MODIFICATION OF ISOTACTIC POLYPROPYLENE BY A COLD-PLASMA OR AN ELECTRON-BEAM AND GRAFTING OF THE ACRYLIC-ACID ONTO THESE ACTIVATED POLYMERS

Surface grafting of polymeric materials, such as films and fibers, may improve their reactive surface properties. Polypropylene active sites that should initiate a surface postgrafting can be formed by either n itrogen cold plasma or an electron-beam irradiation. The plasma-modifi ed polymer surface is cross-linked and functionalized with primary ami no groups and with oxidized groups, and it is almost not degraded. Ele ctron-beam-modified polypropylene is also functionalized through an ag ing reaction, emphasized by a high radical concentration. In both case s, active surface films are susceptible to react with monomers in a po stgrafting reaction. The grafting yield and rate of acrylic acid were shown to be dependent on the formed amino group concentration: The hyd rophilic character of the modified polypropylene surface enhances the acrylic acid approach. The electron-beam treatment leads also to a rea ctive surface that can initiate a grafting reaction. But its yield and rate are dependent on the radical concentration: radicals formed duri ng the irradiation. (C) 1994 John Wiley & Sons, Inc.