Structural Characterization of Vulcanizates. I. Crosslinking Efficiency of Sulfur in Unaccelerated Natural Rubber-Sulfur Systems

1962 ◽  
Vol 35 (1) ◽  
pp. 105-112
Author(s):  
C. G. Moore ◽  
L. Mullins ◽  
P. McL. Swift
Keyword(s):  
Natural Rubber ◽  
Structural Characterization ◽  
Chemical Crosslinking ◽  
Stress Strain ◽  
Strain Measurements

Abstract This paper deals with the determination of crosslinking efficiencies of sulfur in a series of unaccelerated XR-sulfur vulcanizates produced at 140° C. The method used is that described under (1) above, values of the degree of chemical crosslinking being derived from stress-strain measurements on the unextracted vulcanizates.

Structural Characterization of Filled Vulcanizates Part 1. Determination of the Concentration of Chemical Crosslinks in Natural Rubber Vulcanizates Containing High Abrasion Furnace Black

1967 ◽  
Vol 40 (3) ◽  
pp. 866-882 ◽  
Author(s):  
M. Porter
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Volume Fraction ◽  
Exponential Relationship ◽  
Furnace Black ◽  
Simple Linear Relationship ◽  
Chemical Crosslinks ◽  
Natural Rubber Vulcanizates

Abstract The degree to which HAF black restricts the swelling of natural rubber vulcanizates in n-decane has been determined using a vulcanizing system in which the stoichiometry of crosslinking is unaffected by the carbon black. The dependence of the degree of restriction, as measured by the ratio of the volume fractions of rubber in the filled and unfilled vulcanizates swollen to equilibrium, on the concentration of carbon black follows an exponential relationship previously proposed by Lorenz and Parks. This is found to be equivalent to a simple linear relationship between the apparent and actual crosslink concentrations: napparent/nactual=1+Kϕ, where K is a constant characteristic of the filler and φ is its volume fraction in the vulcanizate. The relation has been used to determine actual crosslink concentrations in filled natural rubber vulcanizates. HAF black is found to cause increases of up to 25 per cent in the yield of polymer to polymer crosslinks in conventional sulfur vulcanizing systems, accompanied by changes in rate of cure and of crosslink reversion. All these are small compared with the effect of the filler on many physical properties.

Structural Characterization of α-Terminal Group of Natural Rubber. 2. Decomposition of Branch-Points by Phospholipase and Chemical Treatments

2005 ◽  
Vol 6 (4) ◽  
pp. 1858-1863 ◽  
Author(s):  
Lucksanaporn Tarachiwin ◽  
Jitladda Sakdapipanich ◽  
Koichi Ute ◽  
Tatsuki Kitayama ◽  
Yasuyuki Tanaka
Keyword(s):  
Natural Rubber ◽  
Structural Characterization ◽  
Terminal Group ◽  
Branch Points ◽  
Chemical Treatments

Expert System for Structural Characterization of Phyllosilicates: II. Application to Mixed-Layer Minerals

Clay Minerals ◽  
1994 ◽  
Vol 29 (1) ◽  
pp. 39-45 ◽  
Author(s):  
V. A. Drits ◽  
A. Plançon
Keyword(s):  
Expert System ◽  
Mixed Layer ◽  
Structural Characterization ◽  
Structural Parameters ◽  
Margin Of Error ◽  
Xrd Patterns

AbstractThe expert system described in the first part of this paper has been applied to the identification of mixed-layer phyllosilicates (mica-smectite, mica-vermiculite, chlorite-smectite, chlorite-vermiculite, chlorite-swelling chlorite, chlorite-mica, chlorite-talc, kaolinite-smectite, talc-smectite), and to the determination of their structural parameters (Reichweite, R, and proportions of constituting layers, Wi). The expert system has been run utilizing the data extracted from (1) experimental XRD patterns for which structural parameters had been evaluated by comparison with calculated patterns, or (2) patterns calculated using pre-selected values of the structural parameters. In all cases examined, the expert system provided correct conclusions concerning the identification of a mixed-layer phyllosilicate and the value of the Reichweite, while the abundances of the component layers were evaluated with a margin of error usually <5%.

Single Crystal X-Ray Structural Characterization of [BiX2(S2CNEt2)]Infinity∞, X=Cl, Br

1994 ◽  
Vol 47 (2) ◽  
pp. 405 ◽  
Author(s):  
PK Bharadwaj ◽  
AM Lee ◽  
BW Skelton ◽  
BR Srinivasan ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Sulfur Atom ◽  
Structural Characterization ◽  
Structure Determination ◽  
Room Temperature ◽  
X Ray ◽  
Structure Determinations

Single-crystal room-temperature X-ray structure determinations of the title compounds have been carried out. The two compounds are isomorphous, and isomorphous with the previously determined iodide analogue, being monoclinic, P 21/c, a ≈ 10.0, b ≈ 14.9, c ≈ 7.8 Ǻ, β ≈ 92°, Z = 4 formula units; residuals were 0.037, 0.036 for 2197, 1654 'observed' reflections for X = Cl , Br respectively. As in the iodide, the complexes are infinite polymers, with successive bismuth atoms bridged by the two halides and one sulfur atom of the ligand , which also chelates each bismuth. The structure determination of C5H5NCONEt2]2 [Cl5Bi(NC5H5)], isostructural with its thiocarbamoyl analogue, is also recorded.

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