Proton Modification of Ultra High Molecular Weight Polyethylene to Promote Crosslinking for Enhanced Chemical and Physical Properties

1995 ◽  
Vol 396 ◽  
Author(s):  
J.F. Wilson ◽  
J.R. Liu ◽  
F. Romero-Borja ◽  
W.K. Chu
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Surface Region ◽  
Low Doses ◽  
Carbonyl Groups ◽  
Hydrogen Annealing ◽  
Near Surface ◽  
Gel Permeation ◽  
Ultra High Molecular Weight

AbstractCrosslinking onset was investigated for ultra high molecular weight polyethylene(UHMW-PE) implanted with 2.6 MeV H+ ions at low doses from 6×1011-3×1013 ions/cm2. Crosslinking in the near surface region(20–40μm) was determined from gel permeation chromatography(GPC) of 1,2,4 trichlorobenzene sol fractions and increased with dose. Fourier transform infrared spectroscopy(FTIR) showed irradiation resulted in increased free radicals confirmed from increased carbonyl groups. Hydrogen annealing after ion implantation resulted in 38–49% decrease in FTIR peak associated with carbonyl.

scholarly journals Biosynthesis of glycoproteins by membranes of Acer pseudoplatanus. Incorporation of mannose and N-acetylglucosamine

1980 ◽  
Vol 192 (2) ◽  
pp. 569-577 ◽  
Author(s):  
J Barr ◽  
P Nordin
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Monosaccharide Composition ◽  
Paper Electrophoresis ◽  
Acer Pseudoplatanus ◽  
Gel Permeation ◽  
Chloroform Methanol ◽  
Insoluble Pellet

Membrane preparations from Acer pseudoplatanus suspension cultures were demonstrated to incorporate radioactivity from GDP-[U-14C]mannose and UDP-N-acetyl-[6-(3)H]glucosamine into high-molecular-weight polymers characterized as glycoprotein. From 20 to 25% of the 14C was incorporated as fucose with the remainder as mannose, whereas 90% of the 3H was incorporated as N-acetylglucosamine with the remainder as N-acetylgalactosamine. Pronase digestion yielded radioactive glycopeptides that were separated into four fractions by gel-permeation chromatography and paper electrophoresis. The isolated glycopeptides differed in molecular weight and isotopes incorporated, as well as in amino-acid and monosaccharide composition. The membrane preparation also incorporated radioactivity from the added nucleotides into chloroform/methanol (2:1, v/v)- and chloroform/methanol/water (10:10:3, by vol.)-soluble lipids, and into an insoluble pellet.

Gel permeation chromatography of high molecular weight cellulose trinitrate

Polymer ◽  
1978 ◽  
Vol 19 (12) ◽  
pp. 1421-1426 ◽  
Author(s):  
C. Holt ◽  
W. Mackie ◽  
D.B. Sellen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

Tribotechnical properties of ultra-high molecular weight polyethylene filled with sulfur, diphenylguanidine and 2-mercaptobenzothiazole

2020 ◽  
pp. 91-98
Author(s):  
S. N. Danilova ◽  
A. A. Dyakonov ◽  
A. P. Vasiliev ◽  
Y. S. Gerasimova ◽  
A. A. Okhlopkova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Wear Resistance ◽  
Surface Layer ◽  
Ir Spectroscopy ◽  
High Molecular Weight ◽  
High Wear Resistance ◽  
Carbonyl Groups ◽  
Tribotechnical Properties ◽  
Ultra High Molecular Weight

The paper studies tribotechnical properties, hardness and density of composites based on ultra-high molecular weight polyethylene (UHMWPE) filled with sulfur, diphenylguanidine (DFG) and 2-mercaptobenzothiazole (MBT) and their mixtures. It has been established that the introduction of selected fillers has practically no effect on hardness and density of the composites, but leads to a significant (by 2–3 times) increase in the wear resistance of materials. Using electron microscopy, it has been established that secondary structures are formed in composites containing MBT that protect the surface layer of the material from wear. Using IR spectroscopy, it was established that tribochemical reactions occur during the wear of composites with the formation of hydroxyl and carbonyl groups. The developed materials UHMWPE / MBT and UHMWPE / FGD / MBT have high wear resistance and can be used as materials for tribological purposes.

QUANTITATIVE ASSESSMENT OF THE BRANCHING ARCHITECTURE OF EPDM WITH HIGH CONTENT OF 5-VINYL-2-NORBORNENE AS THIRD MONOMER

2013 ◽  
Vol 86 (4) ◽  
pp. 503-520 ◽  
Author(s):  
Konraad Dullaert ◽  
Gerard van Doremaele ◽  
Martin van Duin ◽  
Herman Dikland
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Quantitative Assessment ◽  
Volume Fraction ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Branched Polymer ◽  
Branching Points ◽  
Gel Permeation ◽  
Branching Architecture

ABSTRACT The branching architecture of high-molecular-weight EPDM polymers with high amounts of 5-vinyl-2-norbornene (VNB) as a third monomer, produced using recently developed Keltan ACE™ technology, was assessed by means of the dilution rheology method proposed by Crosby et al.1 and compared with conventional Ziegler–Natta EPDM grades. First, the dilution rheology results were converted into a single convenient parameter, called the dilution slope. Next, by combining the dilution rheology results with gel permeation chromatography data and assuming trifunctional branching points, we calculated the volume fraction of the branched polymer, the average molecular weight between branching points, and the branching density. It is shown that the high-VNB polymers studied contained a significantly higher amount of branch-on-branch structures.

High Molecular Weight Complexes Derived From Fibrinogen

1981 ◽  
Author(s):  
N Alkjaersig ◽  
A Fletcher
Keyword(s):  
Molecular Weight ◽  
Complex Formation ◽  
High Molecular Weight ◽  
Molecular Size ◽  
Gel Permeation Chromatography ◽  
Linear Increase ◽  
Clot Formation ◽  
High Molecular Weight Complex ◽  
Fibrin Monomer ◽  
Gel Permeation

Fibrinogen, 3×10-5 M, incubated at 25°C with thrombin 10-10 M, is slowly transformed to fibrin. Fibrinopeptide A (FPA) is released at a rate of approximately 1 nM/ml per min, and after 30 min a clot is formed. Prior to clot formation serially timed solution aliquots were examined by gel permeation chromatography on a Bio Gel 5M column (void volume 140 ml). High molecular weight complex concentration and molecular size increased with incubation time. Fibrinogen antigen and FPA concentration was determined for each effluent fraction and relative FPA content (ng FPA/μg fibrinogen equivalent) was linearly related to chromatographic effluent volume between 160 and 260 ml (Ve for fibrinogen 255 ml). Computer analysis of the effluent profiles indicated a linear fall in monomeric fibrinogen to 20% of original concentration, a linear increase in “fibrin” dimer (2 fibrinogen equivalents with 2 FPA) to 30% and in trimer (3 fibrinogen equivalents with 2 FPA) to 20% of original concentration with higher polymers accounting for the remaining protein. These complexes were stable and remained in solution after fractionation. Fibrin monomer, in 3 M urea and devoid of FPA, when added to fibrinogen resulted in clot formation, equivalent to 66% of added monomer, but minimal complex formation, 5% of total fibrinogen equivalents. Thus intermediate fibrin polymers which contain residual FPA are stable soluble molecular entities in contradistinction to fibrin monomer lacking FPA. Fibrin proteolysis products added to fibrinogen also show minimal complex formation with fibrinogen if the products are free of thrombin and FPA. Patient plasma samples can be similarly assayed and distinction can be made between high molecular weight complexes derived from fibrinogen through thrombin action or from fibrin through plasmin action.

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