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A process of plasma-initiated grafting of acrylic acid on commercial porous polypropylene membrane was studied. The influence of parameters of the plasma (power, gas pressure, time plasma-sample distance, sample arrangement) and grafting (solvent composition, monomer concentration, time, inhibitor presence) on the degree of grafting, amount of homopolymer produced and surface electrical resistance was determined. A degree of grafting up to 18 mmol/g was obtained, which resulted in sample resistance as low as 30 mX cm 2 . The molecular weight of AAc homopolymer that can be assumed as equal to the MW of grafted chains, ranged from 25,000 to 50,000,000 da. SEM and water permeability measurements show that grafting causes filling of the pores, which, however, does not stop K þ ions from penetrating the membrane. The performance of nickel-cadmium cells with acrylic acid grafted membranes as separator is also presented.

Two-dimensional measurements were performed of the relation between the charge transported and number of photons emitted, accompanying discharges in air at the surface of a dielectric. The creep discharges were analysed for opaque dielectrics placed in an AC field of v=50 Hz and intensity of 103 V mm-1. A linear relation was found to exist between the number of photons and the charge, Nph= kappa Q, the coefficient kappa varying with the polarity of the electrode at which the discharges occurred, kappa +/ kappa -=0.5-0.8. It is postulated that the difference in kappa + and kappa - is due to the different average energy of electrons giving the discharge channel.