Prediction of molecular weight distributions by probability generating functions. Application to industrial autoclave reactors for high pressure polymerization of ethylene and ethylene-vinyl acetate

2001 ◽  
Vol 41 (8) ◽  
pp. 1413-1426 ◽  
Author(s):  
A. Brandolin ◽  
C. Sarmoria ◽  
A. Lótpez-Rodríguez ◽  
K. S. Whiteley ◽  
B. Del Amo Fernandez
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Vinyl Acetate ◽  
Generating Functions ◽  
Ethylene Vinyl Acetate ◽  
Probability Generating Functions ◽  
Molecular Weight Distributions ◽  
Weight Distributions

The Use of Novel F-RAFT Agents in High Temperature and High Pressure Ethene Polymerization: Can Control be Achieved?

2007 ◽  
Vol 60 (10) ◽  
pp. 788 ◽  
Author(s):  
Markus Busch ◽  
Marion Roth ◽  
Martina H. Stenzel ◽  
Thomas P. Davis ◽  
Christopher Barner-Kowollik
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
High Temperature ◽  
Degree Of Polymerization ◽  
Molecular Weight Distributions ◽  
High Pressure High Temperature ◽  
Reversible Addition ◽  
Weight Distributions ◽  
Raft Agent ◽  
Initial Results

Simulations are employed to establish the feasibility of achieving controlled/living ethene polymerizations. Such simulations indicate that reversible addition–fragmentation chain transfer (RAFT) agents carrying a fluorine Z group may be suitable to establish control in high-pressure high-temperature ethene polymerizations. Based on these simulations, specific fluorine (F-RAFT) agents have been designed and tested. The initial results are promising and indicate that it may indeed be possible to achieve molecular weight distributions with a polydispersity being significantly lower than that observed in the conventional free radical process. In our initial trials presented here (using the F-RAFT agent isopropylfluorodithioformate), a correlation between the degree of polymerization and conversion can indeed be observed. Both the lowered polydispersity and the linear correlation between molecular weight and conversion indicate that control may in principle be possible.

Molecular Weight Determinations Of Low Molecular Weight (LMW) Heparins By Ultracentrifugation And High Pressure Liquid Chromatography

1981 ◽  
Author(s):  
Grant Barlow ◽  
N Sugisaka ◽  
F J Petracek
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Low Molecular Weight ◽  
Analytical Ultracentrifuge ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Heparin Fractions

Molecular weights were independently determined on nitrous acid depolymerized LMW heparin fractions ranging from 2-15 daltons using the analytical ultracentrifuge and high pressure liquid chromatography (HPLC).Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.The HPLC results were obtained using previously described methods (Fed Proc. 36, 89, 1977) and a new highly efficient gel column (TSK gels). Fractionated dextrans were used as reference standards.

High pressure water-initiated ring opening polymerization for the synthesis of well-defined α-hydroxy-ω-(carboxylic acid) polycaprolactones

2017 ◽  
Vol 19 (15) ◽  
pp. 3618-3627 ◽  
Author(s):  
A. Dzienia ◽  
P. Maksym ◽  
M. Tarnacka ◽  
I. Grudzka-Flak ◽  
S. Golba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Carboxylic Acid ◽  
Ring Opening ◽  
Chemical Structure ◽  
Ring Opening Polymerization ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Pressure Water ◽  
Novel Method

A novel method to produce polyesters of a well-defined chemical structure, and narrow molecular weight distributions by using a combination of high pressure, temperature and water was proposed.

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