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Bulgarian Journal of Physics
Print: 1310-0157 Online: 1314-2666
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RECOGNIZED BY THE EUROPEAN PHYSICAL SOCIETY 
Bulg. J. Phys. vol.19 no.1-2 (1992), pp. 089-094
Surface Modulation of Polyimide in a Gas Discharge: Post-Effect
S.I. Ivanov1, D.M. Svirachev1, V.P. Pechenyakova1, Ch.V. Petrov2, E.D. Dobreva2
1Sofia University, Faculty of Physics, 5, J. Bouchier Blvd., 1126 Sofia, Bulgaria
2Technical University, Department of Chemistry, 1156 Sofia, Bulgaria
go back1Sofia University, Faculty of Physics, 5, J. Bouchier Blvd., 1126 Sofia, Bulgaria
2Technical University, Department of Chemistry, 1156 Sofia, Bulgaria
Abstract. The evolution of a polyimide surface treated in a corona discharge for 0.3 s have been investigated. The relaxation was followed from the 12th minute up until 500 hours after discontinuation of the plasma treatment. The acquired adhesivity of the treated surface gradually decreases during ageing, and this is expressed by decrease of the cosine of the wetting angle. The decrease with time of the adhesivity acquired from the treatment follows a law expressed as the snm of two exponents. This is explained in terms of deactivation of two types of adhesive states generated from the action of the corona discharge. The first adhesive state has a lifetime of 17 hours and relative content 0.16. The second adhesive state lasts longer — it has a lifetime of 3140 hours and relative content 0.81.