Modification of polyethylene terephthalate by atmospheric pressure dielectric barrier discharge (DBD) in view of improving the polymer wetting properties

Abstract

Abstract. Surface treatment of polymers by discharge plasmas has increasingly found industrial applications due to its capability of modifying uniformly the surface without changing the material bulk properties. This work deals with surface modification of polyethylene terephthalate (PET) by a dielectric barrier discharge (DBD) at atmospheric pressure. The treatments were conducted in air, nitrogen or argon plasma. The polymer surface was characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results show that the plasma treatment introduces oxygen-and nitrogen-related polar groups on the polymer surface and promotes the surface roughening. Both plasma-induced surface modifications contribute to the enhancement of the polymer wettability. IntroductionPolymers possess good mechanical and chemical properties; however, their use in various applications involving composite and biomaterials, packing, printing, dying etc, has been restricted due to their poor adhesion properties. Improvement of the adhesion can be accomplished by chemical methods (adding functional groups on the surface) and/or trough introducing micro-or nano-scale roughness on the surfaces. Recently, the classical chemical technologies have been gradually replaced by the environmentally friendly, versatile and low-cost plasma treatment. The atmospheric pressure plasmas are especially attractive as surface modification tools due to their applicability to a variety of substrates, easy scaling-up, quick processing time, and low cost [1].This work describes the surface modification of a PET polymer by atmospheric pressure dielectric barrier discharge DBD. This type of discharge occurs between two planar or cylindrical electrodes provided that at least one of them is covered by a dielectric layer. As a consequence, after the gas breakdown takes place, the charge accumulation on the dielectric surface prevents the corona-to-arc transition. The DBD plasmas have many applications ranging from surface functionalization and grafting [2], improvement of adhesion and hydrophylicity [3], sterilization [4], processing of textile and fabrics [5] and, most recently, the so-called plasma medicine [6].

Local Analysis of Pet Surface Functionalization by an Atmospheric Pressure Plasma Jet

“…In this work, a highest possible oxygen concentration of approximately 35% is observed in the center of the PET sample. This is a much higher value in comparison with results presented in literature where for PET samples the maximum obtained oxygen concentration on the surface after atmospheric pressure argon plasma treatment is 28–30% . This observation again proves the very high modification efficiency of the argon plasma jet used in this work.…”

“…Figure also shows that when the PET sample is placed only 2 mm below the edge of the capillary, it is possible to reach a minimum WCA value of 22°. In literature, the lowest WCA value obtained for PET by using an atmospheric pressure argon plasma discharge is 37–38°. This observation, thus, clearly indicates the high modification efficiency of the argon plasma jet used in this study.…”

Ethylene Epoxidation in a Low-Temperature Parallel Plate Dielectric Barrier Discharge System: Effect of Oxygen Source

“…Dielectric barrier discharge (DBD) is a type of nonequilibrium low temperature plasma that has high electron temperatures (10 4 –10 5 K) with a bulk gas temperature close to room temperature. , As a consequence, the energy consumption used for operating the plasma system for various chemical reactions is lower compared to conventional catalytic processes. Accordingly, DBD has been employed for several studies, including chemical synthesis, such as hydrogen (H 2 ) production by methane (CH 4 ) reforming − and ethylene epoxidation, − ozone generation, − soil remediation, − wastewater treatment, , and surface treatment. − …”