RHEOLOGICAL STUDIES OF SOLVENT-BASED POLYURETHANE ADHESIVES CONTAINING SILICA

The influence of the addition of fumed silicas to solvent-based polyur ethane (PU) adhesives on their theological behaviour have been conside red. No previous studies on the theological properties of these adhesi ves have been done, and in this study it war paid specific attention t o the hydrophilic and hydrophobic character of silica. The rheological behavior of the PU adhesives has been correlated with their initial a dhesion to surface-treated synthetic vulcanized styrene-butadiene rubb er. The addition of silica produces an increase in the storage modulus (G') of PU adhesives, the values obtained being independent of the hy drophilic or hydrophobic character of the fumed silica. The increase o f G' and the changes in tag delta of PU adhesives containing silica co rresponded to an improvement in the green adhesion properties of chlor inated rubber/PU adhesive joints.