Investigation of the Molecular Weight Increase of Commercial Lignosulfonates by Laccase Catalysis

2010 ◽  
Vol 11 (4) ◽  
pp. 904-910 ◽  
Author(s):  
Dimitri Areskogh ◽  
Jiebing Li ◽  
Göran Gellerstedt ◽  
Gunnar Henriksson
Keyword(s):  
Molecular Weight ◽  
Weight Increase ◽  
Molecular Weight Increase

scholarly journals Solid-State Polymerization of Poly(Ethylene Furanoate) Biobased Polyester, III: Extended Study on Effect of Catalyst Type on Molecular Weight Increase

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 438 ◽  
Author(s):  
Yosra Chebbi ◽  
Nejib Kasmi ◽  
Mustapha Majdoub ◽  
George Papageorgiou ◽  
Dimitris Achilias ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Solid State ◽  
Intrinsic Viscosity ◽  
Weight Increase ◽  
Degree Of Crystallinity ◽  
Solid State Polymerization ◽  
End Groups ◽  
Poly Ethylene ◽  
Molecular Weight Increase

In this study, the synthesis of poly(ethylene furanoate) (PEF), catalyzed by five different catalysts—antimony acetate (III) (Sb Ac), zirconium (IV) isopropoxide isopropanal (Zr Is Ip), antimony (III) oxide (Sb Ox), zirconium (IV) 2,4-pentanedionate (Zr Pe) and germanium (IV) oxide (Ge Ox)—via an industrially common combination of melt polymerization and subsequent solid-state polymerization (SSP) is presented. In all reactions, proper amounts of 2,5-dimethylfuran-dicarboxylate (DMFD) and ethylene glycol (EG) in a molar ratio of DMFD/EG= 1/2 and 400 ppm of catalyst were used. Polyester samples were subjected to SSP procedure, under vacuum application, at different reaction times (1, 2, 3.5, and 5 h) and temperatures of 190, 200, and 205 °C. Carboxyl end-groups concentration (–COOH), intrinsic viscosity (IV), and thermal properties, via differential scanning calorimetry (DSC), were measured for all resultant polymers to study the effect of the used catalysts on the molecular weight increase of PEF during SSP process. As was expected, it was found that with increasing the SSP time and temperature, the intrinsic viscosity and the average molecular weight of PEF steadily increased. In contrast, the number of carboxyl end-groups content showed the opposite trend as intrinsic viscosity, that is, gradually decreasing during SSP time and temperature increase. It is worthy to note that thanks to the SSP process an obvious and continuous enhancement in the thermal properties of the prepared PEF samples was attained, in which their melting temperatures (Tm) and degree of crystallinity (Xc) increase progressively with increasing of reaction time and temperature. To predict the time evolution of polymers IV, as well as the hydroxyl and carboxyl content of PEF polyesters during the SSP, a simple kinetic model was developed. From both the theoretical simulation results and the experimental measurements, it was demonstrated that surely the Zr Is Ip catalyst shows the best catalytic characteristics compared to all other used catalysts herein, that is, leading in reducing—in a spectacular way—the activation energy of the involved both transesterification and esterification reactions during SSP.

scholarly journals Experimental and Theoretical Investigations of PAN Molecular Weight Increase in Precipitation Polymerization as a Function of H2O/DMSO Ratio

2010 ◽  
Vol 11 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Jing Zhang ◽  
Fengjing Bu ◽  
Yongqiang Dai ◽  
Liwei Xue ◽  
Zhixian Xu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Precipitation Polymerization ◽  
Weight Increase ◽  
Theoretical Investigations ◽  
Molecular Weight Increase

Effect of catalyst type on molecular weight increase and coloration of poly(ethylene furanoate) biobased polyester during melt polycondensation

2017 ◽  
Vol 8 (44) ◽  
pp. 6895-6908 ◽  
Author(s):  
Zoe Terzopoulou ◽  
Elisavet Karakatsianopoulou ◽  
Nejib Kasmi ◽  
Vasileios Tsanaktsis ◽  
Nikolaos Nikolaidis ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Increase ◽  
Two Stage ◽  
Melt Polycondensation ◽  
Polycondensation Process ◽  
Catalyst Type ◽  
Poly Ethylene ◽  
Molecular Weight Increase ◽  
Biobased Polyester

The effect of several catalysts on the synthesis of poly(ethylene furanoate) (PEF) was studied during a two-stage melt polycondensation process.

Molecular weight increase driven by evolution of crystal structure in the process of solid-state polycondensation of poly(l-lactic acid)

Polymer ◽  
2017 ◽  
Vol 126 ◽  
pp. 133-140 ◽  
Author(s):  
Makoto Takenaka ◽  
Yoshiharu Kimura ◽  
Hitomi Ohara
Keyword(s):  
Crystal Structure ◽  
Molecular Weight ◽  
Lactic Acid ◽  
Solid State ◽  
Weight Increase ◽  
Molecular Weight Increase

scholarly journals Rate of Molecular Weight Increase in the Boiling of Linseed Oil1,2

1926 ◽  
Vol 18 (12) ◽  
pp. 1252-1253 ◽  
Author(s):  
J. S. Long ◽  
W. J. Arner
Keyword(s):  
Molecular Weight ◽  
Weight Increase ◽  
Molecular Weight Increase

scholarly journals Determination of some characteristics of comet’s gases by photometry method for comet Hyakutake

2019 ◽  
Vol 14 (29) ◽  
pp. 175-181
Author(s):  
S . Z . Khalaf
Keyword(s):  
Molecular Weight ◽  
Light Intensity ◽  
Velocity Distribution ◽  
Average Molecular Weight ◽  
Weight Increase ◽  
Cometary Tail ◽  
Molecular Weight Increase ◽  
Number Of Particles

The present paper focuses on the study of some characteristics ofcomets ions by photometry method which represent by CCD camerawhich it provide seeing these images in a graded light. From 0-255when Zero (low a light intensity) and 255 (highlight intensity). Thesedifferences of photonic intensity can be giving us a curve whichappear from any line of this image.From these equations the focus is concentrating on determine thetemperature distribution, velocity distribution, and intensity numberdistribution which is give number of particles per unit volume.The results explained the interaction near the cometary nucleuswhich is mainly affected by the new ions added to the density of thesolar wind, the average molecular weight increase and result in manyunique characteristics of the cometary tail.

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