Filler surfaces, bifunctional

The modification of a filler surface with isocyanates is a simple process which involves the reaction of hydroxyl groups on the filler surface with monomeric isocyanate. 2,4-toluene diisocyanate or hexamethylene diisocyanate are commonly used. Since isocyanates are bifunctional they can be further reacted with polyols to form a coating on the surface or they can be used for the reinforcement of polyurethane. A strong covalent bonding can be verified by controlled extraction with the solvent. Bound material will not be removed from the fillefs surface. 

Figure 4.7 Some structures proposed for the reaction of monoalkoxytitanates with filler surfaces, a) Monofunctional reaction b) bifunctional reaction c) complex, partly...

Surface modifiers are generally bifunctional molecules with one end capable of adhering to the filler and the other end compatible wifii the pol5mier, and at times even capable of reacting with it. There have been extensive studies on the effect of surface treatment on the steady shear viscous properties of filled pol)uner systems [9,13,15,18,3234,36,38, 39,5233,60]. 

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