Influence of Crosslink Density on Mechanical Properties of Natural Rubber Vulcanizates

2011 ◽  
Vol 50 (7) ◽  
pp. 1460-1469 ◽  
Author(s):  
Fei Zhao ◽  
Weina Bi ◽  
Shugao Zhao
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Natural Rubber Vulcanizates

Kinetics of Crosslinking and Network Changes in Natural Rubber Vulcanizates with a Dithiodimorpholine Based Accelerator System

1980 ◽  
Vol 53 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. K. De
Keyword(s):  
Natural Rubber ◽  
Rate Constants ◽  
Crosslink Density ◽  
Curing Temperature ◽  
Side Reactions ◽  
Filler Surface ◽  
Natural Rubber Vulcanizates ◽  
Kinetics Of ◽  
Accelerator System

Abstract Kinetics of crosslinking and network changes in unfilled and filled natural rubber vulcanizates with a dithiodimorpholine based accelerator system have been studied at 150° and 180°C. Results show that addition of HAF black enhances the polysulfidic crosslinks as well as the total crosslinks. This has been explained with the help of Coran's model wherein HAK black increases the rate constants. It is likely that the filler surface prevents desulfuration and undesirable side reactions involving the crosslink precursors. Increase of curing temperature by 30°C lowers the total crosslink density and increases the sulfur inefficiency.

HXNBR Coating for Improving Aging Resistance of Natural Rubber Products

2006 ◽  
Vol 79 (4) ◽  
pp. 553-560 ◽  
Author(s):  
Rani Joseph
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Room Temperature ◽  
Oxidative Degradation ◽  
Thin Coating ◽  
Oil Resistance ◽  
Aging Resistance ◽  
Natural Rubber Vulcanizates ◽  
Good Heat ◽  
Accelerator System

Abstract HXNBR (Hydrogenated Carboxylated Nitrile Rubber) has very good heat ageing resistance and oil resistance. A novel accelerator system is designed to bring about the vulcanization of HXNBR at room temperature. The room temperature cured samples showed good mechanical properties equivalent to those of high (150 °C) temperature cured samples. Natural rubber vulcanizates are highly prone to oxidative and ozone degradation. The oil resistance of natural rubber vulcanizates is also very low. The oil resistance, ozone and oxidative degradation resistance of natural rubber vulcanizates are considerably improved by placing a thin coating of HXNBR over it.

Effect of Crosslink Density on Cut Growth in Black-Filled Natural Rubber Vulcanizates

2002 ◽  
Vol 75 (5) ◽  
pp. 935-942 ◽  
Author(s):  
G. R. Hamed ◽  
N. Rattanasom
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Crack Growth ◽  
Crosslink Density ◽  
Longitudinal Crack ◽  
Test Pieces ◽  
Filled Rubber ◽  
Longitudinal Cracks ◽  
Natural Rubber Vulcanizates ◽  
High Crosslink Density

Abstract Tensile strengths, σb, of gum and N115-filled natural rubber test pieces, with and without edge pre-cuts, have been determined. At low crosslink density, the regular (uncut) σb of filled and gum vulcanizates is similar. However, at high crosslink density, the gum NR becomes brittle, while the corresponding filled rubber remains strong and resistant to cut growth. It is proposed that the tightly linked gum does not strain-crystallize appreciably during stretching, but that its filled counterpart does. Carbon black appears capable of inducing crystallization in a network that alone remains amorphous during extension. Filled vulcanizates of various crosslink densities have similar normal tensile strengths ( ≈ 30 MPa), but strengths differ, sometimes more than twofold, if a pre-cut is present. Lightly crosslinked specimens containing a small cut have strengths that depend very weakly on cut size, c. Furthermore, these develop long longitudinal cracks from which catastrophic rupture initiates. With larger cuts, strength decreases more rapidly with increasing c, there is less longitudinal crack growth, and rupture initiates near the original cut tip. In contrast, the strength of a highly crosslinked vulcanizate is sensitive to small cuts and test pieces exhibit minimal longitudinal cracking before failure.

Pyrolysis-mass spectrometry correlations of crosslink density in natural rubber vulcanizates

1985 ◽  
Vol 9 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Jacquelynn L. Savoca ◽  
Robert P. Lattimer ◽  
Joseph M. Richards ◽  
Willem Windig ◽  
Henk L.C. Meuzelaar
Keyword(s):  
Mass Spectrometry ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Pyrolysis Mass Spectrometry ◽  
Natural Rubber Vulcanizates

Improving oxidation stability and mechanical properties of natural rubber vulcanizates filled with calcium carbonate modified by gallic acid

2010 ◽  
Vol 66 (7) ◽  
pp. 965-977 ◽  
Author(s):  
Sirilux Poompradub ◽  
Thirapat Luthikaviboon ◽  
Srisuwan Linpoo ◽  
Rojrit Rojanathanes ◽  
Pattarapan Prasassarakich
Keyword(s):  
Mechanical Properties ◽  
Calcium Carbonate ◽  
Natural Rubber ◽  
Gallic Acid ◽  
Oxidation Stability ◽  
Natural Rubber Vulcanizates

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.

Reinforcing Effect of Silica and Silane Fillers on the Properties of Some Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (5) ◽  
pp. 1290-1310 ◽  
Author(s):  
A. Ansarifar ◽  
R. Nijhawan ◽  
T. Nanapoolsin ◽  
M. Song
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Cyclic Fatigue ◽  
Rubber Matrix ◽  
Stored Energy ◽  
Elongation At Break ◽  
Reinforcing Effect ◽  
Bound Rubber ◽  
Technical Properties ◽  
Natural Rubber Vulcanizates

Abstract The reinforcing effect of up to 6 parts per hundred rubber by weight (phr) bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), a bifunctional organosilane, on the crosslink density, bound rubber, and technical properties of some conventional accelerator/sulfur compounds of natural rubber, containing 30 phr precipitated amorphous white silica was studied. The crosslink density and bound rubber improved as a function of TESPT loading. The tensile strength, elongation at break, stored energy density at rupture, and cohesive tear strength deteriorated at low loading of TESPT, but they subsequently increased after the full amount of TESPT was introduced into the compound. The improved properties of the vulcanizate was due to the better dispersion of the filler in the rubber matrix. However, the cyclic fatigue life was adversely affected, and the hardness hardly changed as a result of adding TESPT to the rubber.

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