Characterizing the naturally occurring sacrificial bond within natural rubber

Polymer ◽  
2019 ◽  
Vol 161 ◽  
pp. 41-48 ◽  
Author(s):  
Xuan Fu ◽  
Cheng Huang ◽  
Yong Zhu ◽  
Guangsu Huang ◽  
Jinrong Wu
Keyword(s):  
Natural Rubber ◽  
Naturally Occurring

Effect of Metallic Poisons. Especially Manganese, on Aging of Vulcanized Natural Rubber

1947 ◽  
Vol 20 (3) ◽  
pp. 821-826
Keyword(s):  
Organic Acids ◽  
Natural Rubber ◽  
Harmful Effect ◽  
Manganese Compound ◽  
Naturally Occurring ◽  
Different Types ◽  
Salts Of Organic Acids ◽  
General Experience ◽  
Manganese Compounds ◽  
Harmful Effects

Abstract 1. Information received from rubber manufacturers on their experience of the effects of manganese and copper on aging is summarized. Although there is evidence that the amounts of these impurities in fillers tended to increase during the early war years (1939–42), it seems to be the general experience that little trouble arose from their effects on the properties of the rubber. Fillers containing as much as 0.05–0.10 per cent of manganese, or 0.005 per cent of copper, have not shown any obvious harmful effects. 2. Experiments with a large number of manganese compounds, including naturally occurring (mineral) forms and salts of organic acids, used in amounts equivalent to 0.01 per cent manganese on the raw rubber, have failed to show any pronounced harmful effect on the aging (oven or oxygen bomb) of a vulcanized natural rubber containing mercaptobenzothiazole, although deterioration was noticeably accelerated in some cases. Probably on account of the smallness of the effects observed, it is not possible as yet to draw any conclusion as to the relative activities of different types of manganese compound. 3. According to results of previous workers, manganese in the amount used in the present experiments can produce a more serious effect than these experiments indicate. The effect of manganese is known to depend on the type of mix used, and this aspect of the problem would thus appear to merit further investigation, as does also the influence of the method and degree of dispersion of the manganese compound in the rubber mix.

Strain-Induced Crystallization of Natural Rubber: Effect of Proteins and Phospholipids

2008 ◽  
Vol 81 (5) ◽  
pp. 753-766 ◽  
Author(s):  
Sureerut Amnuaypornsri ◽  
Jitladda Sakdapipanich ◽  
Shigeyuki Toki ◽  
Benjamin S. Hsiao ◽  
Naoya Ichikawa ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Decomposition Methods ◽  
Uniaxial Deformation ◽  
X Ray Diffraction ◽  
High Mechanical Property ◽  
Naturally Occurring ◽  
Stress Strain Relation ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract The effects of proteins and phospholipids in natural rubber (NR) on the strain-induced crystallization behavior during uniaxial deformation were studied by in-situ synchrotron wide-angle X-ray diffraction (WAXD) technique and simultaneous measurements of stress-strain relation. The influences of proteins and phospholipids in NR were evaluated separately by decomposition methods using deproteinization and lipase treatment, respectively. It was found that both components form a naturally occurring network, which is responsible for the strain-induced crystallizability of unvulcanized NR and the corresponding high mechanical property. This network also plays a significant role in strain-induced crystallization of vulcanized natural rubber.

Crystallization and Morphology of Rubber

1995 ◽  
Vol 68 (3) ◽  
pp. 507-539 ◽  
Author(s):  
J. H. Magill
Keyword(s):  
Natural Rubber ◽  
Developmental Stages ◽  
Synthetic Polymers ◽  
Material Behavior ◽  
Science And Engineering ◽  
Good Science ◽  
Thermodynamics And Kinetics ◽  
Naturally Occurring ◽  
Scientists And Engineers ◽  
Resource Material

Abstract Naturally occurring materials like rubber predate the development of science and engineering as we know it today. Historically, rubber and more generally elastomers, known as a class of high polymers, are versatile and useful materials. Rubber is still an elastomer of choice for many engineering applications. After decades of R&D, scientists and engineers realized that technology needs good science. This position is nicely summarized in Figure 1. This scenario brings together four main items that are essential to create and to maintain quality industry(ies). In the case of rubber, particularly natural rubber, it is not only essential to understand these individual properties, but also to comprehend the important interrelationships that contribute to material behavior. In this respect, rubber has been an enabling resource material that has served as a paradigm amongst synthetic polymers in their developmental stages. In this article crystallization of natural rubber especially, is addressed in order to provide some perspective on items that relate to the relevant areas of the pyramid. This overview is far from exhaustive on the crystallization aspects of rubber, but hopefully it strikes a balance between thermodynamics and kinetics, since each discipline has contributed significantly to improve our understanding of polyisoprenes, and in a wider sense to crystallization and morphology that helps determine properties relevant to rubber and to polymers in general.

Infrared Examination of Various Polyisoprenes

1954 ◽  
Vol 27 (2) ◽  
pp. 348-362
Author(s):  
W. S. Richardson ◽  
A. Sacher
Keyword(s):  
Quantitative Analysis ◽  
Natural Rubber ◽  
Rheological Properties ◽  
General Problem ◽  
Naturally Occurring ◽  
High Polymers ◽  
Effect Of Microstructure

Abstract It is well known that, in general, the laboratory polymerization of diene monomers leads to materials which are intramolecular mixtures of various types of addition products. Thus, synthetic polyisoprene has been shown to contain chemical groupings arising from 1,2, 3,4, and 1,4 addition of the isoprene units. This is in contrast to the naturally occurring high polymers of isoprene, the rubbers and guttas, which appear to be exclusively cis-1,4 and trans-1,4 adducts, respectively. An exception to this last statement is the polyisoprene derived from chicle, which is a mixture of cis-1,4 and trans-1,4 addition. In this case, however, the mixture is an intermolecular one, and fractionation of the material leads to components which are all cis-1,4 and all trans-1,4. The general problem of diene polymerization is, of course, of great importance, and the synthetic polyisoprenes are of particular interest because of their relationship to natural rubber. The following attempt to obtain a quantitative analysis for the various types of addition occurring in synthetic polyisoprenes may lead to a better understanding of the nature of these materials and may be of help in elucidating the effect of microstructure on rheological properties.

Measurement of Tensile Strength of Natural Rubber Vulcanizates at Elevated Temperature

1982 ◽  
Vol 55 (1) ◽  
pp. 66-75 ◽  
Author(s):  
C. L. M. Bell ◽  
D. Stinson ◽  
A. G. Thomas
Keyword(s):  
Tensile Strength ◽  
Elevated Temperature ◽  
Critical Temperature ◽  
Natural Rubber ◽  
Test Piece ◽  
Flaw Size ◽  
High Tensile Strength ◽  
Test Pieces ◽  
Naturally Occurring ◽  
Natural Rubber Vulcanizates

Abstract The tensile strength of test pieces made from natural rubber vulcanizates drops abruptly at a critical temperature which can vary from 40 to 130°C. This variation in critical temperature is shown here to be a result of the variation in critical cut length with temperature. When the naturally occurring flaws in the test piece are smaller than the critical cut length, high tensile strength values occur, but when the flaws are longer than the critical cut length, low tensile strength values occur. The critical cut length decreases as the temperature increases, and the abrupt drop in tensile strength occurs as the critical cut length reaches the natural flaw size in the test piece. The natural flaw size in tensile test pieces depends on the sharpness of the cutter, and for tensile strength measurements at elevated temperature, it is shown that even a slightly blunt cutter may give markedly different results from a sharp one.

scholarly journals The Staining of Polymers

2002 ◽  
Vol 10 (5) ◽  
pp. 5-7
Author(s):  
Ronald W. Smith
Keyword(s):  
Electron Microscopy ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Optical Microscope ◽  
Hot Water ◽  
Polymeric System ◽  
Rubber Latex ◽  
Naturally Occurring ◽  
Contrast Mechanism ◽  
In The Beginning

In the beginning there was water-the first stain that delineated structure within a polymeric system. The polymerwas natural rubber (NR) and the system was an air-dried film of natural latex. Grenquist reported in 1929 that a dried film of natural rubber latex soaked in hot water became milky (Figure 1) and, at that stage, the latex particles could be detected by the optical microscope (OM), The contrast mechanism was provided by the absorption of water by the naturally occurring proteinaceous layers present on the congealed NR particle surfaces. There was little demand for polymer staining until the age of electron microscopy.

Cis-Trans Isomerization in Polybutadiene

1957 ◽  
Vol 30 (4) ◽  
pp. 1142-1145
Author(s):  
M. A. Golub
Keyword(s):  
Natural Rubber ◽  
Structural Changes ◽  
Titanium Tetrachloride ◽  
Present Knowledge ◽  
Low Molecular Weight ◽  
High Polymer ◽  
Gutta Percha ◽  
Naturally Occurring ◽  
Trans Isomerization ◽  
Cis And Trans

Abstract About twenty years ago, in an effort to transform natural rubber into gutta-percha, Meyer and Ferri irradiated a solution of Hevea in cyclohexane with ultraviolet light, but were unable to detect any cis-trans isomerization in polyisoprene. Later, Ferri showed that treatment of both Hevea and Gutta with certain chemicals, such as chlorostannic acid and titanium tetrachloride, gave rise to closely resembling products which were considered at the time to have structures intermediate between the two geometric forms of naturally-occurring polyisoprene. These resulting polymers were, however, crosslinked in the course of chemical treatment and probably also cyclized, so that in the light of present knowledge about the cyclizing tendencies of the materials employed, this change cannot be regarded as a genuine interconversion of cis and trans double bonds. No true instance of cis-trans isomerization unaccompanied by other structural changes has been reported heretofore for a high polymer, except for the polyenes which are conjugated structures of relatively very low molecular weight. This communication reports the successful transformation of the cis-1,4 units in polybutadiene into corresponding trans units by means of ultraviolet irradiation in the presence of a suitable sensitizer, which may be any one of a wide variety of organic bromine or sulfur compounds. Surprisingly, this isomerization could not be induced in natural rubber.

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