scholarly journals Carbon Black Reinforcement of Rubbers No.7: Strain-Induced Crystallization and Self-Reinforcement of NR: (2)A New Model and Concept for the Self-Reinforcement of NR

2004 ◽  
Vol 77 (12) ◽  
pp. 420-426 ◽  
Author(s):  
Yoshihide FUKAHORI
Keyword(s):  
Carbon Black ◽  
The Self ◽  
New Model ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

STRAIN-INDUCED CRYSTALLIZATION AND MECHANICAL PROPERTIES OF NBR COMPOSITES WITH CARBON NANOTUBE AND CARBON BLACK

2012 ◽  
Vol 85 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Sang-Ryeoul Ryu ◽  
Jong-Whan Sung ◽  
Dong-Joo Lee
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Carbon Nanotube ◽  
Carbon Black ◽  
Scanning Calorimetry ◽  
Multiwalled Carbon ◽  
Extension Ratio ◽  
The Matrix ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract The mechanical properties and strain-induced crystallization (SIC) of elastomeric composites were investigated as functions of the extension ratio (λ), multiwalled carbon nanotube (CNT) content, and carbon black (CB) content. The tensile strength and modulus gradually increase with increasing CNT content when compared with the matrix and the filled rubbers with same amount of CB. Both properties of rubber with CB and CNT show the magnitude of each CNT and CB component following the Pythagorean Theorem. The ratio of tensile modulus is much higher than that of tensile strength because of the CNT shape/orientation and an imperfect adhesion between CNT and rubber. The tensile strength and modulus of the composite with a CNT content of 9 phr increases up to 31% and 91%, respectively, compared with the matrix. Differential scanning calorimetry (DSC) analysis reveals that the degree of SIC increases with an increase in CNT content. Mechanical properties have a linear relation with the latent heat of crystallization (LHc), depending on the CNT content. As the extension ratio increases, the glass-transition temperature (Tg) of the composite increases for CB- and CNT-reinforced cases. However, the LHc has a maximum of λ = 1.5 for the CNT-reinforced case, which relates to a CNT shape and an imperfect adhesion with rubber. Based on these results, the reinforcing mechanisms of CNT and CB are discussed.

The Role of Filler Properties in the Creep Deformation of Filled Elastomers

1983 ◽  
Vol 56 (2) ◽  
pp. 465-480
Author(s):  
J. L. Thiele ◽  
R. E. Cohen
Keyword(s):  
Carbon Black ◽  
Creep Deformation ◽  
High Strain ◽  
Filled Elastomers ◽  
Filled Elastomer ◽  
Strain Mechanism ◽  
Sensitive Tool ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract The use of the creep T-jump experiment as a sensitive tool for elucidating the mechanistic behavior during the deformation of a complex material such as the carbon black filled elastomer has been illustrated. The activation energy for creep was determined as a function of stress for various vulcanizates. The effects of the choice of elastomer, and of variations in surface chemistry, structure, and loading of the filler, were studied. The T-jump results combined with electrical conductivity measurements confirmed the presence of a carbon black network which is considerably involved in the creep deformation process at low strain but not at high strain. In NR vulcanizates, there is a high-strain mechanism not observed in SBR vulcanizates; presumably strain-induced crystallization is responsible for the NR behavior. Oxidation of filler surfaces had essentially no effect on the creep deformation mechanisms, suggesting that, during creep, slippage of elastomers along the surface does not occur to any great extent for conventional or oxidized surfaces.

The Behavior of Carbon Black-Filled Natural Rubber under High Strain Rates3

2006 ◽  
Vol 34 (2) ◽  
pp. 119-134 ◽  
Author(s):  
Syeda A. Hussain ◽  
Michelle S. Hoo Fatt
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Natural Rubber ◽  
Strain Rate ◽  
Characteristic Relaxation Time ◽  
Dynamic Tensile Strength ◽  
Extension Ratio ◽  
Strain Induced Crystallization ◽  
Quasistatic Loading ◽  
Induced Crystallization

Abstract Tensile tests were conducted to obtain the deformation and failure characteristics of unfilled natural rubber (NR) and natural rubber with 25, 50, and 75 phr of N550 carbon black filler under quasistatic and dynamic loading conditions. The quasistatic tests were performed on an electromechanical INSTRON machine, while the dynamic test data were obtained from tensile impact experiments using a Charpy impact apparatus. In general, the modulus of the stress-extension ratio curves increases with increasing strain rate up to about 407, 367, 346, and 360 s−1 for unfilled, and 25, 50, and 75 phr for filled NR, respectively. Above these strain rates, the unfilled and filled natural rubber stress-extension ratio curves remained unchanged. The modulus increased with increasing strain rate because there was little time for stress relaxation. Above a critical strain rate, no change in modulus was observed because the time of the experiment was short compared to the lowest characteristic relaxation time of the material. Dynamic stress-extension ratio curves did not have the very sharp upturn at break, which is observed from strain-induced crystallization in natural rubber under quasistatic loading. Strain-induced crystallization appeared to be suppressed at high rates of loading. In fact, the highest dynamic tensile strength for the 25- and 50-phr carbon black-filled natural rubbers was smaller than those under quasistatic loading, while the highest dynamic tensile strength of the 75-phr carbon black-filled NR was greater than that in the static test. This indicated that high amounts of carbon black fillers will impede strain-induced crystallization in natural rubber.

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.

Effect of Interfacial Bonding on the Self-Adhesion of SBR and Neoprene

1984 ◽  
Vol 57 (1) ◽  
pp. 216-226 ◽  
Author(s):  
A. K. Bhowmick ◽  
A. N. Gent
Keyword(s):  
Adhesive Strength ◽  
Room Temperature ◽  
The Self ◽  
Structural Factors ◽  
Viscous Effects ◽  
Threshold Conditions ◽  
Different Types ◽  
Strain Induced Crystallization ◽  
Induced Crystallization ◽  
Strength Of Adhesion

Abstract When two elastomer layers are partially crosslinked in contact with each other, the strength of adhesion increases. This effect has now been studied for simple vulcanizates of SBR and for CR vulcanizates crosslinked with sulfur and/or oxide linkages. Under threshold conditions, e.g., at high temperatures and in the swollen state, when both viscous effects and strain-induced crystallization are virtually eliminated, the work of detachment is small and approximately proportional to the inferred degree of interlinking, rising from a few J/m2 when only Van der Waals' attractions are present, up to 40–70 J/m2 in the fully-interlinked state. No significant differences were observed between SBR and CR vulcanizates, or with different types of crosslinking of CR. The principal structural factors governing the adhesive strength under threshold conditions appear to be the number and length of the molecular strands comprising the network and crossing the interface. The threshold fracture energy is directly proportional to the density of such strands and is smaller for shorter strands, in accord with the theory of Lake and Thomas. Under normal conditions, e.g., at room temperature and in the unswollen state, CR vulcanizates were found to adhere much more strongly for a given degree of interlinking, presumably due to strain-induced crystallization. Indeed, some enhancement of strength persisted even at temperatures of 100–150°C, in the unswollen state.

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