Dual-Stiffness Behavior of Fatigued Tire Rubber

2015 ◽  
Author(s):  
Ruofan Liu ◽  
Erol Sancaktar
Keyword(s):  
Cyclic Loading ◽  
Morphological Changes ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Tire Rubber ◽  
Particle Distributions ◽  
Damage Initiation ◽  
Strain Behavior ◽  
Rubber Tire ◽  
Styrene Butadiene

We report on duality in stiffness values for both carbon black and silica-filled SBR-based (styrene butadiene rubber) tire rubber materials after cyclic loading (and not with no-cycle, neat samples). We believe, this behavior is due to morphological changes occurring due to cycling and not necessarily due to larger scale void/crack initiation. Causes may be chain breakage, reduced crosslinking in all samples, and agglomerate break-up/particle redistribution in silica systems, which represent early damage initiation and morphological changes in these systems. Therefore, we get a dual stiffness vs. strain behavior which is essentially superposition of two separate stiffness vs. strain curves, each being similar to the stiffness-strain curves for the neat (no fatigue) samples. We believe that the second superposed portion represents the sections deteriorated/rearranged due to cyclic loading (lower crosslinking/rearranged particle distributions) coming in-line during the straining process, and when the non-deteriorated/non-rearranged sections weaken.

Application of X-Ray Micro-CT Method to Assess Damage/Flaw Presence and Progression in Tire Rubber Materials

2015 ◽  
Author(s):  
Ruofan Liu ◽  
Erol Sancaktar
Keyword(s):  
Fast Rate ◽  
Fatigue Loading ◽  
Cyclic Fatigue ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Micro Ct ◽  
Tire Rubber ◽  
X Ray ◽  
Rubber Tire ◽  
Styrene Butadiene

We have demonstrated that the X-ray Micro-CT (Computed Tomography – 3D) method can be used to progressively assess damage/flaw presence and progression in SBR-based (styrene butadiene rubber) tire rubber materials. Our experimental results reveal that progression of flaws due to cyclic (fatigue) loading may not occur at a fast rate until a catastrophic failure occurs in the tire material.

scholarly journals Best Practice for De-Vulcanization of Waste Passenger Car Tire Rubber Granulate Using 2-2′-dibenzamidodiphenyldisulfide as De-Vulcanization Agent in a Twin-Screw Extruder

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1139
Author(s):  
Hans van Hoek ◽  
Jacques Noordermeer ◽  
Geert Heideman ◽  
Anke Blume ◽  
Wilma Dierkes
Keyword(s):  
Best Practice ◽  
Chain Scission ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Passenger Car ◽  
Tire Rubber ◽  
Twin Screw ◽  
Styrene Butadiene

De-vulcanization of rubber has been shown to be a viable process to reuse this valuable material. The purpose of the de-vulcanization is to release the crosslinked nature of the highly elastic tire rubber granulate. For present day passenger car tires containing the synthetic rubbers Styrene-Butadiene Rubber (SBR) and Butadiene Rubber (BR) and a high amount of silica as reinforcing filler, producing high quality devulcanizate is a major challenge. In previous research a thermo-chemical mechanical approach was developed, using a twin-screw extruder and diphenyldisulfide (DPDS) as de-vulcanization agent.The screw configuration was designed for low shear in order to protect the polymers from chain scission, or uncontrolled spontaneuous recombination which is the largest problem involved in de-vulcanization of passenger car tire rubber. Because of disadvantages of DPDS for commercial use, 2-2′-dibenzamidodiphenyldisulfide (DBD) was used in the present study. Due to its high melting point of 140 °C the twin-screw extruder process needed to be redesigned. Subsequent milling of the devulcanizate at 60 °C with a narrow gap-width between the mill rolls greatly improved the quality of the devulcanizate in terms of coherence and tensile properties after renewed vulcanization. As the composition of passenger car tire granulate is very complex, the usefulness of the Horikx-Verbruggen analysis as optimization parameter for the de-vulcanization process was limited. Instead, stress-strain properties of re-vulcanized de-vulcanizates were used. The capacity of the twin-screw extruder was limited by the required residence time, implying a low screw speed. A best tensile strength of 8 MPa at a strain at break of 160% of the unblended renewed vulcanizate was found under optimal conditions.

Fatigue-induced dual stiffness behavior of filled styrene–butadiene rubber

2018 ◽  
Vol 233 (10) ◽  
pp. 2006-2014 ◽  
Author(s):  
Ruofan Liu ◽  
Erol Sancaktar
Keyword(s):  
Carbon Black ◽  
Tensile Creep ◽  
Styrene Butadiene Rubber ◽  
Bond Rupture ◽  
Butadiene Rubber ◽  
Fatigue Process ◽  
Strain Behavior ◽  
Rupture Model ◽  
Styrene Butadiene ◽  
Softening Stage

Payne and Mullins effects are widely observed in reinforced rubber materials. The mechanisms by which these two effects work are not fully understood. Several models have been proposed, including molecular slippage model, bond rupture model, and filler rupture model. In this study, two different compounds of styrene–butadiene rubber were prepared using carbon black and silica as reinforcement fillers, respectively, and subjected to cyclic fatigue process. Tensile, creep, and relaxation tests were performed on fatigued samples to assess the residual stress–strain behavior by comparing with the results from similar tests using pristine (no fatigue) samples. When the tensile stiffness behavior of fatigued specimens was evaluated, we noted that the stiffness versus strain behavior which exhibited a monotonic decreasing–increasing behavior with the pristine specimens changed to what we call “dual-stiffness” condition, where the specimens went through a first (low) turning point as with the pristine samples, but then dropped off of a peak to go through a second softening stage, similar to the first softening stage of the pristine material. We believe that such spiking (dual) stiffness behavior characterized by a “Peak” point represents a combination of both Payne and the Mullins effects active during fatigue loading. We conclude that molecular slippage and bond rupture are the main factors affecting the physical properties of carbon black-filled compounds, while breakage and recombination of the filler are the key mechanisms affecting the silica-filled compounds during the fatigue process.

Innovative γ rays irradiated styrene butadiene rubber/reclaimed waste tire rubber blends: a comparative study using mechano-chemical and microwave devulcanizing methods

2020 ◽  
Vol 40 (3) ◽  
pp. 267-277
Author(s):  
Khaled F. El-Nemr ◽  
Heba A. Raslan ◽  
Magdy A.M. Ali ◽  
Medhat M. Hasan
Keyword(s):  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Tire Rubber ◽  
Tetramethylthiuram Disulfide ◽  
Rubber Blends ◽  
Waste Tire ◽  
Γ Rays ◽  
Waste Tire Rubber ◽  
Microwave Techniques ◽  
Styrene Butadiene

AbstractWaste tire rubber was comparatively devulcanized by using two-roll mill mechano-chemical and microwave techniques at room temperature. The former technique was performed utilizing tetramethylthiuram disulfide and mercaptobenzothiazole disulfide. The developed devulcanized elastomer was characterized by scanning electron microscopy, chemical soluble fraction indication, and cross-link density determination. The blend was mixed in two roll mills by replacing a portion of virgin styrene-butadiene rubber (SBR) in a common formulation with the devulcanized waste rubber (DWR) product at various ratios, namely 10, 20 and 50 wt%. The morphological micrographs confirmed marked improvement in compatibility between both rubbery materials. The tensile strength and elastic modulus examinations of the fabricated blends ensured successful substitution of the virgin SBR with DWR. The abrasion resistance of SBR proved unaffected by blending with DWR. The compounded blends were subjected to γ rays at different radiation doses elevated up to 200 kGy and comparatively mechanically investigated.

Characterization of styrene butadiene rubber and microwave devulcanized ground tire rubber composites

2014 ◽  
Vol 34 (6) ◽  
pp. 543-554 ◽  
Author(s):  
Fazliye Karabork ◽  
Erol Pehlivan ◽  
Ahmet Akdemir
Keyword(s):  
Control Sample ◽  
Rubber Matrix ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Elongation At Break ◽  
Styrene Butadiene ◽  
Soluble Part

Abstract Ground tire rubber (GTR) was devulcanized by microwaves at the same heating rate (constant power) and different times of exposure. The devulcanized rubber (DV-R) and untreated GTR were characterized physically and thermally. Composite materials were prepared from different proportions of the GTR, which was used as a filler, and the DV-R, which was used as part of the styrene butadiene rubber (SBR) matrix, and by varying the exposure time of the microwave power. These composites were compared with a control sample that was prepared from virgin SBR. The sol content (soluble part) and Fourier transform infrared spectroscopy (FTIR) analyses of the devulcanized samples were examined to define the efficiency of devulcanization. The cure characteristics and tensile properties of the SBR composites were researched. In this study, it was found that using DV-R as part of the rubber matrix produced much better properties than using GTR as a filler, thereby showing the significant benefits of microwave devulcanization. At the DV-R content of 50 phr, the elongation at break of the DV-R 5 min/SBR composites increased to 445.06% from 217.25% for the GTR/SBR composites, i.e., the elongation at break was enhanced by 105% by the devulcanization of GTR. Scanning electron microscopy (SEM) photographs displayed a better interface coherence between the DV-R 5 min and SBR matrix than the GTR/SBR composites.

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