Surface characteristics and physical properties of wheat straw particleboard with UF resin

Abstract

Agricultural fibers, such as straw and plant stalks, have been considered as renewable alternatives for making particleboard, which would ease the huge demand for wood. The objective of this study was to investigate surface characteristic (surface roughness and wettability) and physical properties (thickness swelling and water absorption) of wheat straw (Triticum aestivum L.)/poplar wood particleboard with UF resin and silane coupling agent. The effects of the silane coupling agent content and straw/poplar wood particles ratio on the surface characteristic and physical properties were examined. The ratios of the mixture of straw and poplar wood particles were 100:0, 85:15, 70:30 and 55:45. Silane coupling agent content was chosen at three levels of 0, 5 and 10 %. The experimental panels were tested for their physical properties according to the procedure in DIN 68763 (Determination of values of surface roughness parameters Ra, Rz, R max using electrical contact(stylus) instruments, concepts and measuring conditions, Berlin, Deutsches institut für Norming, 1982) roughness measurements, average roughness (R_a), mean peak-to-valley height (R_z), root mean square roughness (R_q), were taken from the unsanded samples using a fine stylus tracing technique. Contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Results indicated that physical properties (thickness swelling and water absorption (were improved by the addition of silane coupling agent, but use of poplar wood particles has a negative effect on physical properties (thickness swelling and water absorption). Statistical analysis showed that boards consisting of a greater amount of poplar particles exhibited lower wettability. Furthermore, panels made with higher amount of silane level, showed lower Rq values.