Molecular weight distribution from rheological measurements

1974 ◽  
Vol 13 (2) ◽  
pp. 278-282 ◽  
Author(s):  
G. Locati ◽  
L. Gargani ◽  
A. De Chirico
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Rheological Measurements

Evaluation of molecular weight distribution in linear polymers from rheological measurements

1972 ◽  
Vol 14 (10) ◽  
pp. 2653-2656 ◽  
Author(s):  
V.A. Grechanovskii ◽  
I.Ya. Poddubnyi ◽  
L.A. Nedoinova ◽  
Yu.G. Kamenev
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Linear Polymers ◽  
Rheological Measurements

scholarly journals Analytical Rheology of Polymer Melts: State of the Art

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Sachin Shanbhag
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Polymer Melts ◽  
State Of The Art ◽  
Branched Polymers ◽  
Linear Polymers ◽  
Rheological Measurements ◽  
Unknown Sample ◽  
Extreme Sensitivity

The extreme sensitivity of rheology to the microstructure of polymer melts has prompted the development of “analytical rheology,” which seeks inferring the structure and composition of an unknown sample based on rheological measurements. Typically, this involves the inversion of a model, which may be mathematical, computational, or completely empirical. Despite the imperfect state of existing models, analytical rheology remains a practically useful enterprise. I review its successes and failures in inferring the molecular weight distribution of linear polymers and the branching content in branched polymers.

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. 

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