Force-Based Characterization of the Wetting Properties of LDPE Surfaces Treated with CF 4 and H 2 Plasmas (original) (raw)
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Plasma Chemistry and Plasma Processing, 2008
The surface of a LDPE was modified by Ar, O 2 , N 2 , CO 2 gaseous plasma. The changes in surface morphology and surface wettability were investigated using AFM and SEM. The surface chemical changes of LDPE were also characterized by FTIR-ATR. The SEM and AFM results demonstrated variable changes in surface roughness for different types of plasma gas used, the changes being more for the Ar and N 2 plasma treatments. Considering the nature of the LDPE film, XRD studies were carried out to determine changes in the percentage crystalinity. The results showed that all low pressure O 2 , Ar, N 2 , CO 2 gas plasmas improved the wettability of LDPE films. Contact angles decreased significantly depending on the discharge powers and exposure times. Surface morphology was also found to vary with plasma discharge powers, exposure times, and the type of gas being used. Ar and N 2 gas plasmas in general produced more superior results.
Applied Surface Science, 2014
Owing to the superior physico-chemical properties, the low density polyethylene (LDPE) has been widely used in the various industrial applications; especially in biomedical field for artificial organs, medical devices and disposable clinical apparatus. However, the poor anticoagulation property is one of the main drawbacks of the LDPE due to its poor surface properties. Therefore, in this paper we present the effect of plasma forming gases such as argon (Ar), oxygen (O 2 ), air and argon-oxygen (Ar + O 2 ) mixture on improvement of the surfaces properties of LDPE film using direct current (dc) excited glow discharge plasma. Contact angle with evaluation of surface energy, X-ray photo electron spectroscopy (XPS), atomic force microscopy (AFM) techniques were used to examine the change in surface properties such as hydrophilicity, chemical composition and surface topography, respectively. Furthermore, the hydrophobic recovery of the plasma treated LDPE was analyzed using ageing effect under different storage condition i.e. in air and water. The adhesive strength of the LDPE films was determined using T-peel test. In vitro tests were used to examine the blood compatibility of the surface modified LDPE films. It has been found that the hydrophilicity of the various plasma treated LDPE films was improved significantly due to the formation of oxygen containing polar groups such as OH, COO, C O, C O as confirmed by contact angle and XPS analysis. AFM revealed the changes in surface topography of plasma processed films. The gas mixture Ar + O 2 plasma influenced the remarkable improvement on the surface properties of a LDPE film compared with other gaseous plasmas. These physiochemical changes induced by the plasma on the surface facilitate to improve the adhesive strength and blood compatibility. (K.N. Pandiyaraj). materials, low density polyethylene (LDPE) is an engineering polymer which is mainly used in various fields of automobile, appliances, engineering components and also widely used in biomedical applications . However, the antithrombogenic properties of the material is still not good enough for the demanding blood contacting applications such as cardiovascular implants and devices, which may be due to its poor surface properties such as hydrophobicity, low surface energy, poor adhesion etc of LDPE. Hence, suitable surface treatment is required to improve the surface properties of the material which is a key factor to improve the process of blood-surface interaction. Thus, surface is first interacting with body environment and play significant role than bulk. Furthermore, the hydrophilic groups such as C O, COO, OH etc can effectively improve the adhesion properties as well as reduce the http://dx.
Surface characterization of polyethylene films modified by gaseous plasma
Journal of Applied Polymer Science, 2007
Of the several techniques available for surface modification, plasma processing has proved to be very appropriate. The low temperature plasma is a soft radiation source and it affects the material only over a few hundred angstroms deep, the bulk properties remaining unaffected. Plasma surface treatment also offers the advantage of greater chemical flexibility. The improvement in adhesion was studied by measuring T-peel strength. In addition, printability of plasma-treated PE films was studied by cross test method. It was found that printability increases considerably for plasma treatment of short duration. It was therefore thought of as interesting to study the surface composition and morphology by contact angle measurement, ESCA, and AFM. Surface energy and surface roughness can be directly correlated to the improvement in above-mentioned surface-related properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 449–457, 2007
Polymers for Advanced Technologies, 2007
Low-density polyethylene modified by atmospheric dielectric surface barrier discharge in oxygen using several methods -surface energy measurements, ATR-FTIR spectroscopy, SEM, and AFM have been investigated. The activation of LDPE by oxygen barrier plasma increased significantly the surface energy and its polar component even at very short time of modification. The surface energy of treated LDPE diminished in the course of ageing especially during 10 days after modification by barrier plasma. The ATR-FT-IR spectra manifest the presence of oxygenic, i.e. carbonyl functional groups on the surface of polymer pre-treated by oxygen barrier plasma. It was shown by SEM, and AFM, that the topography of the modified LDPE significantly changed and surface of modified polymer became higher roughness as compared to unmodified polymer.
Modification of Barrier Properties of Polymeric Films of LDPE and HDPE by Cold Plasma Treatment
Journal of Polymer Engineering, 1995
In the present work barrier properties of low density polyethylene (LDPE) and high density polyethylene (HDPE) films have been modified by argon cold plasma surface treatments. This kind of treatment is commonly used to produce modifications on the surface layers of the polymer. The effect on LDPE and HDPE films has been a decrease in the permeability values, with a consequent improvement of their barrier properties. Such effects are strictly related to the operative parameters of the plasma apparatus, transport gas, electrical characteristics and polymer structure.
Wettability of polypropylene films coated with SiOx plasma deposited layers
Surface and Coatings Technology, 2006
Surface wettability of polypropylene (PP) films has been significantly improved by the deposition of thin SiO x layers, elaborated from a mixture of hexamethyldisiloxane (HMDSO) and oxygen in a microwave DECR (distributed electron cyclotron resonance) plasma reactor (2.45 GHz, 400 W). Contact angle measurements, Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to study, respectively, the change in surface free energy, surface topography and chemical composition due to the deposition of thin SiO x layers. Contact angle measurements revealed that the water contact angle value is reduced from about 99°for untreated PP surface to nearly 30°for coated PP film. The polar component of the surface energy is considerably increased from 0.5 to 35 mJ/m 2. For films deposited in the presence of VUV photons, AFM images showed the growth of irregular structure due to substrate etching effect and the deconvolution results of the Si 2p XPS peaks indicated that the proportion of the partly oxidized silicon environment was the major component. However, for films deposited without the presence of VUV radiation, typical SiO 2 agglomerates can clearly be seen on PP surface at a thickness of about 29 nm and the proportion of the silicon dioxide was the major component.
Vacuum, 2008
In this study, the adhesive properties of the plasma modified polypropylene (PP) and polyethylene terephthalate (PET) film surfaces have been investigated. Hydrophilicity of these polymer film surfaces was studied by contact angle measurements. The surface energy of the polymer films was calculated from contact angle data using Fowkes method. The chemical composition of the polymer films was analyzed by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) was used to study the changes in surface feature of the polymer surfaces due to plasma treatment. The adhesion strength of the plasma modified film was studied by T-peel strength test. The results showed a considerable improvement in surface wettability even for short exposure times. The AFM and XPS analyses showed changes in surface topography and formation of polar groups on the plasma modified PP and PET surfaces. These changes enhanced the adhesive properties of polymer film surfaces.
Plasma surface modification of polyethylene
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003
Oxidative (oxygen and air) RF-plasma treatment of HDPE was found as an effective tool for improving wettability, as well as for increasing its surface micro-hardness. The latter plasmas generate wide range of reactive species in the system, which undergo consecutive chemical reactions, creating thus several oxygen based functionalities at the interface (carbonyl, carboxyl, ether, peroxide etc.) as were detected by ATR FTIR and XPS analysis. An increased negative surface charge of plasma treated polyethylene (PE) confirms the presence of functional ionogenic groups containing oxygen. Simultaneously, the vigorous increase of the surface roughness was found as a result of the successful plasma etching. #
Polymer Degradation and Stability, 2013
We demonstrate here the structural, thermal, and wettability characteristics of low density polyethylene powder before and after plasma treatments. The plasma treatment was carried out using different working gas i.e. air, oxygen and a mixture of hydrogen and oxygen at an atmospheric pressure of 100 Pa. The plasma treatment time was kept constant at 2 min for all the specimens. Fourier transform infrared (FTIR), dynamic capillary rising using Washburn method, differential scanning calorimetry (DSC), and thermogravimetric analysis has been carried out for both pristine and plasma treated polyethylene specimens. Our study shows that there is 88% increase in the wettability after plasma treatments. Plasma treatment in air atmosphere gives the maximum wettability. Thermogravimetric analysis (TGA) investigation shows plasma treatment in the H 2 þ O 2 mixture atmosphere gives maximum thermal stability whereas the DSC results reveal the lowest crystallinity for plasma treatment in air atmosphere. The lowest latent heat of fusion (154 J/g) calculated from the melting curve of DSC is observed for LDPE treated in air atmosphere. The FTIR spectroscopy of the plasma-treated LDPE powder reveals that plasma treatment introduces polar group on the LDPE surface leading to the increased surface free energy and surface active sites. The CH 2 concentration increases after plasma treatments.
Effects of DBD plasma operating parameters on the polymer surface modification
Surface & Coatings Technology, 2004
This paper, based on an orthogonal experimental design and analysis method, reports the effects of a dielectric barrier discharge (DBD) plasma surface treatment on polytetrafluoroethylene (PTFE), polyimide (PI) and poly (lactic acid) (PLA) films in terms of changes in surface wettability and surface chemistry. The purpose was to study the influence of the main operating parameters, i.e. plasma power, treatment period duration (treatment cycles) and electrode gap on the resultant surface properties. Statistical analysis was carried out to develop an equation which expresses surface properties (water contact angle and oxygen enrichment, as observed by XPS analysis) in terms of these operational parameters. It was observed that the plasma parameters have a selective effect on the changes observed for the polymers processed. In particular, plasma processing time (treatment cycles), plays an important role in the treatment of PTFE and PI in this study, whereas the size of the electrode gap plays the dominant role in the treatment of PLA. Fast surface activation can be achieved in all cases after only a few seconds of treatment duration. The wettability improvement observed in all cases was attributed to changes in both surface chemistry and surface micro-structure. D