Devulcanization of Automobile Scrap Tyres by a Mechanochemical Process

2005 ◽  
Vol 21 (4) ◽  
pp. 319-331 ◽  
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Chemical Process ◽  
Crosslink Density ◽  
Diallyl Disulfide ◽  
Density Data ◽  
Vulcanized Rubber ◽  
Rubber Waste ◽  
Mechanical Shearing ◽  
Vulcanization Process

The de-vulcanization of rubber waste poses a challenging economical, environmental and social problem. We propose a new de-vulcanization process to re-use the rubber waste. It is a mechano-chemical process (MCP), where the waste is de-vulcanized by a combination of mechanical shearing, heat (110 °C) and the use of a de-vulcanizing agent (diallyl disulfide). A new look at the de-vulcanization mechanism and the influence of the de-vulcanizing agent on the mechanical properties of the ultimate re-vulcanized rubber is also presented. One of the most interesting observations is that the retention of tensile strength of the re-vulcanized rubber with respect to the original tyre was 34.9% when de-vulcanized in the absence of diallyl disulfide and 72.4% in its presence. The formation of extra crosslinks in those re-vulcanized rubbers containing disulfide was confirmed from crosslink density data and from TGA results. DMA analysis revealed that the storage modulus also increased for re-vulcanized rubber containing the disulfide.

Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

2005 ◽  
Vol 21 (3) ◽  
pp. 183-199
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Three Dimensional ◽  
Elongation At Break ◽  
Tear Strength ◽  
Vulcanized Rubber ◽  
Dimensional Network ◽  
Polymeric Chains ◽  
Cure Time

De-vulcanization of vulcanized elastomers represents a great challenge because of their three-dimensional network structure. Sulfur-cured gum natural rubbers containing three different sulfur/accelerator ratios were de-vulcanized by thio-acids. The process was carried out at 90 °C for 10 minutes in an open two-roll cracker-cum-mixing mill. Two concentrations of de-vulcanizing agent were tried in order to study the cleavage of the sulfidic bonds. The mechanical properties of the re-vulcanized rubber (like tensile strength, modulus, tear strength and elongation at break) were improved with increasing concentrations of de-vulcanizing agent, because the crosslink density increased. A decrease in scorch time and in optimum cure time and an increase in the state of cure were observed when vulcanized rubber was treated with high amounts of de-vulcanizing agent. The temperature of onset of degradation was also increased with increasing concentration of thio-acid. DMA analysis revealed that the storage modulus increased on re-vulcanization. From IR spectroscopy it was observed that oxidation of the main polymeric chains did not occur at the time of high temperature milling. Over 80% retention of the original mechanical properties (like tensile strength, modulus, tear strength and elongation at break) of the vulcanized natural rubber was achieved by this mechanochemical process.

The Effect of Thermal Aging on Mechanical Properties and Morphological Properties of Thermoplastic Vulcanizates Based on Natural Rubber and Polystyrene

2020 ◽  
Vol 990 ◽  
pp. 262-266
Author(s):  
Prathumrat Nu-Yang ◽  
Atiwat Wiriya-Amornchai ◽  
Jaehoon Yoon ◽  
Chainat Saechau ◽  
Poom Rattanamusik
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Natural Rubber ◽  
Thermal Aging ◽  
Morphological Properties ◽  
Vulcanized Rubber ◽  
Thermoplastic Vulcanizates ◽  
Internal Mixer ◽  
Processing Properties

Thermoplastic vulcanizates or TPVs is a type of materials exhibiting excellent properties between thermoplastic and elastomer by combining the characteristics of vulcanized rubber with the processing properties of thermoplastics. This research aims to study the effect of thermal aging on the morphology and mechanical properties of thermoplastic vulcanizates (TPVs) based on a mixture of natural rubber (NR) and polystyrene (PS). TPVs samples were prepared using the internal mixer at a mass ratio of NR/PS 70/30, 50/50, 30/70 and 0/100. Tensile properties and impact strength showed that when the amount of NR increased tends of impact strength and elongation at break increased but tends of tensile strength decreased. On the other hand, tends of tensile strength for thermal aging at 70°C for 3 days increased when the amount of PS increase. The blending ratio of NR / PS at 70/30 is the best. It gave a worthy increase from 19.94 MPa to be 25.56 MPa (28.18%).

Influences of Particle Sizes on Properties of Natural Rubber/Waste Ground Rubber Powders Blends

2013 ◽  
Vol 773 ◽  
pp. 668-672
Author(s):  
Jun Liang Liu ◽  
Ping Liu ◽  
Xiao Qiang Tang ◽  
Dong Zeng ◽  
Xing Kai Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Chemical Activation ◽  
Cross Linking ◽  
Particle Sizes ◽  
Elongation At Break ◽  
Tear Strength ◽  
Rubber Waste ◽  
Ground Rubber

In this paper, the blends of natural rubber with waste ground rubber powders have been prepared by mechano-chemical activation method. The influences of particle sizes on both processing performances and mechanical properties have been investigated. The results indicated that: the blends with waste ground rubber powders of smaller particle sizes approached to higher surface tensile and easily mechano-chemical activation, which led to the formation of complete homogenous re-vulcanization cross-linking structure and resulted in the improvements of the whole performances of the final products. The tensile strength, the elongation at break and tear strength approached to the highest value of 20.7MPa, 530% and 33.0 kN/m as the 100mesh waste ground rubber powders were used as the starting materials.

The Mechanical Behavior of Double Network Elastomers

1994 ◽  
Vol 67 (2) ◽  
pp. 359-365 ◽  
Author(s):  
P. G. Santangelo ◽  
C. M. Roland
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Double Network ◽  
Equilibrium Modulus ◽  
Failure Properties ◽  
Residual Strains ◽  
Double Networks

Abstract It was found that at low residual strains, the modulus of double network rubbers can be less than that of an isotropic elastomer of equal crosslink density. At higher residual strains, the equilibrium modulus is higher for the double network. This aspect of the behavior of networks was investigated using two phenomenological descriptions of rubber elasticity, the Mooney-Rivlin (MR) and the Roth, Martin, and Stiehler (RMS) Equations. Calculations using either approach, which make use of the independent network hypothesis, were qualitatively in agreement with the experimental data. The tensile strength of double networks based on natural rubber were found to be independent of the amount of residual strain. This is true even at higher residual strains, wherein the modulus is significantly amplified. This suggests that the conventional compromise between modulus and failure properties can be circumvented using double network rubbers. Their utilization can yield elastomers of better mechanical properties.

Accelerated Aging Tests of HTPB-Based Propellants

2018 ◽  
pp. 246-271
Author(s):  
Roberta Jachura Rocha
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Crosslink Density ◽  
Aging Process ◽  
Low Cost ◽  
Accelerated Aging ◽  
Solid Propellants ◽  
Launch Vehicles ◽  
Late Twentieth ◽  
Late Twentieth Century

In the late twentieth century, liquid and solid propulsion technologies have been integrated into hybrid engines currently apllied in propulsion launch vehicles and missiles. The reaction of polyol (HTPB) and diisocyanate (IPDI) provides the most versatile of the binders in the production of solid propellants due to its ability to withstand high loads combined with low cost and ease of processing. A propellant based on HTPB obtained in this study was submitted to natural and accelerated aging tests, seeking to evaluate the modifications of mechanical properties as tensile strength, elongation and hardness up to 360 days. The mechanism considered in the aging process is the increase of crosslink density by breaking the double bond contained in the HTPB molecule, which causes the instability of the propellant, increasing its handling risk. Samples of these propellants subjected to aging presented variations in their properties that match the values available in the literature.

Superior Mechanical Properties of Ultrasonically Recycled EPDM Rubber

2003 ◽  
Vol 76 (1) ◽  
pp. 253-270 ◽  
Author(s):  
Jushik Yun ◽  
A. I. Isayev
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Power Consumption ◽  
Crosslink Density ◽  
Dynamic Properties ◽  
Extensive Study ◽  
Processing Conditions ◽  
Elongation At Break ◽  
Epdm Rubber ◽  
Superior Mechanical Properties

Abstract This paper describes the results of an extensive study involving the continuous ultrasonic devulcanization of unfilled EPDM rubber. Die pressure and ultrasound power consumption were measured as a function of processing conditions. The mechanical properties of aged and fresh revulcanized EPDM rubber were measured. Gel fraction, crosslink density, and dynamic properties were also determined for the virgin vulcanizate, the ultrasonically devulcanized rubber, and the revulcanized rubber. Additionally, the cure behavior of virgin and devulcanized EPDM rubber was investigated. The tensile strength of revulcanized EPDM rubber was found to be much higher than that of the virgin vulcanizate with the elongation at break being practically intact. A mechanism explaining the increase in mechanical properties of revulcanized rubbers was proposed.

Effect of Thermal Aging on Mechanical Properties of EPDM Rubber

2015 ◽  
Vol 727-728 ◽  
pp. 318-321 ◽  
Author(s):  
Jie Liu ◽  
Lun Wu Zhang ◽  
Bin Wang ◽  
Ze Qi Xu ◽  
Wan Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Electron Microscope ◽  
Thermal Aging ◽  
Crosslink Density ◽  
Aging Process ◽  
Epdm Rubber ◽  
Compressive Testing ◽  
Scanning Electron ◽  
Accelerated Thermal Aging

EPDM rubber was exposed to an accelerated thermal aging environment produced by an air-circulating oven. The changes of morphology, mechanical properties of EPDM were monitored by scanning electron microscope (SEM), tensile/compressive testing. Crosslink density of EPDM was measured by the solvent swell method. The results showed that many cracks and voids appeared on the surface of EPDM with the exposure time. The aging process proceeded predominantly via crosslinking. The tensile strength increased with increase in crosslink density up to a maximum and thereafter decreased with further increase in crosslink density.

Superior Mechanical Properties of Reclaimed SBR with Bimodal Network

1997 ◽  
Vol 70 (2) ◽  
pp. 194-201 ◽  
Author(s):  
A. I. Isayev ◽  
S. H. Kim ◽  
V. Yu Levin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Crosslink Density ◽  
Processing Conditions ◽  
Elongation At Break ◽  
Gel Fraction ◽  
Superior Mechanical Properties

Abstract The correlation between the mechanical properties of revulcanized SBR, total and polysulfidic crosslink density, gel fraction of original vulcanizate, ultrasonically devulcanized, and revulcanized rubber is described. Under some processing conditions the tensile strength of revulcanized SBR is found to be much higher than that of the original vulcanizate with elongation at break being practically intact. A model explaining the increase in mechanical properties of revulcanized rubber is proposed.

Properties of Thermoplastic Natural Rubber (TPNR): Influence of Polypropylene Grades on TPNR Properties

2013 ◽  
Vol 844 ◽  
pp. 127-130 ◽  
Author(s):  
Chanida Manleh ◽  
Charoen Nakason ◽  
Natinee Lopattananon ◽  
Azizon Kaesaman
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Rubber Particle ◽  
Complex Viscosity ◽  
Morphological Properties ◽  
Dynamic Vulcanization ◽  
Thermoplastic Natural Rubber ◽  
Pp Blends ◽  
Vulcanization Process

Thermoplastic vulcanizate (TPV) based on natural rubber (NR) and polypropylene (PP) blends were successfully prepared through a dynamic vulcanization process using Brabender Plastograph EC Plus with a rotor speed of 60 rpm at 180°C. Sulfur vulcanization system was used to cure rubber phase in the TPVs. Three grades of PP (i.e., PP700J, HP553R and HP544T) were used to blend with NR at a fixed blend ratio of NR/PP = 60/40. The mechanical properties, crosslink density, complex viscosity and morphological properties of the blends were examined. The results revealed that the dynamically cured NR/PP700J samples showed the best mechanical properties because of higher crosslink density and smaller rubber particle size when compared with those of the blends combined with HP553R and HP544T. Furthermore, the complex viscosity of the TPVs was highest for the blends with PP700J.

Effect of Curing System on Mechanical Properties of NBR/Nylon-PET Cord Composite

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
G. R. Bakhshandeh ◽  
T. Darestani Farahani ◽  
M. Emamikia
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stearic Acid ◽  
Linear Function ◽  
Acid Concentration ◽  
Crosslink Density ◽  
Nitrile Rubber ◽  
Coating Adhesion ◽  
High Level

AbstractFrom the results of this study it can be concluded that higher stearic acid concentration as a part of curing activator and high level of curative (i.e. sulfur and accelerator) causes higher crosslink density, tensile strength, modulus and hardness, and lower NBR to nylon-PET cord adhesion. Accelerator type also affects NBR/nylon-PET cord adhesion and using NOBS the highest coating adhesion is achieved. Using semi-efficient vulcanizing (i.e. accelerator/sulfur ratio around 1) is the most suitable way for achieving high NBR/nylon cord adhesion. And finally, independent from accelerator type, sulfur amount and efficiency of vulcanizing system, coating adhesion is a semi-linear function of crosslink density of nitrile rubber.

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