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).

Determination of Free Carbon in Cured Rubber Stocks

1951 ◽  
Vol 24 (1) ◽  
pp. 224-227
Author(s):  
I. M. Kolthoff ◽  
R. G. Gutmacher
Keyword(s):  
Nitric Acid ◽  
Carbon Black ◽  
Natural Rubber ◽  
Osmium Tetroxide ◽  
Free Carbon ◽  
Vulcanized Rubber ◽  
Tert Butyl Hydroperoxide ◽  
Inorganic Fillers ◽  
Dilute Nitric Acid

Abstract A method for the determination of free carbon in vulcanized rubber stocks is described. The sample is softened in boiling p-dichlorobenzene before treatment with tert-butyl hydroperoxide in the presence of osmium tetroxide. No difficulties are encountered in the filtration of the carbon black. The carbon black is washed on the filter with dilute nitric acid to remove acid-soluble inorganic fillers. The method has been successfully applied to natural rubber, GR-S, Butyl rubber, and Neoprene. No correction is necessary.

scholarly journals PROCEDURE FOR DETERMINATION OF THE MOLECULAR WEIGHT OF CHITOSAN BY VISCOMETRY

2018 ◽  
Vol XXIII ◽  
pp. 45-54 ◽  
Author(s):  
Renata Czechowska-Biskup ◽  
Radosław A. Wach ◽  
Janusz M. Rosiak ◽  
Piotr Ulański
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Accurate Determination ◽  
Low Molecular Weight ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Experimental Procedure ◽  
Initial Concentration ◽  
Analytical Instruments

The aim of this publication is to facilitate the estimation of chitosan molecular weight (MW) in laboratories with no access to sophisticated analytical instruments, by applying the easily accessible and economical capillary viscometry. The procedure of viscosity-average molecular weight (Mv) determination is described in details. The examples provided encompass testing of the experimental procedure for determination of the Mv of chitosan with a low-molecular weight of 7.7 kDa and 88 kDa, after verification with a high-molecular weight polymer (477 kDa). The experimental work demonstrated the importance of the initial concentration of low-MW chitosan for the accurate determination of intrinsic viscosity and, as a consequence, the viscosity-average molecular weight.

Determination of low molecular weight chlorinated organic compounds in polyamideanine epichlorohydrin solution

2019 ◽  
Vol 34 (3) ◽  
pp. 326-333
Author(s):  
Qi Wei ◽  
Hao Cheng ◽  
Shubin Wu ◽  
Chunxia Chen
Keyword(s):  
Molecular Weight ◽  
Organic Compounds ◽  
Accurate Determination ◽  
Simultaneous Detection ◽  
Low Molecular Weight ◽  
Extraction Temperature ◽  
Chlorinated Organic Compounds ◽  
Relative Standard ◽  
Chlorinated Organic

Abstract A convenient and quick method has been developed for simultaneous detection of several low molecular weight chlorinated organic compounds (LMWC) in polyamideamine-epichlorohydrin (PAE) solution, using headspace-solid phase microextraction-gas chromatography (HS-SPME-GC). The method consists of extracting a sample containing 0.42 g/mL NaCl with an 85 µm polyacrylate (PA) coated fiber at an extraction temperature of {45^{\circ }}\text{C}, for an extraction time of 30 mins, and desorbing the analytes at {240^{\circ }}\text{C} for 6 mins. Under these optimized conditions, relatively low limits of detection (LOD) of the analytes, good linearity ({r^{2}}\ge 0.9934) and precision (relative standard deviation (\text{RSD}\le 4.38\hspace{0.1667em}\% )) were obtained. Taking into account the matrix effect, standard addition methodology was applied to validate this method and recovery values were between 91.59 % and 109.69 %. This method is therefore well-suited for accurate determination of low levels of LMWC in PAE.

COMPARATIVE PROPERTIES OF SILICA- AND CARBON BLACK-REINFORCED NATURAL RUBBER IN THE PRESENCE OF EPOXIDIZED LOW MOLECULAR WEIGHT POLYMER

2014 ◽  
Vol 87 (2) ◽  
pp. 320-339 ◽  
Author(s):  
P. Saramolee ◽  
K. Sahakaro ◽  
N. Lopattananon ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Periodic Acid ◽  
Dynamic Mechanical Properties ◽  
Low Molecular Weight ◽  
Molecular Weight Polymer ◽  
Dynamic Mechanical ◽  
Chemical Structures

ABSTRACT This work investigates the effect of epoxidized low molecular weight natural rubber (ELMWNR) in silica- and carbon black-filled natural rubber (NR) compounds on processing and mechanical and dynamic mechanical properties. The ELMWNRs with different mol% epoxide content were prepared from depolymerization of epoxidized NR using periodic acid in latex state to have a molecular weight in a range of 50 000–60 000 g/mol. Their chemical structures and actual mol% of epoxide were analyzed by 1H NMR. The ELMWNRs were added to the filled NR compounds as compatibilizers at varying loadings from 0 to 15 phr. The addition of ELMWNR decreases compound viscosity and the Payne effect, that is, filler–filler interaction, of the silica-filled compound. In the silica–silane compound and the compound with 28 mol% epoxide (ELMWNR-28), the compound viscosities are comparable. The optimal mechanical properties of silica-filled vulcanizates are obtained at the ELMWNR-28 loading of 10 phr. In contrast, the addition of ELMWNR to a carbon black-filled compound shows only a plasticizing effect. The incorporation of ELMWNR into NR compounds introduces a second glass transition temperature and affects their dynamic mechanical properties. Higher epoxide contents lead to higher loss tangent values of the rubber vulcanizates in the range of the normal service temperature of a tire.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

scholarly journals Simultaneous Determination of Human Serum Albumin and Low-Molecular-Weight Thiols after Derivatization with Monobromobimane

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3321
Author(s):  
Katarzyna Kurpet ◽  
Rafał Głowacki ◽  
Grażyna Chwatko
Keyword(s):  
Molecular Weight ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Simultaneous Determination ◽  
Reversed Phase ◽  
Fluorescence Labeling ◽  
Detector Response ◽  
Low Molecular Weight

Biothiols are extremely powerful antioxidants that protect cells against the effects of oxidative stress. They are also considered relevant disease biomarkers, specifically risk factors for cardiovascular disease. In this paper, a new procedure for the simultaneous determination of human serum albumin and low-molecular-weight thiols in plasma is described. The method is based on the pre-column derivatization of analytes with a thiol-specific fluorescence labeling reagent, monobromobimane, followed by separation and quantification through reversed-phase high-performance liquid chromatography with fluorescence detection (excitation, 378 nm; emission, 492 nm). Prior to the derivatization step, the oxidized thiols are converted to their reduced forms by reductive cleavage with sodium borohydride. Linearity in the detector response for total thiols was observed in the following ranges: 1.76–30.0 mg mL−1 for human serum albumin, 0.29–5.0 nmol mL−1 for α-lipoic acid, 1.16–35 nmol mL−1 for glutathione, 9.83–450.0 nmol mL−1 for cysteine, 0.55–40.0 nmol mL−1 for homocysteine, 0.34–50.0 nmol mL−1 for N-acetyl-L-cysteine, and 1.45–45.0 nmol mL−1 for cysteinylglycine. Recovery values of 85.16–119.48% were recorded for all the analytes. The developed method is sensitive, repeatable, and linear within the expected ranges of total thiols. The devised procedure can be applied to plasma samples to monitor biochemical processes in various pathophysiological states.

scholarly journals Proteomic Determination of Low-Molecular-Weight Glutenin Subunit Composition in Aroona Near-Isogenic Lines and Standard Wheat Cultivars

2021 ◽  
Vol 22 (14) ◽  
pp. 7709
Author(s):  
Kyoungwon Cho ◽  
You-Ran Jang ◽  
Sun-Hyung Lim ◽  
Susan B. Altenbach ◽  
Yong Q. Gu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Allelic Variation ◽  
Reversed Phase ◽  
Glutenin Subunit ◽  
Low Molecular Weight ◽  
Near Isogenic Lines ◽  
Wheat Cultivars ◽  
Reliable Determination ◽  
Isogenic Lines

The low-molecular weight glutenin subunit (LMW-GS) composition of wheat (Triticum aestivum) flour has important effects on end-use quality. However, assessing the contributions of each LMW-GS to flour quality remains challenging because of the complex LMW-GS composition and allelic variation among wheat cultivars. Therefore, accurate and reliable determination of LMW-GS alleles in germplasm remains an important challenge for wheat breeding. In this study, we used an optimized reversed-phase HPLC method and proteomics approach comprising 2-D gels coupled with liquid chromatography–tandem mass spectrometry (MS/MS) to discriminate individual LMW-GSs corresponding to alleles encoded by the Glu-A3, Glu-B3, and Glu-D3 loci in the ‘Aroona’ cultivar and 12 ‘Aroona’ near-isogenic lines (ARILs), which contain unique LMW-GS alleles in the same genetic background. The LMW-GS separation patterns for ‘Aroona’ and ARILs on chromatograms and 2-D gels were consistent with those from a set of 10 standard wheat cultivars for Glu-3. Furthermore, 12 previously uncharacterized spots in ‘Aroona’ and ARILs were excised from 2-D gels, digested with chymotrypsin, and subjected to MS/MS. We identified their gene haplotypes and created a 2-D gel map of LMW-GS alleles in the germplasm for breeding and screening for desirable LMW-GS alleles for wheat quality improvement.

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