Thermal and mechanical behavior of SBR/devulcanized waste tire rubber blends using mechano–chemical and microwave methods

2020 ◽  
Vol 40 (10) ◽  
pp. 815-822
Author(s):  
Magdy A. M. Ali ◽  
Heba A. Raslan ◽  
Khaled F. El-Nemr ◽  
Medhat M. Hassan
Keyword(s):  
Mechanical Behavior ◽  
Treatment Time ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Tire Rubber ◽  
Tetramethylthiuram Disulfide ◽  
Waste Tire ◽  
Waste Rubber ◽  
Waste Tire Rubber ◽  
Styrene Butadiene

AbstractThe engagement of waste tires rubber as source of raw materials for different applications can be a partial solution to the great environmental problems caused by these products. In this study, waste tire rubber was devulcanized using both mechano–chemical and microwave methods. This process was achieved using different concentrations of 2-mercapto benzothiazole disulfide (MBTS) and tetramethylthiuram disulfide (TMTD) as a devulcanizing agent and different microwave devulcanizing times. The optimum content of both MBTS, TMTD and suitable microwave treatment time to make continuous film were noted. The devulcanized waste rubber was then added, at different concentrations, to virgin styrene–butadiene rubber (SBR). The thermal properties and dynamic mechanical behaviors were investigated for all blends. The thermal analysis proved that natural and styrene butadiene rubber are the main two constituents of the waste tire rubber utilized in this study. The mechanical behavior of the SBR blends remarkably improved by using 20 phr waste rubber (WR) devulcanized by 2 phr MBTS and by exposure for 2.2 min to microwaves. Storage modulus, tearing strength and tension set behaviors notably improved for all SBR/WR blends by irradiating with gamma ionizing radiation with a dose of 100 kGy and further improvement could be attained by increasing the dose up to 200 kGy.

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.

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.

scholarly journals Fatigue Performance and Multiscale Mechanisms of Concrete Toughened by Polymers and Waste Rubber

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Bo Chen ◽  
Liping Guo ◽  
Wei Sun
Keyword(s):  
Fatigue Life ◽  
Polyvinyl Alcohol ◽  
Water Soluble ◽  
Fatigue Performance ◽  
Tire Rubber ◽  
Bending Fatigue ◽  
Waste Tire ◽  
Waste Rubber ◽  
Bonding Effect ◽  
Waste Tire Rubber

For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder) and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.

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.

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