Browsing by Author "Dineff P."

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    Physical deposition of thin polyimide layers by applying an argon plasma assisted process
    (2010-01-01) Dimov D.; Georgiev A.; Spassova E.; Assa J.; Dineff P.; Danev G.
    A novel method for physical deposition of thin polyimide layers by applying an argon plasma assisted process has been developed. The influence of the plasma on the combined molecular flux of the two thermally evaporated precursors - 4,4'- oxydianiline and pyromellitic dianhydride was investigated. The process parameters were changed in the limlts 0,4 - 2 A for the anode current and 80 - 170 V for the anode voltage. Their influence was studied using FTIR spectroscopy and electron microscopy techniques. It was proposed that the plasma flux crossing the molecular flows of the polyimide precursors enhances the imidization process by partly activating the precursor molecules in the gas phase. © 2010 IOP Publishing Ltd.
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    Research on cold plasma treatment of leather and fur based materials as ecological alternative
    (2017-01-01) Gaidau C.; Niculescu M.; Surdu L.; Barbu I.; Vladkova T.; Dineff P.
    The paper presents the performances of leathers and fur skins pre-treated with cold plasma through dielectric barrier discharge (DBD) at atmospheric pressure and room temperature followed by treatment with chemical materials. The main improved properties were water repellency and flame resistance, two important characteristics for added value garments (water proof and fireman footwear), high quality furniture and automotive leather upholstery. The water drop resistance in static conditions reveals a hydrophobic effect on dermis surface induced by cold plasma pre-treatment, similar with chemical impregnation. The water resistance in dynamic conditions showed the reactivation of hydrophilic groups inside collagen and keratin based materials, similarly with other materials pre-treated with cold plasma presented in literature. The water quantity which penetrated the fur skins dermis decreased by 22.7% for the pre- treated samples with cold plasma and treated with silicon based materials as compared to samples not pre-treated with plasma. Full grain leathers pre-treated with cold plasma showed impermeable behavior and improved flame resistance. The influence of cold plasma pre-treatment was favorable for water repellency of leathers and fur skins and for flame retardant properties of different kinds of leathers.