Influence of molecular weight and chemical structure of soft segment in reaction kinetics of polycarbonate diols with 4,4′-diphenylmethane diisocyanate

2005 ◽  
Vol 41 (12) ◽  
pp. 3051-3059 ◽  
Author(s):  
A. Eceiza ◽  
K. de la Caba ◽  
G. Kortaberria ◽  
N. Gabilondo ◽  
C. Marieta ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Reaction Kinetics ◽  
Chemical Structure ◽  
Soft Segment ◽  
Diphenylmethane Diisocyanate ◽  
Kinetics Of

The influence of molecular weight and chemical structure of soft segment in reaction kinetics with tolyl isocyanate

2001 ◽  
Vol 37 (8) ◽  
pp. 1685-1693 ◽  
Author(s):  
A Eceiza ◽  
K de la Caba ◽  
V Gascón ◽  
M.A Corcuera ◽  
I Mondragon
Keyword(s):  
Molecular Weight ◽  
Reaction Kinetics ◽  
Chemical Structure ◽  
Soft Segment

Thermoplastic polyurethanes from renewable resources: effect of soft segment chemical structure and molecular weight on morphology and final properties

2012 ◽  
Vol 62 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Ainara Saralegi ◽  
Lorena Rueda ◽  
Borja Fernández-d'Arlas ◽  
Iñaki Mondragon ◽  
Arantxa Eceiza ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Renewable Resources ◽  
Chemical Structure ◽  
Soft Segment ◽  
Thermoplastic Polyurethanes

Study on the Micro-Phase Structure of Hydrophilic Polyurethane with Mixed Polyester and Polyether Soft Segments

2012 ◽  
Vol 554-556 ◽  
pp. 195-199
Author(s):  
Peng Zhang ◽  
Heng Quan
Keyword(s):  
Phase Separation ◽  
Phase Structure ◽  
Chemical Structure ◽  
Soft Segment ◽  
Chain Extender ◽  
Diphenylmethane Diisocyanate ◽  
Soft Segments ◽  
Separation Degree ◽  
Polyethylene Glycol 1000 ◽  
Hydrophilic Polyurethane

Polyether-polyester nonionic hydrophilic polyurethanes with amorphous soft segment phase are prepared from 4,4’- diphenylmethane diisocyanate (MDI), polybutylene adipate glycol 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as chain extender. Further more, the relationships between micro-phase structure and chemical structure of samples is investigated. The studies show that the chemical structure has remarkable effects on the micro-phase structure of hydrophilic polyurethane and micro-phase separation degree of the mixed soft domains.

Reaction Kinetics Analyses of Ethylenediamine Polyurea Curing Process

2011 ◽  
Vol 366 ◽  
pp. 438-443
Author(s):  
Hong Zhu
Keyword(s):  
Reaction Kinetics ◽  
Chemical Structure ◽  
Kinetic Mechanism ◽  
High Reactivity ◽  
Chain Extender ◽  
Order Kinetic ◽  
Curing Process ◽  
Kinetics Equation ◽  
Chain Extenders ◽  
Kinetics Of

Novel sterically hindered chain extender, 2-acetyl-ethylenediamine (MEDA) was synthesized by acetylating of ethylenediamine(EDA) with glacial acetic acid in presence of phosphoric acid, in order to reduce high reactivity of synthesizing polyurea and study its kinetics equation. Its chemical structure was confirmed through FTIR and 1H-NMR analysis. Polyureas were synthesized by reaction of 4,4’-dipheSuperscript textnylmethane diisocyanate(MDI), amine terminated polyether(D-2000) with different chain extenders. The reaction kinetics of polyurea curing process was studied by FTIR. The results showed that extending reaction with MEDA was second order kinetic mechanism, its apparent activation energy was 36.81 kJ•mol-1.

scholarly journals Fragmentation of Chitosan by Acids

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Reza Kasaai ◽  
Joseph Arul ◽  
Gérard Charlet
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Kinetic Data ◽  
Chemical Structure ◽  
Size Exclusion ◽  
Experimental Conditions ◽  
First Order ◽  
H Nmr ◽  
Exclusion Chromatography ◽  
Kinetics Of

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed.

Impact Of Synthesis Route on the Water Oxidation Kinetics of Hematite Photoanodes

2020 ◽  
Author(s):  
Camilo A. Mesa ◽  
Ludmilla Steier ◽  
Benjamin Moss ◽  
Laia Francàs ◽  
James E. Thorne ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Reaction Kinetics ◽  
Water Oxidation ◽  
Oxidation Kinetics ◽  
Oxidation Reaction ◽  
Charge Accumulation ◽  
Optical Signals ◽  
Current Voltage ◽  
Voltage Performance ◽  
Kinetics Of

<p><i>Operando</i> spectroelectrochemical analysis is used to determine the water oxidation reaction kinetics for hematite photoanodes prepared using four different synthetic procedures. Whilst these photoanodes exhibit very different current / voltage performance, their underlying water oxidation kinetics are found to be almost invariant. Lower photoanode performance was found to correlate with the observation of optical signals indicative of charge accumulation in mid-gap oxygen vacancy states, indicating these states do not contribute directly to water oxidation.</p>

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