ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The molecular weight distribution, molecular weight averages Mn, Mw, Mz, polydisperisty coefficient, statistic standard deviation of number and weight distribution, and Hoseman-Schramek index of the polycondensates of urea with formaldehyde have been estimated. The properties of this solution were obtained by the help of the combination of the following methods: GPC, VPO, turbidimetric titration, and fractional precipitation. The course of the polycondensation described was formally divided in the following stages: (1) formation of methylolated urea derivates and of the lowest oligomers, (2) decrease in the content of methylol urea and in the content of the lowest oligomers with M 〈 200, and production of soluble molecules between 103 and 104, and (3) formation of insoluble products.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1981.070260201
Permalink