Removal of Proteins and Its Effect on Molecular Structure and Properties of Natural Rubber
Main Article Content
Abstract
Removal of protein from natural rubber was carried out via deproteinization of natural rubber in the latex stage. Then, its effect on the molecular structure and properties of natural rubber was investigated. Urea, SDS, and acetone were used as denaturing agent, a surfactant, and a polar solvent in the deproteinization, respectively. Various deproteinized natural rubbers were obtained after one, two, and three times of centrifugation with and without acetone, namely DPNR1, DPNR2, DPNR3, DPNR1-A, DPNR2-A, and DPNR3-A. It was found that the total protein content significantly decreased as increasing the number of centrifugations; however, the total fatty acid contents showed a slight decrease. Structural characteristics analyzed by nuclear magnetic resonance spectroscopy indicated no changes in the chemical structure of natural rubber after deproteinization. However, the removal of proteins significantly enhanced the resolution of the NMR signals. Gel content and tensile properties of natural rubber showed a decrease in the removal of proteins, which was associated with the decrease in the number of the inherent branching points formed in natural rubber.
Keywords
deproteinized natural rubber, proteins, NMR signal, tensile property
Article Details
References
[1] N.T. Thuong, Y. Oraphin, P.T. Nghia, S. Kawahara.
Effect of naturally occurring crosslinking junctions on
green strength of natural rubber, Polym. Adv.
Technol., vol. 28, pp. 303–311, 2016.
https://doi.org/10.1002/pat.3887
[2] E.C. Gregg, J.H. Macey, The relationship of properties
of synthetic poly(isoprene) and natural rubber in the
factory. The effect of non rubber constituents of
natural rubber, Rubber. Chem. Technol, vol. 46, pp.
47–66, 1973.
https://doi.org/10.5254/1.3545022
[3] Y. Zhou, K. Kosugi, Y. Yamamoto, S. Kawahara. Effect
of non rubber components on the mechanical properties
of natural rubber, Polym. Adv. Technol, vol. 28, pp.
159–165, 2017.
https://doi.org/10.1002/pat.3870
[4] S. Amnuaypornsri, L. Tarachiwin, J.T. Sakdapipanich,
Character of long chain branching in highly purified
natural rubber. J. Appl. Polym. Sci. vol. 115, pp. 3645-
3650, 2010.
https://doi.org/10.1002/app.31419
[5] Y. Tanaka, Structural characterization of natural
polyisoprenes: solve the mystery of natural rubber
based on structural study, Rubber Chem Technol,
vol.74, pp. 355-375, 2001.
https://doi.org/10.5254/1.3547643
[6] S. Kawahara, Y. Isono, J.T. Sakdapipanich, Y. Tanaka,
E. Aik-Hwee. Effect of gel on the green strength of
natural rubber, Rubber. Chem. Technol, vol 75, 739–
746, 2002.
https://doi.org/10.5254/1.3544999
[7] O. Chaikumpollert, Y. Yamamoto, K. Suchiva, P.T.
Nghia, S. Kawahara, Preparation and characterization
of protein-free natural rubber, Polym. Adv.Technol.,
vol. 23, pp. 825–828, 2011.
https://doi.org/10.1002/pat.1965
[8] S. Kawahara, W. Klinklai, H. Kuroda, Y. Isono,
Removal of proteins from natural rubber with urea,
Polym Adv Technol. Vol 15, pp. 181-184, 2004.
https://doi.org/10.1002/pat.465
[9] Rubber Research Institute of Malaysia, Determination
of nitrogen, SMR Bull. No.1, Part B.7, Now. 1973.
[10] S Toki, J Che, L Rong, BS Hsiao, S Amnuaypornsri,
A Nimpaiboon, J Sakdapipanic, Entanglements and
networks to strain-induced crystallization and stress–
strain relations in natural rubber and synthetic
polyisoprene at various temperatures,
Macromolecules. Vol 46, pp. 5238-5248, 2013.
https://doi.org/10.1021/ma400504k
Effect of naturally occurring crosslinking junctions on
green strength of natural rubber, Polym. Adv.
Technol., vol. 28, pp. 303–311, 2016.
https://doi.org/10.1002/pat.3887
[2] E.C. Gregg, J.H. Macey, The relationship of properties
of synthetic poly(isoprene) and natural rubber in the
factory. The effect of non rubber constituents of
natural rubber, Rubber. Chem. Technol, vol. 46, pp.
47–66, 1973.
https://doi.org/10.5254/1.3545022
[3] Y. Zhou, K. Kosugi, Y. Yamamoto, S. Kawahara. Effect
of non rubber components on the mechanical properties
of natural rubber, Polym. Adv. Technol, vol. 28, pp.
159–165, 2017.
https://doi.org/10.1002/pat.3870
[4] S. Amnuaypornsri, L. Tarachiwin, J.T. Sakdapipanich,
Character of long chain branching in highly purified
natural rubber. J. Appl. Polym. Sci. vol. 115, pp. 3645-
3650, 2010.
https://doi.org/10.1002/app.31419
[5] Y. Tanaka, Structural characterization of natural
polyisoprenes: solve the mystery of natural rubber
based on structural study, Rubber Chem Technol,
vol.74, pp. 355-375, 2001.
https://doi.org/10.5254/1.3547643
[6] S. Kawahara, Y. Isono, J.T. Sakdapipanich, Y. Tanaka,
E. Aik-Hwee. Effect of gel on the green strength of
natural rubber, Rubber. Chem. Technol, vol 75, 739–
746, 2002.
https://doi.org/10.5254/1.3544999
[7] O. Chaikumpollert, Y. Yamamoto, K. Suchiva, P.T.
Nghia, S. Kawahara, Preparation and characterization
of protein-free natural rubber, Polym. Adv.Technol.,
vol. 23, pp. 825–828, 2011.
https://doi.org/10.1002/pat.1965
[8] S. Kawahara, W. Klinklai, H. Kuroda, Y. Isono,
Removal of proteins from natural rubber with urea,
Polym Adv Technol. Vol 15, pp. 181-184, 2004.
https://doi.org/10.1002/pat.465
[9] Rubber Research Institute of Malaysia, Determination
of nitrogen, SMR Bull. No.1, Part B.7, Now. 1973.
[10] S Toki, J Che, L Rong, BS Hsiao, S Amnuaypornsri,
A Nimpaiboon, J Sakdapipanic, Entanglements and
networks to strain-induced crystallization and stress–
strain relations in natural rubber and synthetic
polyisoprene at various temperatures,
Macromolecules. Vol 46, pp. 5238-5248, 2013.
https://doi.org/10.1021/ma400504k