Reactions of Radicals in Filled Rubber Compounds: II. Generation and Subsequent Reactions of Radicals Upon Deformation

2005 ◽  
Vol 78 (4) ◽  
pp. 659-673 ◽  
Author(s):  
Makoto Kawakubo ◽  
Katsunori Tsunoda ◽  
Hirofumi Yajima ◽  
Tadahiro Ishii ◽  
Hiroyuki Kaidou ◽  
...  
Keyword(s):  
Carbon Black ◽  
Crosslink Density ◽  
Bulk Property ◽  
Density Measurements ◽  
First Order ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Bond Scission ◽  
Radical Generation ◽  
Simple Combination

Abstract Effect of stretching on oxidative crosslinking of a carbon black filled IR vulcanizate at a normal temperature was studied by means of ESR and crosslink density measurements. Upon deformation, ESR intensity increased and crosslink density decreased, indicating scission of load supporting bonds generating free radicals. Bond scission increased with increasing strain. Resting after deformation, the ESR intensity decayed steadily following simple combination of first order and second order kinetics. The decay was overwhelmingly caused by first order reactions, which were considered to be irrelevant to crosslinking. On the other hand, crosslink density increased during resting. The results strongly suggested that ESR observed the radicals at the surface of the carbon black filled rubber, while crosslink density evaluated the bulk property. The crosslink density increase during resting outweighed the reduction due to deformation. Deformation accompanied by radical generation apparently accelerated oxidative crosslinking.

States of Carbon Black Dispersion and Extensibility of Rubbers

1993 ◽  
Vol 66 (2) ◽  
pp. 317-328 ◽  
Author(s):  
Asahiro Ahagon
Keyword(s):  
Carbon Black ◽  
Tensile Property ◽  
Crosslink Density ◽  
Hydrodynamic Effect ◽  
Property Variation ◽  
Agglomerate Size ◽  
Filled Rubber ◽  
Two Temperatures ◽  
Confined Polymer ◽  
Carbon Black Dispersion

Abstract Analysis is made for the origin of the mixing-induced tensile property variation of a filled rubber. Attention is paid to the hydrodynamic effect f(ϕe) of the filler, defined here as the factor to adjust the deviation of 100% modulus from the theory of rubber elasticity. For the rubbers mixed under variety of conditions, the f(ϕe)'s are calculated from the observed values of the modulus, at 25°C and 100°C, and the crosslink density. The variation of the f(ϕe) is considered to be governed by the mobility of the polymer confined in agglomerates of the filler. The mobility variation due to mixing seems to be mainly influenced by agglomerate size at 25°C, and by agglomerate size and chemical constraints at 100°C. Therefore, the f(ϕe)'s at the two temperatures are suggested to be useful measures of the state of carbon-black micro-dispersion. The extensibility of the rubbers is closely related f(ϕe). This indicates that the failure property is also governed by the mobility of the confined polymer.

Influence of filler-rubber interactions on the viscoelastic properties of carbon-black-filled rubber compounds

2003 ◽  
Vol 91 (1) ◽  
pp. 577-588 ◽  
Author(s):  
J. Léopoldès ◽  
C. Barrès ◽  
J. L. Leblanc ◽  
P. Georget
Keyword(s):  
Carbon Black ◽  
Viscoelastic Properties ◽  
Filled Rubber ◽  
Rubber Compounds

Effect of Crosslink Density on Cut Growth in Black-Filled Natural Rubber Vulcanizates

2002 ◽  
Vol 75 (5) ◽  
pp. 935-942 ◽  
Author(s):  
G. R. Hamed ◽  
N. Rattanasom
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Crack Growth ◽  
Crosslink Density ◽  
Longitudinal Crack ◽  
Test Pieces ◽  
Filled Rubber ◽  
Longitudinal Cracks ◽  
Natural Rubber Vulcanizates ◽  
High Crosslink Density

Abstract Tensile strengths, σb, of gum and N115-filled natural rubber test pieces, with and without edge pre-cuts, have been determined. At low crosslink density, the regular (uncut) σb of filled and gum vulcanizates is similar. However, at high crosslink density, the gum NR becomes brittle, while the corresponding filled rubber remains strong and resistant to cut growth. It is proposed that the tightly linked gum does not strain-crystallize appreciably during stretching, but that its filled counterpart does. Carbon black appears capable of inducing crystallization in a network that alone remains amorphous during extension. Filled vulcanizates of various crosslink densities have similar normal tensile strengths ( ≈ 30 MPa), but strengths differ, sometimes more than twofold, if a pre-cut is present. Lightly crosslinked specimens containing a small cut have strengths that depend very weakly on cut size, c. Furthermore, these develop long longitudinal cracks from which catastrophic rupture initiates. With larger cuts, strength decreases more rapidly with increasing c, there is less longitudinal crack growth, and rupture initiates near the original cut tip. In contrast, the strength of a highly crosslinked vulcanizate is sensitive to small cuts and test pieces exhibit minimal longitudinal cracking before failure.

Effects of Cure Systems of Ground Rubber and Rubber Matrix on their Adhesion and Crosslink Structures

2006 ◽  
Vol 79 (5) ◽  
pp. 806-819 ◽  
Author(s):  
S. W. Kim ◽  
H. Y. Park ◽  
K. H. Seo
Keyword(s):  
Physical Properties ◽  
Crosslink Density ◽  
Failure Modes ◽  
Rubber Matrix ◽  
Adhesion Forces ◽  
Layered Model ◽  
Cure Characteristics ◽  
Filled Rubber ◽  
Ground Rubber ◽  
Rubber Compounds

Abstract There has been a great deal of research on the effects of ground rubber (GR) on the cure characteristics of GR-filled rubber compounds. It has been known that the cure systems of the rubber matrix and GR also had an effect on the cure characteristics and physical properties of GR-filled compounds. In this study, the variation of the crosslink density and crosslink types of recured vulcanizates and fresh vulcanizates, with respect to the cure systems, were investigated by using a three-layered model. In addition, the adhesion forces between recured vulcanizates and fresh vulcanizates were measured, and the fracture surfaces were examined. Depending on the cure systems, the changes in the crosslink density and crosslink types of recured and fresh vulcanizates varied significantly and the failure modes of adhesion specimens were also different.

Online Method for Characterization of the Homogeneity of Rubber Compounds Filled with Non-Conductive Carbon Black

2006 ◽  
Vol 79 (4) ◽  
pp. 610-620 ◽  
Author(s):  
H. H. Le ◽  
M. Tiwari ◽  
S. Ilisch ◽  
H-J. Radusch
Keyword(s):  
Carbon Black ◽  
Electrical Conductance ◽  
Rubber Compound ◽  
Mixture Ratio ◽  
Dispersion Process ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Conductance Method ◽  
Internal Mixer

Abstract In the present work, the effect of carbon black (CB) type on the electrical conductance of CB filled rubber compounds measured online in the internal mixer and the corresponding CB dispersion were investigated. The CB dispersion is strongly affected by the specific surface area and structure of CB which can be directly monitored by use of the online electrical conductance method. The effect of CB mixture ratio of a high conductive CB and a non-conductive one on the online electrical conductance was investigated for CB filled rubber compounds. By addition of a small amount of a high-conductive CB type into a non-conductive CB filled rubber compound, a characteristic online conductance - time characteristic is observed that is a result of the formation of a joint network of the two CB types. It could be shown, that such a characteristic is suitable to monitor the dispersion process of the non-conductive CB in the rubber compound.

scholarly journals Superharmonic Resonance in Carbon-Black-Filled Rubber by High-Frequency DMA

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1653
Author(s):  
Imran Hussain Syed ◽  
Jorge Lacayo-Pineda
Keyword(s):  
Carbon Black ◽  
High Frequency ◽  
Model Compound ◽  
Resonance Phenomenon ◽  
Superharmonic Resonance ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Resonance Response ◽  
Filler Network ◽  
Main Influence

A systematic study of several SBR compounds filled with carbon black of various grades were analysed with the high-frequency Dynamic Mechanical Analyzer (HF DMA) in order to quantify the degree of nonlinearity induced by fillers in rubber compounds. These filler grades indirectly reflect different degrees of microdispersion, which seems to be the main influence on the superharmonic resonance phenomenon observed in HF DMA. This statement arises from the comparison of the microdispersion observed in TEM images. In the second part of the paper, a model compound filled with carbon black is enhanced with a standard reinforcing resin, which leads to a more compact filler network. This induces a higher superharmonic resonance response as well as a higher transmissibility behaviour.

Bound rubber morphology and loss tangent properties of carbon-black-filled rubber compounds

2015 ◽  
Vol 294 (3) ◽  
pp. 501-511 ◽  
Author(s):  
Dina Gabriel ◽  
Alexander Karbach ◽  
Doris Drechsler ◽  
Jochen Gutmann ◽  
Karlheinz Graf ◽  
...  
Keyword(s):  
Carbon Black ◽  
Loss Tangent ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Bound Rubber

Steady-State Shear Flow Properties of Carbon-Black Filled Rubber Compounds

1994 ◽  
Vol 67 (2) ◽  
pp. 207-216 ◽  
Author(s):  
S. Ertong ◽  
H. Eggers ◽  
P. Schümmer
Keyword(s):  
Carbon Black ◽  
Superposition Principle ◽  
Viscoelastic Behavior ◽  
Shear Rates ◽  
Creep Flow ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Yield Values ◽  
Time Temperature Superposition Principle ◽  
Flow Experiments

Abstract The steady shear viscosities of four model rubber/carbon-black compounds are measured with a modified Weissenberg Rheometer in a range of moderate shear rates. Yield stresses and low-shear viscosities are determined from creep-flow experiments. Yield stresses are found to increase strongly with filler content while their dependence on temperature can be described by an Arrhenius-type function. Flow curves are reduced to master curves by means of the time-temperature superposition principle. The shift factors are well approximated by the WLF-relation. The contribution of the “secondary” carbon-black network to the viscoelastic behavior requires additional vertical shifting for the filled compounds. Viscosities are found to be in very good agreement with the Herschel-Bulkley model when using the experimentally determined yield values.

The Effect of Carbon Black Parameters on the Fatigue Life of Filled Rubber Compounds

1974 ◽  
Vol 47 (1) ◽  
pp. 231-249 ◽  
Author(s):  
E. S. Dizon ◽  
A. E. Hicks ◽  
V. E. Chirico
Keyword(s):  
Fatigue Life ◽  
Carbon Black ◽  
Carbon Black Particle ◽  
Chemical Action ◽  
Beneficial Effects ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
The Matrix ◽  
Black Particle ◽  
As Stress

Abstract Fatigue is defined as decay caused by cyclic deformations at an amplitude less than necessary for fracture in one cycle. Such failures are initiated by flaws which act as stress concentrators. These flaws occur in the material either through mechanical or chemical action during service or through agglomeration of certain ingredients during mixing and fabrication. This paper deals with the latter process, where the nature and size of the flaws as well as the properties of the matrix are contingent on carbon black variables. Using the tearing energy concept of fatigue developed by Lake and Lindley, it was shown that the size of the flaw is primarily determined by carbon black particle size. On the other hand, the cut growth constant depends on carbon black structure. When translated to actual fatigue life using the Monsanto Fatigue-to-Failure Tester, these relationships mean that under constant strain conditions, compounds containing coarse carbons will have a significantly higher fatigue life than those with fine carbons. Under conditions of constant strain, higher structure carbons will impart a slight positive effect. However, under conditions of constant stress, the beneficial effects of structure become magnified. Other factors known to affect fatigue life were also considered. These are : set, stress relaxation, hysteretic energy dissipation, and flaw size distribution.

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