Analysis of Cross-Link Structure of Polybutadiene Latex by Pulsed NMR.

Sakano, Hajime; Ikawa, Kiyoshi; Kojima, Hiroshi

doi:10.1295/koron.54.757

Cited by 2 publications

(1 citation statement)

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“…It can also be roughly extrapolated from the representation of cross-link density over amount of cross-linker. Then, for the mean molar mass between two cross-links M c it follows: It has been demonstrated in earlier papers 13-16,38-41 that this method is a simple and fast tool for network characterization when all experiments are performed at temperatures well above T g + 120 K. Good correlation was obtained between the M c values estimated from different methods for moderately cross-linked samples with M c < 10 4 g/mol, while agreement between them was poor for loosely cross-linked samples with M c > 10 4 g/mol . Parameters characterizing the network such as M c , B , T 2 , and τ s showed a tendency similar to that of the swelling and mechanical data.…”

Section: Theoreticalmentioning

confidence: 84%

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

et al. 2001

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The effect of initial chain length before cross-linking and sulfur/accelerator amount during curing of natural rubber samples on network parameters (effective chain density, gel fraction, amount of chain ends, entanglement density, trapping factor, and relaxation and correlation times) is investigated by means of proton NMR relaxation, equilibrium swelling, and stress−strain analysis. Remarkable differences are observed in the two sample series depending on the variable initial molar mass. The stress−strain data are evaluated with respect to a non-Gaussian tube model of rubber elasticity that considers the finite extensibility of network chains by referring to the path integral approach of Edwards and Vilgis (Rep. Prog. Phys. 1988, 51, 243; Polymer 1986, 27, 483). According to several experimental indications, we assume a nonaffine tube deformation law as first derived by Heinrich et al. (Adv. Polym. Sci. 1988, 85, 33). The NMR relaxation data are analyzed by considering three types of chains (gel, sol and chain ends). The best fit is obtained by assuming an anisotropic motion of the inter-cross-link chains and chain ends. The swelling data are analyzed by assuming phantom like chains. Within the framework of experimental errors, the network parameters evaluated from the three experimental techniques show fair agreement for both sample series.

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Section: Theoreticalmentioning

confidence: 84%