Determination of the Degree of Hydrogenation in Hydrogenated Nitrile-Butadiene Rubber (HNBR)

1990 ◽  
Vol 63 (2) ◽  
pp. 244-255 ◽  
Author(s):  
A. J. Marshall ◽  
I. R. Jobe ◽  
T. Dee ◽  
C. Taylor
Keyword(s):  
Standard Procedure ◽  
Analytical Techniques ◽  
Butadiene Rubber ◽  
Preparation Time ◽  
Mean Values ◽  
Wet Chemical ◽  
Absolute Measurements ◽  
Infrared Methods ◽  
Good Agreement

Abstract A number of analytical techniques are available for the measurement of the residual unsaturation in HNBR polymers. However, to insure that high-quality HNBR products are produced, it is necessary to use a standard procedure throughout the industry which is quick, accurate, and precise. The two infrared methods discussed in this paper show good agreement with one another, as shown by the respective mean values in Table V. Thus, in the absence of a totally independent and universally accepted standard procedure, this crosscheck between two separate and absolute measurements for the degree of hydrogenation is the best possible support for their precision (1H-NMR spectroscopy for IR method #1 and IR spectroscopy for IR method #2). The two iodometric methods each exhibit significantly poorer precision ( 10 to 100 times) than either of the infrared methods. This is not surprising, since these wet chemical techniques are not discriminatory to any type of unsaturation present in the HNBR nor are they inherently precise due to the large number of test variables. This lack of precision, and the fact that these wet chemical methods are time consuming, eliminates them from consideration as quality-oriented testing methods for measuring the degree of hydrogenation in HNBR. Both IR methods exhibit good reproducibility which greatly exceeds that of iodometry. The statistical analysis of these IR techniques does not present any significant differences between them. IR method #1 requires virtually no preparation time, since extraction of the HNBR rubber samples is not required. Furthermore, IR method #1 is less susceptible to impurities and subsequent user interpretation, since the hydrogenated butadiene peaks at 723 cm−1 are not required for the analysis. In conclusion, due to simplicity and speed of the analysis, IR method #1 is much more robust for use by the industry and their customers for the measurement of carbon-carbon double-bond unsaturation in HNBR.

scholarly journals Energy-dispersive spectroscopy for the quantitative determination of the major chemical elements in milk

2021 ◽  
Vol 10 (10) ◽  
pp. e280101018910
Author(s):  
Igor Lima de Paula ◽  
Isis Rodrigues Toledo Renhe ◽  
Rodrigo Stephani ◽  
Ítalo Tuler Perrone ◽  
Antônio Fernandes de Carvalho ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Chemical Elements ◽  
Raw Milk ◽  
Energy Dispersive ◽  
Mean Values ◽  
Milk Samples ◽  
Application Potential ◽  
Major Chemical ◽  
Good Agreement

The present preliminary study aims at the rapid quantitative determination of the major chemical elements in the ashes of raw milk samples, using energy dispersive X-ray fluorescence spectrometry. The precision of the method was satisfactory (variation coefficient ≤ 5%). The mean values (in mmol·kg-1) obtained from the analysis of 32 raw milk samples showed good agreement with data from the Brazilian and international literature: K (26.1 ± 4.6), Ca (33.8 ± 3.7), P (28.4 ± 2.7), Na (21 ± 3.3) and Mg (4.7 ± 0.5). Residual Cl concentration (19.0 ± 3.3 mmol·kg-1) was lower than expected due to incineration losses. The results suggest a good application potential of the method for other dairy products.

Collaborative Study of Infrared Methods for Phorate in Formulations

1964 ◽  
Vol 47 (2) ◽  
pp. 245-247
Author(s):  
N Kobekt Pasarela
Keyword(s):  
Collaborative Study ◽  
Infrared Method ◽  
Infrared Methods ◽  
Good Agreement

Abstract An infrared method for the determination of phorate in 5% and 10% granules was studied by 10 collaborators. In the method, the formulation is eluted from the carrier with acetonitrile, the solvent is removed by evaporation, and the residue is dissolved in cyclohexane. The absorbance of the solution is measured at 8.32 μ and the phorate content is determined by comparison with a sample of purified phorate treated in the same manner. Results show good agreement between replicates and laboratories. It is recommended that the method for phorate in granular formulations be adopted as official, first action.

Absolute wavelength measurement of the Lyman-α transition of hydrogen-like silicon

2002 ◽  
Vol 80 (8) ◽  
pp. 867-874 ◽  
Author(s):  
J Tschischgale ◽  
D Klöpfel ◽  
P Beiersdorfer ◽  
G V Brown ◽  
E Förster ◽  
...  
Keyword(s):  
Electron Beam ◽  
Lamb Shift ◽  
Ion Trap ◽  
Wavelength Measurement ◽  
Electron Beam Ion Trap ◽  
Absolute Measurements ◽  
Good Agreement

The wavelengths of the 1s1/2–2p1/2 and 1s1/2–2p3/2 Lyman-α transitions have been measured in hydrogenic silicon with an accuracy of 70 ppm. The measurement was carried out with an electron-beam ion trap with a calibrated double-faced monolithic crystal that enabled absolute measurements of the transition wavelengths. The values for the Lyman-α wavelengths are λLyα1 = 6.180 49(44) Å and λLyα2 = 6.185 56(66) Å. The wavelengths are in good agreement with calculations and allow a determination of the 1s Lamb shift to within 28% in a region that has received little experimental attention. PACS Nos.:32.30Rj, 31.30Jv

Determination of the cation exchange capacity of clays with copper complexes revisited

Clay Minerals ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 441-453 ◽  
Author(s):  
L. Ammann ◽  
F. Bergaya ◽  
G. Lagaly
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Copper Complexes ◽  
Standard Procedure ◽  
Reference Method ◽  
Exchange Capacity ◽  
Equilibrium Solutions ◽  
Spectral Photometry ◽  
Good Agreement

AbstractThe determination of the cation exchange capacity (CEC) of clays by exchange with the cationic copper complexes [Cu(en)2]2+ and [Cu(trien)]2+ is revisited. The procedures reported by Bergaya & Vayer (1997) and Meier & Kahr (1999) are modified slightly. The concentration of the copper complexes in the equilibrium solutions is measured by spectral photometry. Correct CEC values of the [Cu(en)2]2+ exchange are only obtained when a buffer (‘tris’, tris (hydroxymethyl) aminomethane, pH = 8) is added to the equilibrium solution after separation of the clay, because the molar extinction coefficient of this complex depends on the pH of the solution. A standard procedure is recommended as a reference method. In most cases, tris addition is not needed for the determination with [Cu(trien)]2+ cations. Nevertheless, tris addition is recommended in the standard procedure. Determination of CEC for 40 samples (kaolins, ‘common clays’, bentonites, montmorillonites and beidellite) shows a good agreement between measurements using [Cu(en)2]2+ and [Cu(trien)]2+ cations and with results by the ammonium acetate method.

scholarly journals Elemental Composition of Norwegian Rivers

1979 ◽  
Vol 10 (2-3) ◽  
pp. 115-140 ◽  
Author(s):  
B. Salbu ◽  
A. C. Pappas ◽  
E. Steinnes
Keyword(s):  
Geometric Mean ◽  
Ore Deposits ◽  
Weighted Mean ◽  
Mean Values ◽  
Marine Deposits ◽  
Water Composition ◽  
Alkaline Earths ◽  
The Individual ◽  
Good Agreement

Instrumental neutron activation analysis has been applied for the determination of up to 40 elements in waters from eleven Norwegian rivers. In order to represent the composition of an average river in the region of Norway and possibly the greater part of the Scandinavian peninsula, weighted mean values are calculated on the basis of geometric mean values and discharge of the individual rivers. Factor analysis shows that Cambro-Silurian sedimentary and vulcanic rocks influence the water composition considerably compared to Precambrian gneisses and granites. An influence of airborne supply is evident in coastal areas. In addition ore deposits are important for Zn and associated elements. Comparison with literature data from Sweden shows good agreement for the elements concerned. The present values concerning alkalies, alkaline earths and halogens are, however, significantly lower than the estimated “world averages”. This is probably due to a low abundance of marine deposits and sedimentary rocks in Scandinavia. Low values are also found for elements which are often associated with particulate matter (Fe, Al, V, Mo, As, Sb, Th, U), while the values obtained for rare earths (La, Ce, Sm) and some additional elements (Sc, Mn, Au) are significantly higher than the estimated “world averages”.

Single Stable Reagent (Arsenazo III) for Optically Robust Measurement of Calcium in Serum and Plasma

1992 ◽  
Vol 38 (6) ◽  
pp. 904-908 ◽  
Author(s):  
N O Leary ◽  
A Pembroke ◽  
P F Duggan
Keyword(s):  
Arsenazo Iii ◽  
External Quality Control ◽  
External Quality ◽  
Mean Values ◽  
Standard Curve ◽  
Control Schemes ◽  
Stable Reagent ◽  
Good Agreement ◽  
Positive Interference

Abstract We describe a method based on a single stable reagent for the determination of calcium in serum and plasma with use of Arsenazo III, 200 mumol/L in 50 mmol/L 1,4-piperazinediethanesulfonic acid (PIPES) buffer. The method showed significant positive interference in plasma at pH less than 6.6 because of the precipitation of fibrinogen, which was eliminated by increasing the pH to 6.8. The assay showed no interference from as much as 600 mumol of bilirubin and 12 g of hemoglobin per liter when applied in a simple monochromatic procedure at 660 nm. The standard curve for calcium was linear from 0 to 5.0 mmol/L. Addition of Intralipid at concentrations greater than 3 g/L demonstrated positive interference, which could be eliminated by using a 700-nm blanking wavelength. The procedure showed good agreement with all-method mean values from two external quality-control schemes.

Determination of Chlorinated Pesticides in Whole Blood

1973 ◽  
Vol 56 (5) ◽  
pp. 1173-1177
Author(s):  
Paula E Stretz ◽  
Henry M Stahr
Keyword(s):  
Sulfuric Acid ◽  
Whole Blood ◽  
Gas Liquid Chromatography ◽  
Chlorinated Pesticides ◽  
Blood Samples ◽  
Mean Values ◽  
Sulfuric Acid Method ◽  
Large Systematic Error ◽  
Good Agreement

Abstract Eight whole blood samples spiked with lindane, dieldrin, and p,p′-DDT at levels of 2.5, 12.6, 126, and 630 ppb each were sent to 11 collaborators for analysis. The method evaluated uses sulfuric acid to liberate the pesticides from the blood matrix. The pesticides are then extracted with 10% acetone in hexane. Pesticides were identified and quantitatively analyzed by gas-liquid chromatography, using an electron capture detector. Mean values at all levels are in good agreement with the spiking levels. However, statistical analysis of the data reveals a large systematic error. Further evaluation of the sulfuric acid method by comparison with other methods is recommended.

Modeling of Fracture Behaviours of Ultrasonically Welded Cu-Cu Joints Under Different Loading Conditions

2015 ◽  
Author(s):  
Liang Xi ◽  
Mihaela Banu ◽  
S. Jack Hu ◽  
Wayne Cai ◽  
Teresa Rinker
Keyword(s):  
Failure Modes ◽  
Standard Procedure ◽  
Lithium Ion ◽  
Mechanical Tests ◽  
Battery Pack ◽  
Actual Behavior ◽  
Modes Of Failure ◽  
Lap Shear ◽  
Good Agreement

A lithium-ion battery pack for electric vehicles may consist of several hundreds of battery cells joined together. Each cell contains joints of multiple thin sheets of electrodes of different conductive materials such as nickel coated copper, copper and / or aluminum. These within-cell and cell-to-cell joints must withstand static and dynamic mechanical loading. Determination of their maximum loading capacity is a very important task in order to predict the life of a battery pack. The standard procedure is to apply mechanical tests, such as lap shear and pull test to each joint. This procedure is time consuming and costly. There is a strong interest nowadays in developing validated models which can predict the actual behavior of the joints under different loadings and the associated failure modes. In this paper, two finite element models are developed to predict the strength of ultrasonically welded two-, three- and four layer joints of 0.2 mm thickness copper tabs with a 1mm thickness busbar. These models have the ability to predict three modes of failure of these joints depending on the weld quality, e.g., interfacial fracture, combined interfacial-circumferential fracture, and circumferential failure. These models are experimentally validated with very good agreement between experimental and predicted results.

Determination of Molecular Weight Distributions of Elastomers with the Ultracentrifuge

1965 ◽  
Vol 38 (4) ◽  
pp. 817-822 ◽  
Author(s):  
J. F. Henderson ◽  
J. M. Hulme ◽  
R. M. B. Small ◽  
H. L. Williams
Keyword(s):  
Molecular Weight ◽  
Solution Concentration ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Styrene Butadiene ◽  
Elution Chromatography ◽  
Good Agreement

Abstract The ultracentrifuge has been used to obtain molecular weight distributions of cis-1,4-polybutadiene and styrene/butadiene rubber. When corrections are made for the effects of centrifugal pressure and solution concentration, distributions are obtained that are in good agreement with those determined by elution chromatography. Rapid comparisons of polymers are sometimes possible, especially if the polymers are chemically similar.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

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