Stephan V. Drappel

Grafting of living cationic poly-THF on carbon black

Abstract The grafting of polytetrahydrofuran (poly-THF) onto carbon black has been studied. It is shown that living cationic poly-THF can be grafted onto C.B. by reaction at living sites in a controlled way. The parameter which determines the amount of grafting is not the number of chemical sites on the surface of the C.B. but the bulkiness of the living poly-THF chains. Thus a large number of small chains or a few long chains can be attached.

Adhesion of Wax Droplets to Porous Substrates

The adhesion of solid wax ink droplets to porous polyethylene and Teflon substrates was studied experimentally. Wax droplets with a diameter of 3 mm and an initial temperature of 110°C were dropped onto test surfaces from heights varying from 20–50 mm. The Teflon surfaces had holes drilled in them to create idealized porous surfaces while the porous polyethylene sheets had mean pore sizes of either 35 or 70 μm. The force required to remove the wax splats from the substrates was measured by a pull test. The detachment force increased with droplet impact velocity. A simple analytical model is proposed to predict the force attaching the wax splat to the surface: it has an adhesive component, calculated by multiplying the contact area between the splat and substrate by the strength of adhesion; and a cohesive component, calculated by multiplying the area of the pores into which wax penetrates by the ultimate tensile strength of wax. Predictions from the model agreed reasonably well with measurements.Copyright