Kinetic theory of anionic copolymerization with constant monomer ratio, 2 . Molecular weight distribution

1992 ◽  
Vol 1 (3) ◽  
pp. 173-185 ◽  
Author(s):  
Xiaodong Hu ◽  
Deyue Yan ◽  
Jing Feng
1967 ◽  
Vol 40 (2) ◽  
pp. 532-543 ◽  
Author(s):  
S. D. Gehman

Abstract Calculations and experimental results both indicated that effects of a molecular weight distribution of network chains may become evident in swelling pressure curves under favorable circumstances. More precise experiments are required to establish this definitely. The calculations assume that a simple integration such as is used for a continuous medium may be applied to molecular units of structure deduced from the kinetic theory of rubber elasticity. The validity of this can only be determined by further comparisons with experience. Refinement of the theory might take into account interactions of the units.


2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe

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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