Effect of the Molecular Weight of Rubber on the Kinetics of Vulcanization and on the Formation of a Spatial Network

1954 ◽  
Vol 27 (4) ◽  
pp. 925-929 ◽  
Author(s):  
A. S. Novikov ◽  
G. M. Bartenev ◽  
F. A. Galil-Ogly
Keyword(s):  
Molecular Weight ◽  
Sodium Sulfide ◽  
Scientific Literature ◽  
Hydraulic Press ◽  
Butadiene Rubber ◽  
Spatial Network ◽  
Molecular Weights ◽  
Equilibrium Modulus ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract From scientific literature it is known that the rate of vulcanization and the mechanical properties of rubbers depend on the value of the initial molecular weight of the rubber. However, the cause of the slow vulcanization of olw molecular rubbers and the effect of the molecular weight of the rubber on the formation of a spatial network and the structure of the vulcanizate remain unclear. In the present work the kinetics of vulcanization of separate fractions of butadiene rubber SKS-30A of molecular weight from 100,000 to 1,170,000 was studied by measurements of the equilibrium modulus and the proportion of combined sulfur. The SKS-30A rubber was divided into five fractions of molecular weights: I 1,170,000; II 700,000; III 500,000; IV 140,000; and V 100,000. The molecular weights were calculated from viscometric data according to the formula previously established for this rubber by the authors: [η]=2.96×10−4 M0.71. In order to keep the molecular weight of the rubber constant, sheets for vulcanization were prepared from a dispersion of the ingredients in a benzene-rubber solution. The composition of the mixture was the same for all the fractions, i.e., 100 parts by weight of rubber, 3 parts of sulfur, 1 part of mercapto-benzothiazole, 5 parts of zinc oxide, 2 parts of stearic acid, and 1 part of phenyl-β-naphthylamine. The sheets were vulcanized in a hydraulic press at 143° C for various periods. The amount of sulfur combined with the rubber was determined by Bolotnikov's method, specially adapted to small batches of vulcanizate. The rubber specimens, weighing 0.2–0.3 gram, were extracted in 50 cc. of sodium sulfide, and titrated with 0.01N iodine solution.

scholarly journals Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 850
Author(s):  
Donghyuk Kim ◽  
Byungkyu Ahn ◽  
Kihyun Kim ◽  
JongYeop Lee ◽  
Il Jin Kim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
High Performance ◽  
Crosslink Density ◽  
Functional Group ◽  
Vital Role ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Mooney Viscosity ◽  
Silica Dispersion

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

Probing the molecular weights of sweetgum and pine kraft lignin fractions

TAPPI Journal ◽  
2021 ◽  
Vol 20 (6) ◽  
pp. 381-391
Author(s):  
JULIANA M. JARDIM ◽  
PETER W. HART ◽  
LUCIAN LUCIA ◽  
HASAN JAMEEL
Keyword(s):  
Molecular Weight ◽  
Black Liquor ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Systematic Investigation ◽  
Kraft Pulping ◽  
Molecular Weights ◽  
Lignin Recovery ◽  
Lignin Reactivity ◽  
Kinetics Of

The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physicochemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to deter- mine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weightlignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.

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.

Vulcanization behavior of NBR with organically modified clay

2011 ◽  
Vol 44 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Fabiula D. B. de Sousa ◽  
Carlos H. Scuracchio
Keyword(s):  
Butadiene Rubber ◽  
Modified Clay ◽  
Nitrile Butadiene Rubber ◽  
Modified Montmorillonite ◽  
Organically Modified Montmorillonite ◽  
Organically Modified ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

The rheometric measurements were used to study the kinetics of vulcanization of the nanocomposites nitrile butadiene rubber (NBR)/organically modified montmorillonite in different concentrations. The presence of clay has modified the rheometric properties of rubber. However the Ea values were not significantly modified with the presence of nanofiller.

Effect of Molecular Weight on Dynamic Mechanical Properties of SKD cis-1,4-Butadiene Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 517-521
Author(s):  
A. I. Marei ◽  
E. A. Sidorovich
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Average Molecular Weight ◽  
Dynamic Mechanical Properties ◽  
Considerable Effect ◽  
Butadiene Rubber ◽  
Dynamic Mechanical ◽  
Temperature Range ◽  
Molecular Weights ◽  
Dynamic Mechanical Behavior

Abstract In the high-elastic temperature range the molecular weight has a considerable effect on the dynamic mechanical properties of linear (uncrosslinked) SKD cis-1, 4-butadiene rubber. In this temperature range an unequivocal correlation exists between the rebound resilience at a given temperature and the viscosity average molecular weight, and the determination of the resilience can therefore be recommended as a rapid method of finding the molecular weight of SKD. A similarity is found in the dynamic mechanical behavior of rubbers of different molecular weights in the high-elastic temperature range. In the low-temperature range an increase in the molecular weight of crystalline polymers of SKD is accompanied by an impairment of their elastic properties.

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.

Effect of Initial Molecular Weight of a Rubber on the Strength and Fatigue of Its Vulcanizates

1957 ◽  
Vol 30 (1) ◽  
pp. 54-60
Author(s):  
G. M. Bartenev ◽  
A. S. Novikov ◽  
F. A. Galil-Ogly
Keyword(s):  
Molecular Weight ◽  
Dynamic Testing ◽  
Three Dimensional ◽  
Maximum Load ◽  
Testing Conditions ◽  
Maximum Deformation ◽  
Molecular Weights ◽  
Permanent Set ◽  
Dimensional Network ◽  
Equilibrium Modulus

Abstract (1) With decrease of the original molecular weight of rubber, there is a parallel decrease of the durability of its vulcanizates when they contain the same percentage of combined sulfur. On the other hand, this decrease of durability with decrease of the original molecular weight is only slight for vulcanizates having the same equilibrium modulus, i.e., the same density of crosslinks in the three-dimensional network. (2) In dynamic testing which involves repeated stretching, the durability depends on the testing conditions when the vulcanizates contain the same percentage of combined sulfur and at the same time when either the original molecular weight of the rubber is low or the equilibrium modulus is small. On the contrary, when the original molecular weight or the modulus is high, the durability does not depend on the testing conditions. When vulcanizates have the same equilibrium modulus, their durability depends on the original molecular weight. In this latter case the durability increases with increase of the molecular weight, independent of the testing conditions (given maximum load, given maximum deformation, etc.), and reaches a practically constant value at high molecular weights. (3) The fundamental influence of the original molecular weight on the strength and dynamic durability of vulcanizates containing the same percentage of combined sulfur is manifest in the retardation of the formation of a spatial network in low-molecular rubbers when vulcanized. With rubber of low original molecular weight, vulcanization leads to the formation of a thin space network and consequently a large number of molecular chain ends outside the network. For this reason, vulcanizates of low-molecular rubbers when tested are characterized by high permanent set.

Effect of Primary Molecular Weight on the Dynamic Properties of Cured Rubber

1959 ◽  
Vol 32 (3) ◽  
pp. 651-661
Author(s):  
E. V. Kuvshinskiĭ ◽  
M. M. Fomicheva
Keyword(s):  
Molecular Weight ◽  
Dynamic Modulus ◽  
Room Temperature ◽  
Dynamic Properties ◽  
Molecular Weights ◽  
Vulcanized Rubber ◽  
Equilibrium Modulus ◽  
Modulus Of Resilience ◽  
Molecular Weight Fractions ◽  
Butadiene Styrene

Abstract 1. Studied were the moduli of resilience and rebound elasticity of the vulcanized rubbers made from fractions of butadiene-styrene rubber “SKS-30-A” at temperatures of 20, 60, and 100° C in the region of molecular weights from 45,000 to 620,000 with various degrees of vulcanization (with variation in the pseudoequilibrium modulus from 5 to 70 kg/cm2). 2. The dynamic modulus of resilience is little dependent on the molecular weight of the original rubber both at room temperature and at higher temperatures. 3. At higher temperatures the elasticity of vulcanized rubber is mainly determined by the degree of vulcanization, the measure of which is the pseudo-equilibrium modulus, and is little dependent on the initial molecular weight. At low temperatures (20° C) elasticity increases with the degree of vulcanization, but it increases at different rates for vulcanized rubbers made from fractions with different molecular weights. At 20° C the increase in the degree of vulcanization increases the elasticity of vulcanized rubbers made from low-molecular fractions (45,000) to a lower degree than of those made from high molecular weight fractions (above 133,000). 4. The value of the maximum elasticity of vulcanized rubbers obtained from rubbers of the same molecular weight is not dependent on the type of accelerator used.

Bonding of Ultra High Molecular Weight Polyethylene to Styrene-Butadiene Rubber

1993 ◽  
Vol 66 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Gary R. Hamed ◽  
Hasan S. Dweik
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Average Molecular Weight ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Order Of Magnitude ◽  
High Bond ◽  
Styrene Butadiene ◽  
Ultra High Molecular Weight

Abstract The adhesion between a sulfur-vulcanized SBR and polyethylenes (PE) of various molecular weights has been determined using a T-peel geometry. When the viscosity average molecular weight of the polyethylene exceeds about 700 k, bonding is sufficient to cause rubber tear during peeling. In contrast, with PE of Mv≈147k, joint strength is reduced by more than an order of magnitude and fracture proceeds between the SBR and PE. It is hypothesized that the high bond strength with the ultra high molecular weight polyethylene (UHMWPE) is due to the formation of entrapped tangles between chains of the two adherends. Consistent with this, SBR-UHMWPE bonds are not disrupted after extensive swelling in toluene.

scholarly journals The use of terephthalic acid diamide in rubbers based on NBR-40

2020 ◽  
Vol 82 (2) ◽  
pp. 161-168
Author(s):  
M. A. Vokhmyanin ◽  
R. L. Vesnin ◽  
V. V. Pyatina ◽  
V. A. Sedykh
Keyword(s):  
Terephthalic Acid ◽  
Acid Amide ◽  
Physical And Mechanical Properties ◽  
Butadiene Rubber ◽  
Elongation At Break ◽  
Optimum Point ◽  
Degradation Reaction ◽  
Kinetics Of ◽  
High Polarity ◽  
Kinetics Of Vulcanization

In the present work, the kinetics of aminolytic degradation of polyethylene terephthalate with a mixture of amino alcohols (monoethanolamine and triethanolamine) was studied to obtain terephthalic acid diamide (N, N'-bis (2-hydroxyethyl) terephthalamide).The degradation reaction was carried out at atmospheric pressure and periodically stirring the reaction mass, followed by purification of the product by recrystallization.The dependence of the yield of the target product (N, N'-bis (2-hydroxyethyl) terephthalamide) on the reaction time and temperature, as well as on the ratio of the components, was revealed. The possibility of using diamide as one of the components of rubbers to expand the ingredient base in the rubber industry is considered. The effect of the obtained diamide on the kinetics of vulcanization of rubbers based on nitrile butadiene rubber (NBR-40) was studied, and the physicochemical and physicomechanical properties of the obtained vulcanizates were examined. In a similar way, the effect of an oligomer obtained by polycondensation of this terephthalic acid diamide was studied. The choice of SKN-40 rubber as the basis is due to the high polarity of the rubber and its good compatibility with the obtained terephthalic acid diamide and its oligomer.The accelerating effect of terephthalic acid diamide in combination with 2-mercaptobenzothiazole (MBT) on sulfur vulcanization of rubbers based on NBR-40 was revealed. The time to reach the optimum vulcanization is reduced by 4 min. In the case of using only terephthalic acid diamide, without the use of common accelerators, the optimum point of vulcanization shifts toward a longer time.In the case of using only terephthalic acid diamide, without the use of common accelerators, the optimum point of vulcanization shifts toward a longer time. Introduction diamide of terephthalic acid or its oligomer results in a change of physical and mechanical properties of the rubber - strength at break and elongation at break. The kinetics of the swelling of the resulting rubbers in toluene and gasoline was studied for four hundred hours. A decrease in the degree of swelling of vulcanizates in gasoline was observed with the introduction of terephthalic acid diamide instead of the zinc oxide vulcanization activator. Possible options for further application and use of the obtained terephthalic acid amide and its oligomer are considered.

Sign in / Sign up

Export Citation Format

Share Document