Effects of surface treatments on changes in low-voltage SEM of polymers

The effects of surface treatment of polymers is important in many areas of technology. Polymer surfaces may be treated for a variety of reasons including: increased wettability for printing; improved fiber bonding in composites; and improved bonding in powder sintering. A variety of techniques are used to study surface changes after treatments including hydrophobicity, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Another technique which has good potential for surface characterization is the effect of surface treatment on the crossover voltage, “E2,” in low voltage SEM. E2 is the accelerating voltage at which there is 0 potential on surface of an insulator because the electron emission current is equal to the primary beam current. We have previously demonstrated that changes in E2 are correlated to changes in hydrophobicity. These results also correlated well with XPS and weight loss measurements. In this research we are reporting on the effects of surface roughness, chemical treatment and electrical discharges on changes in E2 for teflon (polytetrafluoroethylene).

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Increased Filiform Corrosion Resistance Utilizing a Zirconium-Based Conversion Coating on an Al-Zn-Mg-Cu (AA7075-T6) Alloy as well as Selected Surface Treatments

CORROSION ◽

10.5006/3510 ◽

2020 ◽

Author(s):

Carol Glover ◽

Mary Lyn Lim ◽

John Scully

Keyword(s):

Surface Treatment ◽

Photoelectron Spectroscopy ◽

Conversion Coating ◽

Surface Treatments ◽

Treatment Processes ◽

Filiform Corrosion ◽

Alkaline Cleaning ◽

Vinyl Butyral ◽

Subsequent Acid ◽

Effect Of Surface

This study investigates the effect of surface treatment on the formation of Zr-based conversion coatings on AA7075-T6 automotive aluminum alloys and their resistance to filiform corrosion (FFC). Two different surface treatments were studied (A) alkaline-cleaning and (B) alkaline-cleaning with a subsequent acid deoxidation step. A model poly-vinyl butyral (PVB) primer coating was used as the topcoat and specimens were studied with and without the application of a Zr-based conversion coating. Comparisons were made against a control that had no surface treatment. The FFC filament initiation time and propagation kinetics were of particular interest. Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) were used to examine the conversion coating thickness and composition. A bi-layer conversion coating structure is demonstrated and both surface treatments are shown to produce copper enrichment that promotes the formation of the Zr-rich coating. Specimens prepared by alkaline cleaning-only resulted in a substantially thicker oxide layer of which 97% was ZrO2. These specimens provide superior resistance to FFC where the thick Zr-rich oxide is thought to provide a dense blocking layer that prevents electron transfer at the interface. In contrast, the control specimen, exposed only to the copper additions present in the conversion bath is shown to produce an Al oxide-rich layer with only a 33% ZrO2 contribution in the outer layer. The findings demonstrate that the redistribution of functional copper species, that is shown to occur during surface treatment processes, is crucial for the formation of a robust Zr film.

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Improvement of Water Resistance by Fe2O3/TiO2 Photoelectrocatalysts for Formaldehyde Removal: Experimental and Theoretical Investigation

10.21203/rs.3.rs-164964/v1 ◽

2021 ◽

Author(s):

Jing Dong ◽

Qing Li ◽

Wenjie Xia ◽

Bihong Lv ◽

Guohua Jing ◽

...

Keyword(s):

Electric Field ◽

Photoelectron Spectroscopy ◽

Density Functional ◽

Surface Characterization ◽

Gas Flow ◽

Competitive Adsorption ◽

Low Voltage ◽

Experimental Tests ◽

Inhibitory Effect ◽

Hydrogen Atoms

Abstract TiO2-based photocatalysts are a potential technology for removing indoor formaldehyde (CHOH) owing to their strong photooxidation ability. However, their photooxidation performance is generally weakened when suffering from the competitive adsorption of H2O. In a method inspired by the oxygen evolution reaction (OER) to generate intermediates with hydroxyl radicals on the anode electrode catalysts, an electric field was employed in this research and applied to the photooxidation of CHOH to prevent the competitive adsorption of H2O. Additionally, 0.5-5% Fe2O3 decorated TiO2 was employed to improve the photoelectrocatalytic activity. The influence of an electric field on hydroxyl-radical production was investigated by both density functional theory (DFT) with direct-imposed dipole momentum and photoelectrocatalytic experimental tests. The surface characterization of the photocatalysts, including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR), was conducted. DFT results show that a positive electric field with a strength of 0.05 Å/V was more favorable to produce hydroxyl on Fe2O3/TiO2(010) than was a negative electric field. Fe2O3 decoration can significantly boost hydroxyl formation, resulting from a decrease in the binding energy between the Fe of Fe2O3 and the oxygen and hydrogen atoms of H2O. The dissociated hydrogen atom of the H2O preferentially remained on the catalysts’ surface rather than being released into the gas flow. The experimental results demonstrated that the application of a low-voltage of 150 V could not directly enhance the photooxidation of CHOH by either TiO2 or Fe2O3/TiO2 but that it could relieve the H2O inhibitory effect by more than 10% on the Fe2O3/TiO2.

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Thrombus formation on artificial surfaces: Correlative microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010016176x ◽

1990 ◽

Vol 48 (3) ◽

pp. 840-841

Author(s):

Quintin J. Lai ◽

Stuart L. Cooper ◽

Ralph M. Albrecht

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Low Voltage ◽

Thrombus Formation ◽

Blood Platelets ◽

Polymer Surfaces ◽

Flow Conditions ◽

Transmission Electron ◽

Adhesion Of Platelets ◽

Microscopic Techniques

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.

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Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180963 ◽

1990 ◽

Vol 48 (1) ◽

pp. 442-442

Author(s):

Galen Powers ◽

Ray Cochran

Keyword(s):

Low Voltage ◽

Beam Current ◽

Microchannel Plate ◽

Normal Operation ◽

Microscopy Imaging ◽

Backscatter Signal ◽

Vacuum Interface ◽

Width Measurements ◽

Working Distance ◽

Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

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Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178665 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1106-1107

Author(s):

W.W. Adams ◽

G. Price ◽

A. Krause

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

High Resolution ◽

Single Crystals ◽

Low Voltage ◽

Polymer Surface ◽

Beam Current ◽

Image Features ◽

First Results ◽

Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

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Electrostatic Charging of Fumed Silica Particles: Effect of Surface Treatment with Fluoroalkylsilanes

Journal of Imaging Science and Technology ◽

10.2352/j.imagingsci.technol.56.5.050403 ◽

2013 ◽

Author(s):

Jinsong Liu

Keyword(s):

Surface Treatment ◽

Fumed Silica ◽

Silica Particles ◽

Electrostatic Charging ◽

Effect Of Surface

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Effect of surface treatment on mechanical, physical and morphological properties of oil palm/bagasse fiber reinforced phenolic hybrid composites for wall thermal insulation application

Construction and Building Materials ◽

10.1016/j.conbuildmat.2020.122239 ◽

2021 ◽

Vol 276 ◽

pp. 122239

Author(s):

Nor Azlina Ramlee ◽

Mohammad Jawaid ◽

Shaikh Abdul Karim Yamani ◽

Edi Syams Zainudin ◽

Salman Alamery

Keyword(s):

Surface Treatment ◽

Thermal Insulation ◽

Oil Palm ◽

Hybrid Composites ◽

Morphological Properties ◽

Fiber Reinforced ◽

Bagasse Fiber ◽

Effect Of Surface

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Effect of sizing agent on interfacial properties of carbon fiber-reinforced PMMA composite

Composites and Advanced Materials ◽

10.1177/2633366x20978657 ◽

2021 ◽

Vol 30 ◽

pp. 2633366X2097865

Author(s):

Li Jian

Keyword(s):

Shear Strength ◽

Surface Treatment ◽

Photoelectron Spectroscopy ◽

Resin Composite ◽

Contact Angles ◽

Static Contact ◽

Before And After ◽

C Value ◽

Interlayer Shear Strength ◽

Pmma Resin

The surface treatment of carbon fibers (CFs) was carried out using a self-synthesized sizing agent. The effects of sizing agent on the surface of CFs and the interface properties of CF/polymethyl methacrylate (PMMA) composites were mainly studied. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and static contact angle were used to compare and study the CFs before and after the surface treatment, including surface morphology, surface chemical element composition, and wettability of the surface. The influence of sizing agent on the mechanical properties of CF/PMMA resin composite interface was investigated. The results show that after sizing treatment, the CF surface O/C value increased by 35.1% and the contact angles of CF and resin decreased by 16.2%. The interfacial shear strength and interlayer shear strength increased by 12.6%.

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Effect of surface treatments on push-out bond strength of calcium silicate-based cements to fiber posts

BMC Oral Health ◽

10.1186/s12903-021-01518-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Amr M. Elnaghy ◽

Ayman Mandorah ◽

Ali H. Hassan ◽

Alaa Elshazli ◽

Shaymaa Elsaka

Keyword(s):

Bond Strength ◽

Surface Treatment ◽

Glass Fiber ◽

Calcium Silicate ◽

Surface Treatments ◽

The Other ◽

Fiber Posts ◽

Glass Fiber Posts ◽

Push Out ◽

Effect Of Surface

Abstract Background To evaluate the effect of surface treatments on the push-out bond strength of Biodentine (BD) and white mineral trioxide aggregate (WMTA) to fiber posts. Methods Two brands of fiber posts were used: Reblida post; RP and RelyX post; RX. Each type of post (n = 80/group) was divided into four groups (n = 20/group) and exposed to surface treatment as follows: Control (no treatment), sandblasting (SB), hydrofluoric acid (HF), and TiF4 4 wt/v%. Each group was further subdivided into two subgroups (n = 10/subgroup) based on the type of CSCs used as follows: Subgroup A: BD and Subgroup B: WMTA. Push-out bond strength of BD and WMTA to glass fiber posts was assessed. Data were statistically analyzed using three-way ANOVA and Tukey’s test. A Weibull analysis was performed on the push-out bond strength data. Results BD showed higher bond strength than WMTA (P < 0.001). The push-out bond strength for posts treated with TiF4 4 wt/v% showed greater bond strength than the other surface treatments (P < 0.05). The BD/RP-TiF4 4 wt/v% showed the greater characteristic bond strength (σ0) (15.93) compared with the other groups. Surface treatments modified the surface topography of glass fiber posts. Conclusions The BD/RP-TiF4 4 wt/v% showed greater bond strength compared with the other groups. The TiF4 4 wt/v% surface treatment enhanced the bond strength of BD and WMTA to glass fiber posts than the other treatments. Surface treatment of fiber post with TiF4 4 wt/v% could be used to improve the bond strength with calcium silicate-based cements.

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