Comparison of different methods for the determination of the molar mass and molar mass distribution of poly(ethylmethylsiloxane)

2000 ◽  
Vol 201 (12) ◽  
pp. 1311-1316 ◽  
Author(s):  
H. Götz ◽  
U. Maschke ◽  
T. Wagner ◽  
C. Rosenauer ◽  
K. Martin ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution

scholarly journals Size-exclusion chromatography of cellulose: observations on the low-molar-mass fraction

Cellulose ◽  
2020 ◽  
Vol 27 (16) ◽  
pp. 9217-9225
Author(s):  
Leena Pitkänen ◽  
Herbert Sixta
Keyword(s):  
Mass Distribution ◽  
Size Exclusion Chromatography ◽  
Mass Fraction ◽  
Molar Mass ◽  
Accurate Determination ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
Universal Method ◽  
Exclusion Chromatography

AbstractAccurate determination of molar mass distribution for disperse cellulose samples has proved to be a challenging task. While size-exclusion chromatography coupled to multi-angle light scattering (MALS) and differential refractive index (DRI) detectors has become the most commonly used method for molar mass determination of celluloses, this technique suffers low sensitivity at the low-molar mass range. As discussed here, the universal method for accurate molar mass distribution analysis of cellulose samples not exists and thus thorough understanding on the differences of the various methodological approaches is important. In this study, the focus is in the accurate determination of the low-molar mass fraction. The results obtained by combining the two calibration strategies, MALS/DRI for polymeric region of a cellulose sample and conventional calibration for oligomeric region, was compared to the results obtained using only MALS/DRI (with extrapolation of the curve where signal-to-noise of MALS is low). For birch pulp sample, the results from the two approaches were comparable; it should be highlighted, however, that MALS/DRI slightly overestimates the molar masses at the low-molar-mass region.

scholarly journals On the Recovery of PLP-Molar Mass Distribution at High Laser Frequencies: A Simulation Study

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 501 ◽  
Author(s):  
Shaghayegh Hamzehlou ◽  
M. Ali Aboudzadeh ◽  
Yuri Reyes
Keyword(s):  
Mass Distribution ◽  
Simulation Study ◽  
Molar Mass ◽  
Laser Frequency ◽  
Molar Mass Distribution ◽  
Reliable Determination ◽  
Degree Of Branching ◽  
High Laser ◽  
Laser Frequencies

Due to the inherent difficulties in determination of the degree of branching for polymers produced in pulsed laser polymerization (PLP) experiments, the behavior of the degree of branching and backbiting reaction in high laser frequency and relatively high reaction temperatures have not been well-established. Herein, through a simulation study, the validity of different explanations on the recovery of PLP-molar mass distribution at high laser frequencies is discussed. It is shown that the reduction of the backbiting reaction rate at high laser frequency, and consequent decrease in the degree of branching, is not a necessary condition for recovering the PLP-molar mass distribution. The findings of this work provide simulation support to a previous explanation about the possibility of using high laser frequency for reliable determination of the propagation rate coefficient for acrylic monomers.

Determination of molar mass distribution of alkyl polyethylene glycol ethers

1981 ◽  
Vol 58 (5) ◽  
pp. 650-655 ◽  
Author(s):  
L. Farkas ◽  
J. Morgós ◽  
P. Sallay ◽  
I. Rusznák ◽  
B. Bartha ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Glycol Ethers

Methods of investigation determination of molar mass distribution of polyamidobenzimidazole from a single sedimentogram

1988 ◽  
Vol 30 (11) ◽  
pp. 2631-2638
Author(s):  
I.K. Nekrasov ◽  
Ye.B. Tarabukina ◽  
Z.N. Slavina ◽  
L.G. Shirokova
Keyword(s):  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution

Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the method

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 459-468 ◽  
Author(s):  
Stéphanie Baumberger ◽  
Alfred Abaecherli ◽  
Mario Fasching ◽  
Gäoran Gellerstedt ◽  
Richard Gosselink ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Size Exclusion Chromatography ◽  
Molar Mass ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
High Molar Mass ◽  
Wide Range ◽  
Exclusion Chromatography ◽  
Technical Lignins

Abstract The reactivity and physicochemical properties of lignins are partly governed by their molar mass distribution. The development of reliable standard methods for determination of the molar mass distribution is not only relevant for designing technical lignins for specific applications, but also for monitoring and elucidating delignification and pulping processes. Size-exclusion chromatography (SEC) offers many advantages, such as wide availability, short analysis time, low sample demand, and determination of molar mass distribution over a wide range. A collaborative study has been undertaken within the “Eurolignin” European thematic network to standardise SEC analysis of technical lignins. The high-molar-mass fraction of polydisperse lignins was shown to be the main source of intra- and interlaboratory variations, depending on the gel type, elution solvent, detection mode, and calculation strategy. The reliability of two widespread systems have been tested: one based on alkali and a hydrophilic gel (e.g., TSK Toyopearl gel) and the other based on THF as solvent and polystyrene-based gels (e.g., Styragel). A set of practical recommendations has been deduced.

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