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Water‐soluble sulfonated amino‐formaldehyde resins. V. Effect of reaction condition on molecular weight distribution
Author(s) -
Lahalih S. M.,
Hovakeemian G.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070400511
Subject(s) - melamine , formaldehyde , molar mass distribution , chemistry , urea , alkalinity , condensation reaction , urea formaldehyde , mass fraction , polymer chemistry , organic chemistry , catalysis , polymer , adhesive , layer (electronics)
The effect of reaction conditions of sulfonated urea‐melamine formaldehyde on molecular weight distribution was studied. It was found that the molecular weight distribution of these materials is influenced by the percent of urea to melamine in the mixture, the concentration of the reaction mixture, the pH and the time of reaction of the low pH condensation step, and finally, the reaction time during the high pH condensation and rearrangement step. Weight average molecular weights increased as percent melamine to urea, concentration of reaction mixture, the alkalinity of the third step, and the reaction time of the fourth step increased. The weight average molecular weight decreased as the reaction time of the third step decreased. The reaction variables influenced the fraction of the high molecular weight species that, in turn, influenced these materials performance. Finally, it appeared that the final product contained separate sulfonated urea formaldehyde and sulfonated melamine formaldehyde components in addition to sulfonated urea‐melamine formaldehyde polycondensates.