Effects of plasma treatment and sanding process on surface roughness of wood veneers
An ideal veneer surface is crucial for good panel properties in plywood manufacturing. The aim of this study was to compare plasma treatments and sanding (mechanical) processes with respect to the surface roughness of veneers. Rotary-cut veneers with a thickness of 2 mm from Scots pine (Pinus sylvestris) logs were used as material. After rotary peeling, veneer sheets were dried at 110 °C in a veneer dryer. Veneer sheets were divided into 4 main groups. The surfaces of the control veneer sheets were left untreated. Two different grits of sandpaper, 80 and 180, were used for sanding the surfaces of veneers. Plasma treatment was applied to the last veneer group with 3 different gases (oxygen, nitrogen, and ammonia) and 3 different plasma times (1 min, 5 min, and 15 min). The Mitutoyo Surftest SJ-301 instrument was used to determine surface roughness of samples. Average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) parameters were measured to evaluate the surface roughness of the samples based on DIN 4768. It was found that the smoothest veneer surfaces were obtained with the sanding processes. Surface roughness values (Rz) of veneer sheets sanded with 180 grit sandpaper were lower than those of veneers sanded with 80 grit sandpaper. Compared with the plasma treatment in terms of surface roughness, plasma-treated veneers had higher Rz values. It was also determined that Rz values were the lowest in the veneers treated with nitrogen plasma. Additionally, the surface roughness values of Scots pine veneers treated with ammonia plasma were a little higher than those of veneer sheets treated with oxygen plasma. The effect of plasma treatment time on surface roughness was not found to be statistically significant.
Effects of plasma treatment and sanding process on surface roughness of wood veneers
An ideal veneer surface is crucial for good panel properties in plywood manufacturing. The aim of this study was to compare plasma treatments and sanding (mechanical) processes with respect to the surface roughness of veneers. Rotary-cut veneers with a thickness of 2 mm from Scots pine (Pinus sylvestris) logs were used as material. After rotary peeling, veneer sheets were dried at 110 °C in a veneer dryer. Veneer sheets were divided into 4 main groups. The surfaces of the control veneer sheets were left untreated. Two different grits of sandpaper, 80 and 180, were used for sanding the surfaces of veneers. Plasma treatment was applied to the last veneer group with 3 different gases (oxygen, nitrogen, and ammonia) and 3 different plasma times (1 min, 5 min, and 15 min). The Mitutoyo Surftest SJ-301 instrument was used to determine surface roughness of samples. Average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) parameters were measured to evaluate the surface roughness of the samples based on DIN 4768. It was found that the smoothest veneer surfaces were obtained with the sanding processes. Surface roughness values (Rz) of veneer sheets sanded with 180 grit sandpaper were lower than those of veneers sanded with 80 grit sandpaper. Compared with the plasma treatment in terms of surface roughness, plasma-treated veneers had higher Rz values. It was also determined that Rz values were the lowest in the veneers treated with nitrogen plasma. Additionally, the surface roughness values of Scots pine veneers treated with ammonia plasma were a little higher than those of veneer sheets treated with oxygen plasma. The effect of plasma treatment time on surface roughness was not found to be statistically significant.
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- Acda MN, Devera EE, Cabangon RJ, Ramos HJ (2012). Effects of plasma modification on adhesion properties of wood. Int J Adhes Adhes 32: 70–75.
- Aydin İ (2004). Activation of wood surfaces for glue bonds by mechanical pre-treatment and its effects on some properties of veneer surfaces and plywood panels. Appl Surf Sci 233: 268–274.
- Aydin I, Demirkir C (2010). Activation of spruce wood surfaces by plasma treatment after long terms of natural surface inactivation. Plasma Chem Plasma P 30: 697–706.
- Bekhta P, Hiziroglu S, Shepelyuk O (2009). Properties of plywood manufactured from compressed veneer as building material. Mater Design 30: 947–953.
- Berman D, Krim J (2012). Impact of oxygen and argon plasma exposure on the roughness of gold film surfaces. Thin Solid Films 520: 6201–6206.
- Custodio J, Broughton J, Cruz H, Hutchinson A (2008). A review of adhesion promotion techniques for solid timber substrates. J Adhesion 84: 502–529.
- Davis EM (1962). Machining and Related Characteristics of United States Hardwoods. Washington, DC, USA: USDA.
- Deutsches Institut für Normung (1990). DIN 4768. Determination of Values of Surface Roughness Parameters Ra, Rz, Rmax Using Electrical Contact (Stylus) Instruments, Concepts and Measuring Conditions. Berlin, Germany: Deutsches Institut für Normung.
- Dilsiz N (1994). Plasma modified carbon fiber-epoxy composite system. PhD, Middle East Technical University, Ankara, Turkey.
- Dundar T, Akbulut T, Korkut S (2008). The effects of some manufacturing factors on surface roughness of sliced Makoré (Tieghemella heckelii Pierre Ex A.Chev.) and rotary-cut beech (Fagus orientalis L.) veneers. Build Environ 43: 469–474.
- Gurau L, Mansfield-Williams H, Irle M (2007). Separation of processing roughness from anatomical irregularities and fuzziness to evaluate the effect of grit size on sanded European oak. Forest Prod J 57: 110–115.
- Hendarto B, Shayan E, Ozarska B, Carr R (2006). Analysis of roughness of a sanded wood surface. Int J Adv Manuf Tech 28: 775–780.
- Liu Y, Tao Y, Lv X, Zhang Y, Di M (2010). Study on the surface properties of wood/polyethylene composites treated under plasma. Appl Surf Sci 257: 1112–1118.
- Mahlberg R, Niemi HE, Denes FS, Rowell RM (1999). Application of AFM on the adhesion studies of oxygen-plasma-treated polypropylene and lignocellulosics. Langmuir 15: 2985–2992.
- Mitchell P, Lemaster R (2002). Investigation of machine parameters on the surface quality in routing soft maple. Forest Prod J 52: 85–90.
- Podgorski L, Chevet B, Onic L, Merlin A (2000). Modification of wood wettability by plasma and corona treatments. Int J Adhes Adhes 20: 103–111.
- Pykönen M, Silvaani H, Preston J, Fardim P, Toivakka M (2009). Effects of atmospheric plasma activation on surface properties of pigment-coated and surface-sized papers. Colloid Surface A 352: 103–112.
- Pykönen M, Sundqvist H, Jarnstrom J, Kaukoniemi OV, Tuominen M, Lahti J, Peltonen J, Fardim P, Toivakka M (2008). Effects of atmospheric plasma activation on surface properties of pigment-coated and surface-sized papers. Appl Surf Sci 255: 3217–3229.
- Seredych M, Hulicova-Jurcakova D, Lu GQ, Bandosz TJ (2008). Surface functional groups of carbons and the effects of their chemical character, density and accessibility to ions on electrochemical performance. Carbon 46: 1475–1488.
- Sofuoğlu SD, Kurtoğlu A (2014). Some machining properties of 4 wood species grown in Turkey. Turk J Agric For 38: 420–427.
- Tan PL, Sharif S, Sudin I (2012). Roughness models for sanded wood surfaces. Wood Sci Technol 46: 129–142.
- Vander Wielen LC, Östenson M, Gatenholm P, Ragauskas AJ (2006). Surface modification of cellulosic fibers using dielectric-barrier discharge. Carbohyd Polym 65: 179–184.
- Wengert EM, Lamb FM (1994). A Handbook for Improving Quality and Efficiency in Rough Mill Operations. Princeton, WV, USA: RC Byrd Hardwood Technology Center.
- Wolkenhauer A, Avramidis G, Cai Y, Militz H, Viöl W (2007). Investigation of wood and timber surface modification by dielectric barrier discharge at atmospheric pressure. Plasma Process Polym 4: S470–S474.
- Wolkenhauer A, Avramidis G, Hauswald E, Militz H, Viöl W (2009). Sanding vs. plasma treatment of aged wood: a comparison with respect to surface energy. Int J Adhes Adhes 29: 18–22.
- Yaman N, Özdoğan E, Seventekin N (2009). A study on changing properties of poliamid fabrics by using atmospheric plasma treatments. Electronic Journal of Textile Technologies 3: 1–10 (in Turkish with English abstract).