Ultraviolet Microscopy of Hevea Rubber Latex

1938 ◽  
Vol 11 (2) ◽  
pp. 405-422
Author(s):  
Francis F. Lucas
Keyword(s):  
Latex Particle ◽  
Chemical Analyses ◽  
Rubber Latex ◽  
Vulcanized Rubber ◽  
Ultraviolet Microscopy ◽  
Composition And Structure

Abstract This paper is a report of studies made on two bulk samples of commercial rubber latex by means of the ultraviolet microscope. This apparatus does not appear to have been used to an appreciable extent for the study of the rubber latex particle. Green (1) applied it to vulcanized rubber latex and apparently made some observations on unvulcanized latex. The author is indebted to A. R. Kemp of these laboratories for suggesting the microscopical studies here reported. In his paper Kemp gives chemical analyses of the two latices used in this investigation, and their composition and structure are discussed.

Composition and Structure of Hevea Latex

1938 ◽  
Vol 11 (2) ◽  
pp. 394-404
Author(s):  
A. R. Kemp
Keyword(s):  
Chemical Analyses ◽  
Ultraviolet Microscopy ◽  
Composition And Structure

Abstract Many properties of rubber are intimately related to the composition and structure of latex from which it is made. Some of these relations, however, remain obscure since our knowledge of latex structure and of the inner properties of rubber is lacking. The purpose of this paper is to help clear up some of the important questions relating to latex and rubber structure and to discuss their possible bearing on rubber properties. Composition of Ammonia-Preserved Latex This work and that of F. F. Lucas on ultraviolet microscopy of latex were carried out on commercial ammonia-preserved plantation latex taken from fresh shipments coming from two suppliers. The chemical analyses of these latices are given in Table I and are typical, although the composition of commercial liquid latex may vary somewhat, depending on many causes which will not be dealt with here.

Cryo-sectioning and chemical-fixing ultramicrotomy techniques for imaging rubber latex particle morphology

2004 ◽  
Vol 63 (2) ◽  
pp. 111-114 ◽  
Author(s):  
Nadaraja Subramaniam ◽  
Anne Simpson ◽  
Michael J. Monteiro ◽  
Olga Shaffer ◽  
Christopher M. Fellows ◽  
...  
Keyword(s):  
Latex Particle ◽  
Particle Morphology ◽  
Rubber Latex

scholarly journals Relationship Between Edaphic Factors and Vegetation in Savannas of the Brazilian Midwest Region

2015 ◽  
Vol 39 (3) ◽  
pp. 821-829 ◽  
Author(s):  
Michellia Pereira Soares ◽  
Paula Reys ◽  
Daniel Salgado Pifano ◽  
Janaílson Leônidas de Sá ◽  
Patrícia Oliveira da Silva ◽  
...  
Keyword(s):  
Soil Properties ◽  
Species Abundance ◽  
Basal Area ◽  
Floristic Composition ◽  
Chemical Analyses ◽  
Breast Height ◽  
Composition And Structure ◽  
Midwest Region ◽  
Abundance And Distribution ◽  
Physical And Chemical

The Brazilian savanna is a mosaic of phytophysiognomies influenced by edaphic and topographic factors that range from the occurrence of fires to anthropic disturbance. The goal of this study was a comparative analysis between two cerrado areas in southeastern Goiás, relating the floristic composition and structure of the vegetation to soil properties to better understand the physiognomic characteristics of the region. Twenty-five 20 × 20 m plots were used. All plants with circumference at breast height of more than 15 cm were measured. Soil samples collected at a depth of 0-20 cm were subjected to physical and chemical analyses. Canonical correspondence analysis (CCA) was used to detect possible correlations between the soil properties and species abundance and distribution. The density and total basal area were 1,647 ind/ha and 15.57 m2/ha, respectively, in Ouroana. At this site, 107 species were sampled. In Montes Claros de Goiás, the density and total basal area were 781 ind/ha and 17.62 m2/ha, and 120 species were sampled. The soil texture of Ouroana was sandy and significantly different from the medium to clayey texture of Montes Claros. The soils of both areas are dystrophic, however, more fertile in Montes Claros and aluminum-toxic in Ouroana. The species of vegetation were distributed according to soil fertility levels. The CCAs grouped species according to soil properties that defined location and abundance as well as the phytophysiognomies of the studied areas.

Chemical Compatibility as a Factor in the Dispersion of Fillers in Rubber

1962 ◽  
Vol 35 (4) ◽  
pp. 881-888 ◽  
Author(s):  
C. A. Carlton
Keyword(s):  
Zinc Oxide ◽  
Organic Acid ◽  
Resin Acids ◽  
Chemical Analyses ◽  
White Pigment ◽  
Inorganic Oxides ◽  
Vulcanized Rubber ◽  
Synthetic Rubber ◽  
Rubber Compounds ◽  
Time Dispersion

Abstract Poor dispersion of fillers in rubber compounds has been a troublesome problem since the beginning of the rubber industry. An example of this kind of difficulty is the presence of white pigment lumps in black or dark-colored compounds that are surface buffed, such as some types of shoe soling. Chemical analyses of filler agglomerates removed from a large number of unvulcanized and vulcanized rubber compounds revealed the fact that in practically every instance a substantial amount of zinc oxide was present. This is of major importance since good dispersion of zinc oxide is necessary for the proper vulcanization of a rubber compound. It is quite difficult to identify positively the specific variable or variables in any one given formulation which may cause filler agglomerates. They may be due to the composition of one or more of the ingredients present in the mix, the order in which the ingredients are added, or to the mixing procedure. However, a series of tests indicated one major cause, the addition of acidic materials such as fatty acids, organic acid vulcanization retarders, or acidic accelerators to natural rubber or some synthetic rubbers simultaneously with basic activators such as lime, litharge, magnesia, and zinc oxide, or with some basic fillers such as finely divided calcium and magnesium carbonates. High-temperature mixing (about 325° F) gave better dispersion than low-temperature mixing (about 220° F) when acidic or basic materials were added simultaneously, but in some instances poor dispersion resulted even at temperatures up to 325° F. This was particularly true of litharge and magnesia. It was also found that when zinc oxide and stearic acid were added to synthetic rubber at the same time, dispersion was better in some types of rubber than in others. The stiffer mixes of NBR (nitrile) and cold, unfilled SBR gave better dispersions than those of the softer IIR (butyl) and oil-extended SBR. Regardless of the type of rubber being used, the safest procedure to insure satisfactory dispersion of inorganic oxides is to add any acidic materials separately during the mixing procedure. This approach is particularly necessary if the mix contains resin acids and/or organic acid vulcanization retarders such as benzoic or salicylic acids. If it is not feasible to add the acidic and basic compounding materials separately to the rubber, then the inorganic oxides should be added to the mix in the form of masterbatches.

FOSSILIZATION OF THE EOCENE “MONKEYHAIR” LATICIFER TREE FROM GEISELTAL, GERMANY: A DEEPER UNDERSTANDING USING MICRO-CT AND PYROLYSIS GC/MS

Palaios ◽  
2021 ◽  
Vol 36 (1) ◽  
pp. 1-14
Author(s):  
VICTORIA E. MCCOY ◽  
ARNOUD BOOM ◽  
OLIVER WINGS ◽  
TORSTEN WAPPLER ◽  
CONRAD C. LABANDEIRA ◽  
...  
Keyword(s):  
Secondary Xylem ◽  
Middle Eocene ◽  
Early Diagenesis ◽  
Organic Sulfur ◽  
Micro Ct ◽  
Chemical Analyses ◽  
Parent Plant ◽  
X Ray ◽  
Vulcanized Rubber ◽  
First Time

ABSTRACT Although the fibrous plant material called Affenhaar from the middle Eocene lignites of Geiseltal in Germany has been repeatedly studied for over 172 years, modern imaging and chemical analyses have enabled a deeper understanding of its chemical composition and preservation within the parent plant. Known in English as “monkeyhair,” the fibrous material represents a very rare case of fossil laticifers, the latex-bearing ducts of plants. Here we use high-resolution X-ray microcomputed tomography (micro-CT) for the first time to elucidate the anatomy of tissues and their differential degradation within the monkeyhair tree. Even in large, fairly intact stem axes, the center cylinder of secondary xylem inside the trunks or branches is completely absent, presumably due to diagenetic degradation. Nevertheless, there is a moderately well-preserved outer layer of bark and mats of excellently preserved laticifers in the extraxylary zone beneath the bark. Previous chemical analyses revealed that the latex in these laticifers was dominated by natural rubber (cis-1,4-polyisoprene), but also included various triterpenoids. These fossil laticifers also contained large amounts of organic sulfur, suggesting the rubber may have been naturally vulcanized. Pyrolysis GC/MS is also applied to the fossil laticifers for the first time to identify the organic sulfur constituents of this ancient latex. The chemical analysis yields 12 major sulfur compounds, mostly thiophenes, consistent with vulcanized rubber. The vulcanization of these laticifers most likely occurred during early diagenesis, before the degradation of the wood, at low temperatures, and may have been facilitated with other compounds that served as accelerators, activators, and fillers.

scholarly journals ADSORPTION STUDIES IN A SYNTHETIC RUBBER LATEX-OVALBUMIN SYSTEM

1950 ◽  
Vol 34 (2) ◽  
pp. 183-192 ◽  
Author(s):  
H. B. Williams ◽  
A. R. Choppin
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Latex Particle ◽  
Particle Surface ◽  
Rubber Latex ◽  
Active Centers ◽  
Multilayer Adsorption ◽  
Synthetic Rubber ◽  
Synthetic Latex

1. Adsorption of ovalbumin on the latex surface was in excess of the quantity required to produce coverage of the surface over most of the protein concentrations range which was investigated. 2. "S" shaped isothermals which probably indicated multilayer adsorption were obtained. 3. The quantity of ovalbumin required to produce a constant surface charge density on the latex particle surface was a function of the pH, and a theory of active centers on the latex particles has been suggested. 4. A shift in the isoelectric point from that of native ovalbumin has been observed for the protein when adsorbed on a synthetic latex.

scholarly journals Effect of protein on the thermogenesis performance of natural rubber matrix

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yue-Hua Zhan ◽  
Yan-Chan Wei ◽  
Jing-jing Tian ◽  
Yuan-Yuan Gao ◽  
Ming-Chao Luo ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Heat Generation ◽  
High Speed ◽  
Soy Protein Isolate ◽  
Protein Isolate ◽  
Rubber Matrix ◽  
Rubber Latex ◽  
Early Failure ◽  
Vulcanized Rubber

Abstract Under high-speed strain, the thermogenesis performance of natural rubber products is unstable, leading to aging and early failure of the material. The quality of rubber latex and eventually that of the final products depends among others on the protein content. We found that when the protein is almost removed, the heat generated by the vulcanized rubber increases rapidly. After adding soy protein isolate to the secondary purification rubber, the heat generation of the vulcanized rubber is reduced, and the heat generation is the lowest when the added amount is 2.5–3.0 phr, which on account of protein promotes the construction of a vulcanization network and increases the rigidity of the rubber chain, resulting in a decrease in the potential frictional behavior of the rubber chain during the curl up-extension process.

METHOD TO VULCANIZE NATURAL RUBBER FROM MEDIUM AMMONIA LATEX BY USING GLUTARALDEHYDE

2012 ◽  
Vol 85 (4) ◽  
pp. 565-575 ◽  
Author(s):  
Jobish Johns ◽  
Charoen Nakason ◽  
Anoma Thitithammawong ◽  
Pairote Klinpituksa
Keyword(s):  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Ammonium Hydroxide ◽  
Mechanical Analysis ◽  
Cross Linking ◽  
Mechanical And Thermal Properties ◽  
Rubber Latex ◽  
Vulcanized Rubber ◽  
Link Density ◽  
The Cross

ABSTRACT A novel and inexpensive method for vulcanizing natural rubber by using glutaraldehyde was introduced. The vulcanized rubber samples were prepared by adding various amounts of glutaraldehyde to medium ammonia natural rubber latex. Cross-linking reaction occurred only in the presence of ammonium hydroxide in natural rubber latex upon the addition of glutaraldehyde. Cross-linked rubber has been obtained by reacting natural rubber with pentane-1,5-diylidenediamine formed from the reaction between glutaraldehyde and ammonia. The vulcanized materials were characterized by mechanical analysis and thermogravimetry. The results revealed an improvement in mechanical and thermal properties by vulcanization. Activation energy of degradation has been calculated using the Horowitz-Metzger equation. The cross-link density of the vulcanized rubber was determined from swelling experiments in benzene. Fourier transform infrared spectroscopy has been employed to confirm the cross-linking reaction between rubber molecules. From the overall characterizations, natural rubber vulcanized with 12 mL of 10% glutaraldehyde exhibited better properties.

Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

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