Determination of the number-average molecular weight of polysaccharides by end-group reduction with borohydride-t

1973 ◽  
Vol 27 (1) ◽  
pp. 185-191 ◽  
Author(s):  
G.N. Richards ◽  
W.J. Whelan
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Group Reduction ◽  
End Group

End-Group Method for Molecular Weight Determination of PET Depolymerization under Microwave Irradiation

2012 ◽  
Vol 554-556 ◽  
pp. 1933-1937 ◽  
Author(s):  
Qing Hua Feng ◽  
Qing Hua Tang ◽  
Wei Lu Zhang ◽  
Yan Hua Jia ◽  
Dong Zhang
Keyword(s):  
Molecular Weight ◽  
Microwave Irradiation ◽  
Average Molecular Weight ◽  
Relative Number ◽  
Group Method ◽  
Molecular Weight Determination ◽  
Stannous Oxide ◽  
Hydrolytic Depolymerization ◽  
End Group

A series of catalysis hydrolytic depolymerization of PET catalyzed by zinc acetate, zinc sulfate, stannous oxide respectively under microwave irradiation at different temperature with time was studied, in which the microwave power was 260W, the ratio of water to PET was 10:1 and the dosage of the catalysts was 0.5% of PET. The relative number average molecular weight of the undepolymerized PET was determined by end-group method. The results show that the molecular weight of the undepolymerized PET decreases with the reaction time increasing, and tends to be stable at the end of the depolymerization reaction. Under the same time, the temperature is higher, the molecular weight is smaller. The molecular weight of the undepolymerized PET reduces most quickly with stannous oxide among the three catalysts.

EBULLIOMETRY AND THE DETERMINATION OF THE MOLECULAR WEIGHTS OF POLYMERS: PART I. THE SMALL EBULLIOMETER

1959 ◽  
Vol 37 (9) ◽  
pp. 1508-1516 ◽  
Author(s):  
W. R. Blackmore
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Molecular Weights

An ebulliometer that has been in routine use for the determination of the number average molecular weight of polymers is described. The results obtained with two different series of polythenes (which were also measured elsewhere) are given. These results show this ebulliometer to be subject to experimental difficulties which limit it to number average molecular weights of perhaps 20,000 depending on the precision required.

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