Modification of deproteinized natural rubber via grafting polymerization with maleic anhydride

Abstract The linear character of transesterified deproteinized natural rubber (DPNR-TE) was confirmed by the analysis of terminal groups with NMR and viscometric analyses. The branch content of DPNR rubber from fresh latex was found to range from 0.3 to 1.3 and 0.7 to 3.2, based on tri- and tetra-functionalities, respectively. The plot between the number of branch-points and molecular weight (MW) can be divided into three fractions: (A) the rubber fractions in MW ranging from 2.4×105 to 1.9×106; (B) between 1.9×105 and 2.4×105; and (C) those of MW less than 1.9×105. The fraction (A) showed the number of branch-points per a branched molecule (m) higher than that of fractions (B) and (C). This plot is superimposable with the bimodal molecular-weight distribution (MWD) of Hevea rubber, showing a good coinciding of peak-tops at the high and low MW fractions. It seems likely that there is a close relationship between the number of branch-point and bimodal MWD of natural rubber.

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Thermal and Thermo-Oxidative Degradations of Deproteinized Natural Rubber and Natural Rubber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.306-307.50 ◽

2011 ◽

Vol 306-307 ◽

pp. 50-57 ◽

Cited By ~ 1

Author(s):

Can Zhong He ◽

Zheng Peng ◽

Jie Ping Zhong ◽

Shuang Quan Liao ◽

Xiao Dong She ◽

...

Keyword(s):

Thermal Stability ◽

Natural Rubber ◽

Oxidative Stability ◽

Natural Rubber Latex ◽

Oxidative Degradation ◽

Decomposition Reaction ◽

Nitrogen Atmosphere ◽

Degradation Temperature ◽

Air Atmosphere ◽

Deproteinized Natural Rubber

Deproteinization of natural rubber was achieved in the latex stage. The structure of deproteinized natural rubber (DPNR) was characterized by fourier transform infrared spectroscopy (FTIR). The thermo degradation of DPNR was studied by thermogravimetry analysis (TG) under air atmosphere and nitrogen atmosphere. The kinetic parameters apparent activation energies (Ea) of the thermal decomposition reaction been calculated from the TG curves using the method described by Broido. And the results were compared with the thermo degradation of natural rubber (NR) under the same conditions. The effect of proteins in natural rubber latex on thermal/ thermo-oxidative stability of NR was discussed. The results show that: the absorptions of the proteins in DPNR at 1546 ㎝-1, compared to NR, become significantly weaker, nearly disappear, which indicates most of proteins has been removed from NR. The thermo degradation of DPNR in nitrogen atmosphere is a one-step reaction. The initial degradation temperature (T0) 、the maximum degradation temperature（Tp） and the final degradation temperature（Tf）as well as the Ea of DPNR are higher than those of NR, which indicates that DPNR represents a better thermal stability than NR under nitrogen atmosphere. Thermo-oxidative degradation of DPNR and NR are two-step reaction. The characteristic temperatures (T0, Tp and Tf) of DPNR are lower than those of NR. The Ea during the First Step of Thermooxidative Degradation of DPNR are also lower than those of NR. These results prove that the thermo-oxidative stability of DPNR is worse than that of NR. Protein is the key role to the thermal stability of natural rubber.

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Natural Rubber Composites Filled with Cereals Straw Modified with Acetic and Maleic Anhydride: Preparation and Properties

Journal of Polymers and the Environment ◽

10.1007/s10924-018-1285-5 ◽

2018 ◽

Vol 26 (10) ◽

pp. 4141-4157 ◽

Cited By ~ 9

Author(s):

Marcin Masłowski ◽

Justyna Miedzianowska ◽

Krzysztof Strzelec

Keyword(s):

Maleic Anhydride ◽

Natural Rubber ◽

Rubber Composites ◽

Natural Rubber Composites

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PROTEIN INFLUENCE ON THE MECHANICAL PROPERTIES OF NR

Rubber Chemistry and Technology ◽

10.5254/rct.21.79916 ◽

2021 ◽

Author(s):

Yayoi Akahori ◽

Misao Hiza ◽

Soki Yamaguchi ◽

Seiichi Kawahara

Keyword(s):

Mechanical Properties ◽

Nmr Spectroscopy ◽

Sodium Dodecyl Sulfate ◽

Carbon Black ◽

Natural Rubber ◽

Hevea Brasiliensis ◽

Sodium Dodecyl ◽

Swelling Degree ◽

Deproteinized Natural Rubber ◽

Rubber State

ABSTRACT Protein effect on vulcanization of NR, obtained from Hevea brasiliensis, was investigated by analyzing the crosslinking structure of the resulting vulcanizates prepared from untreated NR, deproteinized natural rubber (DPNR), and protein-free natural rubber (PFNR) by swelling methods and rubber-state NMR spectroscopy. The proteins present in NR were removed by three methods: deproteinization with enzyme, urea, or urea–acetone in the presence of sodium dodecyl sulfate. The amount of proteins present in NR, approximately 0.238 w/w%, was reduced to 0.000 w/w% by urea–acetone deproteinization, whereas it was reduced to approximately 0.003 and 0.019 w/w% by enzyme and urea deproteinizations, respectively. Hardness, swelling degree, and crosslinking structure depended on the amount of proteins. Changes in mechanical properties for the vulcanizates prepared from not only non-filler compounds but also carbon black–filled and silica-filled compounds were attributed to the amount of proteins.

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