Wettability of grafted poly(ethylene terephthalate) fibers

Graft copolymerisation of perfluorooctyl-2 ethanol acrylic monomer/stearyl methacrylate monomer mixture onto poly(ethylene terephthalate) fibers using benzoyl peroxide as initiator was carried out in order to improve water repellency. By characterising the surface free energy, the degree of water repellency can be evaluated. In this article, the Wilhelmy plate method is used to determinate the surface fiber wettability by probe liquids (water, mineral oil, glycerol, polyethylene glycol). This is accomplished by monitoring the wetting force experienced by a fiber suspended from a microbalance during immersion into and emersion from the fluid. Poly(ethylene terephtalate) fibers were characterised by a dynamic contact angle (DCA) apparatus (Cahn Instruments).