Model Compound Vulcanization—Part II. Comparison of Accelerators

1979 ◽  
Vol 52 (5) ◽  
pp. 1030-1043 ◽  
Author(s):  
F. K. Lautenschlaeger ◽  
P. Zeeman
Keyword(s):  
Liquid Chromatography ◽  
Natural Rubber ◽  
Model Compound ◽  
Gas Liquid Chromatography ◽  
Product Yields ◽  
Isomer Distribution ◽  
Different Types ◽  
Natural Rubber Vulcanizates

Abstract The efficiency of each of 20 accelerators to convert sulfur into sulfidic products has been evaluated by Model Compound Vulcanization. The sulfidic products can be isolated and identified by gas-liquid chromatography. The sulfidic products can be separated into groups of mono-, di- and trisulfides, with several isomeric products within each group. This paper has reported on the analysis of such isomeric products which correspond to different types of sulfur crosslinks in natural rubber vulcanizates. The analysis of monosulfidic product yields and of the isomer distribution within the monosulfide group is sufficient to characterize an accelerator.

Model Compound Vulcanization—Part IV. Comparative Assessment of Sulfenamide and Triazine Accelerators

1979 ◽  
Vol 52 (5) ◽  
pp. 1050-1056
Author(s):  
F. K. Lautenschlaeger ◽  
K. Edwards ◽  
M. C. Kirkham
Keyword(s):  
Natural Rubber ◽  
Relative Efficiency ◽  
Model Compound ◽  
Product Yield ◽  
Comparative Assessment ◽  
Natural Rubber Vulcanizates

Abstract The application of model compound vulcanization (MCV) to the rating of the relative efficiency of CBS (N-Cyclohexylbenzothiazole-2-sulfenamide) and an experimental triazine-based accelerator is demonstrated. The sulfur to accelerator ratios were established at which both accelerators lead to the same total sulfidic product yield. At these ratios, selected initial properties of natural rubber vulcanizates and their reversion resistance are similar. Hence, the increased reversion resistance of triazine-accelerated natural rubber vulcanizates is essentially due to their greater efficiency in converting sulfur into sulfidic crosslinks. A higher level of the less efficient CBS leads to similar results. This analysis shows that MCV simplifies the evaluation of accelerators.

Dielectric Relaxation of Natural Rubber Vulcanizates

1951 ◽  
Vol 24 (2) ◽  
pp. 320-327 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Relaxation Time ◽  
Dielectric Loss ◽  
Natural Rubber ◽  
Dielectric Relaxation ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Dielectric Relaxation Time ◽  
Different Types ◽  
Cross Links ◽  
Natural Rubber Vulcanizates

Abstract The dielectric loss tangent of different types of vulcanizates of natural rubber has been measured as function of the frequency. Comparisons of the losses in different vulcanizates containing the same amount of combined sulfur show that they decrease with increasing modulus, and it is suggested that the dielectric loss is mostly due to sulfur which has been combined in forms other than cross-links. The dielectric relaxation time is approximately an exponential function of the percentage of combined sulfur. It has been found that moisture increases the audiofrequency losses in rubber more than the radiofrequency losses.

Gas—Liquid Chromatography on Polymers. II. Temperature Coefficients for Polyisobutylene—Hydrocarbons

1975 ◽  
Vol 48 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Yu-Kwan Leung ◽  
B. E. Eichinger
Keyword(s):  
Liquid Chromatography ◽  
Natural Rubber ◽  
Gas Phase ◽  
Sparse Data ◽  
Gas Liquid Chromatography ◽  
Comparable Data ◽  
Vapor Sorption ◽  
Temperature Coefficients ◽  
High Concentrations ◽  
Very High

Abstract Studies of the thermodynamics of polymer solutions by conventional static methods at very high concentrations of polymer are relatively few. Therefore, comparisons between enthalpy parameters obtained by the methods of glc and vapor sorption are limited to only a few cases. One other system for which comparable data are available is natural rubber and benzene. In this case, the glc value of κs is +0.18, while κs = 0.01 ± 0.1 has been obtained by vapor sorption. It appears from the somewhat sparse data collected to date that estimates of the residual enthalpy obtained by glc methods are as reliable as those obtained by static methods. Corrections for gas phase imperfection must be very carefully applied.

The Formation of Monomeric and Dimeric Nitro Nitrates in the Reaction of Phenanthrene With Nitrogen Dioxide: X-Ray Crystal Structure of trans-10-Nitro-9,10-dihydrophenanthren-9-yl Nitrate

1990 ◽  
Vol 43 (1) ◽  
pp. 125 ◽  
Author(s):  
MC Judd ◽  
MP Hartshorn ◽  
RJ Martyn ◽  
WT Robinson ◽  
GJ Wright ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Liquid Chromatography ◽  
Nitrogen Dioxide ◽  
Benzene Solution ◽  
Gas Liquid Chromatography ◽  
X Ray ◽  
Product Yields

Reaction of phenanthrene (1) with nitrogen dioxide in benzene solution gives the dimeric nitro nitrate (3), trans and cis nitro nitrates (7) and (8), and 9-nitro- (4), 3-nitro- (5) and 1-nitro-phenanthrene (6). The X-ray crystal structure of the trans nitro nitrate (7) is reported. The effect of the phenanthrene (1) concentration on product yields is reported. Gas-liquid chromatography results for the nitro nitrates (3) and (7) point to difficulties in using this technique for product analyses in reactions of phenanthrene (1) with nitrogen dioxide.

scholarly journals THE FATE AND EFFECTS OF DISPERSANT-TREATED COMPARED WITH UNTREATED CRUDE OIL, WITH PARTICULAR REFERENCE TO SHELTERED INTERTIDAL SEDIMENTS

1981 ◽  
Vol 1981 (1) ◽  
pp. 283-293 ◽  
Author(s):  
S. J. Rowland ◽  
P. J. C. Tibbetts ◽  
D. Little ◽  
J. M. Baker ◽  
T. P. Abbiss
Keyword(s):  
Liquid Chromatography ◽  
Crude Oil ◽  
Water Table ◽  
Field Experiments ◽  
Sediment Surface ◽  
Gas Liquid Chromatography ◽  
Sedimentary Environments ◽  
Hydrocarbon Analysis ◽  
Different Types ◽  
Spilled Oil

ABSTRACT Dispersant use is a factor that may partly determine the fate and effects of spilled oil. A series of quantitative field experiments has been initiated to simulate conditions following nearshore treatment of a floating oil slick or following the cleaning of a spill stranded on the shore. The basic experimental design is a series of treatments (Forties or Nigerian crude oil, BP 1100WD dispersant, or oil plus dispersant) applied to sets of experimental plots in a range of intertidal and subtidal communities. Biological recording includes frequency and density measurements of plants and animals, and hydrocarbon analysis is by capillary gas liquid chromatography and computerised gas chrornatography–mass spectrometry. Additionally, the effects of dispersant on the movement and fate of oil in different types of sediment is being investigated using a laboratory sediment column and controllable temperature seawater system. The columns have been successfully used in the modeling of low-energy sedimentary environments. Particular attention has been paid to the nature of water table fluctuations within the sediment, to grain size and sorting, to permeability, and also to the number of simulated “tides” that the columns experience after treatment. Hydrocarbon analysis is primarily by ultraviolet spectrophotometry, which has the advantage that the large number of samples generated by each experimental run can be quickly analysed. Gas liquid chromatography is used for checking selected samples. Preliminary results from the field and laboratory experiments indicate that some dispersant treatments increase penetration of oil, and that it may be retained below the sediment surface. Interacting factors include time of treatment in relation to tidal cycle and behaviour of the water table in the sediment.

Spectroscopic Studies on Reaction between Squalene and Vulcanizing Agents in the Presence and Absence of Zinc-2-Mercaptopyridine-N-Oxide

2004 ◽  
Vol 77 (2) ◽  
pp. 201-213
Author(s):  
C. C. Pierre ◽  
R. N. Datta
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Nmr Spectroscopy ◽  
Carbon Black ◽  
Natural Rubber ◽  
High Performance ◽  
Model Compound ◽  
Spectroscopic Studies ◽  
Reversed Phase ◽  
Zinc Stearate

Abstract Model compound vulcanization in combination with reversed-phase high-performance liquid chromatography and NMR spectroscopy was used to elucidate the reactions of accelerator, sulfur, zinc stearate and zinc-2-mercaptopyridine-N-oxide (ZPNO) in natural rubber vulcanization. Studies of different curing ingredient formulations in squalene have been done to determine the influence of each component during the vulcanization. It was found that 2-mercaptopyridine-N-oxide bridged adducts (R-Sx-Pyr(O)) were formed when squalene was heated in the presence of sulfur, curing ingredients and 2,2′-dithiobis(pyridine-N-oxide) (PyrO-S2-PyrO). Possible interactions of R-Sx-Pyr(O) with carbon black have been proposed.

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