scholarly journals Biobased Contents of Natural Rubber Model Compound and Its Separated Constituents

Polymers ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 423-442 ◽  
Author(s):  
Masao Kunioka ◽  
Kazuhiro Taguchi ◽  
Fumi Ninomiya ◽  
Mari Nakajima ◽  
Akira Saito ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Model Compound ◽  
Rubber Model

Halogenation of Butyl Rubber—A Model Compound Approach

1984 ◽  
Vol 57 (2) ◽  
pp. 275-283 ◽  
Author(s):  
R. Vukov
Keyword(s):  
Model Compound ◽  
Product Distribution ◽  
Butyl Rubber ◽  
Methyl Groups ◽  
Reaction Site ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Basic Study ◽  
Rubber Model ◽  
Trisubstituted Alkenes

Abstract The study of the halogenation behavior of butyl rubber model compounds has brought about a better understanding of the behavior of these systems. It has been established that the presence of methyl groups, in a position B to the reaction site in the butyl rubber model compound, profoundly influences the course of halogenation. Due to the steric hindrance imposed by these groups, both the products of chlorination and bromination deviate from patterns typical of other trisubstituted alkenes. In the case of chlorination, this deviation is demonstrated by the absence of addition products of chlorine across the double bond. In the case of bromination reactions, the change in product distribution is even more dramatic. Thus, substitution products normally not observed in bromination reactions of other trisubstituted alkenes become predominant products found in yields of between 70–90% depending on the precise reaction conditions. The behavior of the butyl model compound appears to be entirely consistent with the behavior of butyl rubber itself; the model compound approach is therefore a valuable tool for use in the basic study of this type of system.

Model Compound Vulcanization—Part IV. Comparative Assessment of Sulfenamide and Triazine Accelerators

1979 ◽  
Vol 52 (5) ◽  
pp. 1050-1056
Author(s):  
F. K. Lautenschlaeger ◽  
K. Edwards ◽  
M. C. Kirkham
Keyword(s):  
Natural Rubber ◽  
Relative Efficiency ◽  
Model Compound ◽  
Product Yield ◽  
Comparative Assessment ◽  
Natural Rubber Vulcanizates

Abstract The application of model compound vulcanization (MCV) to the rating of the relative efficiency of CBS (N-Cyclohexylbenzothiazole-2-sulfenamide) and an experimental triazine-based accelerator is demonstrated. The sulfur to accelerator ratios were established at which both accelerators lead to the same total sulfidic product yield. At these ratios, selected initial properties of natural rubber vulcanizates and their reversion resistance are similar. Hence, the increased reversion resistance of triazine-accelerated natural rubber vulcanizates is essentially due to their greater efficiency in converting sulfur into sulfidic crosslinks. A higher level of the less efficient CBS leads to similar results. This analysis shows that MCV simplifies the evaluation of accelerators.

ZINC OXIDE VERSUS MAGNESIUM OXIDE REVISITED. PART 1

2012 ◽  
Vol 85 (1) ◽  
pp. 38-55 ◽  
Author(s):  
Manuel Guzmán ◽  
Berta Vega ◽  
Núria Agulló ◽  
Ulrich Giese ◽  
Salvador Borrós
Keyword(s):  
Zinc Oxide ◽  
Environmental Impact ◽  
Natural Rubber ◽  
Metal Oxides ◽  
Environmental Effects ◽  
Model Compound ◽  
Rubber Industry ◽  
Sulfur Vulcanization ◽  
Activator System

Abstract Zinc oxide is a widely used compound in the rubber industry due to the excellent properties that it shows as activator, and consequently, its role in the mechanism of accelerated sulfur vulcanization has been extensively studied. Due to the increased concern about its environmental effects, several research studies have been carried out in order to substitute it with different metal oxides such us MgO. The effect of the activator system in order to minimize the environmental impact of the rubber goods has been explored. The work developed is presented in two parts. In Part 1, the influence of different mixtures of ZnO and MgO on the vulcanization of natural rubber has been investigated. In Part 2, model compound vulcanization has been used to study the role of MgO on the mechanism to gain a better understanding of the differences shown in Part 1.

ZINC OXIDE VERSUS MAGNESIUM OXIDE REVISITED. PART 2

2012 ◽  
Vol 85 (1) ◽  
pp. 56-67 ◽  
Author(s):  
Manuel Guzmán ◽  
Berta Vega ◽  
Núria Agulló ◽  
Salvador Borrós
Keyword(s):  
Zinc Oxide ◽  
Environmental Impact ◽  
Natural Rubber ◽  
Metal Oxides ◽  
Environmental Effects ◽  
Model Compound ◽  
Rubber Industry ◽  
Sulfur Vulcanization ◽  
Activator System

Abstract Zinc oxide is a widely used compound in the rubber industry due to the excellent properties that it shows as an activator and, consequently, its role in the mechanism of accelerated sulfur vulcanization has been extensively studied. Due to the increased concern about its environmental effects, several research studies have been carried out in order to substitute it with different metal oxides such us MgO. The effect of the activator system in order to minimize the environmental impact of the rubber goods has been explored. The work developed is presented in two parts. In Part 1, the influence of different mixtures of ZnO and MgO in the vulcanization of natural rubber has been investigated. In Part 2 of the study, model compound vulcanization has been used to study the role of MgO on the mechanism to gain a better understanding of the differences shown in the first part.

Study of the Influence of Microwaves in the Mechanism of Sulfenamide Accelerated Vulcanization of Natural Rubber Using Squalene as a Model Compound

2007 ◽  
Vol 80 (5) ◽  
pp. 739-750 ◽  
Author(s):  
B. Vega ◽  
N. Agulló ◽  
S. Borrós
Keyword(s):  
Natural Rubber ◽  
Model Compound ◽  
Rate Increase ◽  
Heating System ◽  
Conventional Heating ◽  
Crosslinking Degree ◽  
Reaction Rate Increase ◽  
Heating Source ◽  
Sulfur Transfer

Abstract The natural rubber vulcanization mechanism has been studied using microwaves as a heating source. The influence of such heating system on the mechanism reaction has been elucidated. In order to simplify the study of this process, squalene has been used as a Model Compound Vulcanization (MCV) for natural rubber and N-cyclohexyl-2-benzothiazolesulfenamide (CBS) as an accelerator. The accelerator fading, the crosslinking degree, the reversion process and the effect of the double bond have been studied and the results have been compared with previous results of our group using MCV with conventional heating. As well as the expected reaction rate increase, a noticeable change in the crosslink degree has been observed. Furthermore, some differences have been detected in the amount of the intermediate compounds formed during the reaction and in the sulfur transfer to the squalene chain. Strong differences have been also observed regarding the role of the activator in the vulcanization when microwaves are used.

Morphology and Crystallization Behavior of Lightly Crosslinked Natural Rubber in Blend

2003 ◽  
Vol 76 (5) ◽  
pp. 1164-1176 ◽  
Author(s):  
Tetsuji Kawazura ◽  
Seiichi Kawahara ◽  
Yoshinobu Isono
Keyword(s):  
Natural Rubber ◽  
Homogeneous Nucleation ◽  
Crosslink Density ◽  
Model Compound ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Gel Content ◽  
Gel Fraction ◽  
Compound Model ◽  
Styrene Butadiene

Abstract Isothermal crystallization of natural rubber (NR) dispersed in styrene-butadiene rubber (SBR) was made at −25 °C to investigate effects of both gel fraction of the rubber and morphology of the blend on the crystallization. NR, thus used, was lightly crosslinked model compound (model-NR), which was cured with dicumylperoxide at 160 °C after mastication. The model-NR was mechanically mixed with a large amount of SBR to form droplets of the rubber, a size of which was dependent upon both gel content and crosslink density of the gel fraction. The crystallization of the model-NR in the droplets was quite slow, corresponding to the level reported in the previous work. A rate of crystallization and Avrami exponent were dependent upon the size of the droplets, but not on the gel content and the crosslink density of the model-NR. The suppression in the crystallization was attributed to the homogeneous nucleation occurring in the droplets. This finding was proved, using rubbers obtained from two clones of Hevea brasiliensis, i.e. RRIM600 and RRIM2025, respectively.

Model Compound Vulcanization—Part II. Comparison of Accelerators

1979 ◽  
Vol 52 (5) ◽  
pp. 1030-1043 ◽  
Author(s):  
F. K. Lautenschlaeger ◽  
P. Zeeman
Keyword(s):  
Liquid Chromatography ◽  
Natural Rubber ◽  
Model Compound ◽  
Gas Liquid Chromatography ◽  
Product Yields ◽  
Isomer Distribution ◽  
Different Types ◽  
Natural Rubber Vulcanizates

Abstract The efficiency of each of 20 accelerators to convert sulfur into sulfidic products has been evaluated by Model Compound Vulcanization. The sulfidic products can be isolated and identified by gas-liquid chromatography. The sulfidic products can be separated into groups of mono-, di- and trisulfides, with several isomeric products within each group. This paper has reported on the analysis of such isomeric products which correspond to different types of sulfur crosslinks in natural rubber vulcanizates. The analysis of monosulfidic product yields and of the isomer distribution within the monosulfide group is sufficient to characterize an accelerator.

Spectroscopic Studies on Reaction between Squalene and Vulcanizing Agents in the Presence and Absence of Zinc-2-Mercaptopyridine-N-Oxide

2004 ◽  
Vol 77 (2) ◽  
pp. 201-213
Author(s):  
C. C. Pierre ◽  
R. N. Datta
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Nmr Spectroscopy ◽  
Carbon Black ◽  
Natural Rubber ◽  
High Performance ◽  
Model Compound ◽  
Spectroscopic Studies ◽  
Reversed Phase ◽  
Zinc Stearate

Abstract Model compound vulcanization in combination with reversed-phase high-performance liquid chromatography and NMR spectroscopy was used to elucidate the reactions of accelerator, sulfur, zinc stearate and zinc-2-mercaptopyridine-N-oxide (ZPNO) in natural rubber vulcanization. Studies of different curing ingredient formulations in squalene have been done to determine the influence of each component during the vulcanization. It was found that 2-mercaptopyridine-N-oxide bridged adducts (R-Sx-Pyr(O)) were formed when squalene was heated in the presence of sulfur, curing ingredients and 2,2′-dithiobis(pyridine-N-oxide) (PyrO-S2-PyrO). Possible interactions of R-Sx-Pyr(O) with carbon black have been proposed.

Model Compound Studies on the Devulcanization of Natural Rubber Using 2,3-Dimethyl-2-Butene

2005 ◽  
Vol 78 (4) ◽  
pp. 572-587 ◽  
Author(s):  
V. V. Rajan ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer ◽  
R. Joseph
Keyword(s):  
Molecular Weight ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Natural Rubber ◽  
High Performance ◽  
Model Compound ◽  
Zinc Stearate ◽  
Low Molecular Weight ◽  
Second Stage ◽  
Weight Model

Abstract The mechanism of devulcanization of sulfur-vulcanized natural rubber with aromatic disulfides and aliphatic amines has been studied using 2,3-dimethyl-2-butene (C6H12) as a low-molecular weight model compound. First C6H12 was vulcanized with a mixture of sulfur, zinc stearate and N-cyclohexyl-2-benzothiazylsulfenamide (CBS) as accelerator at 140 °C, resulting in a mixture of addition products (C6H11−Sx−C6H11). The compounds were isolated and identified by High Performance Liquid Chromatography (HPLC) with respect to their various sulfur ranks. In a second stage, the vulcanized products were devulcanized using the agents mentioned above at 200 °C. The kinetics and chemistry of the breakdown of the sulfur-bridges were monitored. Both devulcanization agents decompose sulfidic vulcanization products with sulfur ranks equal or higher than 3 quite effectively and with comparable speed. Diphenyldisulfide as devulcanization agent gives rise to a high amount of mono- and disulfidic compounds formed during the devulcanization, hexadecylamine, as devulcanization agent, prevents these lower sulfur ranks from being formed.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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