Studies on the stability of MF resin solutions: Investigations on network formation

The phenomenon of thixotropy of melamine-formaldehyde (MF) resins has been investigated. A series of MF-resins with varying F/M ratios, different condensation times and pH during the condensation has been prepared. The storage stability at room temperature was measured using viscosimetry, polarization microscopy, NMR-spectroscopy and XRD. The visible changes observed in polarization microscopy (i. e. the formation of micron sized structures) correlate with the increase of viscosity related to the formation of thixotropy. The formation of a transient network can be concluded on basis of nmr-relaxation measurements and viscosimetry.