6.1 Control of Polymer-to-Solid Surface Adhesive Bond Strength by Addition of Fillers

The present chapter deals with the possibility of controlling adhesive bonds from an essentially new point of view, based on the principle of directed change of the interaction of polymer chains in systems containing two fillers of different chemical natures and macro structures, namely, fibrous reinforcing fillers and finely dispersed ones. Mineral filler with lyophilic or lyophobic surface character, imparted by chemisorbed long-chain aliphatic molecules, was used as the finely dispersed filler. These interactions occur in two types of surface layers formed in polymeric composite materials: polymer on the surface of finely dispersed fillers, and a surface layer of the filled polymer on the surface of the fibrous reinforcing component. The principal feature here is the contribution of organic molecules grafted to the filler surface in changing the polymer properties in the boundary layer, since the modified filler surface of this kind promotes polymer plasticization at the phase boundary under the influence of modifier molecules, resulting in improvement of the physical-mechanical properties of the composite material.

This section gives experimental support for the novel method of improving adhesion of polymer coatings by introduction of dispersed or reinforcing filler, or both, into the polymer.

Polyurethanes were used that were based on trimethylolpropane-toluylene diisocyanate (TMP-TDI) and tetrahydrofuran and propylene oxide copolymer (THF-PO) obtained with various ratios of isocyanate and hydroxyl groups; as fillers, amorphous silicon dioxide (aerosil) with specific surface area of 1.75 10 m ²/kg (A-175) and...