scholarly journals Precise modulation of molecular weight distribution for structural engineering

2019 ◽  
Vol 10 (46) ◽  
pp. 10698-10705 ◽  
Author(s):  
Rui Tan ◽  
Dongdong Zhou ◽  
Baolei Liu ◽  
Yanxiao Sun ◽  
Xinxin Liu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Structural Engineering ◽  
Model Platform

Modulating MWD through precise blending of discrete macromolecules provides a model platform for highlighting the importance of chain length heterogeneity.

Application of the Monte Carlo simulation method to the Investigation of the effect of chain-length-dependent bimolecular termination on ATRP

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Mohammad Najafi ◽  
Vahid Haddadi-Asl ◽  
Mehdi Salami-Kalajahi ◽  
Hossein Roughani Mamaghani
Keyword(s):  
Molecular Weight ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Reaction Time ◽  
Chain Length ◽  
Molecular Weight Distribution ◽  
Rate Constant ◽  
Weight Distribution ◽  
Polymer Chains ◽  
Termination Rate

AbstractAn optimized and high-performance Monte Carlo simulation is developed to take thorough account of the influence of chain-length-dependent termination rate constant on polymer microstructure in ATRP. According to the simulation results, bimolecular termination rate constant sharply drops throughout the polymerization when chain length dependency is applied to the program. The dependence of on reaction time, as a common feature of ATRP, is almost linear. Moreover, the polymerization proceeds to higher conversion when the chain-length-dependent termination rate constant is applied to the simulation model. In addition, the plot of against reaction time is completely linear; also, the initiator is entirely decomposed at the early stages of the polymerization as the plot of CIagainst time shows. The concentration of the catalyst in lower oxidation state decreases first and then plateaus at higher conversion. Furthermore, the amount of Mtn Y/L used in the polymerization is lower when the chain-length-dependent termination rate constant is employed in the simulation. Finally, the peak of molecular weight distribution of polymer chains shifts toward higher molecular weight during the reaction. Besides, the molecular weight distribution broadens at higher conversion. However, the molecular weight distribution of polymer chains produced under conditions of applying chain-lengthdependent termination rate constant is narrower.

The Mechanism of Isoprene Polymerization Initiated with Ticl4-Trialkylaluminum. Molecular Weight Distribution of the Polymer

1960 ◽  
Vol 33 (3) ◽  
pp. 689-695 ◽  
Author(s):  
S. E. Bresler ◽  
M. I. Mosevitskiĭ ◽  
I. Ya Poddubnyĭ ◽  
N. N. Chesnokova
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Molecular Weight Distribution ◽  
Polymer Chain ◽  
Weight Distribution ◽  
Titanium Tetrachloride ◽  
Chain Scission ◽  
Degree Of Conversion ◽  
Isoprene Polymerization

Abstract The molecular weight distribution of polyisoprene obtained by polymerization under the influence of complexes of titanium tetrachloride with tri-isobutylaluminum has been found within broad limits to be independent of the degree of conversion. On the basis of this finding an hypothesis is offered to explain the limitation of polymer chain length according to which chain scission is assumed to increase with the size of the chain.

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