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

2008 ◽  
Vol 41 (13) ◽  
pp. 4717-4729 ◽  
Author(s):  
J. L. Valentín ◽  
J. Carretero-González ◽  
I. Mora-Barrantes ◽  
W. Chassé ◽  
K. Saalwächter
Keyword(s):  
Natural Rubber ◽  
Cross Link ◽  
Equilibrium Swelling ◽  
Link Density ◽  
Cross Link Density

Reclaiming of waste guayule natural rubber vulcanizate—reclaim rubber for green tire applications: An approach for sustainable development

2018 ◽  
Vol 51 (3) ◽  
pp. 193-210 ◽  
Author(s):  
Soumyajit Ghorai ◽  
Dipankar Mondal ◽  
Sawar Dhanania ◽  
Santanu Chattopadhyay ◽  
Madhusudan Roy ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Polymer Chains ◽  
Cross Link ◽  
Scanning Calorimetry ◽  
Infrared Study ◽  
Differential Scanning Calorimetry Study ◽  
Link Density ◽  
Cross Link Density ◽  
Silica Dispersion ◽  
The Fourier Transform

This article illustrates the reclaiming of guayule natural rubber (GNR) vulcanizate by bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT), and as-grown reclaim rubber facilitates the silica dispersion in GNR product application without adding any coupling agent. This article deals with the performance evaluation of silica-filled revulcanizates with promising application in green tire. The extent of reclaiming was monitored through the measurement of sol content, cross-link density, Mooney viscosity, and degree of reclaiming. The differential scanning calorimetry study was carried out to evaluate the fraction of immobilized polymer chains and its dependence on cross-link density of the vulcanizates. The Fourier transform infrared study and also sulfur analysis independently indicate the attachment of the fragmented TESPT with the polymer chain and cross-link bonds. The study of mechanical properties clearly shows that in revulcanized GNR, the optimum property is achieved when reclaiming time is set for 40 min. The effect of reclaiming time on dynamic mechanical behavior such as storage modulus and loss tangent was studied. The scanning electron microscopy studies show the coherency and homogeneity of silica-filled revulcanize rubber with reclaiming time.

ROLE OF COAGENTS IN PEROXIDE VULCANIZATION OF NATURAL RUBBER

2013 ◽  
Vol 86 (3) ◽  
pp. 488-502 ◽  
Author(s):  
Rejitha Rajan ◽  
Siby Varghese ◽  
K. E. George
Keyword(s):  
Natural Rubber ◽  
Hydrogen Abstraction ◽  
Polymer Chains ◽  
Hydrocarbon Chains ◽  
Equilibrium Swelling ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
Curing Agents

ABSTRACT The drawbacks of peroxide vulcanization can largely be overcome by introducing suitable co-curing agents (coagents) in the formulation. The role of various coagents, such as zinc diacrylate (ZDA), trimethylolpropane trimethacrylate (TMPTMA), and triallyl cyanurate (TAC) in the peroxide vulcanization of natural rubber (NR) was studied by Fourier transform infrared spectroscopy. Cross-link density was measured by the equilibrium–swelling technique. Cross-linking mechanism of peroxide in NR was interpreted by comparing the spectra of cured and uncured vulcanizates. The predominance of hydrogen abstraction over the radical addition was established (at 160 °C). Coagent ZDA produces ionic as well as covalent cross-links in the vulcanizate. Ionic cross-links have the ability to slip along the hydrocarbon chains and thus resemble polysulfidic cross-links. Hence, ZDA can be chosen for applications where good mechanical properties are required. Coagent TMPTMA produces covalent cross-links between polymer chains and is suitable for high-modulus applications. TAC, although it bridges through covalent cross-links, is not a suitable coagent for highly unsaturated rubbers like NR.

Determination of Cross-Link Density in Ion-Irradiated Polystyrene Surfaces from Rippling

Langmuir ◽  
2009 ◽  
Vol 25 (5) ◽  
pp. 3108-3114 ◽  
Author(s):  
Yogesh Karade ◽  
Sascha A. Pihan ◽  
Wilhelm H. Brünger ◽  
Andreas Dietzel ◽  
Rüdiger Berger ◽  
...  
Keyword(s):  
Cross Link ◽  
Link Density ◽  
Cross Link Density

Determination of the Local Cross-Link Density in Polyisobutylene-Based Elastomers by NMR Imaging

2003 ◽  
Vol 36 (3) ◽  
pp. 706-711 ◽  
Author(s):  
Peter Adriaensens ◽  
Anne Pollaris ◽  
Mauritz Kelchtermans ◽  
Jan Gelan
Keyword(s):  
Nmr Imaging ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density

VULCANIZATION CHARACTERISTICS OF NATURAL RUBBER COAGULATED BY MICROORGANISMS

2018 ◽  
Vol 91 (1) ◽  
pp. 64-78
Author(s):  
Si-Dong Li ◽  
Jing Chen ◽  
Le-Fan Li ◽  
Zhi-Fen Wang ◽  
Jie-Ping Zhong ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Natural Rubber ◽  
Transverse Relaxation Time ◽  
Cross Link ◽  
Mass Percentage ◽  
Transverse Relaxation ◽  
1H Nuclear Magnetic Resonance ◽  
Link Density ◽  
Cure Time ◽  
Cross Link Density

ABSTRACT The network variations of natural rubber (NR) during the vulcanization process were investigated by 1H chemical shift by liquid-state 1H nuclear magnetic resonance (NMR) spectroscopy. NR latex coagulated by microorganisms (NR-m) was contrasted with NR latex coagulated by acid (NR-a). The influences of the coagulation process on the structures, vulcanization characteristics, and mechanical properties of NR were analyzed. The results show that the cross-link density (XLD) and mass percentage of cross-link network (A(Mc)) can be increased with the increment of the vulcanization time; while the mass percentage of dangling free ends of the hydrocarbon and small molecules (A(T2)), the longitudinal relaxation time (T1), transverse relaxation time (T2), and molecular mass of inter–cross-link chains (Mc) decreased with the prolonging of vulcanization time both NR-m and NR-a. NR-m exhibits shorter scorch times (ts1, ts2) and optimum cure time (t90) and shows higher maximum torque (MH) and minimum torque (ML) than that of NR-a. It is obvious that the higher XLD and A(Mc) and lower A(T2), T1, T2, and Mc values of NR-m result in higher stress, tensile strength, and tear strength of NR compounds.

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