Evaluation of a reel-to-reel atmospheric plasma system for the treatment of polymers (original) (raw)
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Polymers Surface Treatment by Cold Atmospheric Plasma in Air
Cold atmospheric plasma (CAP) is a non equilibrium ionized gas formed by a collection of charged particles, radicals and UV radiations. In many applications, polymers suffer from hydrophobicity and low surface energy, this can be remediate by applying CAP to polymers' surfaces. Plasma may add large numbers of functional groups on polymeric surfaces giving them interesting properties without using environmentally unfriendly chemicals. In this work, an Atmospheric pressure plasma jet (APPJ) is constructed and operated in a DC mode by applying high voltage up to 5500 V between two coaxial electrodes separated by a ceramic insulator. APPJ is applied to different polymers' types as polypropylene (PP), polyurethane (PU) and polycarbonate (PC) using air as working gas. Polymers' samples of PP, PU and PC are exposed to plasma for different time intervals and at different distances from plasma. Polymeric surface wettability is measured by water drop contact angle method on polymer surface. Contact angles are found to decrease with increasing plasma treatment time and decreasing distance. This indicates wettability improvement by plasma treatment measured for different polymers considered. Induced chemical changes on polymers surface by plasma are investigated by Fourier Transform Infrared Spectroscopy (FTIR) analysis. FTIR provide chemical structure of polymer surface layer and changes in layer structures caused by plasma treatment. Noticeable amount of hydrophilic CO and C=O bonding species were created on the polymer surface after treatment. IR thermal camera results show moderate temperature increase on polymer surface during plasma treatment.
Comparison of low and atmospheric pressure air plasma treatment of polyethylene
Surface Engineering, 2013
Surface activation of polyethylene (PE) samples has been carried out using low pressure plasmas (at two different operating frequencies, namely, 40 kHz and 13?56 MHz) and dielectric barrier discharge (DBD) (50 Hz frequency and at atmospheric pressure), and the results are compared. The surface of the PE samples has been exposed to these different plasmas for various time durations ranging from 1 to 30 min. The treated samples have also been studied for their aging behaviour by exposing them to the ambient atmosphere for up to 7 days. The plasma induced morphological changes were studied using an scanning electron microscope and an atomic force microscope, while the formation of various functional groups was identified using Fourier transform infrared analysis. The surface energy values were observed to increase from 27?5 dyne cm 21 (of untreated PE) to 73?8 and 52?2 dyne cm 21 after low pressure 40 kHz and 13?56 MHz air plasma treatment respectively and to 35?6 dyne cm 21 after the DBD air plasma treatment. The low pressure plasma treatment at an operating frequency of 40 kHz has produced the best results in the surface activation of PE. During the aging process, the formation of C5C bonds was observed on the surface of PE.
Characterization of plasma processing for polymers
Surface and Coatings Technology, 2003
Some selective plasma treatments are described, aiming at modifying specific surface properties of textile polymeric materials, such as their hydrorepellence and dyeability. The prevailing plasma-polymer interactions were identified by correlating the physico-chemical modification of treated polymer surfaces to the characteristics of the plasma sources. ᮊ
Surface and Coatings Technology, 2018
This work reports on surface modification of polyethylene terephthalate (PET) polymer by an atmospheric pressure plasma jet (APPJ) operated with argon. A distinguishable feature of this device is that it terminates with a conical horn-like nozzle. Three different nozzles diameters were employed with the purpose to obtain uniform surface modification over large area. Treatments in small 3D objects that fit inside the conical horn were also conducted. In this study, water contact angle (WCA) measurements and X-ray photoelectron spectroscopy (XPS) were performed to assess the samples wettability and the surface elemental composition, as well as, their radial distribution. Plasma-induced changes on the polymer surface morphology were evaluated by Atomic Force Microscopy (AFM). Electrical characterization of the plasma and investigation of the effect of the gas flow rate on the discharge power were carried out. After the plasma treatment PET surface became more hydrophilic over the entire area covered by the nozzle. This effect is caused by the incorporation of oxygen containing polar groups on the surface. It was also observed that depending on process parameters, the plasma treatment can extend even outside the area of the conical horn. The degree of surface modification depends on plasma dose while the treatment uniformity is determined mostly by the distance to the sample. Overall, a quite uniform surface modification was obtained over the entire area covered by the jet nozzle. Thus, the results suggest that by simply changing the jet geometry and choosing the right treatment parameters one can achieve a uniform treatment over an area whose size is determined by the horn diameter.
Plasma surface modification of polystyrene and polyethylene
Applied Surface Science, 2004
Polystyrene (PS) and polyethylene (PE) samples were treated with argon and oxygen plasmas. Microwave Electron Cyclotron Resonance (ECR) was used to generate the argon and oxygen plasmas and these plasmas were used to modify the surface of the polymers. The samples were processed at different microwave powers and treatment time and the surface modification of the polymer was evaluated by measuring the water contact angle of the samples before and after the modification. Decrease in the contact angle was observed with the increase in the microwave power for both polystyrene and polyethylene. Plasma parameters were assessed using Langmuir probe measurements.
Polymers
In the last decade atmospheric pressure plasma jets (APPJs) have been routinely employed for surface processing of polymers due to their capability of generating very reactive chemistry at near-ambient temperature conditions. Usually, the plasma jet modification effect spans over a limited area (typically a few cm²), therefore, for industrial applications, where treatment of large and irregular surfaces is needed, jet and/or sample manipulations are required. More specifically, for treating hollow objects, like pipes and containers, the plasma jet must be introduced inside of them. In this case, a normal jet incidence to treated surface is difficult if not impossible to maintain. In this paper, a plasma jet produced at the end of a long flexible plastic tube was used to treat polyethylene terephthalate (PET) samples with different incidence angles and using different process parameters. Decreasing the angle formed between the plasma plume and the substrate leads to increase in the m...
Plasma treatment of polymers for surface and adhesion improvement
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2003
Different plasma treatments in a rf discharge of Ar, He, or N 2 are used to etch, cross-link, and activate polymers like PC, PP, EPDM, PE, PS, PET and PMMA. Due to the numerous ways a plasma interacts with the polymer surface, the gas type and the plasma conditions must be adjusted on the polymer type to minimize degradation and aging effects. Wetting and friction properties of polymers can be improved by a simple plasma treatment, demonstrated on PC and EPDM, respectively. However, the deposition of ultra-thin layers by plasma enables the adjustment of wetting properties, using siloxane-based or fluorocarbon films, and further reduction of the friction coefficient, applying siloxane or a-C:H coatings. Nevertheless, the adhesion of plasma-deposited coatings should be regarded, which can be enhanced by depositing a graded layer.
Improving the Hydrophilicity of Polymers by Atmospheric Plasma Treatments
Due to the hydrophobic nature of polymer such as thermoplastic polyurethane (TPU) and polystyrene (PS), the advantage of atmospheric pressure plasma treatment in enhancing surface wettability on polymer was investigated. The atmospheric plasma reactor used in this study was constructed using a "V" type glass column with its inlet port connected to helium or nitrogen gas at a controlled rate. Electron spectroscopy for chemical analysis (ESCA), water contact angle, and scanning electron microscopy (SEM) were used for surface characterization. The untreated TPU and PS surface was hydrophobic (contact angle θ H2O = 94° and 78°). The nitrogen plasma treated PS θ H2O =37°. Additionally the atmospheric helium plasma treatment of the polymer resulted in oxidation of the surface, a significant increase in hydrophilicity, contact angle of helium plasma treated TPU θ H2O = 50° and PS θ H2O less then 10°. The ESCA results demonstrated oxygen percentage of PS raised from 11.7％ to 23.6％ using atmospheric helium plasma and 16％ using nitrogen plasma, indicating the effective in plasma treatment. Compared with the nitrogen plasma treatment, the helium plasma treatment considerably reduced water contact angle values thus showing clearly an increase in surface wettability.
Applied Surface Science, 2011
In this paper, an atmospheric pressure plasma jet sustained in pure argon and an argon/water vapour mixture has been used to modify the surface of polypropylene (PP) films. The gas temperature of the plasma jet was found to be 625 K in an active zone between the electrodes and was found to increase in the afterglow. Based on these results, the PP films are placed as close as possible to the edge of the capillary in order to avoid thermal damage to the polymer. XPS results on the untreated and modified PP samples revealed incorporation of a significant amount of oxygen on the polymer surface, however, this oxygen inclusion is more pronounced for the argon/water vapour jet due to the higher radicals density in the jet afterglow. One can therefore conclude that adding water vapour to an argon plasma jet can be a convenient way to increase the efficiency of plasma surface modification.