Effect Of Different Plasma Treatments Research Articles

The Effect of Different Plasma Treatments on the Surface Properties and Bond Strength between Lithium Disilicate and Resin Cement.

To evaluate the roughness, surface energy, and the bond strength of lithium disilicate yielded by two different types of nonthermal plasma (NTP), oxygen- or argon-based, compared to the conventional method. Ninety-three lithium disilicate (IPS e.max Press) samples were divided into 3 groups: HF (hydrofluoric acid group); ONTP (oxygen-based NTP group); ANTP (argon-based NTP group). Surface energy and roughness analyses were performed before and after surface treatment, and bond strength testing was performed before and after 5000 thermocycles. Scanning electron microscopy (SEM) was used to characterize the surface treatments. Data were submitted to ANOVA and Bonferroni's test with statistical significance set at 5%. The ONTP group presented the highest surface energy values, followed by ANTP and HF. In addition, the ONTP group had higher surface roughness. SEM revealed exposed lithium disilicate crystals in the HF group, but a homogeneous film coverage in both NTP groups. Regarding bond strength, ANTP presented statistically significantly higher values than the other groups before thermocycling, and statistically significantly lower values than the other groups after thermocycling. The HF and ONTP groups presented statistically similar values after thermocycling. The bond strength of resin cement to lithium disilicate obtained after oxygen-based NTP was comparable with that obtained after conventional hydrofluoric acid treatment.

Effects of different plasma treatments of short fibers on the mechanical properties of polypropylene‐wood composites

In this work, a custom‐made reactor was developed to treat batches of short wood fibers with plasma. Three different plasma gases were tested: air, methane (CH4) and sulfur hexafluoride (SF6). The latter showed very promising results and was therefore used to prepare additional samples to determine the effects of plasma treatment and conditions on the wood fiber surface properties as well as the adhesion in a polypropylene matrix. As a result, composites made out of fibers plasma treated for 40 min at 60 W demonstrated an increase in the elastic modulus of more than 25%. Scanning electron microscope micrographs of the composites’ fracture surfaces indicated stronger interactions between treated fibers and the matrix. The incorporation of fluorine on treated fiber surfaces, mostly in covalent bonds with carbon, was clearly observed and analyzed by X‐ray photoelectron spectroscopy. The water contact angle on wood specimens treated under similar conditions displayed hydrophobic to superhydrophobic behavior, with contact angles exceeding 130°. POLYM. COMPOS., 39:1468–1479, 2018. © 2016 Society of Plastics Engineers

Response surface methodology optimized dyeing of wool with cumin seeds extract improved with plasma treatment

In this study, the aqueous extract of Cuminum Ciminum L. seed was applied on wool as a novel natural colorant. Gas chromatography coupled with mass spectrometry was conducted to identify the composition of the extract. Response surface methodology and D-optimal design were employed to investigate and optimize the effects of three independent factors including mordant concentration, dyeing pH and temperature on the color strength of dyed samples. A statistical model was obtained to correlate between the amounts of three independent factors and color strength of dyed samples as the response. Low pressure plasma treatment using oxygen, argon, and their mixture was employed to improve the dyeability of wool fibers. The effect of different plasma treatments on the surface chemistry and morphology of wool fibers were studied using attenuated total reflectance-Fourier transform infrared spectroscopy and field emission scanning electron microscopy, respectively. The fastness properties of dyed samples were also investigated.

Atomic Layer Deposition of TiO2 on Surface Modified Nanoporous Low-k Films

This paper explores the effects of different plasma treatments on low dielectric constant (low-k) materials and the consequences for the growth behavior of atomic layer deposition (ALD) on these modified substrates. An O2 and a He/H2 plasma treatment were performed on SiCOH low-k films to modify their chemical surface groups. Transmission FTIR and water contact angle (WCA) analysis showed that the O2 plasma changed the hydrophobic surface completely into a hydrophilic surface, while the He/H2 plasma changed it only partially. In a next step, in situ X-ray fluorescence (XRF), ellipsometric porosimetry (EP), and Rutherford backscattering spectroscopy (RBS) were used to characterize ALD growth of TiO2 on these substrates. The initial growth of TiO2 was found to be inhibited in the original low-k film containing only Si-CH3 surface groups, while immediate growth was observed in the hydrophilic O2 plasma treated film. The latter film was uniformly filled with TiO2 after 8 ALD cycles, while pore filling was delayed to 17 ALD cycles in the hydrophobic film. For the He/H2 plasma treated film, containing both Si-OH and Si-CH3 groups, the in situ XRF data showed that TiO2 could no longer be deposited in the He/H2 plasma treated film after 8 ALD cycles, while EP measurements revealed a remaining porosity. This can be explained by the faster deposition of TiO2 in the hydrophilic top part of the film than in the hydrophobic bulk which leaves the bulk porous, as confirmed by RBS depth profiling. The outcome of this research is not only of interest for the development of advanced interconnects in ULSI technology, but also demonstrates that ALD combined with RBS analysis is a handy approach to analyze the modifications induced by a plasma treatment on a nanoporous thin film.

PDMS/Kapton Interface Plasma Treatment Effects on the Polymeric Package for a Wearable Thermoelectric Generator

The present work highlights the progress in the field of polymeric package reliability engineering for a flexible thermoelectric generator realized by thin-film technology on a Kapton substrate. The effects of different plasma treatments on the mechanical performance at the interface of a poly(dimethylsiloxane) (PDMS)/Kapton assembly were investigated. To increase the package mechanical stability of the realized wearable power source, the Kapton surface wettability after plasma exposure was investigated by static contact-angle measurements using deionized water and PDMS as test liquids. In fact, the well-known weak adhesion between PDMS and Kapton can lead to a delamination of the package with an unrecoverable damage of the generator. The plasma effect on the adhesion performances was evaluated by the scratch-test method. The best result was obtained by performing a nitrogen plasma treatment at a radio-frequency power of 20 W and a gas flow of 20 sccm, with a measured critical load of 1.45 N, which is 2.6 times greater than the value measured on an untreated Kapton substrate and 1.9 times greater than the one measured using a commercial primer.

A reliability study of adhesion mechanism between liquid crystal polymer and silicone adhesive

Liquid crystal polymer (LCP) and silicone adhesives are widely used in electronics manufacturing. The integrity of the adhesion between the two materials is crucial to the reliability of electronic products, however, the adhesion mechanism and associated reliability has not been thoroughly understood. In this paper, the adhesion mechanism between a commonly used LCP and a silicone adhesive is evaluated by employing the 85°C/85% RH temperature humidity test, autoclave test, boiling water test (BWT), and dry air reflow aging test. The effects of different plasma treatments of the LCP surface are evaluated by the surface analysis methods, namely XPS and FTIR–ATR spectroscopy, as well as the surface roughness and energy measurements. Moreover, the adhesion strength between the LCP and silicone adhesive is measured by a shear strength tester. The shear strength testing process is simulated by the finite element method for a better understanding of the failure mechanism. The experimental results indicate that the adhesion between the LCP and silicone adhesive is based solely on the hydrogen bonds. It is found that the humidity significantly weakens the adhesion strength between the LCP and silicone adhesive. This is related to the breakdown of hydrogen bonds when water molecules are introduced to the system. Furthermore, the reflow test shows that the weakened adhesion strength can be recovered by removing the moisture from the interface.

The Effect of Different Plasma Treatments on the Pigment Dyeing of Cotton Fabrics

In this paper, the application of glow discharge (low pressure) and dielectric barrier discharge (atmospheric) prior to pigment dyeing of cotton fabric was studied. Different parameters of power and time during the process were also discussed. The dyeing effect after different plasma treatment was analyzed by SEM observations and measurements of the K/S value, levelness and color fastness. The results indicated that the particle diameter of pigment affected pigment dyeing, and the K/S value increased as particle diameter decreased. These two plasma treatments could enhance the properties of pigment dyeing with satisfied color fastnesses. Fabrics treated by plasma should be dyed within 2 hours of plasma treatment to ensure optimum results. The power of atmospheric plasma treatments was relatively high without maintaining a vacuum atmosphere, and it could be processed continuously with high efficiency and K/S value.

Effect of plasma treatments on interface adhesion between SiOCH ultra-low- k film and SiCN etch stop layer

The effect of different plasma treatments on the interfacial bonding configurations and adhesion strengths between porous SiOCH ultra-low-dielectric-constant film and SiCN etch stop layer have been investigated in this study. From X-ray photoelectron spectroscopic analyses, interlayer regions of about 10 nm thick with complicated mixing bonds were found at SiOCH/SiCN interfaces. With plasma treatments, especially H 2/NH 3 two-step plasma, a carbon-depletion region of about 30 nm thick with more Si–O related bonds of high binding energy formed at the interface. Furthermore, the adhesion strengths of the SiOCH/SiCN interfaces were measured by nanoscratch and microscratch tests. For the untreated interface, the adhesion energy was obtained as about 0.22 and 0.44 J/m 2 by nanoscratch and microscratch tests, respectively. After plasma treatments, especially the H 2/NH 3 treatment, the interfacial adhesion energy was effectively improved to 0.41 and 0.89 J/m 2 because more Si–O bonds of high binding energy formed at the interfaces.

Effect of plasma treatments on a low-k dielectric polymer surface

The ongoing transition to lower dimension devices requires the replacement of SiO2 by a lower-k dielectric insulator. Such materials are porous, introducing the need for sealing against penetration of gaseous and/or liquid species during subsequent processing. In this work, we investigate the effect of different plasma treatments on a porous low-k polymer film. Ion bombardment induces the formation of a dense surface layer capable of sealing the polymer. A competing etching reaction by the plasma gases determines the extent of the densified layer. Structural and chemical changes induced by the plasma treatments can extend into the bulk of the film and irreversibly change its properties. Exposing the plasma treated films to chemical precursors during an atomic layer deposition process is used to test sealing. The sealing behavior is discussed in view of the reactivity of the plasma and the post sealing temperature treatment.

Polymeric meshes for internal sutures with differentiated adhesion on the two sides

The aim of this work is to investigate the effects of different plasma treatments on ePTFE abdominal prostheses with the final goal of obtaining a new prosthesis, made of a single strand of ePTFE, with clearly differentiated adhesion properties on the two sides, which should be able to promote tissue ingrowth on one side and prevent post surgical visceral adhesions on the other. Samples obtained from ePTFE Bard Dulex Meshes have been treated sequentially with three different gases (N(2), O(2) and NH(3)) in order to choose the optimal treatment conditions to improve ePTFE wettability. In particular, no modification was induced by N(2) treatment, while the full treatment after the final ammonia gas resulted in the best suitable candidate. As demonstrated by scanning electron microscopy, AFM analyses and contact angle measurements, ammonia plasma treatment increases ePTFE surface roughness and renders it more hydrophilic, thus promoting adhesion without any alteration of the material's bulk properties. The reported results also evidence the possibility to obtain the maximum wettability with a cheap treatment by optimizing plasma exposure time. As a preliminary cell adhesion study, Swiss 3T3 fibroblasts (mouse, embryo) have been seeded on the treated and untreated materials in order to assess whether there was any difference in terms of cell attachment and spreading. Cells seeded on the ammonia plasma treated material showed a better adhesion and spreading when compared to the untreated material.

Acrylic Fabrics Treated with Plasma for Outdoor Applications

The increasing interest in the application of plasma processes on textiles is due both to the necessity of adding value to products and to develop new pollution free technologies. In fact, plasma treatments allow modification of the textile surface behaviour with a flexible process, which can impart particular properties to the fabrics, such as waterproofing, oil repellence, antistatic behaviour, etc. In addition, plasma processes are characterised by the very small quantity of chemicals involved and by the absence of solvent or water, which are usually employed in traditional finishing processes. In this work the effect of different plasma treatments on the properties of acrylic fabrics for outdoor applications was explored. In particular, the possibility of substituting plasma processes for the traditional cleaning and waterproofing processes of outdoor acrylic fabrics was evaluated. The properties of the plasma treated acrylic fabrics have been compared with the characteristics of the fabrics traditionally treated. The resistance of plasma treatments to wear, UV and weather exposure has been also evaluated.