Uni. Fen Edebiyat Fak. Kimya Bo ¨l., 48000 Ko ¨tekli-Mug ˘la, Turkey
1. Introduction
PP possess combination of some useful properties such as high tensile strength, lightness, excellent resistance to many chemicals, good rot resistance, etc., which makes it an essential component of modern textile market from upholstery to apparels.
Although PP fibers have a lot of advantages, they cannot be dyed with commercial textile dyestuffs. Some inherent properties of PP such as maximum hydrophobicity, high crystallinity and stereo regularity in its isotactic form and completely nonpolar structure make PP very difficult to be dyed. Many attempts such as spin coloration, physical and chemical modification were made to confer dyeability to isotactic PP [1].
Acid and basic dyestuffs are water soluble dye class for textile materials. Acid dyestuffs have an anionic character and can dye fibres that have cationic groups [2]. Basic dyestuff consists of an organic cation and can dye negatively charged macromolecules. These dyestuffs are not used for PP dyeing because of nonpolar structure of polypropylene.
The formation of active sites on the polymer backbone can be carried out by several methods such as plasma treatment [3], ultraviolet (UV) light radiation [4], decomposition of chemical initiator [5] and high-energy radiation [6]. A conventional method used for imparting the desired permanent hydrophilicity is chemical graft polymerisation requiring the use of organic solvents and a catalyst that, however, presents both health and environmental concerns. Plasma treatments, which are alternative to the use of organic solvents, are eco-friendly treatments for the activation of the textile materials; where polar molecular fragments affecting the wettability and radicals serving as the reactive species for the graft polymerisation are formed on the fibre surfaces. The plasma surface activation makes it possible to use water-based catalyst-free grafting solutions having good operability and properties to environment [7].
The dielectric barrier discharge (DBD), which provides nonthermal and non-equilibrium plasma, is produced at atmospheric pressure and almost at room temperature is submitted to an electric field. The result is an atmosphere full of ions, atoms, molecules and free radicals [8,9]. When a polymeric material is inserted in such environment, many phenomena can occur, depending on the plasma/surface interaction of the material.
One of the main effects of the interaction between active chemical species due to the plasma colliding with a polymeric surface is the breaking of molecules chains, the formation of new functional groups and/or morphological alterations, like the formation of microporosity [10].