Molecular Mechanics/Experimental Methods Applied to Varnish/Primer/Wood Interactions

Abstract

Molecular mechanics modelling is used to calculate the energies of interaction, hence the molecular level energy of adhesion at the interface with crystalline cellulose I of three different photopolymerisable primers and of a polyester varnish at the interface with the primer/cellulose assembly. The energy of interaction for just one of the primers with the statistically most common conformation of amorphous cellulose has also been obtained for comparison. Experimental results of adhesion by a standard peel test and by thermomechanical analysis, in which the effect of energy dissipation by crack tip propagation has been respectively minimised or is not present, hence in which the energy of interfacial interaction S is nothing else than the work of adhesion, correlated well with the energies of interaction calculated by molecular mechanics. An equation correlating energy of interaction at each finish/cellulose interface with the deflection and flexibility derived by thermomechanical analysis, and with the number of bond rotational degrees of freedom as well as degree of networking of the finish has been derived and is presented. Discussion of the relationship of the effects found with the glass transition temperature of the finish is also presented.