Plasma induced effects within the bulk material of wood veneers

Wascher, Richard; Avramidis, Georg; Vetter, U.; Damm, Roland; Peters, Frauke; Militz, Holger; Viöl, Wolfgang

doi:10.1016/j.surfcoat.2014.07.005

Cited by 23 publications

(12 citation statements)

References 28 publications

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“…To determine the power which was injected into the plasma, the applied voltage was measured by a high voltage probe PVM‐1 from HVP High Voltage Products GmbH, Martinsried/Planegg, Germany, and the transferred charge by the voltage curve on a capacitance (WIMA, FKP1.2× 100 nF) …”

Section: Methodsmentioning

confidence: 99%

Plasma treatment of wood–polymer composites: A comparison of three different discharge types and their effect on surface properties

Hünnekens

Peters²,

Avramidis³

et al. 2016

J of Applied Polymer Sci

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Three different discharge types, based on the principle of a dielectric barrier discharge at atmospheric pressure, were investigated with regard to their influence on the adhesion properties of a series of wood–polymer composites. Wood flour (Picea abies L.) filled polypropylene and various proportions of polyethylene were manufactured either through extrusion or injection molding. The composites’ surfaces were activated by coplanar surface barrier discharge, remote plasma, and direct dielectric barrier discharge. The changes in wettability due to the pretreatment were investigated by contact angle measurement using the sessile drop method and calculation of surface free energy (SFE). It could be shown that wettability was improved by all three types of discharge, the contact angle decreased and the SFE correspondingly increased. X-ray photoelectron spectroscopy revealed an increase in the O/C ratio at the material's surface. An improvement in coating adhesion was demonstrated by crosscut and pulloff tests

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Section: Methodsmentioning

confidence: 99%

Plasma treatment of wood–polymer composites: A comparison of three different discharge types and their effect on surface properties

Hünnekens

Peters²,

Avramidis³

et al. 2016

J of Applied Polymer Sci

Self Cite

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“…The buffering capacity is caused by weak acids, such as acetic acid (Risholm-Sundman et al 1998), originating from the wood. A degradation of these weak acids is plausible for the DDBD due to the depth effect and direct electron bombardment (Meiners et al 2012;Wascher et al 2014b). The RP shows only half the pH reduction seen for CSBD and DDBD and about half of the CSBD nitrate concentrations.…”

Section: Resultsmentioning

confidence: 96%

“…A pH reduction after a plasma treatment was measured using a surface pH electrode (Odrášková et al 2008;Helmke et al 2009;Wascher et al 2014b). However, the increased wettability of wooden surfaces leads to absorption of test liquid into the material after plasma treatments, which causes a systematical error of measurements with pH surface electrodes.…”

Section: Introductionmentioning

confidence: 99%

Decrease of the surface pH of maple and the production of nitrate by three pulsed dielectric barrier discharges

et al. 2018

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In this study, the influence of dielectric barrier discharges at atmospheric pressure on maple sapwood was analyzed. Three common discharge types, a coplanar surface barrier discharge (CSBD), a direct dielectric barrier discharge and a jet discharge/remote plasma, were realized by the same electrodes and power supply. In general, plasma treatments are known to modify various surface properties leading to improved adhesion. For resins such as urea formaldehyde, the curing behavior is dependent on the pH. Therefore, the change of the surface pH value of maple is measured. As the main product of plasma-generated nitrogen oxides, the nitrate concentrations and consequently the nitric acid concentrations of the surfaces were determined. A significant pH reduction from about pH 5.6 to pH 4.6 was reached after a 30 s plasma treatment. An increase in the nitrate concentration over the plasma treatment duration was measured for all three discharges with a maximum of 6.6 mg/L for the CSBD, which corresponds to a concentration of 8.25 mg per m 2 wooden surface.

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“…Wascher et al [37] demonstrated plasma-induced effects within the bulk of beech veneers and ascribed these effects to the occurrence of discharges within the wood capillaries leading to enhanced capillary penetration. However, thermally modified beech veneers show a more pronounced effect in terms of water uptake, melamine uptake, and the corresponding WPG when plasmatreated as unmodified beech veneers, which is reflected in the dimensional stability of plywood.…”

Section: Discussionmentioning

confidence: 99%

Plywood made from plasma-treated veneers: melamine uptake, dimensional stability, and mechanical properties

et al. 2017

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This study investigates the dimensional stability and mechanical properties of plywood boards made of thermally modified and unmodified beech veneers that have undergone plasma pre-treatment before melamine resin impregnation. The water and melamine resin uptake and resulting weight percent gain of the veneers were investigated, whereby the air plasma pre-treated veneers showed improved liquid uptake. Five-layer plywood boards were then manufactured and tested for their dimensional stability, compressive strength, bending strength, and tensile strength. Plywood boards made of thermally modified and plasma pre-treated veneers showed a significantly improved dimensional stability, along with small influences on their mechanical properties.

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Plasma induced effects within the bulk material of wood veneers

Cited by 23 publications

References 28 publications

Plasma treatment of wood–polymer composites: A comparison of three different discharge types and their effect on surface properties

Plasma treatment of wood–polymer composites: A comparison of three different discharge types and their effect on surface properties

Decrease of the surface pH of maple and the production of nitrate by three pulsed dielectric barrier discharges

Plywood made from plasma-treated veneers: melamine uptake, dimensional stability, and mechanical properties

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