Molecular Weight Distribution and Reaction Sequence in Polymerization Kinetics

1961 ◽  
Vol 35 (6) ◽  
pp. 2101-2107 ◽  
Author(s):  
F. C. Goodrich
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Polymerization Kinetics ◽  
Reaction Sequence

Investigation of Ethylene Polymerization Kinetics over Ziegler-Natta Catalysts: Employing Moment Equation Modeling to Study the Effect of Different Active Centers on Homopolymerization Kinetics

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Mehdi Salami-Kalajahi ◽  
Vahid Haddadi-Asl ◽  
Mohammad Najafi ◽  
Sayyed Mehdi Ghafelebashi Zarand
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Ethylene Polymerization ◽  
Monomer Concentration ◽  
Moment Equation ◽  
Polymerization Kinetics ◽  
Equation Modeling ◽  
Active Centers ◽  
Olefin Polymerizations

AbstractIn the present work, ethylene polymerization kinetics was modeled using moment equations. According to the results obtained, the molecular weight distribution of each active center follows a Schultz-Flory distribution. However, the molecular weight distribution of polymer produced is much broader than a Schultz- Flory distribution. Besides, the order of polymerization with regard to monomer concentration is higher than unity. Moreover, the catalyst active centers deteriorate in the presence of hydrogen and consequently catalyst yield drops; nevertheless, polymerization kinetics is not mainly affected by hydrogen. Hydrogen also reduces polymer molecular weight since it is a strong transfer agent in olefin polymerizations. Notwithstanding, it does not affect polydispersity index. Last of all, although increasing cocatalyst concentration does not influence the activity of active centers, it lessens the molecular weight as a transfer agent

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

Sign in / Sign up

Export Citation Format

Share Document