Mesostructure Evolution during Storage of Rubber Films from Washed Cream Latex and Skim Latex

Abstract:

Fresh field latex (FL) of Hevea brasiliensis was centrifuged to separate the major compartments: (i) the cream, (ii) the skim plus the C-serum, and (iii) the bottom fraction. Cream was dispersed in distilled water to prepare cream washed latex or CL sample. Skim was collected together with C-serum to prepare the skim latex or SKL sample. Then, films were made from FL, CL and SKL. The mesostructure (macromolecular structure and aggregates or gel) of the natural rubber films was studied by size exclusion chromatography coupled to a multiangular light scattering detector (SEC-MALS). The mesostructure was analyzed on fresh films and on films stored in the laboratory for three months (slow structuring). This study showed that FL and CL films had bimodal elution profiles of long and short polyisoprene chains as revealed by the two peaks on the chromatograms at low and high elution volumes, respectively. On the contrary, SKL films exhibited unimodal elution profiles at low elution volume and a highly abnormal molar masses elution profiles. After 3 months storage, the mesostructure of FL evolved dramatically especially the number-average molar masses (M_n), which increased by 60%. The mesostructure of CL films evolved at a lesser extent and, the mesostructure of SKL films exhibited no significant change. These results indicated (i) the skim rubber particles are not prone to slow structuring during storage in presence of serum and (ii) some constituents either in the serum or/and in the bottom fraction could still be present with cream and be involved in the slow structuring of cream particles latex.

• Periodical: Advanced Materials Research (Volume 844)
• Pages: 417-420
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.844.417
• Online since: November 2013
• Authors: Chalao Thepchalerm, Suwaluk Wisunthorn, Laurent Vaysse, Suda Kiatkamjornwong, Charoen Nakason, Frederic Bonfils
• Keywords: Gel, Mesostructure, Natural Rubber (NR), SEC-MALS

References

[1] P. W. Allen and G. M. Bristow, The Gel Phase in Natural Rubber, Rubb. Chem. Technol., 36 (1963) 1024–1034.

[2] Y. Tanaka, Structure Characterization of Natural Polyisoprenes : Solve the Mystery of Natural Rubber Based on Structural Study, Rubb. Chem. Technol., 74 (2001) 355–375.

DOI: 10.5254/1.3547643

[3] J. Yunyongwattanakorn, Y. Tanaka, S. Kawahara, and W. Klinklai, Effect of non-rubber components on storage hardening and gel formation of natural rubber during accelerated storage under various conditions, Rubb. Chem. Technol., 76 (2003).

DOI: 10.5254/1.3547799

[4] C. Kim, M. H. Morel, J. S. Beuve, S. Guilbert, A. Collet and F. Bonfils, Characterization of natural rubber using size-exclusion chromatography with online multi-angle light scattering: Study of the phenomenon behind the abnormal elution profile, J. Chromatogr. A, 1213 (2008).

DOI: 10.1016/j.chroma.2008.10.052

[5] S. Dubascoux, C. Thepchalerm, E. Dubreucq, S. Wisunthorn, L. Vaysse, S. Kiatkamjornwong, C. Nakason and F. Bonfils, Comparative study of the mesostructure of natural and synthetic polyisoprene by size exclusion chromatography-multi-angle light scattering and asymmetrical flow field flow fractionation-multi-angle light scattering, J. Chromatogr. A, 1224 (2012).

DOI: 10.1016/j.chroma.2011.12.010

[6] S.N. Gan, Storage hardening of natural rubber, Pure Appl. Chem., A 33 (1996) 1939–(1948).

[7] S. Wisunthorn, S. Liengprayoon, L. Vaysse, J. S. Beuve and F. Bonfils, SEC-MALS Study of Dynamic Structuring of Natural Rubber: Comparative Study of Two Hevea brasiliensis Genotypes, J. Appl. Polym. Sci., 124 (2012) 1570–1577.

DOI: 10.1002/app.35099

[8] R. Wititsuwannakul, P. Pasitkul, P. Jewtragoon, and D. Wititsuwannakul, Hevea Latex Lectin Binding Protein in C-serum as an Anti-latex Coagulating Factor and Its Role in a Proposed New Model for Latex Coagulation, Phytochem. 69 (2008) 656–662.

DOI: 10.1016/j.phytochem.2007.09.021