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AYDEMİR, CEM

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Subject: contact angle ×

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Now showing 1 - 3 of 3
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    Time-Dependent Behavior of a Sessile Water Droplet on Various Papers
    (TAYLOR & FRANCIS AS, 2010) AYDEMİR, CEM; Aydemir, Cem
    In this paper the results of an extensive experimental study on the volume change of a water sessile droplet on various papers such as gloss and matte-coated papers and high-grade papers and boards with certain specifications are reported. The droplet on a paper is observed using a computer-controlled and fully automated instrument. The total volume and the contact angle of the sessile droplet are recorded in short time intervals (as short as 150 milliseconds) for about 6-10min. The evaporation effect on the change of the volume of the water droplet is controlled by measuring the size change of a droplet on a glass surface. The instruments and the material used in the experiments are introduced in detail and the results are displayed in a series of figures and tables. The effects of possible mechanisms on the behavior of the water droplet are discussed, and directions of future studies are indicated. It is concluded that the relationship between water and a cellulose-based substrate cannot be fully understood if the microstructure of the cellulose-based materials and the three main mechanisms, namely evaporation, absorption and hygroexpansion, are not taken into account simultaneously.
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    Surface analysis of polymer films for wettability and ink adhesion
    (WILEY, 2021) AYDEMİR, CEM; Aydemir, Cem; Altay, Bilge Nazli; Akyol, Merve
    The interaction between inks and substrates is critical during printing. Adhesion of the ink film is determined by the reciprocal interactions of polar and nonpolar (dispersive) components between polymer films and inks. The greater the similarity between the polar and dispersive components of inks, coating and substrates, the better the wetting and adhesion on the surface of printing substrate. Various liquid materials in printing such as inks, varnishes, lacquers, and adhesives contain high ratios of water. The highly polar nature of water makes the interaction of these materials unsuitable with predominantly disperse polymer surfaces. Some films with polyolefin structure, especially polypropylene, and polyethylene, are nonpolar and cannot form strong bonds with ink, varnish, or lacquer coatings due to their chemical structure. Increasing surface energy components overcomes the poor wetting and adhesion on polymer surfaces. In this review, the topics of water contact angle measurement and determination of surface energy, surface tension, and using sessile drop method for the wettability and ink adhesion of polymer films are surveyed. Information on structural and chemical processes was given that assists in obtaining wettable film surfaces. Recommendations were made for good adhesion and printability based on surface treatment methods and ink modification.
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    The examination of vegetable- and mineral oil-based inks' effects on print quality: Green printing effects with different oils
    (SAGE PUBLICATIONS LTD, 2018-07) AYDEMİR, CEM; Aydemir, Cem; Yenidogan, Semiha; Karademir, Arif; Kandirmaz, Emine Arman
    Introduction: Printing inks oil selection is related to the desired nature of the varnish in the ink production. Petroleumderived mineral oils and vegetable oils can be used in offset inks. Methods: In this study, the behaviors of vegetable- and mineral oil-based inks on uncoated and coated paper surfaces were investigated in terms of printability. Solid tone test prints were done with offset printing of these inks. Print gloss of the printed samples was measured and a light fastness test was implemented on these samples in order to determine the resistance to fading. Absorption behavior and contact angles of the ink-printed films on the test papers were measured with the sessile water drop method depending on time, and surface energies were calculated. Results: On both paper types, linseed-soybean oil-based vegetable ink gave the highest brightness value. The lowest print gloss results on the paper were obtained from soybean oil-based inks. The lowest color change was recorded with mineral oil-based inks on gloss-coated papers. According to the ink-film-surface relation, when the contact angle is high, surface energy decreases and the absorbency of the ink-film is lower. Conclusions: In this study, the behaviors of vegetable- and mineral oil-based inks on different paper surfaces, and the effect on the quality of printability as well as differences, have been evaluated, taking environmental and health factors into consideration.