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.

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.

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.

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.

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

MÖSSBAUER AND CHEMICAL ANALYSES OF SOME SEDIMENTS FROM THE ROMANIAN SHORE OF THE BLACK SEA

1979 ◽  
Vol 40 (C2) ◽  
pp. C2-445-C2-448
Author(s):  
D. Barb ◽  
L. Diamandescu ◽  
M. Morariu ◽  
I. I. Georgescu
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Chemical Analyses

Specific composition and structure of population phytopathogens of vegetable crops

2019 ◽  
Vol 326 (3) ◽  
pp. 76-78
Author(s):  
V.L. Nalobova ◽  
◽  
N.S. Opimah ◽  
M.V. Nalobova ◽  
I.V. Haponenka ◽  
...  
Keyword(s):  
Vegetable Crops ◽  
Specific Composition ◽  
Composition And Structure ◽  
Structure Of Population

The diatoms as a component of bottom algocenoses in the mouth of the Oka River

2019 ◽  
Author(s):  
Alexander G. Okhapkin ◽  
Tabet Hhedairia
Keyword(s):  
Water Temperature ◽  
Preliminary Estimation ◽  
Composition And Structure

The preliminary estimation of composition and structure of diatoms in the benthos of the Oka River allowed to determine the clear spatiotemporal confinedness of structure in such communities of them which has the most diverse composition in the low water period while water temperature decreasing.

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