Molecular weight distribution of a bulk ultra-high molecular weight polyethylene product?impax 5M+ UHMW-NAT

1986 ◽  
Vol 20 (9) ◽  
pp. 1373-1389 ◽  
Author(s):  
R. P. Kusy ◽  
J. Q. Whitley
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Ultra High Molecular Weight

Improved EOR Polymer Selection Using Field-Flow Fractionation

2021 ◽  
Author(s):  
Johannes Steindl ◽  
Rafael Eduardo Hincapie ◽  
Ante Borovina ◽  
Christoph Puls ◽  
Johann Badstöber ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Field Flow Fractionation ◽  
Molecular Weights ◽  
Chemical Eor ◽  
Flow Fractionation ◽  
Polymer Retention ◽  
Ultra High Molecular Weight

Abstract Various polyacrylamide polymers have been successfully applied in chemical EOR projects. These polymers are characterised by high molecular weights (MW) to achieve high viscosifying power. The molecular weight distribution (MWD) of the polymers has a major impact on polymer properties and performance. Measuring the molecular weight distribution is challenging using conventional methods. Field-Flow Fractionation (FFF) enables the determination of the distribution to select and quality check various polymers. Polymers with high molar masses (> 1 MDa) are used for EOR to obtain highly viscous aqueous solutions. The MWD of the polymers is crucial for the solution characteristics. Conventional analysis of polymers is performed using either viscometry – which is able to determine the average MW but does not give information on MWD, or size-exclusion chromatography – which is restricted to molecular weights of < 20 MDa. FFF is based on the analytes flowing at different speeds in a channel dependent on their size and mass. This effect leads to separation, which is then used to determine the MWD. FFF allows to determine the MW and MWD of various ultra-high molecular weight polyacrylamides (HPAAMs). The FFF measurements showed, that despite similar MWs are claimed, substantial differences in MWD are observed. This technology offered the quantification the MWD of HPAAMs up to a MW of 5 GDa. Furthermore, gyration radii of the HPAAM molecules were determined. Selecting polymers on viscosifying power only is not addressing issues related to different MW and MWDs such as selective polymer retention and degradation of the high molar mass part of the distribution. The results were used to improve the polymer selection for chemical EOR projects. Overall, this work presents a new technique for analysis of ultra-high molecular weight EOR polymers, which enables the possibility to determine the full range of polymer MWD. This available information enhances the EOR polymer selection process addressing selective polymer retention and mechanical degradation in addition to the viscosifying power of polymers.

Equilibrium Molecular Weight Distribution of Cyclic and Linear Methylsiloxanes

1967 ◽  
Vol 40 (4) ◽  
pp. 1084-1093 ◽  
Author(s):  
Jack B. Carmichael ◽  
James Heffel
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Equilibrium Constants ◽  
Molecular Size ◽  
Size Distributions ◽  
Flory Theory ◽  
Molecular Weights ◽  
Cyclic Molecules

Abstract Data are reported for the equilibrium molecular size distributions of cyclic and linear methylsiloxanes in five polymers with number average molecular weights ranging from 459 to 1348. The distributions of linear species agree with the earlier work of Scott and agree reasonably well with the Flory theory of random reorganization. The amounts of cyclic molecules are sharply dependent on molecular weight. However, the equilibrium constants for cyclic formation for cyclic species with four to eight units are shown to be virtually identical with the equilibrium constants for cyclic formation in high molecular weight polymers reported in a previous publication. For octamethylcyclotetrasiloxane, Kav in moles of siloxane units per liter was found to be 0.72 in this study. For high polymers, Kav was previously reported to be 0.74.

Bis(phenolate) N-heterocyclic carbene rare earth metal complexes: synthesis, characterization and applications in the polymerization of n-hexyl isocyanate

RSC Advances ◽  
2015 ◽  
Vol 5 (101) ◽  
pp. 83295-83303 ◽  
Author(s):  
Min Zhang ◽  
Jingjing Zhang ◽  
Xufeng Ni ◽  
Zhiquan Shen
Keyword(s):  
Molecular Weight ◽  
Rare Earth ◽  
Metal Complexes ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Rare Earth Metal ◽  
Weight Distribution ◽  
Earth Metal ◽  
Narrow Molecular Weight Distribution ◽  
Rare Earth Metal Complexes

Polyhexyl isocyanantes catalyzed by N-heterocyclic carbene rare earth metal complexes show high molecular weight with narrow molecular weight distribution.

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