bioresources. com
PEER-REVIEWED ARTICLE
Effect of Cold Plasma Surface Pre-treatment of Wheat Straw Particles on Straw Board Properties Štěpán Hýsek, a, * Milan Podlena, a Martin Böhm, a Henry Bartsch, b and Christoph Wenderdel b
Effects of the plasma treatment were evaluated for particles from winter wheat stalks relative to the properties of particleboards manufactured from such treated particles. Using urea-formaldehyde adhesive, boards with a nominal density of 540 kg/m 3 and a thickness of 6 mm were manufactured. Two degrees of plasma treatment were selected: cold plasma applied at atmospheric pressure by jet system, with a generator output voltage of 26.9 V and a current of 6.9 A; and in the second treatment, a maximum voltage of 28.6 V was used with a current of 8.7 A. The physical properties (equilibrium moisture content and thickness swelling depending on relative humidity) and mechanical properties (bending strength and tensile strength perpendicular to the plane of the board) were determined. The results showed that the plasma pre-treatment of particles had a statistically significant effect on the resulting composite properties. The mechanical properties of the boards increased with both plasma treatments, but the physical properties changed negatively. Boards manufactured from particles treated with a higher degree of plasma treatment resulted in significantly higher equilibrium moisture contents and thickness swelling than the reference boards.
.H\ZRUGV &ROGSODVPD :KHDWVWUDZ 3DUWLFOHERDUG 6XUIDFHPRGLILFDWLRQ :DWHUXSWDNH &RQWDFWLQIRUPDWLRQ D )DFXOW\RI)RUHVWU\DQG:RRG6FLHQFHV&]HFK8QLYHUVLW\RI/LIH6FLHQFHV3UDJXH .DPêFNi3UDJXH±6XFKGRO&]HFK5HSXEOLF E ,QVWLWXWIU+RO]WHFKQRORJLH'UHVGHQ *HPHLQQW]LJH*PE+>,QVWLWXWHIRU:RRG7HFKQRORJ\'UHVGHQ@=HOOHVFKHU:HJ'UHVGHQ *HUPDQ\ &RUUHVSRQGLQJDXWKRU K\VHNV#IOGF]XF] INTRODUCTION Cellulose and lignin-based plant materials are often used in composite materials, where they can act as fillers and reinforcing materials. It is always important to ensure the thorough bonding of the plant particle and the polymer. It has been proposed that a basic prerequisite for solid particle-polymer bonding is the presence of reactive groups on the interface of both materials to provide high surface energy (Mwaikambo and Ansell 2002; Bekhta HWDO 2013). In composites hardened by plant materials, the opposite phenomenon is usually encountered, in which the solid bond between polar cellulose and nonpolar polymer is not easily formed. The wettability of a natural fibre or a particle by polymer is further worsened by the waxy substances that natural fibres often contain. In addition, the presence of water and free hydroxyl groups, in particular in amorphous portions, reduce the possibility of creating a strong bond between plant materials and most adhesives. Furthermore, a high water and moisture uptake causes dimensional changes in plant fibres, implying a reduction in the mechanical and physical properties of the composite material (Mwaikambo and Ansell 2002; Xie HWDO 2010; Gajdačová HWDO 2018).
5065
Hýsek et al . (2018). “Cold plasma & straw board,” B io R esources 13(3), 5065-5079.
Made with FlippingBook Ebook Creator