Rheological behaviour of urea-formaldehyde adhesive resins

Peep Christjanson, Aime Suurpere, Kadri Siimer
2004 E-Polymers  
AbstractAn attempt is made to describe the complicated rheokinetic behaviour of urea-formaldehyde resins during storage, in close connection with the changes in their chemical structure. The alkali-promoted non-linear polycondensation during resin storage is evaluated by pre-gel viscosity measurements. Viscosity changes are described by a power law function using extrapolation to zero shear and infinitely high shear rates. During most of the period of viscosity increase, the rheological
more » ... rheological behaviour of studied resins is similar. The deviation from the power law dependence occurring in the initial low-rate growth of viscosity takes place because of formaldehyde redistribution, which does not lead to covalent network build-up. In the presence of methanol this period is extended due to the formation of stable methoxymethylene groups.
doi:10.1515/epoly.2004.4.1.398 fatcat:6rogjodzh5getawxwq2hcst4se