Determination of Crosslink Density and Network Structure of NR Vulcanizates by Means of TSSR

Abstract:

Unfilled vulcanizates based on natural rubber (NR) were investigated by temperature scanning stress relaxation (TSSR) measurements. Different sulfur based cure systems, i.e. conventional (CV), semi-efficient (SEV) and efficient (EV) vulcanization system, were used to prepare the vulcanizates. It was found that sulfur/accelerator - ratio has a strong impact on the shape of the relaxation spectrum, deduced from TSSR measurements. By deconvolution of the relaxation spectra, peak separation was performed and 3 different peaks were found in case of CV - cured samples. In contrast, only a single peak was found, in case of the EV-cured sample. After thiolamine treatment the shape of the relaxation spectra altered significantly in case of the CV-cured sample whereas the spectra of the SEV-and EV-cured sample exhibited only slight differences. Additionally, the crosslink density of the samples decreased after thiolamine treatment. This is due to selective cleavage of polysulfidic crosslinks. It has been concluded, that the significant peak in the relaxation spectrum at about 120 °C can be attributed to the cleavage of polysulfidic crosslinks. Furthermore, a linear relationship between the percentage of polysulfidic crosslinks and the sulfur/accelerator - ratio is assumed.

• Periodical: Advanced Materials Research (Volume 844)
• Pages: 482-485
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.844.482
• Online since: November 2013
• Authors: Norbert Vennemann*, Christina Schwarze, Claudia Kummerlöwe
• Keywords: Crosslink Density, Natural Rubber (NR), Network Structure, Temperature Scanning Stress Relaxation (TSSR)

References

[1] P.J. Flory, J. Rehner, J Chem Phys., 11 (1943) 521.

[2] U. Eisele, Progr. Colloid & Polymer Sci., 66 (1979) 59.

[3] M. Garbaraczyk, F. Grinberg, N. Nestle, W. Kuhn, J. Polym. Sci. Part B: Polym. Phys. 39 (2001) 2207.

[4] A. Barbe, K. Bökamp, C. Kummerlöwe, H. Sollmann, N. Vennemann, S. Vinzelberg, Polym. Eng. and Science 45 (2005) 1498 – 1507.

DOI: 10.1002/pen.20427

[5] N. Vennemann, Characterization of Thermoplastic Elastomers by Means of Temperature Scanning Stress Relaxation Measurements, in: A. Z. El-Sonbati (Ed. ), INTECH, Rijeka (Croatia), 2012, pp.347-370.

DOI: 10.5772/35976

[6] M. Wu, N. Vennemann, Rubber Fibres Plastic for China, 8 (Vol. 3) (2011) 18 – 28.

[7] N. Vennemann, M. Wu, M. Heinz, Rubber World 246 (Vol. 6) (2012) 18-23.

[8] M. Wu, M. Heinz, N. Vennemann, Adv. Mat. Research Vols. 718-720 (2013) 117-123.

[9] A. Mosch, PhD Thesis, University of Hanover, Germany (2002).