Stress-Strain Properties of Natural Rubber under Biaxial Strain

1951 ◽  
Vol 24 (1) ◽  
pp. 70-82 ◽  
Author(s):  
B. B. S. T. Boonstra
Keyword(s):  
Natural Rubber ◽  
Biaxial Strain ◽  
Stress Strain ◽  
Relaxation Constant ◽  
Vulcanized Rubber ◽  
Stress Curve

Abstract (1) The stress-strain curves of vulcanized rubber held at definite tangential elongations during stretching differ more from the simple unidirectional-extension-stress curve than the theory predicts. The differences are larger at higher tangential elongations. (2) The relaxation constant determined at 600 per cent elongation is practically unaffected by tangential elongations up to 300 per cent.

The Influence of the Test-Specimen on the Results Obtained In Tensile Tests of Soft Vulcanized Rubber Mixtures

1953 ◽  
Vol 26 (2) ◽  
pp. 465-480
Author(s):  
R. Herzog ◽  
R. H. Burton
Keyword(s):  
Natural Rubber ◽  
Tensile Properties ◽  
Test Specimen ◽  
Tensile Tests ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Different Types ◽  
Small Test ◽  
Soft Rubber

Abstract The small test-specimen of the VSM-1 type should not be used for measuring the tensile properties of pure-gum vulcanizates; instead, the VSM-1a type of test-specimen should be used for such vulcanizates. Results obtained with the different types of test-specimen differ greatly; hence, in reporting the results of any tests of this kind, the type of test-specimen used should be stated, and only results obtained with one particular type of test-specimen should be compared. For example, substitution of the VSM-2 type of test-specimen by the KTA-II type of test-specimen, which is of approxmately the same size, unfortunately does not result in any better agreement. Based on these differences, which in the case of natural rubber have been found to vary from one type of vulcanizate to another, it is natural to expect corresponding unpredictable differences with various synthetic elastomers. The determination of stress-strain properties of soft rubber vulcanizates is, therefore, fundamentally a problem of agreement on methods of testing, i.e., of standardization.

Aging of Natural Rubber Vulcanizates in the Presence of Dithiocarbamates

1959 ◽  
Vol 32 (3) ◽  
pp. 739-747 ◽  
Author(s):  
J. R. Dunn ◽  
J. Scanlan
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Protective Action ◽  
Dicumyl Peroxide ◽  
Vulcanized Rubber ◽  
Aging Properties ◽  
Photochemical Aging ◽  
Natural Rubber Vulcanizates

Abstract The thermal and photochemical aging of extracted dicumyl peroxide-, TMTD (sulfurless)- and santocure-vulcanized rubber, in presence of a number of metal and alkylammonium dithiocarbamates, has been investigated by measurements of stress relaxation. The dithiocarbamates have a considerable protective action upon the degradation of peroxide- and TMTD-vulcanizates, but they accelerate stress decay in santocure-accelerated vulcanizates. The reasons for this behavior are discussed. It is suggested that the excellent aging properties of unextracted TMTD vulcanizates are due to the presence of zinc dimethyldithiocarbamate formed during vulcanization.

Adhesion of Vulcanized Rubber Surfaces: Characterization of Unmodified and Electron Beam Modified EPDM Surfaces and Their Co-vulcanization with Natural Rubber

2009 ◽  
Vol 23 (13-14) ◽  
pp. 1763-1786 ◽  
Author(s):  
Ganesh C. Basak ◽  
Abhijit Bandyopadhyay ◽  
Y. K. Bharadwaj ◽  
S. Sabharwal ◽  
Anil K. Bhowmick
Keyword(s):  
Electron Beam ◽  
Natural Rubber ◽  
Vulcanized Rubber

The Oil Resistance of Rubber. I Study of the Swelling of Vulcanized Rubber

1936 ◽  
Vol 9 (1) ◽  
pp. 70-73
Author(s):  
Yoshio Tanaka ◽  
Shû Kambara ◽  
Jirô Noto
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
Mixed Solvents ◽  
Experimental Results ◽  
Stress Strain ◽  
Oil Resistance ◽  
Effect Of Solvents ◽  
Vulcanized Rubber

Abstract To study the effect of solvents on the elastic properties of vulcanized rubber, the following three points were investigated. 1. The swelling maximum obtained by various mixed solvents. 2. The stress-strain curves of rubber swollen to different degrees. 3. Time-swelling and time-deswelling curves. The spiral theory of molecular structure of rubber proposed by Fikentscher and Mark is utilized to explain the experimental results.

scholarly journals Preparation and stress-strain behavior of in-situ epoxidized natural rubber/SiO2 hybrid through a sol-gel method

2018 ◽  
Vol 12 (2) ◽  
pp. 180-185 ◽  
Author(s):  
S. M. Li ◽  
T. W. Xu ◽  
Z. X. Jia ◽  
B. C. Zhong ◽  
Y. F. Luo ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Epoxidized Natural Rubber ◽  
Stress Strain ◽  
Gel Method ◽  
Sol Gel Method ◽  
Strain Behavior

Influence of Crosslink Characteristics Induced by Aromatic-Based Antioxidants on the Swelling and Stress-Strain Behavior of Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Tarek M. Madkour ◽  
Rasha A. Azzam
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Induced Crystallization ◽  
Elastomeric Chains ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

Abstract Stress-strain measurements were performed on dry and swollen natural rubber vulcanizates prepared using both sulfur as the crosslinking agent and aromatic-based bound antioxidants acting as a second crosslinking agent. The aromatic-based antioxidants were synthesized and analyzed spectroscopically in order to relate the final behavior of the vulcanizates to the nature of the crosslink characteristics. The anomalous upturn in the modulus values of these networks in response to the imposed stress was shown to persist in the dry as well as the swollen state. Since the swollen elastomeric chains cannot undergo a strain-induced crystallization, the abnormal upturns in the modulus values in an absence of a filler were explained on the basis of the limited extensibility of the short chains of networks prepared using two different crosslinking agents in line with earlier modeling predictions. Remarkably, the swelling experiments revealed the increase in the crosslink density of the networks in the early stages of the thermal oxidative degradation procedure indicating a post-cure of the chemically bound antioxidants to the elastomeric chains, which incidentally corresponds to a maximum in the modulus values of the networks. The rheological and other mechanical properties such as the hardness were shown not to have been affected as a result of the incorporation of the chemically bound antioxidants.

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 Behavior of Raw Rubber When Stretched Isothermally

1938 ◽  
Vol 11 (4) ◽  
pp. 647-652 ◽  
Author(s):  
H. Hintenberger ◽  
W. Neumann
Keyword(s):  
Room Temperature ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Steep Ascent ◽  
Flow Effect ◽  
Vulcanized Rubber ◽  
Flow Phenomena ◽  
Entropy Effect ◽  
The Subject

Abstract The S-shaped form of the stress-strain curve of rubber is today explained in a quite satisfactory way. In the first part of the curve, i. e., the gradual ascent, work must be expended because of the van der Waals forces of attraction of the molecules; in the second part, i. e., the steep ascent, the elasticity is chiefly an entropy effect, which is finally exceeded by crystallization phenomena. The phenomenon of crystallization itself has been the subject of extensive investigations, but in most cases vulcanized rubber has been employed, and because of the various accelerators and fillers which the rubber has contained, the products have been rather ill-defined. It is evident that the phenomena involved in crystallization would be much more clearly defined if the substance under investigation were to be in a higher state of purity. If experiments are carried out with raw rubber, a flow effect is added to the various other phenomena. As a result of this flow effect, Rosbaud and Schmidt, and Hauser and Rosbaud as well, found that the stress-strain curve depends on the rate of elongation at very low extensions, with a greater stiffness at high rates of elongation. As found recently by Kirsch, there is no evidence of any flow phenomena in vulcanized rubber at room temperature. Most investigations have been so carried out that the stress has been measured at a definite elongation. It was therefore of interest to determine the elongation at constant stress, and the changes in this relation with time and with temperature, of various types of raw rubber.

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%).

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