In this study the effect of an atmospheric pressure plasma treatment by a dielectric barrier discharge (DBD) on the wettability and absorption characteristics of thermally modified beech veneer is investigated. A common immersion test using water and melamine solution has been conducted and showed improved wettability and liquid uptake after plasma treatment. Determination of the weight percent gain (WPG) confirmed increased melamine content after plasma treatment.
[Show abstract][Hide abstract] ABSTRACT: Modification of wood is a method that is used to improve the material properties of wood by altering its chemical nature and in a broader sense it is also a passive process, where changes in properties also occur, but without an alteration of the chemistry of the material.
A typical example of passive modification is, for instance, filling of wood cell lumens with resins. Surface modification of wood has the same purpose as the bulk modification, but it is restricted only to treatments of first few layers of wood surface. This review provides an overview of
the development of surface modification of wood in the last 10–15 years. This topic has been extensively studied, especially in relation to research and production of wood based composites. However, in the present review the references dealing with modification of lignocellulosic and
wood particulates (for instance, wood dust, flakes, and fibres) are in general excluded and the review is focused on surface modification of solid wood and of veneers. Mainly, modification in a narrow sense was considered, i.e. alternating chemical composition of wood building polymers and
other compounds in wood. Nevertheless, some less conventional passive surface treatment techniques, for example sol-gel processes, deposition of nanoparticles or mechanical operations have been considered as well. In the first part, an overview of the most common surface modification methods
is presented and in the second part the properties that are affected are illustrated through selected publications in literature. It is shown that the topic of surface modification of wood is currently a very viable area of research in wood science and technology. Wood surfaces can be treated
by plasmas from various sources; by chemical or enzymatic grafting of functional molecules; coating by application of sol-gel methods, including deposition of nanoparticles; by surface impregnation and with various mechanical operations. The target properties to be improved or even introduced
are mostly surface activation for better gluing and adhesion of surface coatings, wettability and resistance to weathering. However, resistance to wood pests, fire retardancy and mechanical properties, especially hardness and abrasion resistance, can also be effectively improved by wood surface
[Show abstract][Hide abstract] ABSTRACT: Sample material from spruce (Picea abies), beech (Fagus sylvatica) and ash (Fraxinus excelsior) with radial and tangential section was treated by diffuse coplanar surface barrier discharge (DCSBD) plasma generated in air at atmospheric pressure. Plasma activated samples exhibited significantly lower water uptake times of 50 μl droplets and minimal differences in wetting between the two cutting planes (radial and tangential), when compared to the untreated surface. Simultaneously, more uniform spreading of the droplets and increased area of wetting on the activated surface were achieved. The plasma treatment had no effect on the water absorption coefficient of the wood samples. FTIR measurements confirmed the presence of oxygen containing functional groups and structural changes in lignin on the activated wood surface. The minimal heating of the treated samples suggests this method to be applicable to treat heat sensitive wooden materials.
Holz als Roh- und Werkstoff 09/2013; 71(5). DOI:10.1007/s00107-013-0706-3 · 1.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Using molecular dynamics simulations, we determined the threshold energy for creating defects as a function of the incident angle for all carbon and oxygen atoms in the cellulose monomer. Our analysis shows that the damage threshold energy is strongly dependent on the initial recoil direction and on average slightly higher for oxygen atoms than for carbon atoms in cellulose chain. We also performed cumulative bombardment simulations mimicking low-energy electron irradiation (such as TEM imaging) on cellulose. Analyzing the results, we found that formation of free molecules and broken glucose rings were the most common forms of damage, whereas cross-linking and chain scission were less common. Pre-existing damage was found to increase the probability of cross-linking. V C 2014 AIP Publishing LLC.
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