fluorocarbon and chlorinated fluorocarbon polymers and their copolymers naturally carry a negative charge and nylon naturally carriers a positive charge hydrophilic nylon discussed below in detail with respect to the hme concepts of this invention is particularly desirable because of its high hydrophilic properties however other forms of nylon polymer are also effective in this application the nature of the fluorocarbon or chlorinated fluorocarbon polymers and copolymers used is generally dictated by their spinning properties halar u00ae ectfe fluoropolymer commercially available from ausimont usa inc a subsidiary of montedison is the preferred material for this use although other fluorocarbon polymers or chlorinated fluorocarbon polymers or copolymers of such polymers may be used for several applications of the instant inventive concepts for simplification the following discussion will refer to halar u00ae as exemplary of any such materials a homogeneous mixture of fibers having surfaces of these polymers provides unexpectedly improved filtration properties even with reduced weight of materials since halar u00ae is quite expensive bicomponent fibers comprising on the order of 10 u2013 20 by weight of a halar u00ae sheath over a nylon core in a homogeneous mix with monocomponent fibers formed of nylon significantly reduces the cost the apparatus illustrated in fig3 u2013 43 may be advantageously used to produce such a mixture of fibers although a 50 50 mixture of these fibers is particularly adapted for many applications the nylon fibers which act as a bonding agent may be present at levels of 40 or even less alternatively using the apparatus of fig1 u2013 33 a homogeneous mix.