Kinetic study of the initiation reaction by a dilithium initiator used for the preparation of ABA triblock copolymers in non-polar medium

Polymer ◽  
2009 ◽  
Vol 50 (23) ◽  
pp. 5368-5373 ◽  
Author(s):  
Kristof Janssens ◽  
Els Loozen ◽  
Alexander Yakimansky ◽  
Marcel Van Beylen
2020 ◽  
Vol 20 (4) ◽  
pp. 919
Author(s):  
Heri Budi Wibowo ◽  
Widhi Cahya Dharmawan ◽  
Ratih Sanggra Murti Wibowo ◽  
Adi Yulianto

A kinetic study of HTPB synthesis by radical polymerization of butadiene with hydrogen peroxide initiator was conducted using infrared spectroscopy. HTPB conversion was determined based on the conjunction termination rate constant, and all polymerization kinetics were evaluated to identify the constant. All polymerization steps (decomposition, initiation, propagation, conjunction, and proportional termination) can be evaluated based on polymer conversion and functionality from data provided by infrared spectroscopy. The investigation variables included the initial molar ratio of initiator to monomer (H2O2/butadiene) and the reaction temperature. These steps were assumed as the first-order reactions, giving constant reaction rates of kd, ka, kp, kt, ktc, and ktd. The reaction rates obtained for these constants were 4.2 × 10–5 sec–1, 8.9 × 10–4, 7.7 × 103, 8.5 × 107, 3.2 × 107 and 5.3 × 107 L mol–1 sec–1, respectively, with activation energy of 7608, 14188, 2247, 105, 87 and 135 kJ mol–1, respectively. The determining step of the reaction rate was identified as the initiation reaction. HTPB conversion can be measured if all polymerization kinetics constants have been evaluated.


2008 ◽  
Vol 105 (12) ◽  
pp. 601-608
Author(s):  
Seung Min Han ◽  
Dong Joon Min ◽  
Joo Hyun Park ◽  
Jung Ho Park ◽  
Jong Min Park
Keyword(s):  

1983 ◽  
Vol 49 (03) ◽  
pp. 199-203 ◽  
Author(s):  
V M Yomtova ◽  
N A Stambolieva ◽  
B M Blagoev

SummaryIt was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and α-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2×10-6 M), plasmin (Ki = 4.9×10-6 M) and urokinase (Ki = l.0×10-7 M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.


1981 ◽  
Vol 31 (1) ◽  
pp. 388-394 ◽  
Author(s):  
Mahmoud El-Sawi ◽  
Antonio Iannibello ◽  
Fernando Morelli ◽  
Ganfranco Gatalano ◽  
Francesco Intrieri ◽  
...  
Keyword(s):  

2011 ◽  
Vol 3 (5) ◽  
pp. 585-588
Author(s):  
B Dharma Rao B Dharma Rao ◽  
◽  
M Sridevi M Sridevi ◽  
P Vani P Vani

Sign in / Sign up

Export Citation Format

Share Document