Influence of Preparation Conditions on Network Parameters of Sulfur-Cured Natural Rubber

Klüppel, Manfred; Menge, H.; Schmidt, Harold R.; Schneider, H.; Schuster, R. H.

doi:10.1021/ma010490v

Cited by 51 publications

(55 citation statements)

References 45 publications

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“…Different combined studies have been published, [69][70][71][72][73][74][75] and many of them use NMR. It is in fact well-known that a linear relationship exists between the network parameters determined by equilibrium swelling and by NMR.…”

Section: Rtmentioning

confidence: 99%

Uncertainties in the Determination of Cross-Link Density by Equilibrium Swelling Experiments in Natural Rubber

et al. 2008

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Equilibrium swelling is a feasible and simple experiment to determine the cross-link density of networks. It is the most popular and useful approach; however, in most of the cases, the given values are highly uncertain if not erroneous. The description of the complex thermodynamics of swollen polymer networks is usually based on the Flory-Rehner model. However, experimental evidence has shown that both the mixing term described by the Flory-Huggins expression and the elastic component derived from the affine model are only approximations that fail in the description and prediction of the rubber network behavior. This means that the Flory-Rehner treatment can only give a qualitative evaluation of cross-link density because of its strong dependence on the thermodynamic model. In this work, the uncertainties in the determination of the cross-link density in rubber materials by swelling experiments based on this model are reviewed. The implications and the validity of some of the used approximations as well as their influence in the relationship of the cross-link densities derived from swelling experiments are discussed. Importantly, swelling results are compared with results of a completely independent determination of the cross-link density by proton multiple-quantum NMR, and the correlation observed between the two methods can help to validate the thermodynamic model.

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Section: Rtmentioning

confidence: 99%

Uncertainties in the Determination of Cross-Link Density by Equilibrium Swelling Experiments in Natural Rubber

et al. 2008

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“…Previous work [1][2][3] on the analysis of the cross-linking junctions primary used high-resolution solid-state NMR spectroscopy, because the cross-linked natural rubber was insoluble in organic solvents as a result of the threedimensional network formed after vulcanization and the structural heterogeneity of the cross-linking junctions. However, in the previous work, pulse sequences applicable to analyze the cross-linking junctions of the cross-linked natural rubber were limited to onedimensional solid-state 13 C-NMR spectroscopy because of highpower decoupling.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and cross-linking structure of cross-linked natural rubber

Chaikumpollert

Yamamoto

Suchiva

et al. 2012

Polym J

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Molecular singularity of cross-linked natural rubber was proposed to be a significant cross-linking junction of rubber, on the basis of the assignment of nuclear magnetic resonance (NMR) signals achieved in our previous work. This molecular singularity was observed to have an important role in the most outstanding mechanical properties of the rubber, through the investigation of the relationships between the structure of cross-linking junctions and the mechanical properties of various cross-linked rubbers. The various cross-linked natural rubbers were prepared by conventional vulcanization (CV), efficient vulcanization (EV) and semi-EV (SemiEV) to have nearly identical cross-link densities. These rubbers were analyzed using solid-state NMR spectroscopy. Using 1 H-NMR spectroscopy, the amount of tertiary carbons linking to sulfur in the CV rubber was observed to be the same as those of the EV and SemiEV rubbers. 13 C-NMR spectroscopy revealed that the number of quaternary carbons linking to sulfur in the CV rubber was the largest among the rubbers. The CV rubber exhibited the best mechanical properties; hence, a cross-linking junction of quaternary carbons linked to sulfur was assigned to the molecular singularity.

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“…Such result has been found repeatedly in the past when comparing physical measurements with different theoretical predictions, most recently [23] with the Edwards-Vilgis slip-link theory [22]. This has been commonly interpreted as being due to the presence, in the network, of trapped chain entanglements which behave more or less as ordinary network junctions-covalent crosslinks [9,23,[27][28][29][30][31][32][33][34]. Let us denote the contribution of trapped entanglements to the connectivity term as affine entanglement modulus, (2C 1 KnRT), or, alternatively, phantom entanglement modulus (2C 1 KxRT).…”

Section: Parameters and Structurementioning

confidence: 76%

A Langevin-elasticity-theory-based constitutive equation for rubberlike networks and its comparison with biaxial stress–strain data. Part II

Meissner

Matějka

2004

Polymer

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A structure-based constitutive equation for rubberlike networks (ABGIL) was proposed in Part I of this communication. It is a combination of the connectivity term based on Langevin statistics (Arruda and Boyce, AB) and a constraint term which follows from some theoretical treatments and may be expressed in the form of the first invariant of the generalized deformation tensor (GI). The ABGIL equation was tested in Part I using published biaxial stress-strain data on networks of natural and isoprene rubbers and further tests are performed in Part II on networks of poly (dimethylsiloxane) and styrene-butadiene rubber. Parameters of the equation were obtained from the fitting procedure. Apart from the region of very low (!10%) strains, a good, or even very good description (less than 5% deviation) of the experimental biaxial stress-strain behavior was obtained. In the region of very high strains, the previously introduced concept of a strain-dependent finiteextensibility parameter was applied. The effects of polymer and network structure and presence of a diluent in the course of endlinking on the fitted parameter values are discussed. The values of the exponent n in the constraint term were found to lie in a rather wide range (K0.2 to C 1) which includes predictions of four different tube theories. q

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Influence of Preparation Conditions on Network Parameters of Sulfur-Cured Natural Rubber

Cited by 51 publications

References 45 publications

Uncertainties in the Determination of Cross-Link Density by Equilibrium Swelling Experiments in Natural Rubber

Uncertainties in the Determination of Cross-Link Density by Equilibrium Swelling Experiments in Natural Rubber

Mechanical properties and cross-linking structure of cross-linked natural rubber

A Langevin-elasticity-theory-based constitutive equation for rubberlike networks and its comparison with biaxial stress–strain data. Part II

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