scholarly journals Devulcanization of ground tire rubber: microwave and thermomechanical approaches

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dániel Ábel Simon ◽  
Dávid Zoltán Pirityi ◽  
Tamás Bárány
Keyword(s):  
Microwave Treatment ◽  
Chain Scission ◽  
Polymer Chains ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Elongation At Break ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
Internal Mixer

Abstract We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx’s analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such a trend. Mechanical properties improved with increased vulcanizing agent contents. The examined properties of the samples improved even further with the use of thermomechanically devulcanized samples. Horikx’s analysis showed that this is attributable to moderate polymer chain scission.

ROLE OF COAGENTS IN PEROXIDE VULCANIZATION OF NATURAL RUBBER

2013 ◽  
Vol 86 (3) ◽  
pp. 488-502 ◽  
Author(s):  
Rejitha Rajan ◽  
Siby Varghese ◽  
K. E. George
Keyword(s):  
Natural Rubber ◽  
Hydrogen Abstraction ◽  
Polymer Chains ◽  
Hydrocarbon Chains ◽  
Equilibrium Swelling ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
Curing Agents

ABSTRACT The drawbacks of peroxide vulcanization can largely be overcome by introducing suitable co-curing agents (coagents) in the formulation. The role of various coagents, such as zinc diacrylate (ZDA), trimethylolpropane trimethacrylate (TMPTMA), and triallyl cyanurate (TAC) in the peroxide vulcanization of natural rubber (NR) was studied by Fourier transform infrared spectroscopy. Cross-link density was measured by the equilibrium–swelling technique. Cross-linking mechanism of peroxide in NR was interpreted by comparing the spectra of cured and uncured vulcanizates. The predominance of hydrogen abstraction over the radical addition was established (at 160 °C). Coagent ZDA produces ionic as well as covalent cross-links in the vulcanizate. Ionic cross-links have the ability to slip along the hydrocarbon chains and thus resemble polysulfidic cross-links. Hence, ZDA can be chosen for applications where good mechanical properties are required. Coagent TMPTMA produces covalent cross-links between polymer chains and is suitable for high-modulus applications. TAC, although it bridges through covalent cross-links, is not a suitable coagent for highly unsaturated rubbers like NR.

scholarly journals Synergistic Effects of Bitumen Plasticization and Microwave Treatment on Short-Term Devulcanization of Ground Tire Rubber

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1265 ◽  
Author(s):  
Łukasz Zedler ◽  
Marek Klein ◽  
Mohammad Reza Saeb ◽  
Xavier Colom ◽  
Javier Cañavate ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Microwave Treatment ◽  
Gas Chromatography Mass Spectrometry ◽  
Short Term ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Chemically Modified ◽  
Static Mechanical ◽  
Combined Impact ◽  
Static Mechanical Properties

Ground tire rubber (GTR) was mechano-chemically modified with road bitumen 160/220 and subsequently treated using a microwave radiation. The combined impact of bitumen 160/220 content and microwave treatment on short-term devulcanization of GTR was studied by thermal camera, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF), static headspace, and gas chromatography-mass spectrometry (SHS-GC-MS), thermogravimetric analysis combined with Fourier transform infrared spectroscopy (TGA-FTIR), oscillating disc rheometer and static mechanical properties measurements. The obtained results showed that bitumen plasticizer prevents oxidation of GTR during microwave treatment and simultaneously improves processing and thermal stability of obtained reclaimed rubber.

scholarly journals Magnetic composites based on NR and strontium ferrite

2019 ◽  
Vol 12 (1) ◽  
pp. 63-69
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Carbon Black ◽  
Strontium Ferrite ◽  
Rubber Matrix ◽  
Cross Link ◽  
Magnetic Composites ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
The Cross ◽  
Thermo Physical Properties

Abstract Two types of composites based on natural rubber (NR) and strontium ferrite were tested in this study. Composites of the first type were prepared by incorporation of strontium ferrite in the concentration range ranging from 0 to 100 phr (parts per hundred rubber) into pure NR based rubber matrix, while with those of the second type, strontium ferrite was dosed in the same concentration level into NR based rubber batch with constant amount of carbon black — 25 phr. For rubber matrices cross-linking, a standard sulfur based curing system was used. This work is focused on the effect of magnetic filler content on physico-mechanical, magnetic and thermo-physical properties of composite materials. Subsequently, the cross-link density and the structure of the formed sulfidic cross-links were examined. The results showed that the cross-link density of both types of composites increased with the increasing content of magnetic filler, while the structure of the sulfidic cross-links was almost not influenced by the amount of strontium ferrite. Tensile strength of rubber composites with pure rubber matrix was slightly improved by the incorporation of ferrite, while in case of composites based on a carbon black batch, the incorporation of magnetic filler resulted in the decrease of this characteristic. The presence of magnetic filler in both types of composites leads to a significant increase of the remanent magnetic induction.

Correlation between mechanical and microstructural properties of vulcanized polyisoprene, polychloroprene, and nitrile-butadiene rubber subjected to accelerated thermal aging

2018 ◽  
Vol 51 (6) ◽  
pp. 493-511
Author(s):  
Fabián E Hernández ◽  
C Medina ◽  
G Moraga ◽  
J Ramírez ◽  
AF Jaramillo ◽  
...  
Keyword(s):  
Thermal Aging ◽  
Butadiene Rubber ◽  
Raman Analysis ◽  
Elongation At Break ◽  
Vulcanized Rubber ◽  
Peak Intensity ◽  
Link Density ◽  
Cross Link Density ◽  
Mechanical And Microstructural Properties ◽  
Accelerated Thermal Aging

The purpose of this work was to correlate the effects of thermal aging on the macroscopic properties and microstructural changes for three vulcanized rubber types. The materials were subjected to accelerated thermal aging for periods between 0 and 168 h at 100°C. This aging was evaluated by investigating the mechanical properties and by Fourier transform infrared (FTIR) and Raman analysis. The results showed that subjecting the materials to thermal aging for a longer time decreased the elongation at break and tear strength and increased the hardness, while tensile strength exhibited different behavior and followed a different trend. The spectroscopy analyses indicated that there is a decrease in the amount of C=C present in the polymer as the aging time increased, which could be identified by the decrease in peak intensity at 1537 and 1600 cm−1 in the FTIR and Raman spectrum, respectively. These results were attributed mainly to an increase in cross-link density, which caused degradation of the material, essentially by a loss of ductility. A good linear relation ( R2 approximately 0.95) between changes in the intensity of FTIR peaks for the C=C signal and changes in elongation at break and hardness was found, concluding that these are good indicators of degradation in elastomers.

Elongation at Break as a Measure of Cross-Link Density in Vulcanized Elastomers

1966 ◽  
Vol 39 (3) ◽  
pp. 726-739 ◽  
Author(s):  
E. DiGiulio ◽  
G. Bellini ◽  
G. V. Giandinoto
Keyword(s):  
Crosslink Density ◽  
Cross Linking ◽  
Total Degree ◽  
Cross Link ◽  
Elongation Ratio ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
First Approximation ◽  
Link Density ◽  
Cross Link Density

Abstract After recalling the reaction mechanism suggested for the crosslinking of ethylene propylene copolymers with organic peroxides, the authors consider the relation between concentration of curing agent and crosslink density. It is experimentally found that, as a first approximation, the elongation ratio at break of vulcanizates (unfilled or filled with small quantities of carbon black) is a function of molar concentration of peroxide only: αR=K/P1/2 This relation can be theoretically justified on the basis of the extensibility of polymer chain segments and of the criterion for rupture originally put forward by Taylor and Darin. By applying the above relation to ethylene propylene copolymers it is possible to evaluate the influence of the chain-splitting reaction during cross-linking. The reciprocal of the square of elongation ratio at break (1/αR2) measures the total degree of crosslinking.

scholarly journals Influence of trans-polyoctylene rubber content on styrene-butadiene rubber properties

2020 ◽  
Vol 13 (1) ◽  
pp. 1-5
Author(s):  
Patrik Macúrik ◽  
Rafal Anyszka ◽  
Ivan Hudec ◽  
Terézia Malčeková ◽  
Ján Kruželák
Keyword(s):  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Curing Time ◽  
Cross Link ◽  
Rubber Content ◽  
Elongation At Break ◽  
Rubber Compounds ◽  
Link Density ◽  
Cross Link Density ◽  
Styrene Butadiene

AbstractThe study was focused on the investigation of trans-polyoctylene (TOR) influence on cross-linking as well as mechanical and rheological properties of rubber compounds based on styrene-butadiene rubber (SBR). SBR was compounded with different proportions of TOR in the concentration range from 0 to 30 phr. Integration of TOR into rubber leads to the prolongation of the optimum curing time and scorch time and thus the decrease of the curing rate. Higher content of TOR led to less viscous rubber due to the plasticizing effect. Cross-link density of vulcanizates was reduced, which correlates with higher elongation at break. Tensile strength and hardness of vulcanizates increased with the increasing TOR content, probably due to the increasing amount of the crystalline phase.

Reclaiming of waste guayule natural rubber vulcanizate—reclaim rubber for green tire applications: An approach for sustainable development

2018 ◽  
Vol 51 (3) ◽  
pp. 193-210 ◽  
Author(s):  
Soumyajit Ghorai ◽  
Dipankar Mondal ◽  
Sawar Dhanania ◽  
Santanu Chattopadhyay ◽  
Madhusudan Roy ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Polymer Chains ◽  
Cross Link ◽  
Scanning Calorimetry ◽  
Infrared Study ◽  
Differential Scanning Calorimetry Study ◽  
Link Density ◽  
Cross Link Density ◽  
Silica Dispersion ◽  
The Fourier Transform

This article illustrates the reclaiming of guayule natural rubber (GNR) vulcanizate by bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT), and as-grown reclaim rubber facilitates the silica dispersion in GNR product application without adding any coupling agent. This article deals with the performance evaluation of silica-filled revulcanizates with promising application in green tire. The extent of reclaiming was monitored through the measurement of sol content, cross-link density, Mooney viscosity, and degree of reclaiming. The differential scanning calorimetry study was carried out to evaluate the fraction of immobilized polymer chains and its dependence on cross-link density of the vulcanizates. The Fourier transform infrared study and also sulfur analysis independently indicate the attachment of the fragmented TESPT with the polymer chain and cross-link bonds. The study of mechanical properties clearly shows that in revulcanized GNR, the optimum property is achieved when reclaiming time is set for 40 min. The effect of reclaiming time on dynamic mechanical behavior such as storage modulus and loss tangent was studied. The scanning electron microscopy studies show the coherency and homogeneity of silica-filled revulcanize rubber with reclaiming time.

scholarly journals Poly (Lactic Acid) (PLA) / Ground Tire Rubber (GTR) Blends Using Peroxide Vulcanization

2021 ◽  
Author(s):  
Nicolas Candau ◽  
Oguzhan Oguz ◽  
Noel León Albiter ◽  
Gero Förster ◽  
Maria Lluïsa Maspoch
Keyword(s):  
Lactic Acid ◽  
Carbon Black ◽  
Automotive Industry ◽  
Crosslinking Agent ◽  
Mechanical Damage ◽  
Poly Lactic Acid ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Clay Particles ◽  
Cross Links

Poly (Lactic Acid) (PLA) / Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared as a route to recycle wastes rubber from the automotive industry. The GTR were exposed to grinding and exhibited mechanical damage, traduced at the rubber network scale by chains scission and/or chemical cross-links breakage. Such damage is accompanied by a decrease of 80% of the rubber chains network density of the initial tire buffing but found independent on the type of grinding (cryogenic, dry ambient) or on the GTR size (from <400 µm to <63 µm). Moreover, the finest sieved GTR contain the largest the amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. The melt-blending of these finest GTR particles obtained by cryo-grinding at an amount of 15 wt.% and in presence of the crosslinking agent (DCP), resulted in an optimum improvement of the ductility, energy at break and impact strength of the PLA/GTR blends as compared to neat PLA, while maintaining its stiffness. The results were attributed to (i) the good dispersion of the fine GTR particles into the PLA matrix, (ii) the partial re-crosslinking of the GTR particles and co-crosslinking at PLA/GTR interface and (iii) the presence of reinforcing carbon black into the GTR particles and clay particles dispersed into the PLA matrix.

Degradation Behaviour of Thin Polymer Films of Poly(Amide Ester) Hydrogel Using Quartz Crystal Microbalance

2013 ◽  
Vol 812 ◽  
pp. 38-45
Author(s):  
Dzaraini Kamarun ◽  
Ahmat Norizan ◽  
Steffi Krause ◽  
Chris Hunter ◽  
Lilia Milanesi
Keyword(s):  
Quartz Crystal Microbalance ◽  
Polymer Films ◽  
Quartz Crystal ◽  
Base Catalysis ◽  
Degradation Behaviour ◽  
Thin Polymer ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density

Quartz Crystal Microbalance (QCM) has been typically used as a mass sensor in the study of monolayer and multilayer depositions and dissolution, mass transport in polymer films on electrodes, corrosion processes at electrodes and mass changes caused by protein adsorption at electrodes. Thin films of an aromatic poly (amide ester) hydrogel with hydrolyzable cross links were prepared in-situ on a gold-coated quartz crystal which is the transducing element of a Quartz Crystal Microbalance (QCM). Here we report the synthesis and degradation behavior of an aromatic poly (amide ester) hydrogel with hydrolyzable cross links using QCM. Degradation of the hydrogel films was found to proceed with Δf increment, indicating mass decrease and is in line with the theory proposed by Sauerbrey. Films with a higher cross-link density underwent partial degradation with swelling; and are depicted as a decrease in the Δf values with time. Deviation from the general base catalysis of ester hydrolysis was observed at higher base concentration due to the biphasic environment of the hydrolysis reaction.

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