scholarly journals REVIEW: APPLICATION OF IRRADIATION TECHNOLOGY IN NATURAL RUBBER VULCANIZATION PROCESS

2021 ◽  
Vol 15 (1) ◽  
pp. 1
Author(s):  
Andri Saputra, S.ST., M.Eng.
Keyword(s):  
Natural Rubber ◽  
Vulcanization Process ◽  
Irradiation Technology

Radical Mechanisms in Saturated and Olefinic Systems. II. Disubstitutive Carbon-Carbon Cross-Linking by Tertiary Alkoxy Radicals in Isoprenic Olefins and Rubber

1951 ◽  
Vol 24 (4) ◽  
pp. 777-786
Author(s):  
E. H. Farmer ◽  
C. G. Moore
Keyword(s):  
Natural Rubber ◽  
Cross Linking ◽  
Chain Molecules ◽  
Alkoxy Radicals ◽  
Full Extent ◽  
Carbon Chains ◽  
Butyl Peroxide ◽  
High Degree ◽  
Vulcanization Process

Abstract The high degree of dehydrogenation effected by tert.-butoxy radicals at the α-methylenic groups of olefins enables these radicals to be used for the carbon-to-carbon cross-linking of unsaturated carbon chains, and especially of the polyisoprenic chains of natural rubber. Such cross-linking amounts to a vulcanization process in which the connecting links between chain molecules are just C—C bonds, which may be expected to have appropriate attributes. An examination has first been made of the cross-linking produced by tert.- butoxy radicals (from di-tert.-butyl peroxide) at 140° between the short iso-prenic chains in 1-methylcyclohexene, 4-methylhept-3-ene, 2,6-dimethylocta-2, 6-diene, and digeranyl. Cross-linking proceeds efficiently in each case, and the points of union in these isoprene units which become directly joined are not confined to original α-methylenic carbon atoms. Where the reagent radicals are in considerable deficit, e.g., one per two or three of the isoprene units present, those olefin molecules which are attacked become linked together mostly by single unions to form aggregates containing two, three or four molecules; but in the tetraisoprenic olefins the extent to which more than one union is formed between some of the directly linked molecules becomes appreciable. In natural rubber, cross-linking occurs smoothly and to nearly the full extent corresponding to the (in practice restricted) proportion of peroxidic reagent employed. Good vulcanizates can be so obtained in which the tensile stength is found to increase towards a maximum and then to decline rapidly as the degree of cross-linking steadily increases. Thus to obtain vulcanizates of the optimum physical characteristics, the degree of cross-linking must be suitably chosen. The role of the peroxidic reagent is almost entirely non-additive and non-degradative.

Simulation of Irradiation-Based Processing System for Natural Rubber Vulcanization

2017 ◽  
Vol 751 ◽  
pp. 252-257
Author(s):  
Kittiya Kosaentor ◽  
Ekkachai Kongmon ◽  
Chitrlada Thongbai ◽  
Sakhorn Rimjaem
Keyword(s):  
Electron Beam ◽  
Natural Rubber ◽  
Beam Energy ◽  
Natural Rubber Latex ◽  
Processing System ◽  
Electron Beam Energy ◽  
Rubber Latex ◽  
Electron Beam Processing ◽  
Study Results ◽  
Vulcanization Process

Natural rubber is an important export product of Thailand, which presently contributes about 40% of global production and export. In order to make the natural rubber latex to be durable material, the proper vulcanization process is needed. In typical vulcanization process, chemical substances are added to improve the rubber properties. This may cause some problems e.g. toxicity, blooming effects and unpresented smell due to the additive substances. Vulcanization using an accelerated electron beam does not need to add possibly toxic chemical compounds, especially sulfur. Thus, it was proved to be an alternative method for high quality natural rubber vulcanization. This paper presents about simulation of electron beam irradiation for natural rubber vulcanization with variable electron beam energy and current of 0.5-4 MeV and 10-100 mA, respectively. These ranges of the electron beam energy and current will give adjustable absorb dose, which is the most important parameter for electron beam processing. The absorb energy and its distribution in the natural rubber latex are simulated by using a Monte Carlo method program, GEometry ANd Tracking 4 (GEANT4), with the aim to find the optimal conditions of electron beam properties for sufficient natural rubber vulcanization. Study results of the energy distribution for electron beam penetration in the natural rubber latex are presented and discussed in this paper.

The Effect of Pre-Vulcanization Temperature on Mechanical and Rheological Properties of Starch Filled Natural Rubber Latex Compounds

2013 ◽  
Vol 858 ◽  
pp. 184-189
Author(s):  
Siti Rohana Yahya ◽  
Farah Nadiah Hamdan ◽  
Azura A. Rashid ◽  
Baharin Azahari
Keyword(s):  
Natural Rubber ◽  
Rheological Properties ◽  
Room Temperature ◽  
Natural Rubber Latex ◽  
Shear Thickening ◽  
Filler Loading ◽  
Latex Films ◽  
Rubber Latex ◽  
Thickening Behavior ◽  
Vulcanization Process

The main objective of this study was to investigate the effect of the pre-vulcanization temperature on mechanical and rheological properties of starch filled natural rubber (NR) latex films. The 10 phr filler loading of starch was added into the latex prior to the pre-vulcanization process at 60°C to 140°C. The dipped films were cured in the oven at 100°C for 20 minutes and cooled at room temperature for 24 hours before stripping. The rheological properties of NR latex compounds were studied based on the viscosity measurement. The tensile and tear tests of starch filled NR latex films were also carried out. The results indicated that the rheological properties of the latex compounds showed shear thickening behavior where viscosity was increased with the increase in shear rate and pre-vulcanization temperature proportionally. The pre-vulcanization temperature at 80°C showed the optimum mechanical properties of starch filled NR latex films.

Characterization of the Reversion Process in Accelerated Sulfur Curing of Natural Rubber

1981 ◽  
Vol 54 (4) ◽  
pp. 734-750 ◽  
Author(s):  
C. H. Chen ◽  
J. L. Koenig ◽  
J. R. Shelton ◽  
E. A. Collins
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Structural Basis ◽  
Rubber Vulcanizate ◽  
Chemically Induced ◽  
Vulcanization Process ◽  
Sulfur Curing

Abstract From studies of a series of accelerated sulfur vulcanizations of natural rubber, the structural basis of the reversion in macroscopic physical-mechanical properties has been determined. The amount of chemically induced trans-methine butadiene-like structure increases as the reversion process proceeds. When there is no observable reversion, there is no detectable trans-methine butadiene-like structure. The presence of the trans-methine butadiene-like structure is detrimental to the properties of the natural rubber vulcanizate. The vulcanization process involves two competing processes, namely, crosslinking and desulfuration. The latter process produces the trans-methine structure which is responsible for the reversion in properties.

scholarly journals Sulfur Vulcanization of Natural Rubber for Benzothiazole Accelerated Formulations: From Reaction Mechanisms to a Rational Kinetic Model

2003 ◽  
Vol 76 (3) ◽  
pp. 592-693 ◽  
Author(s):  
Prasenjeet Ghosh ◽  
Santhoji Katare ◽  
Priyan Patkar ◽  
James M. Caruthers ◽  
Venkat Venkatasubramanian ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Natural Rubber ◽  
Reaction Mechanisms ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Wide Range ◽  
Sulfur Vulcanization ◽  
Vulcanization Process ◽  
Single Set

Abstract The chemistry of accelerated sulfur vulcanization is reviewed and a fundamental kinetic model for the vulcanization process is developed. The vulcanization of natural rubber by the benzothiazolesulfenamide class of accelerators is studied, where 2-(morpholinothio) benzothiazole (MBS) has been chosen as the representative accelerator. The reaction mechanisms that have been proposed for the different steps in vulcanization chemistry are critically evaluated with the objective of developing a holistic description of the governing chemistry, where the mechanisms are consistent for all reaction steps in the vulcanization process. A fundamental kinetic model has been developed for accelerated sulfur vulcanization, using population balance methods that explicitly acknowledge the polysulfidic nature of the crosslinks and various reactive intermediates. The kinetic model can accurately describe the complete cure response including the scorch delay, curing and the reversion for a wide range of compositions, using a single set of rate constants. In addition, the concentration profiles of all the reaction intermediates as a function of polysulfidic lengths are predicted. This detailed information obtained from the population balance model is used to critically examine various mechanisms that have been proposed to describe accelerated sulfur vulcanization. The population balance model provides a quantitative framework for explicitly incorporating mechanistically reasonable chemistry of the vulcanization process.

A Vibrational Spectroscopic Analysis of the Structure of Natural Rubber

1987 ◽  
Vol 60 (4) ◽  
pp. 647-658 ◽  
Author(s):  
F. J. Lu ◽  
S. L. Hsu
Keyword(s):  
Natural Rubber ◽  
Functional Groups ◽  
Spectroscopic Analysis ◽  
Extraction Solvent ◽  
Gel Fraction ◽  
Gel Phase ◽  
Composition Structure ◽  
Vulcanization Process ◽  
Structural Aspects ◽  
Soluble Part

Abstract It is not an overstatement to say that natural rubber (NR) is one of the most used polymers. There are numerous studies dealing with the structural aspects of rubber which give rise to its elastic property. However, it should be emphasized that the majority of these studies are generally concerned with rubber in the vulcanized state or, in fact, dealing with the vulcanization process. Relatively few studies have actually been directed at a better understanding of the composition, structure, and properties of raw rubber. This area of study is also important because the composition and the structure of NR differ from synthetic polyisoprene in that the presence of functional groups on main chains and nonrubbery materials, such as proteins, can significantly affect the rheological properties and the processing conditions of rubber before the vulcanization process. Raw rubber can be divided into two different fractions, sol (soluble part) and gel (insoluble part). Of course, this definition depends somewhat on the solvent used. Even though the main chain in both portions of rubber are chemically similar, their significantly distinct mechanical properties have, in fact, been attributed to the nonrubbery materials such as proteins interacting with isoprene chains. It is generally accepted that the amount of nonrubbery materials in the gel fraction is much higher than the sol fraction. The protein apparently interacts quite strongly with specific functional groups on the isoprene chain and is difficult to remove from the gel phase by physical means. It is probable that the different properties between sol and gel rubber is due to the amount of crosslinking of the main chains, but several aspects of the structure need to be answered in greater detail. We know, for example, that the amount of gel fraction can change as a function of extraction solvent. Therefore, one cannot conclude that the interaction between rubber chains even in the gel fraction is strictly chemical in nature. Our premise is that the protein is an important component connecting the isoprene chains.

Acceleration by Thiourea and Related Compounds of the Tetramethylthiuram Disulfide Vulcanization of Natural Rubber

1961 ◽  
Vol 34 (3) ◽  
pp. 795-797 ◽  
Author(s):  
C. G. Moore ◽  
B. Saville ◽  
A. A. Watson
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Tetramethylthiuram Disulfide ◽  
Reasonable Explanation ◽  
Vulcanization Process ◽  
Related Compounds ◽  
Curing Systems

Abstract It has recently been discovered that thiourea and certain of its N-derivatives and chemically related compounds, accelerate the vulcanization of natural rubber (NR) by tetramethylthiuram disulfide (TMTD)-zinc oxide combinations to such an extent that excellent vulcanizates can be produced at 100° C or lower. A reasonable explanation of this acceleration is now offered, based on a theory of vulcanization by TMTI) and related “sulfurless” curing systems currently being developed here. This theory recognizes the importance of polysulfidic intermediates (I, m>2), formed during the vulcanization process, which subsequently react with the polyisoprene to yield further intermediates (II) which finally react to yield sulfurated crosslinks. The process is broadly schematized as follows:

Properties of Thermoplastic Natural Rubber (TPNR): Influence of Polypropylene Grades on TPNR Properties

2013 ◽  
Vol 844 ◽  
pp. 127-130 ◽  
Author(s):  
Chanida Manleh ◽  
Charoen Nakason ◽  
Natinee Lopattananon ◽  
Azizon Kaesaman
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Rubber Particle ◽  
Complex Viscosity ◽  
Morphological Properties ◽  
Dynamic Vulcanization ◽  
Thermoplastic Natural Rubber ◽  
Pp Blends ◽  
Vulcanization Process

Thermoplastic vulcanizate (TPV) based on natural rubber (NR) and polypropylene (PP) blends were successfully prepared through a dynamic vulcanization process using Brabender Plastograph EC Plus with a rotor speed of 60 rpm at 180°C. Sulfur vulcanization system was used to cure rubber phase in the TPVs. Three grades of PP (i.e., PP700J, HP553R and HP544T) were used to blend with NR at a fixed blend ratio of NR/PP = 60/40. The mechanical properties, crosslink density, complex viscosity and morphological properties of the blends were examined. The results revealed that the dynamically cured NR/PP700J samples showed the best mechanical properties because of higher crosslink density and smaller rubber particle size when compared with those of the blends combined with HP553R and HP544T. Furthermore, the complex viscosity of the TPVs was highest for the blends with PP700J.

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