block ◽  
Induction Time ◽  
High Selectivity ◽  
Rubber Compounds ◽  
Aldehydes And Ketones ◽  
Diene Rubbers ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Kinetics Of Vulcanization

ABSTRACT 2-amino-1,3-propandiol (serinol) was used as the starting building block of synthetic pathways that led to the preparation of innovative chemicals suitable as ingredients for rubber compounds. Serinol based reactions were performed in the frame of a sustainable process, in the absence of any solvent and catalyst, with aldehydes and ketones, such as acetone, cinnamaldehyde and camphor. The synthesis of either imines or oxazolidines was obtained with high selectivity. Serinol, imine and oxazolidine derivatives of serinol were used as accelerator for the vulcanization of diene rubbers. They were proved to be efficient secondary accelerators in silica based compounds based on poly(styrene-co-butadiene) in place of diphenyl guanidine. The kinetics of vulcanization was investigated for natural rubber based compounds in the absence of any filler. With respect to serinol, the imine derivatives were able to enhance the induction time of vulcanization and to afford a similar vulcanization rate.

Structural Changes in Rubber Caused by the Action of Molecular Oxygen. V. Destructive Solution of Vulcanized Synthetic Rubbers

1953 ◽  
Vol 26 (4) ◽  
pp. 787-797
Author(s):  
Z. Tarasova ◽  
B. Dogadkin
Keyword(s):  
Natural Rubber ◽  
Molecular Oxygen ◽  
Structural Changes ◽  
Axial Ratio ◽  
Colloid Solution ◽  
Butadiene Rubber ◽  
Rate Of Absorption ◽  
The Mean ◽  
Kinetics Of ◽  
Butadiene Styrene

Abstract 1. Vulcanized synthetic rubbers, when heated in a hydrocarbon medium containing molecular oxygen, dissolve completely. The kinetics of destructive solution of vulcanized synthetic rubbers follows the pattern established for the destructive solution of vulcanized natural rubber. 2. The rate of destructive solution of a vulcanizate depends on the molecular structure of the rubber. Rubbers are classified in the following order according to the increase of rate of solution of their vulcanizates : Butyl rubber < sodium-butadiene rubber < butadiene-styrene rubber < polychloroprene < natural rubber. The apparent energy of activation of natural rubber is 19 kcal. per mole, for sodium-butadiene rubber 31.2 kcal. per mole, and for butadiene-styrene rubber 27.1 kcal. per mole. 3. The rate of destructive solution of vulcanized butadiene rubbers depends linearly on the extent of 1,4-structure in the rubber molecule. 4. The mechanical properties of vulcanizates do not appreciably influence the rate of their destructive solution. The type of accelerator used, however, is of essential importance; in fact, its influence corresponds to its influence on the rate of absorption of oxygen. 5. The presence of water slows down the dissolution of vulcanizates of natural and sodium-butadiene rubbers, since it retards their absorption of oxygen. 6. The rate of destructive solution of a vulcanizate in various solvents depends linearly on the coefficient of absorption of oxygen in the solvents. 7. The viscosity of a solution of decomposed vulcanized sodium-butadiene rubber depends linearly on the concentration up to 50 per cent. 8. The mean specific molecular weight, measured cryoscopically, of sodium-butadiene rubber was 2400– 3600, and the osmotic weight, 16,000. The axial ratio of the particles was 1:15. 9. The hypothesis is advanced that solutions of decomposed vulcanizates constitute a special type of colloid solution.

The Plasticization of Butadiene-Styrene Rubber

1956 ◽  
Vol 29 (2) ◽  
pp. 485-491 ◽  
Author(s):  
B. Karmin ◽  
B. Bets
Keyword(s):  
Structure Formation ◽  
Elevated Temperatures ◽  
Relative Elongation ◽  
Physical And Mechanical Properties ◽  
High Recovery ◽  
Styrene Copolymer ◽  
Recovery Capacity ◽  
Kinetics Of ◽  
Cold Mill ◽  
Butadiene Styrene

Abstract 1. The kinetics of the plasticization of a butadiene-styrene copolymer on a cold laboratory mill was studied. It was established that, at temperatures of 20–30° C, the plasticity rises steadily and that, consequently, under these conditions a monodirectional destructive process takes place. 2. The kinetics of plasticization of a butadiene-styrene copolymer was investigated in a laboratory banbury at 140° C, both with and without a plasticization aid (chemical). Plasticization at a high temperature is accompanied by the simultaneous operation of the two reactions of destruction and structure formation proceeding at cross-purposes, and may be described by a kinetic equation of the type: P=P0 (1+a⋅m)(1−b⋅n) 3. Plasticized rubbers obtained by breakdown on a cold mill have a smaller capacity for recovery than those obtained by treatment in a boiler or a banbury at temperatures above 120° C. 4. Plasticized rubbers obtained by milling on a cold mill give stocks with higher tensile strength and higher relative elongation than rubbers plasticized by hot treatment. 5. The high recovery capacity of rubbers plasticized at elevated temperatures and the lowering of the physical and mechanical properties of vulcanizates of those rubbers are explained by the branched molecules which they form during structure formation.

Property Enhancement of Silica-Filled Natural Rubber Compatibilized with Epoxidized Low Molecular Weight Rubber by Extra Sulfur

2013 ◽  
Vol 844 ◽  
pp. 235-238 ◽  
Author(s):  
Prachid Saramolee ◽  
Kannika Sahakaro ◽  
Natinee Lopattananon ◽  
Wilma Dierkes ◽  
Jacques W.M. Noordermeer
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Network Formation ◽  
Periodic Acid ◽  
Low Molecular Weight ◽  
Molecular Weight Range ◽  
Small Influence ◽  
Silane Molecule ◽  
Mooney Viscosity

The properties of both compounds and vulcanizates of silica-filled natural rubber (NR) compatibilized with epoxidized low molecular weight natural rubbers (ELMWNRs) consisting of 12 and 28 mol% epoxide are investigated. The ELMWNRs with a molecular weight range of 50,000 to 60,000 g/mol are produced by depolymerization of epoxidized natural rubber (ENR) latex using periodic acid, and then used as compatibilizer in a range of 0 to 15 phr in virgin NR. The compounds with LMWNR without epoxide groups, and with bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent are also prepared for comparison purpose. Incorporation of ELMWNRs lowers Mooney viscosity and Payne effect to the level closed to that of silica/TESPT compound, and clearly enhances the modulus and tensile strength of vulcanizates compared to the compounds with no compatibilizer and LMWNR. The higher epoxide groups content results in the better tensile properties but somewhat less than the compound with TESPT. Addition of extra sulfur into the compounds with LMWNR and ELMWNRs to compensate for the sulfur released from silane molecule in the silica/TESPT system shows small influence on Mooney viscosity, but remarkably enhances 300% modulus, tensile strength and loss tangent at 60°C as a result of the better network formation.

The Dispersion of Carbon Black in Rubber Part IV. The Kinetics of Carbon Black Dispersion in Various Polymers

1994 ◽  
Vol 67 (2) ◽  
pp. 237-251 ◽  
Author(s):  
A. Y. Coran ◽  
F. Ignatz-Hoover ◽  
P. C. Smakula
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Kinetic Parameters ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Rapid Technique ◽  
Rubber Part ◽  
Kinetics Of ◽  
Carbon Black Dispersion

Abstract A rapid technique for evaluating the rate and state of dispersion of carbon black in natural rubber has been extended to study the dispersion of carbon black in various polymers. The technique measures the extent and rate of dispersion of the black in the rubber. The kinetics of dispersion was characterized for a variety of polymers (e.g. SBR, EPDM, IR, IIR, BR and NR). Kinetic parameters were correlated with molecular weight and molecular weight distribution.

Vulcanization of Elastomers. 39. Vulcanization of Natural and Synthetic Rubbers by Sulfur and Sulfenamides. II

1965 ◽  
Vol 38 (1) ◽  
pp. 176-188 ◽  
Author(s):  
W. Scheele ◽  
G. Kerrutt
Keyword(s):  
Natural Rubber ◽  
Concentration Dependence ◽  
Intermediate Compound ◽  
Kcal Mole ◽  
Experimental Conditions ◽  
Molar Ratios ◽  
Induction Periods ◽  
Induction Times ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract The dependence of the kinetics of vulcanization of natural rubber by sulfur in presence of N-cyclohexyl-benzothiazolylsulfenamide (CHBS) on temperature and for varied molar ratios of accelerator and sulfur was more exactly investigated. 1. Although the vulcanization of natural rubber accelerated with N-cyclohexyl-benzothiazolylsulfenamide with conventional experimental conditions is characterized by very long induction times, nevertheless—as also for other accelerated vulcanization reactions—sulfur decrease follows a time law with nt<1 and the activation energy, as in other cases, is calculated to be 29 kcal/mole. 2. The value nt=0.6 is found for the exponent of the time law, independent of temperature and concentration of reactants. 3. The concentration dependence of the rate of sulfur decrease under conditions of constant sulfur content and increasing sulfenamide concentration is found to be consistent with catalysis by an intermediate compound. 4. The actual accelerator may be essentially cyclohexylammonium-benzothiazoylmercaptide. 5. The temperature and concentration dependence of the induction periods for sulfur decrease and crosslinking were investigated. The course of crosslinking with reaction time, which is characterized by strong reversion, is discussed.

Control of Mechanical Properties and Permeability of Electrospun Natural Rubber with Different Composite Systems

2010 ◽  
Vol 93-94 ◽  
pp. 619-622 ◽  
Author(s):  
Sarawuth Sithornkul ◽  
Poonsub Threepopnatkul
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Testing Machine ◽  
Acrylonitrile Butadiene Styrene ◽  
Optimum Conditions ◽  
Fiber Mats ◽  
Vapour Permeability ◽  
Composite Systems ◽  
Butadiene Styrene

The electrospun natural rubber (NR) with two different components namely: acrylonitrile butadiene styrene (ABS) and carbon black (CB) have been extensively studied. The main objective was to investigate the mechanical properties and permeability dependency of NR/ABS and NR/CB as well as its contents. NR/CB was compounded by torque rheometer (Brabender) while ABS was dissolved with NR using tetrahydrofuran (THF) as its solvent. Sulfur was used as the vulcanizing agent in both systems. Mechanical properties were evaluated by universal testing machine and permeability was observed by water vapour permeability. The optimum conditions for electrospun NR/ABS and NR/CB non-woven mats were as follows: flow rate 30 ml/h, voltage 15 kV, collector distance 20 cm and collected on rotating circular plate at 1000 rpm. The results of mechanical properties showed that for electrospun NR/CB fiber membranes, the higher the CB loading it had, the lower its tensile strength and elongation it would be. Whilst electrospun NR/ABS fiber mats, the elongation behavior was affected by the ABS loading but not the tensile strength. For permeability, NR/CB was shown to possess relatively higher permeability than the NR/ABS non-woven mats.

Studies on the Kinetics of Vulcanization of Rubber

1964 ◽  
Vol 37 (2) ◽  
pp. 557-562
Author(s):  
H. L. Taneja ◽  
S. Banerjee
Keyword(s):  
Zinc Oxide ◽  
Steady State ◽  
Natural Rubber ◽  
Square Root ◽  
Initiator Concentration ◽  
Appreciable Increase ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Free Sulfur

Abstract The dependence of the rate of accelerated vulcanization of natural rubber (smoked sheet) on the concentration of mercaptobenzothiazole accelerator has been reported on in this paper. The rate of decrease of free sulfur at the steady state has been found to be proportional to the square root of the initiator concentration expressed as grams/100 grams of rubber. The rate has also been found to be enhanced by the addition of 1% of zinc oxide. Higher amounts of zinc oxide does not lead to a further appreciable increase in the rate.

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