New analytical methods as tools for the determination of resin properties
The adhesive systems used in the manufacture of timber products are generally characterized by their classic properties (e.g. solid content, pH-value, viscosity). This gives an inadequate description of their technological properties. To fill this knowledge-gap, methods of polymer analysis can usefully be employed. The most suitable analytical techniques for adhesives are described here. The power of these "new" analytical tools is demonstrated by studies of the colloidal behaviour of UF-resins and of the reactivity of PMDI. The first example demonstrates that the disperse part of an UF-resins has got almost the same molecular weight distribution and structure element than the non-disperse part, but influences some typical resin properties like viscosity or solid content. In the second part it is shown, that PMDI is not only polymeric 4,4'-MDI. The molecular weight distribution and the isomeric ratio have a great influence on the adhesive performance.