Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Wpływ działania plazmy niskotemperaturowej na zmiany zwilżalności wybranych polimerów

Hołysz Lucyna, Kamela (Rymuszka) Diana, Terpiłowski Konrad, Chibowski Emil

Wiadomości Chemiczne

2021

[Z] 75, 9-10

1270--1295

The effects of air, oxygen and argon plasma treatment on wetting and energetic properties of polymers: polymethylmethacrylate (PMMA), polyetheretherketone (PEEK), polyoxymethylene (POM), polyamide (PA6G), polycarbonate (PC) and polypropylene (PP) were studied. The changes in surface properties of PMMA, PEEK, POM, PA6G polymers after the air plasma treatment, and PP and PC polymers after the Ar or O2 plasma treatment were determined via the measurement of advancing and receding contact angles of three liquids having different polarity, i.e. water, formamide and diiodomethane. Having the determined contact angles the surface free energy and its components of the polymers were calculated using three different theoretical approaches, namely: acid-base Lifsthitz-van der Waals (LWAB), contact angle hysteresis (CAH) and Owens and Wendt (O-W). The effects of plasma treatment were further determined by calculations of the adhesion work and work of spreading of water on modified polymer and compared to values calculated for the unmodified surfaces. Then for the PEEK and POM modified with the air plasma, their surface wettability was determined after 14 days from the exposure to the plasma. It was found that plasma treatment caused better wettability what reflected in a decreased contact angles measured on the modified polymer surfaces. The greatest changes appeared for polar liquids, i.e. water and formamide. It pointed to an increased the surface hydrophilicity after the plasma treatment. The changes correlated also with the increased polar interactions due to appearance polar groups on the surface. For the studied polymer surfaces, generally the dispersive interactions practically did not change, regardless the treatment time and plasma type. The total surface free energy values calculated for the polymers from three different approaches to interfacial interactions are similar. However, the energy values are apparent because they depend s upon the kind of liquid used for the contact angles measurement. Irrespectively of the plasma type, for all polymers an increase of the adhesion work of water in reference to the unmodified surfaces was observed. The most appropriate time to improve the adhesion between the polymer surface and liquid was found to be 25 or 60 s. However, the effects of plasma treatment are not permanent. With the storage time the contact angles have increased. This can be due to the structure reorganization within a few nm thick the surface layer.

Magnetic field effects on surfactants adsorption on the solid surface as regards of its wettability

Hołysz Lucyna, Chibowski Emil, Terpiłowski Konrad

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 6

101--113

The static magnetic field MF (0.44 T) effects on the adsorption of three surfactants: cationic bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB), and anionic sodium dodecylsulfate (SDS) from their 10-3 M solutions were studied on bare and low-temperature air plasma treated glass plates. The surface properties of the adsorbed surfactants layers were determined via the water advancing and receding contact angles measurements and then calculation of the apparent surface free energy. An optical profilometer was used to determine the structure and topography of the adsorbed layers. The DTAB and SDS concentrations were below their critical micelle concentration and that of CTAB very close to its cmc. The results showed that in the case of DTAB solution (much below its cmc) a small decrease in the contact angle appeared while in CTAB (close to its cmc) an increase in the contact angle value was observed if adsorbed in the MF presence. Quite good reproducibility of the contact angle values was obtained. This was not the case for the SDS solution where the contact angle values were scattered. The reason was that the anionic surfactant did not adsorb homogeneously on the negatively charged glass surface. The contact angles and the calculated values of the work of water spreading clearly show that MF influences the structure of the surfactant adsorbed layer which was also supported by the optical profilometry images.