Crystallization and Strength of Natural Rubber and Synthetic cis-1,4-Polyisoprene

1998 ◽  
Vol 71 (4) ◽  
pp. 668-678 ◽  
Author(s):  
A. N. Gent ◽  
S. Kawahara ◽  
J. Zhao
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Melting Temperature ◽  
Wide Temperature Range ◽  
Critical Factor ◽  
Tear Strength ◽  
Temperature Range ◽  
Low Speeds ◽  
Structural Irregularities ◽  
Lower Tensile Strength

Abstract Crosslinked samples of natural rubber (NR, SMR-5L) and a synthetic cis-1,4-polyisoprene (IR, Natsyn 2200, The Goodyear Tire & Rubber Company) were crystallized at −25 °C at various strains, and then slowly melted. Crystallization was somewhat slower for IR under all conditions, taking two to three times as long as for NR crosslinked to the same degree. The melting temperature was also a few degrees lower. These effects are consistent with the presence of a small fraction of non-cis material in the IR molecule. Measurements of tensile strength and tear strength were made over a wide temperature range. The results were closely similar for the two materials at low rates of stretching although the abrupt fall in tensile strength associated with a failure to crystallize occurred at slightly lower temperatures for IR. Tear strength at low speeds showed a steady fall on raising the temperature, with little difference between the two materials. However, at high rates of strain the IR materials appeared to have significantly lower tensile strength, and at high tear speeds the tear strength was markedly lower, about one-half of that for NR. Thus, the minor structural irregularities in IR appear to be of little consequence at low rates of strain, but cause significant weakening at high rates, when the lower rate of crystallization is inferred to become a critical factor.

Mechanical And Superconducting Properties Of Cu-Nb3Sn In Situ Produced Composite Wires

1981 ◽  
Vol 12 ◽  
Author(s):  
A. Kolb-Telieps ◽  
B.L. Mordike ◽  
M. Mrowiec
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Wide Temperature Range ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
Temperature Range ◽  
Composite Wires ◽  
Strength And Ductility

ABSTRACTCu-Nb composite wires were produced from powder, electrolytically coated with tin and annealed to convert the Nb fibres to Nb 3Sn. The content was varied between 10 wt % and 40 wt %. The superconducting properties of the wires were determined. The mechanical properties, tensile strength, yield strength and ductility were measured as a function of volume fraction and deformation over a wide temperature range. The results are compared with those for wires produced by different techniques.

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.

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.

scholarly journals Reinforcement of natural rubber and epoxidized natural rubbers with fillers

2019 ◽  
Vol 1 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Indra Surya ◽  
Nabil Hayeemasae
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Surface Chemistry ◽  
Natural Rubber ◽  
The Other ◽  
Reinforcement Effect ◽  
Cure Time ◽  
Filler Dispersion ◽  
The Difference ◽  
Lower Tensile Strength

The reinforcement of natural rubber (NR) and epoxidized natural rubbers (ENRs) with silica or carbon black (CB) by using a semi-efficient sulfur accelerated vulcanization system has been carried out. It was found that silica caused a longer in cure time compared to CB and due to the dissimilarity of their surface chemistry, it was also found that silica and CB caused the difference in reinforcement effect to those rubbers. Silica caused in filled-vulcanizates of those rubbers with a higher modulus and lower tensile strength compared to their unfilled ones. On the other hand, CB caused enhancements in both modulus and tensile to those rubbers. The investigation on reinforcing efficiencies of those fillers on the rubbers found that the higher reinforcing efficiency of CB was attributed to its better degree of filler dispersion when compared to silica.

scholarly journals Preparation and modification of natural rubber blends for water purification treatment usage

2020 ◽  
Author(s):  
Wenfa Dong ◽  
Ruogu Tang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Relative Volume ◽  
Curing Time ◽  
Water Industry ◽  
High Modulus ◽  
Elongation At Break ◽  
Tear Strength ◽  
Rubber Blends

<div>The water industry used NR was selected for blending with SBR. A series of NR/SBR vulcanizates were prepared through three different vulcanization systems, conventional vulcanization (CV), effective vulcanization (EV) and semi-effective vulcanization (SEV) respectively, basing on each formulation and optimum curing time. We examined the mechanical properties of NR/SBR vulcanizates including tensile strength, tear strength, elongation at break, modulus, Shore A hardnessand and relative volume abrasion. The results indicated that NR/SBR vulcanizates prepared in different systems differed in mechanical properties. Vulcanizates prepared via CV showed higher tensile and tear strength; vulcanizates prepared via EV had high modulus and hardness, and vulcanizates prepared via SEV performed high abrasion resistance. </div>

Effect of Oyster Shell Powder Loading on the Mechanical and Thermal Properties of Natural Rubber/Oyster Shell Composites

2017 ◽  
Vol 25 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Lefan Li ◽  
Zongqiang Zeng ◽  
Zhifen Wang ◽  
Zheng Peng ◽  
Xiaodong She ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Coupling Agent ◽  
Oyster Shell ◽  
Absorption Bands ◽  
Tear Strength ◽  
Oyster Shell Powder ◽  
Shell Powder

The oyster shell powder/natural rubber composites were successfully prepared by blending the modified oyster shell powder with natural rubber (NR). The oyster shell powder with a particle size of 209 nm were well distributed within the rubber matrix. The characteristic Fourier transform infrared spectroscopy (FTIR) absorption bands of both oyster shell powder and natural rubber were observed in the FTIR spectra of NR/oyster shell powder composites. The C-O absorption bands in carbonates of composites exhibit a shift from 1425 cm−1 to 1446 cm−1 which suggests the bonds formed among oyster shell powder, earth coupling agent and NR. The tensile strength and stress at 500% elongation increased with rising of the earth coupling agent. Composites with 1.5 parts per hundred rubber (phr) coupling agent achieved the highest mechanical properties, where an increase of 13.4% in tensile strength was found. The tensile strength and tear strength increased along with an increment of oyster shell powder. When the content of oyster shell powder attained 25–30 phr, the composites exhibited the best mechanical properties. In particular, the tensile strength and tear strength increased by 27.9% and 17.2% when compared with those of the control samples. Furthermore, the addition of the oyster shell powder leads to the improvement of thermal stability which is evidenced by an increase of 8 °C in the initial degradation temperature. The improvement of the mechanical properties and thermal stability of the composites have demonstrated that the oyster shell powder can be used as potential fillers for natural rubber.

Reinforcement of Natural Rubber with Silanized Precipitated Silica Nanofiller

2005 ◽  
Vol 78 (5) ◽  
pp. 793-805 ◽  
Author(s):  
A. Ansarifar ◽  
N. Ibrahim ◽  
M. Bennett
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Zinc Oxide ◽  
Reaction Mechanism ◽  
Energy Density ◽  
Natural Rubber ◽  
Elemental Sulfur ◽  
Stored Energy ◽  
Tear Strength ◽  
Precipitated Silica

Abstract The effect of a large amount of precipitated amorphous white silica nanofiller, pre-treated with bis[3-triethoxysilylpropyl-)tetrasulfide (TESPT), on the mechanical properties of a sulfur-cured natural rubber (NR) was studied. TESPT chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur-cure. The silica particles were fully dispersed in the rubber, which was cured primarily by using sulfur in TESPT, or, by adding a small amount of elemental sulfur to the cure system. The cure was also optimized by incorporating sulphenamide accelerator and zinc oxide into the rubber. The hardness, tear strength, tensile strength, and stored energy density at break of the vulcanizate were substantially improved when the filler was added. Interestingly, these properties were also enhanced when the rubber was cured primarily by using sulfur in TESPT.

Rupture of Rubber. VII. Effect of Rate of Extension in Tensile Tests

1961 ◽  
Vol 34 (1) ◽  
pp. 76-84 ◽  
Author(s):  
H. W. Greensmith
Keyword(s):  
Tensile Strength ◽  
Wide Temperature Range ◽  
Tensile Tests ◽  
Subsequent Paper ◽  
Not Given ◽  
Temperature Range ◽  
Extensive Data ◽  
Extension Curve ◽  
Similar Range

Abstract There are few published measurements on the effect of rate of extension in tensile rupture tests on rubber vulcanizates. The most extensive data on a single vulcanizate are those of Dogadkin and Sandomirskii˘ and of Smith. These measurements were made on GR-S gum vulcanizates and covered a similar range of rates of extension, from about 0.02 to 20%/sec. Ring specimens were used in both cases, and tensile strength and breaking extension were measured over a wide temperature range. Villars has made tensile strength and breaking extension measurements on double dumbbell specimens of several gum and filled vulcanizates extended at various rates in the range 10,000 to 100,000%/sec. Kainradl and Handler have reported tensile strength measurements for several filled vulcanizates, obtained with dumbbell specimens extended at four different rates of extension covering a range from about 1 to 100,000%/sec. All these results indicate that tensile strength and breaking extension can vary appreciably with the rate of extension of the specimen. Complete load-extension curves are not given in any of these papers. In the present paper an autographic method is described for obtaining the load-extension curves of ring specimens extended at various rates from about 0.1 to 2000%/sec. Results showing the effect of the rate of extension on the tensile strength and breaking extension and on the load-extension curve are given for GR-S vulcanizates. The data were obtained primarily for the comparisons of tear and tensile rupture measurements given in a subsequent paper (Part VIII).

The Effect of Organic Modificaition Method onto Montmorillonite on Mechanical Properties of Natural Rubber

2008 ◽  
Vol 55-57 ◽  
pp. 341-344 ◽  
Author(s):  
Chanchai Thongpin ◽  
N. Tangchantra ◽  
P. Kaewpetch ◽  
J. Dejkun ◽  
A. Chartsiriwattana
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Organic Molecule ◽  
Elongation At Break ◽  
Tear Strength ◽  
Cure Characteristics ◽  
Modified Montmorillonite

Montmorillonite is a type of clays that has been used to reinforce polymer including rubber. Therefore this research is aimed to modify mechanical properties of natural rubber (NR) using montmorillonite (MMT) comparing with the organic modified montmorillonite (CTAB-MMT) and organic molecule grafted MMT. The affect of MMT, CTAB-MMT and HTMS-g-CTABMMT on cure characteristics of NR were studied. It was found from the research that the increase of MMT content could prolong the scorch time whereas CTAB-MMT and HTMS-g-CTABMMT could shorten the scorch time. The cure times of the compounds in all cases were not much different. In term of mechanical properties, modulus, tensile strength and tear strength of NR/HTMS-g-CTABMMT vulcanizate were higher than those of NR/MMT and NR/CTAB-MMT vulcanizates. Meanwhile, elongation at break of the NR/ HTMS-g-CTABMMT vulcanizate decreased more than the latter cases

Effect of Epoxidized Oil on Tensile and Tear Strength of NR Vulcanizate and its Comparison with Aromatic Oil NR Vulcanizates

2013 ◽  
Vol 812 ◽  
pp. 204-209 ◽  
Author(s):  
Mohamed Rahmah ◽  
Wan Zain Norazira ◽  
Ahmad Faiza Mohd ◽  
Mohd Nurazzi Norizan
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Rubber Compound ◽  
Tear Strength ◽  
Green Component ◽  
Strength Tests ◽  
Tearing Energy ◽  
Polymer Industry ◽  
Natural Rubber Vulcanizates

Epoxidized oil (EO) is a sustainable oil that can be obtained form edible or non-edible naturals oil. The incorporation of epoxidized oil can increase the green component in rubber compound. It can contributes to worldwide technology specially in green tyre manufacturing. Epoxidized oil has the potential to replace aromatic oil (AO) to rubber and polymer industry. The effect of incorporation of EO and AO into natural rubber vulcanizates (NR) was studied via tensile and tear strength tests according to ISO 31-1977 and ISO 6133, respectively. Tensile strength of AO value showed greather value compared to EO. Gradual increases of elongation were observed form both AO and EO. Both moduli at 100% and 300% elongation, showed reductions as oil loading were increased. The tear strength results showed that tearing energy insignificantly increased with oil loading. EO compound was found to possess higher tearing energy compared to AO compound for most composition except for 15 pphr EO.

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