l-Lactide polymerization studied by 1H NMR with diffusion-ordered spectroscopy (DOSY): a “One NMR Tube Experiment” providing data on monomer conversion, polymer structure, Mn and Mw

2015 ◽  
Vol 6 (24) ◽  
pp. 4353-4357 ◽  
Author(s):  
P. Lewinski ◽  
S. Sosnowski ◽  
S. Kazmierski ◽  
S. Penczek
Keyword(s):  
1H Nmr ◽  
Molar Mass ◽  
Monomer Conversion ◽  
Polymer Structure ◽  
Polymerization Kinetics ◽  
Average Molar Mass ◽  
On Line ◽  
First Time ◽  
Lactide Polymerization

The standard NMR and DOSY techniques allowed for the first time the on-line study of the polymerization kinetics together with the determination of number average molar mass Mn and mass average molar mass Mw.

Inter-laboratory evaluation of SEC-post-column calcofluor for determination of the weight-average molar mass of cereal β-glucan

2015 ◽  
Vol 124 ◽  
pp. 254-264 ◽  
Author(s):  
Anne Rieder ◽  
Svein Halvor Knutsen ◽  
Ann-Sissel T. Ulset ◽  
Bjørn E. Christensen ◽  
Roger Andersson ◽  
...  
Keyword(s):  
Molar Mass ◽  
Laboratory Evaluation ◽  
Average Molar Mass

scholarly journals Determination of the Average Molar Mass of the Vapour Above Molten Sodium Chloride by the Transpiration Method.

1979 ◽  
Vol 33a ◽  
pp. 407-412 ◽  
Author(s):  
Halvor Kvande ◽  
Oldrich Strouf ◽  
Pär Svanström ◽  
Elina Näsäkkälä ◽  
Eberhard Hoyer ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Molar Mass ◽  
Average Molar Mass ◽  
Molten Sodium ◽  
Transpiration Method

Hydrolytic stability of water-soluble spruce O-acetyl galactoglucomannans

Holzforschung ◽  
2009 ◽  
Vol 63 (1) ◽  
Author(s):  
Chunlin Xu ◽  
Andrey Pranovich ◽  
Jarl Hemming ◽  
Bjarne Holmbom ◽  
Simone Albrecht ◽  
...  
Keyword(s):  
Food Processing ◽  
Molar Mass ◽  
Hydrolytic Stability ◽  
Water Soluble ◽  
Average Molar Mass ◽  
Acidic Conditions ◽  
The Stability ◽  
Stability Of Water ◽  
Hydrolysis Of

Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce is a polysaccharide that can be produced in an industrial scale. To develop GGM applications, information is needed on its stability, particularly under acidic conditions. Therefore, acid hydrolysis of spruce GGM was investigated at various pH levels and temperatures. The results allow an estimation of the stability of GGM under food processing conditions and in biological systems. Determination of the average molar mass demonstrated that spruce GGM was stable at pH 1 and 37°C, as well as at pH 3 and 70°C. GGM was hydrolysed at pH 1 and 90°C. GGM oligomers and monomers were detected after degradation. Some of the oligomers contained O-acetyl groups. Monosaccharides were the predominant products in the hydrolysates after treatment at pH 1 and 90°C for 48 h. Pentoses, present in GGM samples as impurities, were released more easily than GGM hexoses. Glucose was more difficult to release than mannose. Traces of 6-deoxy-mannose and levoglucosan were found in the hydrolysates, indicating further degradation of hydrolysed monosaccharides.

scholarly journals Experimental Investigation of Methyl Methacrylate in Stirred Batch Emulsion Reactor: AGET ATRP Approach

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5793
Author(s):  
Mohammed Awad ◽  
Thomas Duever ◽  
Ramdhane Dhib
Keyword(s):  
Methyl Methacrylate ◽  
Reaction Temperature ◽  
Molar Mass ◽  
Batch Reactor ◽  
Monomer Conversion ◽  
Polymer Mixture ◽  
Temperature Threshold ◽  
Average Molar Mass ◽  
Aget Atrp ◽  
Pmma Polymer

This study examines the ab initio emulsion atom transfer radical polymerization (ATRP) initiated by an eco-friendly reducing agent to produce poly(methyl methacrylate) (PMMA) polymer with controlled characteristics in a 2 L stirred batch reactor. The effect of the reaction temperature, surfactant concentration, monomer to water ratio, and stirring speed was thoroughly investigated. The results showed that PMMA coagulation becomes quite severe at a certain temperature threshold. However, the coagulation could be avoided at mild reaction temperature, since the outcomes showed that loading more surfactant to the system under high mixing speed has balanced the polymer mixture and yielded high monomer conversion. The PMMA product was analyzed by gravimetry and GPC measurements and after 5 h of polymerization at a reaction temperature of 50 °C, monomer conversion of 64.1% was obtained, and PMMA polymer samples produced had an average molar mass of 4.5 kg/mol and a polydispersity index of 1.17. The structure of the PMMA polymer was successfully proved by FTIR and nuclear magnetic resonance (NMR) spectroscopy. The results confirm the living feature of MMA AGET ATRP in emulsion medium and recommend further investigation for other types of surfactant.

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

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