Relationship between intrinsic viscosity and mean molecular weight of polyvinylpyrrolidone in the low-molecular-weight region

1979 ◽  
Vol 13 (10) ◽  
pp. 1104-1104 ◽  
Author(s):  
T. M. Karaputadze ◽  
V. I. Svergun ◽  
S. V. Tarabakin ◽  
V. P. Panov ◽  
Yu. �. Kirsh
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Low Molecular Weight ◽  
Mean Molecular Weight

Intrinsic viscosity–molecular weight relationship for low molecular weight nylon 6

1968 ◽  
Vol 12 (9) ◽  
pp. 2105-2109 ◽  
Author(s):  
P. Hague ◽  
M. B. Huglin ◽  
B. L. Johnson ◽  
J. Smith
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Nylon 6 ◽  
Low Molecular Weight ◽  
Weight Relationship

Sodium-Catalyzed Copolymerization of 1,3-Butadiene and Styrene

1947 ◽  
Vol 20 (1) ◽  
pp. 1-13
Author(s):  
C. S. Marvel ◽  
W. J. Bailey ◽  
G. E. Inskeep
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Monomer Mixture ◽  
Laboratory Procedure ◽  
Styrene Content ◽  
Polymerization Method

Abstract 1. A convenient laboratory procedure for the sodium-catalyzed copolymerization of butadiene and styrene has been described. Earlier attempts to accomplish this probably failed because the monomers were not sufficiently pure. 2. The copolymer of butadiene and styrene which results from sodium polymerization is different from the emulsion copolymer, GR-S, in several important respects. The sodium-catalyzed copolymer has a more nearly constant styrene content at different stages of conversion; it is made up of molecules with a relatively narrow molecular weight spread; it has a higher intrinsic viscosity; it is 100 per cent soluble in benzene (i.e., there is no gel) even at 100 per cent conversion; when treated with standard rubber antioxidant, it ages better; and it has a greater amount of the butadiene joined in the 1,2 manner (i.e., greater vinyl side-chain content). 3. The effects of such variables as temperature of polymerization, method of adding the monomer mixture to the catalyst, size of catalyst particles, and possible butadiene impurities on the polymerization have been studied. 4. The method has been extended to cover copolymerization of butadiene and m-methylstyrene to give a soluble copolymer of low molecular weight. Other styrene-type monomers gave less interesting copolymers.

Chromatographic Fractionation of Some Synthetic Elastomers

1948 ◽  
Vol 21 (3) ◽  
pp. 682-683 ◽  
Author(s):  
Ivan Landler
Keyword(s):  
Molecular Weight ◽  
Cellulose Acetate ◽  
Active Carbon ◽  
Low Molecular Weight ◽  
High Polymer ◽  
Acrylonitrile Copolymer ◽  
Molecular Weights ◽  
The Mean ◽  
Mean Molecular Weight ◽  
Poor Solvent

Abstract Mark and Saito were the first to fractionate a high polymer (cellulose acetate) by chromatographic adsorption on blood carbon. They found that molecules of low molecular weight were adsorbed first, and that the mean molecular weight of the product which remained unadsorbed was higher than the original molecular weight. Levi and Giera confirmed this result, but did not succeed in fractionating Buna-S or polyisoprene, for these polymers were eluted by the solvent during the washing operation in the column. The present authors have carried out further experiments in this field with a study of three commercial synthetic elastomers, viz., GR-S (butadienestyrene copolymer), Perbunan-N (butadiene-acrylonitrile copolymer), and Visitanex (polyisobutylene). The polymer was adsorbed by starting with a poor solvent composed of a mixture of toluene and methanol ; the quantity of alcohol added was just below the threshold of precipitation. The adsorbent used was a mixture of 75 per cent of lamp black (80 square meters per gram) and 25 per cent of coarse active carbon. The latter served to prevent agglomeration of the lamp black. The adsorbent was divided into three layers, of 10 grams each. At the end of the tube was a filter of fritted glass. Filtration was carried out under pressure, the rate of flow thereby being maintained constant, The polymers were characterized by their intrinsic viscosities. The molecular weights which were estimated by means of the relation, found experimentally between the molecular weight and viscosity, are only approximate, for this relation holds true only for narrow fractions.

Effects of an Enzymatically Depolymerized Heparin as Compared with Conventional Heparin in Healthy Volunteers

1987 ◽  
Vol 57 (01) ◽  
pp. 097-101 ◽  
Author(s):  
Thomas Mätzsch ◽  
David Bergqvist ◽  
Ulla Hedner ◽  
Per Østergaard
Keyword(s):  
Molecular Weight ◽  
Body Weight ◽  
Healthy Volunteers ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Normal Range ◽  
Factor Xa Inhibition ◽  
At Iii ◽  
Mean Molecular Weight ◽  
Enzymatic Depolymerization

SummaryA low molecular weight heparin (LMW-heparin) with a mean molecular weight of 4900 dalton was prepared by controlled enzymatic depolymerization of conventional porcine mucosal heparin. The effects of 2,500, 5,000 and 10,000 U (Xal; 29,58 and 116 mg) on factor Xa inhibition (Xal), factor Ila inhibition (Hal), APTT, AT III and platelet count were compared to those of 5,000 U (Xal; 26 mg) of conventional heparin given s. c. to 6 healthy volunteers. 5,000 U (Xal; 58 mg) of LMW-heparin was given i. v. A dose related response with regard to the Xal and the Ila-inhibitory activities with peak values at 4 hours after the s. c. injections was obtained. An increase of the Xal/IIal ratio over the time after injection was seen only after i. v. administration of the LMW-heparin. The APTT was only slightly prolonged and remained within normal range after s. c. injection. AT III and platelet counts were unaffected. The biological half life of the LMW-heparin was 111 minutes if assayed by Xa inhibition, 76 minutes if assayed by Ila inhibition and 40 minutes if assayed by APTT. A strong correlation between the Xal activities obtained and body weight was seen, indicating that LMW-heparin should be administered individually according to body weight.

Four Heparin Preparations: Anti-Xa Potentiating Effect of Heparin after Subcutaneous Injection

1976 ◽  
Vol 35 (03) ◽  
pp. 586-591 ◽  
Author(s):  
E. A Johnson ◽  
T. B. L Kirkwood ◽  
Yvonne Stirling ◽  
J. L Perez-Requejo ◽  
G. I. C Ingram ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Randomized Trial ◽  
High Molecular Weight ◽  
Subcutaneous Injection ◽  
Low Molecular Weight ◽  
Mean Values ◽  
Sodium Heparin ◽  
Calcium Heparin ◽  
Mean Molecular Weight ◽  
Plasma Heparin

SummaryFour different heparin preparations - sodium and calcium salts of the same batch of heparin (mean molecular weight 15,000), low molecular weight sodium heparin (mean m. w. 9,000) and high molecular weight sodium heparin (mean m. w. 22,000) were injected subcutaneously on different days each into 6 healthy young volunteers in a randomized trial. Plasma heparin levels were measured using the anti-Xa assay at 1 hour, 3-4 hours and 6-7 hours after the injection. The highest anti-Xa potentiating effect was obtained after the injection of the low molecular weight sodium heparin (mean 0.381 i. u./ml) at 3-4 hours after the injection. With sodium heparin (m. w. 15,000) the highest values (0.135 i. u./ml) were found at 1 hour. Significantly lower anti-Xa potentiating effect was obtained 1 hour after the injection of calcium heparin and in particular after the injection of high molecular weight heparin (mean values 0. 072 i. u./ml and 0.043 i. u./ml respectively). Both these preparations showed an increase from 1 hour after injection to 3-4 hours after injection (mean values 0.082 i. u./ml and 0.057 1. u./ml at 3-4 hours after injection).These results indicate that the salt and the molecular weight of the preparation may strongly influence the degree of anticoagulation achieved after subcutaneous injection.

Interaction Between Low Molecular Weight Dextran Sulphate and Bentonite adsorbed Plasma

1979 ◽  
Author(s):  
T. Matsuda ◽  
M. Ogawara ◽  
T. Seki ◽  
R. Miura ◽  
M. Yokouchi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Antithrombin Iii ◽  
Low Molecular Weight ◽  
Thrombin Time ◽  
Dextran Sulphate ◽  
Bothrops Atrox ◽  
Plasmin Inhibitor ◽  
Mean Molecular Weight

Effects of low molecular weight dextran sulphate (D.S.; mean molecular weight = 6,0006,500; S content = 17-19%) and/or bentonite (Wako Pure Chemical Industries, Osaka, Japan) adsorbed plasma (supernatant from plasma mixed with 300 mg/ml of bentonite for 10 minutes at 37°C), which contains no fibrinogen nor antithrombin III but α2 macro-globulin, α1-antitrypsin and α2-plasmin inhibitor, on thrombin time or batroxobin (purified fraction of venom of Bothrops atrox) time of fibrinogen solution were investigated. Addition of D.S. or bentonite adsorbed plasma to fibrinogen solution resulted in prolongations of thrombin time and batroxobin time. These results indicate that both D.S. and bentonite adsorbed plasma inhibit conversion of fibrinogen to fibrin by thrombin or batroxobin. However, when appropriately diluted bentonite adsorbed plasma and D.S. were added to fibrinogen solution simultaneously, thrombin times and batroxobin times were shorter compared to those when either bentonite adsorbed plasma or D.S. but not both was added. From these results, it is concluded that D.S. and bentonite adsorbed plasma interact to inhibit each other.

The Synthesis of Benzothiazole Polymers with Perpendicularly Attached Phenyl Substituents

1988 ◽  
Vol 134 ◽  
Author(s):  
William A. Feld ◽  
YiHua Chang ◽  
John D. Peak ◽  
Scott G. Wierschke ◽  
Join Pin Chen
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Low Molecular Weight ◽  
Enhanced Solubility

ABSTRACTA series of 2-aryl-4,7-benzothiazoledicarboxylic acids have been synthesized from the corresponding dimethyl derivatives. These derivatives contain the phenyl, and the p-bromo-, mchloro-, p-chloro-, m-methoxy-, and p-methoxyphenyl aryl substituents. The phenyl, pchlorophenyl and p-methoxyphenyl substituted diacids were polymerized with 2,5-diamino-1,4- benzenedithiol dihydrochloride to yield the corresponding poly(benzothiazole)s. The polymers were of low molecular weight (intrinsic viscosity as high as 1.7) and did not show enhanced solubility in common solvents.

Extraction and Partial Characterisation of Hydrocolloid Gums from Some African Legumes

2011 ◽  
Vol 7 (3) ◽  
Author(s):  
Clément Saidou ◽  
Jean Bosco Tchatchueng ◽  
Robert Ndjouenkeu ◽  
Denis CD Roux
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Intrinsic Viscosity ◽  
The Other ◽  
Low Molecular Weight ◽  
Water Emulsion ◽  
Viscosity Measurements ◽  
Galactose Residue ◽  
Partial Characterisation ◽  
Oil Water

In an attempt to understand the potential valorisation of local African legumes, hydrocolloids of five legumes (Corchorus olithorus, Triumfetta cordifolia, Cerathoteca sesamoides, Adansona digitata, and Bridelia thermifolia) were extracted and characterised as polysaccharides. All the gum extracted were rich in galactose residue (31-62 percent), suggesting a galactan backbone for the polysaccharides structure. The other sugar residues of the polysaccharides were arabinose (22-30 percent) in T. cordifolia and B. thermifolia, glucose (22-36 percent) in B. thermofolia, A. digitata and C. olithorus, and mannose (32.9 percent) in C. sesamoides. The intrinsic viscosity measurements showed that gums from T. cordifolia, B. thermifolia, C sesamoides and C. olithorus are high molecular weight polymers, while A. digitata contains low molecular weight polymers. The gum extracts also showed oil/water emulsion activity and were able to keep 60-90 percent of the emulsion stable on heating.

Low Molecular Weight Heparins: Anti-Xa/Aptt And Platelet Aggregation

1981 ◽  
Author(s):  
F Fussi ◽  
M R Smith ◽  
A Girolami ◽  
L Visentini ◽  
F Fabris
Keyword(s):  
Molecular Weight ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Significant Inhibition ◽  
Significant Rise ◽  
Low Molecular Weight ◽  
Inhibiting Activity ◽  
Low Molecular Weight Heparins ◽  
Platelet Release ◽  
Mean Molecular Weight

Porcine mucosal Heparin (mean molecular weight= 15.000 Dalton) has been chemically depolymerized in presence of peroxides and N-sulphate groups have been re-introduced by reaction with sulpho- trioxides of amines. The depolymerization has been stopped at different times and the products are essayed for Anti-Xa, APTT and their ratio. A rise in the ratio Anti-Xa/APTT has been observed.In order to check for an activity on the platelet aggregation, two sets of experiments have been carried out: in a first model, the 5-hydroxytrip- tamine (5-HT) release has been measured after addition of different quantities of products to washed platelets. One commercil Heparin gave a significant rise in 5-HT release whereas a normal porcine mucosal Heparin did not show any modification in basal values, nor significant modifications have been observed for low molecular weight heparins (10.000 to 7.000 D). Heparansulphate (HS) and Dermatansulphate (DS) show a slight anti-aggregating activity in this test.In a second model, the percentage inhibition in collagen induced platelet release has been measured in a platelet rich plasma (PRP). All the tested heparins show a very significant inhibition, whereas HS and DS have no inhibiting activity in this test.

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