scholarly journals Multiple Structural Changes Found around Crack Tip of Carbon Black-filled Natural Rubber Vulcanizate

2019 ◽  
Vol 92 (5) ◽  
pp. 171-173
Author(s):  
Masatoshi TOSAKA ◽  
Takayuki MARUYAMA
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Structural Changes ◽  
Crack Tip ◽  
Rubber Vulcanizate ◽  
Multiple Structural Changes

Longitudinal Cracking in a Carbon Black Filled Natural Rubber Vulcanizate during Chemical Stress Relaxation

1998 ◽  
Vol 71 (2) ◽  
pp. 157-167 ◽  
Author(s):  
G. R. Hamed ◽  
J. Zhao
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Natural Rubber ◽  
Longitudinal Crack ◽  
Chemical Stress ◽  
Loading Direction ◽  
Rubber Vulcanizate ◽  
Edge Cracks ◽  
Forced Air ◽  
Oxidative Attack

Abstract Thin specimens of a black-filled, natural rubber vulcanizate have been held in uniaxial tension at 72°C and 200% elongation in a forced air oven. After substantial oxidative attack (inferred from stress relaxation), small edge cracks formed. Initially, these cracks grew perpendicular to the loading direction, but, upon reaching about 0.1 mm in depth, longitudinal crack growth commenced and fracture progressed by a kind of 0°-peel process with “splitting-off” of successive strands of rubber. This phenomenon is attributed to anisotropy in strength caused both by straining and by oxidative attack.

Influence of Chemical Structure on the Dynamic Properties of Sulfur-Vulcanized, Carbon Black-Reinforced Natural Rubber

1972 ◽  
Vol 45 (4) ◽  
pp. 1051-1063 ◽  
Author(s):  
G. M. Doyle ◽  
R. E. Humphreys ◽  
R. M. Russell
Keyword(s):  
Service Life ◽  
Carbon Black ◽  
Natural Rubber ◽  
High Temperatures ◽  
Network Structure ◽  
Thermal Aging ◽  
Chemical Structure ◽  
Dynamic Properties ◽  
Rubber Vulcanizate ◽  
Operating Temperatures

Abstract A comparison is made of the composition and properties of the different rubber vulcanizate networks obtained by varying the ratio of sulfur to sulfenamide accelerator and by the thermal aging of vulcanizates containing predominantly polysulfide crosslinks. It is concluded that the changes in network structure which can take place, for example, during the service life of natural rubber tires are not the direct cause of failures of the type associated with rubber fatigue at high temperatures. However, a reduction in the total number of crosslinks can accelerate failure by increasing the amount of heat generated during flexing. More stable networks giving improved resistance to fatigue at high operating temperatures are obtained by the use of higher ratios of accelerator to sulfur than are conventionally employed.

Thermal destruction of carbon black network structure in natural rubber vulcanizate

2011 ◽  
Vol 122 (2) ◽  
pp. 1300-1315 ◽  
Author(s):  
Atsushi Kato ◽  
Toshiya Suda ◽  
Yuko Ikeda ◽  
Shinzo Kohjiya
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Network Structure ◽  
Thermal Destruction ◽  
Rubber Vulcanizate

Effect of modified carbon black on the properties of natural rubber vulcanizate

1997 ◽  
Vol 66 (4) ◽  
pp. 683-693 ◽  
Author(s):  
A. K. Ghosh ◽  
S. Maiti ◽  
B. Adhikari ◽  
G. S. Ray ◽  
S. K. Mustafi
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Rubber Vulcanizate

scholarly journals Structural Changes during Mechanical Mixing in Carbon Black-Natural Rubber Systems Studied by Pulsed NMR

1982 ◽  
Vol 14 (2) ◽  
pp. 149-154 ◽  
Author(s):  
Hajime Serizawa ◽  
Masayoshi Ito ◽  
Tetsuo Kanamoto ◽  
Koji Tanaka ◽  
Akimasa Nomura
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Structural Changes ◽  
Mechanical Mixing ◽  
Pulsed Nmr

Microstructural Changes in the Crack Tip Region of Carbon-Black-Filled Natural Rubber

1987 ◽  
Vol 60 (5) ◽  
pp. 910-923 ◽  
Author(s):  
D. J. Lee ◽  
J. A. Donovan
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Fracture Resistance ◽  
Crack Tip ◽  
Microstructural Changes ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract CB facilitates strain-induced crystallization and increases the size of the crystallized zone at the stressed crack tip. Both effects are major reinforcement mechanisms that increase the fracture resistance of CB-reinforced NR.

scholarly journals FATIGUE CRACK GROWTH BEHAVOR OF CARBON BLACK–REINFORCED NATURAL RUBBER

2021 ◽  
Author(s):  
Lewis B. Tunnicliffe
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Carbon Black ◽  
Natural Rubber ◽  
Crack Growth ◽  
Crack Tip ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Amplification Factors

ABSTRACT Fatigue crack growth behavior of carbon black–reinforced natural rubber is investigated. Rubber compounds of Shore A = 70 are prepared by varying the formulation loadings of a wide range of carbon black types based on their structure and surface area properties. The resulting fatigue crack growth behavior shows significant variation in β exponent values, depending on the properties of the carbon black. These variations are rationalized by considering the strain amplification of natural rubber by carbon black aggregates in the region of compound directly ahead of the crack tip. An assumption is made that little networking of the carbon black aggregates exists in this region of very high strain and that hydrodynamic calculations that consider occluded rubber can therefore provide realistic values for strain amplification. A reasonable scaling of power law crack growth parameters to calculated strain amplification factors is found, with the exponent, β, decreasing with increasing strain amplification. The implication here is that enhanced strain amplification promotes the formation of strain-induced crystallites in the crack tip region. Performance tradeoffs resulting from the crossover of crack growth data sets dependent on the carbon black type are discussed. Of practical significance is the fact that the strain amplification factors can be calculated directly from knowledge of carbon black type and loading in rubber formulations.

Relaxation Processes in Vulcanized Rubber. III. Relaxation at Large Strains and the Effect of Fillers

1963 ◽  
Vol 36 (3) ◽  
pp. 697-708 ◽  
Author(s):  
A. N. Gent
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Natural Rubber ◽  
Progressive Failure ◽  
Large Strains ◽  
Relaxation Processes ◽  
Vulcanized Rubber ◽  
Rubber Vulcanizate ◽  
Finite Extensibility ◽  
Creep And Stress Relaxation

Abstract Some experimental measurements are described of stress relaxation and creep at room temperatures in vulcanizates of natural rubber, butyl, and SBR. In an unfilled natural rubber vulcanizate the rate of stress relaxation is found to rise sharply for extensions of more than about 200%. Reasons are given for attributing this to the growth of a crystalline phase. Similar rates are observed at all extensions for a carbon black filled natural rubber vulcanizate. This is shown to be in satisfactory accord with the Mullins-Tobin model structure for filled vulcanizates, when the whole of the observed relaxation occurs in “softened” regions at rates appropriate to the high local deformations. The failure of rubber-carbon black associations with time does not appear to constitute a major relaxation process. In noncrystallizing unfilled vulcanizates the rate of relaxation is found to decrease somewhat with extension, possibly due to finite-extensibility effects. Preliminary measurements on a filled SBR vulcanizate suggest that a significant contribution to the observed relaxation arises from progressive failure of rubber-filler associations in this case. The relation derived previously between the rates of creep and stress relaxation at equivalent deformations is confirmed in all cases, within experimental error. Its validity in highly-irreversible systems is thus established experimentally.

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