scholarly journals Effects of maximum strain and aging time on the fatigue lifetime of vulcanized natural rubber

2015 ◽  
Author(s):  
C. S. Woo ◽  
H. S. Park
Keyword(s):  
Natural Rubber ◽  
Aging Time ◽  
Maximum Strain ◽  
Fatigue Lifetime

COMPARISON OF STRESS–SOFTENINGS IN CARBON-BLACK FILLED NATURAL RUBBER AND STYRENE–BUTADIENE RUBBER

2013 ◽  
Vol 86 (4) ◽  
pp. 572-578 ◽  
Author(s):  
Julie Diani ◽  
Yannick Merckel ◽  
Mathias Brieu ◽  
Julien Caillard
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Cyclic Softening ◽  
Styrene Butadiene Rubber ◽  
Amplitude Dependence ◽  
Butadiene Rubber ◽  
Fatigue Lifetime ◽  
Filled Rubber ◽  
Filled Rubbers ◽  
Styrene Butadiene

ABSTRACT The authors compared the mechanical behavior and, more precisely, the Mullins and the cyclic (post-Mullins) softenings of two filled rubbers. A crystallizing natural rubber and a noncrystallizing styrene–butadiene rubber of similar compositions resulting in similar cross-link densities and filled with 40 phr of N347 carbon-black fillers were tested in cyclic uniaxial tension at room temperature and at 85 °C. Crystallization in filled rubbers is known to increase stress at high stretch, stretch at break, cycle hysteresis, and fatigue lifetime and to reduce crack propagation. In this study, it is shown that crystallization also seems to enhance the Mullins softening (softening at the first cycle) and to favor the apparent cyclic softening. Results reveal that natural rubber shows an amplitude dependence on the cyclic softening, whereas the styrene–butadiene rubber does not. Finally, results demonstrate that studying filled rubber softening cannot help predict lifetime.

A Model for Hyper-Elastic Material Behavior Under Thermal Aging With an Application to Natural Rubber

2018 ◽  
Author(s):  
Ahmed G. Korba ◽  
Abhishek Kumar ◽  
Mark E. Barkey
Keyword(s):  
Natural Rubber ◽  
Aging Time ◽  
Elastic Material ◽  
Thermal Aging ◽  
Least Square ◽  
Material Behavior ◽  
Model Parameters ◽  
Stress Strain ◽  
Strain Behavior ◽  
Hyper Elastic

Numerous hyper-elastic theoretical material models have been proposed over the past 60 years to capture the stress-strain behavior of large deformation incompressible isotropic materials. Among them, however, only few models have considered the thermal aging effect on model parameters. Having a simple, closed-form equation that includes the effect of aging temperature and time in describing the stress-strain behavior could facilitate fatigue analysis and life time prediction of rubber-like materials. In this vein, this paper defines a new and simple Weight Function Based (WFB) model that describes hyper-elastic materials’ behavior as a function of aging time and temperature variations. More than 130 natural rubber specimens were thermally aged in an oven and tested under uni-axial loading to observe their stress-strain behavior at various temperatures and aging times. The temperature ranged from 76.7 °C to 115.5 °C, and the aging time from zero to 600 hours. The proposed WFB model is based on the Yeoh model and basic continuum mechanics assumptions, and it was applied to the tested natural rubber materials. Moreover, it was verified against Treloar’s historic tensile test data for uni-axial tension of vulcanized natural rubber material, and also compared to the Ogden and the Yeoh models. A non-linear least square optimization tool in Matlab was used to determine all hyper-elastic material model parameters and all other fitting purposes. The proposed model has better accuracy in fitting Treloar’s data compared to the Ogden and the Yeoh models using the same fitting tool under the same initial numerical conditions.

OXIDATIVE STRESS RELAXATION OF NATURAL RUBBER GUM VULCANIZATES CONTAINING VARIOUS ANTIOXIDANTS. I: EFFECT OF SAMPLE THICKNESS

2017 ◽  
Vol 90 (4) ◽  
pp. 633-641
Author(s):  
Junling Zhao ◽  
G. R. Hamed
Keyword(s):  
Oxidative Stress ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
Aging Time ◽  
Oxygen Concentration ◽  
Chain Scission ◽  
Sample Thickness ◽  
Oxygen Absorption ◽  
Square Root ◽  
Diffusion Controlled

ABSTRACT Conventional sulfur-vulcanized natural rubber gums containing various antioxidants have been subjected to oxidative stress relaxation at 72 °C and 25% strain. Oxidation is diffusion controlled, even for samples as thin as 0.15 mm. Assuming that the rate of chain scission is proportional to the rate of oxygen absorption, which previously has been shown to depend on the square root of the oxygen concentration, an equation is derived predicting that stress decay is proportional to aging time to the three-quarters power. Moreover, slopes of these plots are predicted to depend inversely on thickness. Experimental results are in reasonable accord with these predictions.

Effect of Grit Type, Aging Temperature, and Aging Time on Particle Size of Ground Natural Rubber/Zeolite Composite Powder

2016 ◽  
Vol 705 ◽  
pp. 24-29
Author(s):  
Karl C. Ondoy ◽  
Bryan B. Pajarito
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Natural Rubber ◽  
Aging Time ◽  
Aging Temperature ◽  
Composite Powder ◽  
Chain Structure ◽  
Particle Size Range ◽  
Zeolite Composite

This study reports the results of investigation on the main and interaction effects of grit type, aging temperature, and aging time on particle size of ground natural rubber/zeolite (GNR/Z) composite powder using general factorial design of experiment. GNR/Z composite powder produced by mechanical grinding is porous, like an aggregated chain structure. These aggregates exist in clusters of irregular shape. Analysis of variance (ANOVA) shows that the effects of aging temperature and aging time depend on the particle size range. GNR/Z composite powder with large particle size is produced when aging is done at low temperature and short time due to high resistance of rubber to oxidation. On the other hand, GNR/Z composite powder with small particle size is produced when aging is done at low or high temperature and longer aging time. Low temperature condition offers high O2 concentration available to oxidize rubber while high temperature condition leads to more chain scissions due to higher oxidation rate.

scholarly journals Aging of Natural Rubber in Air and Seawater

2001 ◽  
Vol 74 (1) ◽  
pp. 79-88 ◽  
Author(s):  
P. H. Mott ◽  
C. M. Roland
Keyword(s):  
Natural Rubber ◽  
Oxygen Concentration ◽  
Failure Strain ◽  
Accelerated Aging ◽  
Activation Energies ◽  
Effect Of Temperature ◽  
Arrhenius Law ◽  
Fatigue Lifetime ◽  
Rubber Vulcanizate ◽  
The Difference

Abstract Accelerated aging experiments were carried out on a natural rubber vulcanizate exposed to air and to seawater. Failure strain, shown to correlate well with the fatigue lifetime, was used to monitor the extent of degradation. The effect of temperature on the rate of aging followed an Arrhenius law, with activation energies equal to 90 ± 4 and 63 ± 3 kJ/mol for air and seawater aging, respectively. The difference can be accounted for by the difference in oxygen concentration for the two environments.

scholarly journals The Role of Parent Phase Compliance on the Fatigue Lifetime of Ni–Ti

2019 ◽  
Vol 5 (4) ◽  
pp. 407-414 ◽  
Author(s):  
Craig Bonsignore ◽  
Ali Shamini ◽  
Tom Duerig
Keyword(s):  
Fatigue Test ◽  
Parent Phase ◽  
Fatigue Tests ◽  
Parent Material ◽  
Maximum Strain ◽  
Fatigue Lifetime ◽  
Bending Fatigue ◽  
Purity Material ◽  
Mean Strain

AbstractIt has been previously suggested that the fatigue lifetime of superelastic Ni–Ti might be improved if the R-phase were the parent to martensite rather than austenite. This body of work tests that hypothesis in two separate side-by-side fatigue tests both carefully constructed to match the superelastic properties in the two study arms. Both experiments show the R-phase parent to be more durable than the more commonly considered austenitic parent phase. The first experiment considers straight wire specimens fabricated from standard purity material, in a tension–tension fatigue test to 107 cycles, at mean strain ranging of 0.5–5.8% and strain amplitudes of 0.15–0.45%. The second experiment considers formed wire specimens in bending fatigue, more representative of realistic medical components, with a maximum mean strain of 1.2%, and maximum strain amplitudes ranging from 0.72 to 1.64%. Compared with the austenitic parent material, the R-phase material tolerated 0.1–0.3% higher strain amplitudes.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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