Determination of Rubber Hydrocarbon by a Gravimetric Rubber Bromide Method

1947 ◽  
Vol 20 (1) ◽  
pp. 320-328 ◽  
Author(s):  
C. O. Willits ◽  
M. L. Swain ◽  
C. L. Ogg
Keyword(s):  
Natural Rubber ◽  
Physical Properties ◽  
Difference Method ◽  
Direct Determination ◽  
Chemical Processes ◽  
Rubber Content ◽  
Low Concentration ◽  
Hydrocarbon Analysis ◽  
The Difference

Abstract Direct determination of rubber hydrocarbon in crude rubbers and in latices has been generally considered so inaccurate and unreliable that determination of rubber hydrocarbon by difference has been a common practice. The difference method usually suffices in the analysis of products derived from Hevea rubber, in which the nonrubber components have been well characterized or occur in low concentration. In the analysis of natural rubber products obtained from sources other than Hevea, such as guayule, kok-saghyz, and Cryptostegia, the situation is different. The chemical and physical properties of the nonrubber components of such products are largely unknown, and in many cases the nonrubber contaminants are present in excessive amounts, sometimes more than 50 per cent of the total. Since the rubber hydrocarbon analysis usually affords the most reliable means for estimating the rubber content of plants and for following the concentration and purification of rubber by mechanical and chemical processes, it appeared desirable to devise or adapt a method which would permit direct determination of this constituent in the presence of relatively large amounts of natural and added contaminants.

scholarly journals Fast Determination of the Rubber Content in Taraxacum Kok-Saghyz Fresh Biomass Using Portable Near Infrared Spectroscopy and Pyrolysis-Gas Chromatography

2021 ◽  
Author(s):  
Ying Chen ◽  
Dong Yiyang ◽  
Xiang Ma ◽  
Jiaru Li ◽  
Minmin Guo ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Infrared Spectroscopy ◽  
Natural Rubber ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Low Cost ◽  
Rubber Content ◽  
Pyrolysis Gas ◽  
Pyrolysis Gas Chromatography

Abstract Background: Taraxacum kok-saghyz (TKS), a plant native to the Tianshan valley on the border between China and Kazakhstan and inherently rich in natural rubber, inulin and other bioactive ingredients, is an important industrial crop. TKS rubber is a good substitute for natural rubber. TKS's breeding work necessitates the need to screen high-yielding varieties, hence rapid determination of rubber content is essential for the screening. Conventional analytical methods cannot meet actual needs in terms of real-time testing and economic cost. Near-infrared spectroscopy analysis technology, which has developed rapidly in the field of industrial process analysis in recent years, is a green detection technology with obvious merits of fast measurement speed, low cost and no sample loss. This research aims to develop a portable non-destructive near-infrared spectroscopic detection scheme to evaluate the content of natural rubber in TKS fresh roots. Pyrolysis gas chromatography (PyGC), was chosen as the reference method for the development of NIR prediction model. Results: 208 TKS fresh root samples were collected from the Inner Mongolia Autonomous Region of China. Near-infrared spectra were acquired for all samples. Randomly two-thirds of them were selected as the calibration set, the remaining one-third as the verification set, and the partial least squares method was successfully used to establish a good NIR prediction model at 1080-1800nm with a performance to deviation ratio (RPD) of 5.54 and coefficient of determination (R2) of 0.95. Conclusions: This study showed that portable near-infrared spectroscopy could be used with ease for large-scale screening of TKS plants in farmland, and could greatly facilitate TKS germplasm preservation, high-yield cultivation, environment-friendly, high-efficiency and low-cost rubber extraction, and comprehensive advancement of the dandelion rubber industry thereof.

Apparatus for the Direct Determination of the Dynamic Bulk Modulus

1957 ◽  
Vol 30 (2) ◽  
pp. 449-459
Author(s):  
J. E. McKinney ◽  
S. Edelman ◽  
R. S. Marvin
Keyword(s):  
Natural Rubber ◽  
Bulk Modulus ◽  
Direct Measurement ◽  
Static Pressure ◽  
Direct Determination ◽  
Preliminary Evaluation ◽  
Air Bubbles ◽  
Frequency Range ◽  
Piezoelectric Crystals

Abstract An apparatus has been developed for the direct measurement of the real and imaginary parts of the dynamic bulk modulus of solid and liquid materials over the frequency range of 50 to 10,000 cps. Piezoelectric crystals serving as driver and detector, together with the sample and a confining liquid, are contained in a cavity small compared with the wavelength of sound at these frequencies. Static pressure is superposed to eliminate the effect of small air bubbles. The complex compliances of the sample, confining liquid, and the cavity, are additive in this region, where the compliance is pure dilatation. The dynamic compliances of several natural rubber-sulfur mixtures were obtained in a preliminary evaluation of the behavior of the apparatus.

Ozonolytic Degradation of Interpolymers of Natural Rubber with Methyl Methacrylate and Styrene

1958 ◽  
Vol 31 (1) ◽  
pp. 82-85
Author(s):  
D. Barnard
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Accurate Determination ◽  
Synthetic Polymers ◽  
Polymer Chains ◽  
Low Molecular Weight ◽  
Rubber Content ◽  
Tert Butyl Hydroperoxide

Abstract The preparation of graft and block interpolymers of natural rubber and synthetic polymers has made it desirable that the number and size of polymer chains attached to rubber be readily determinate. The degradation of unsaturated polymers with tert-butyl hydroperoxide in the presence of osmium tet oxide has been used for the determination of free polystyrene in SBR and carbon black in several elastomers, and has recently been applied to the present problem. The accurate determination of the rubber content of interpolymers by quantitative ozonolysis essentially according to the method of Boer and Kooyman suggested that this might be made the basis of isolation of the attached polymer, the rubber being degraded into fragments of low molecular weight, from which the polymer could be separated by conventional techniques. The method should be applicable to any interpolymer, or mixture, of a polyunsaturated and a saturated polymer and is illustrated with reference to interpolymers of natural rubber (NR)-polymethyl methacrylate (PMM) and NR-polystyrene (PS).

The Direct Determination of Oxygen in Rubber. The Adaptation of the Ter Meulen Method to Rubber and Its Application to the Study of Aging

1939 ◽  
Vol 12 (2) ◽  
pp. 269-282 ◽  
Author(s):  
H. I. Cramer ◽  
I. J. Sjothun ◽  
L. E. Oneacre
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Direct Determination ◽  
Sulfur Poisoning ◽  
Oxidation Products ◽  
Oxygen Bomb ◽  
Vulcanized Rubber ◽  
Relationship Of ◽  
The Relationship

Abstract The ter Meulen method for the direct determination of oxygen has been adapted, with modifications, to the analysis of raw and vulcanized rubbers. Raney nickel has been found to be quite effective as the reducing catalyst and to be satisfactorily resistant to sulfur poisoning. The method has been applied to the study of the aging of vulcanized rubber in the Geer oven and oxygen bomb. From this study the following conclusions may be drawn: (1) The increase in combined oxygen is greater in the oxygen bomb than in the Geer oven. (2) Deterioration of rubber in the oxygen bomb involves oxidation primarily, whereas that occurring in the Geer oven involves not only oxidation but also thermal decomposition followed by volatilization of oxidation products. (3) The effectiveness of an antioxidant in retarding the absorption of oxygen in oxygen-bomb aging agrees well with its ability to maintain the physical properties of the stock in which it is present. (4) The deterioration in physical properties of a rubber stock in the oxygen bomb during the early stages of aging is a linear function of the increase in combined oxygen. For stocks containing antioxidants and diphenylguanidine as the accelerator, an increase in combined oxygen of approximately 1.2% corresponds to a decrease in tensile strength of 50%. (5) The relationship of increase in combined oxygen to decrease in tensile strength seems to be affected not only by antioxidants, but also by accelerators of vulcanization.

COMPARATIVE ANALYSIS OF 14C AND TGA TECHNIQUES FOR THE QUANTIFICATION OF THE BIOMASS CONTENT OF END-OF-LIFE TIRES

2014 ◽  
Vol 87 (4) ◽  
pp. 664-678 ◽  
Author(s):  
Leticia Saiz-Rodríguez ◽  
José María Bermejo-Muñoz ◽  
Andrés Rodríguez-Díaz ◽  
Alberto Fernández-Torres ◽  
Antonio Rubinos-Pérez
Keyword(s):  
Thermogravimetric Analysis ◽  
Stearic Acid ◽  
Natural Rubber ◽  
End Of Life ◽  
Rubber Content ◽  
Thermogravimetric Method ◽  
Precise Method ◽  
Different Types ◽  
Reference Samples

ABSTRACT Thermogravimetric analysis (TGA) and 14C techniques were compared for the determination of the biomass content of end-of-life tires (ELTs). Samples of different types (of ELTs) were prepared, and the biomass fraction of each sample was measured using the two methods (TGA and 14C). Six reference samples were also prepared with known quantities of natural rubber and stearic acid in order to establish the calibration curve necessary for the thermogravimetric analysis and to verify the accuracy of the results of the 14C analysis. The conclusions were that the 14C technique is the more valid, reliable, and precise method for determining the biomass content of end-of-life tires, since the results of the 14C tests of the reference samples coincided perfectly with the actual natural rubber and stearic acid content. On the other hand, the results of the thermogravimetric method differed considerably from the known natural rubber content of the reference samples as well as from the results of the 14C technique. This method is therefore not appropriate for use in determining the biomass content of end-of-life tires.

scholarly journals 116 Direct vs. difference method to determine amino acid digestibility in ingredients fed to pigs

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 67-68
Author(s):  
Maryane S Faria de Oliveira ◽  
John K Htoo ◽  
Hans H Stein
Keyword(s):  
Difference Method ◽  
Direct Method ◽  
Sole Source ◽  
Cereal Grains ◽  
Mixed Diet ◽  
Ileal Digestibility ◽  
Method Of Determination ◽  
Wheat Middlings ◽  
The Difference

Abstract An experiment was conducted to test the hypothesis that values for standardized ileal digestibility (SID) of amino acids (AA) in cereal grains and fiber rich ingredients obtained using the direct method are not different from values obtained using the difference method. Sixteen ileal-cannulated barrows (69.45 ± 5.01 kg) were allotted to an 8 diets × 4 period Youden square design. Each period consisted of 5 d of adaptation and 2 d of ileal digesta collection. Four diets were based on soybean meal (SBM), corn, wheat, or wheat middlings as the only AA-containing ingredients. Three additional diets were based on a mixture of SBM and corn, wheat, or wheat middlings and a N-free diet was also used. The SID of AA in the 4 diets containing SBM, corn, wheat, or wheat middlings as the sole source of AA were calculated using the direct method. The SID of AA in corn, wheat, and wheat middlings were also calculated by difference from the 3 diets containing SBM and corn, wheat, or wheat middlings by subtracting the contribution from SBM of each AA from the SID values for the mixed diet. Data were analyzed using a model that included the method of determination of AA digestibility as the fixed effect, and pig and period as random effects. There was no difference between the direct and the difference method for the SID of most AA in corn, wheat, and wheat middlings, although the SID of Trp was lower (P < 0.05) for the difference method than values derived by the direct method for both corn and wheat middlings (Table 1). Therefore, values for SID of AA in cereal grains or fiber-rich ingredients could be obtained using either the direct method or the difference method.

Molecular Weight and Polydispersivity of Rubber by Diffusion Measurements

1947 ◽  
Vol 20 (2) ◽  
pp. 377-379
Author(s):  
A. G. Pasynskii ◽  
T. V. Gatovskaya
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Average Value ◽  
Type Iv ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
The Difference ◽  
Diffusion Curves ◽  
Fair Degree

Abstract The study of diffusion in solutions of natural rubber (light crepe) by Lamm's method showed that even with a concentration of 0.1 per cent the normalized experimental diffusion curves diverge from the ideal Gaussian curve (Figure 1), in that they are characterized by a marked asymmetry and an excess of the maximal ordinate. It follows from an analysis of the experimental curves by the method of moments (up to moments of the fourth order) that they belong to Type IV Pearson curves, that is, to asymmetrical distribution curves with asymptotic branches. The determination of the perturbation multiplier enables us to calculate the course of the experimental curves with a fair degree of accuracy. The physical cause of asymmetry of the diffusion curves is the difference in the rate of diffusion to both sides of the interface (of the polymer into the solvent and back) due to a marked intermolecular interaction in the solution of the polymer at a given concentration. With a decrease of the concentration or of the molecular weight of the dissolved substance, the asymmetry of the diffusion curves becomes less pronounced. However, this asymmetry does not preclude the computation of the average diffusion coefficient D from the standard deviation of the curve. It can, indeed, be shown that the probable error does not exceed 1 per cent. The average value found for natural rubber in carbon tetrachloride is D20°=0.71×10−7 sq. cm. per sec.

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