Straw Board Surface Properties And The Density Gradient On The Performance Of Veneer Finishes

Median density straw board was a new composite, was potential, and there is much market prospect for this composite. Overlaid median density straw develops with the proceeding of straw board. Therefore, in the view of studying median density straw, the influence of substrate performance on overlaying and other mechanical performance of sample was discussed in this paper by means of studying density gradient and surfacial performance of board. In the studying surfacial performance of straw board, the author established feasible logical parameters in hot-pressing, surfacial free energy of material, the different adhesives'wettability to straw board, the change of board's wettability with different treating methods and the influence of board surfacial roughness on wettability were all analysed. These analysis and results could be functioned as reference for the manufacturing of median density straw's overlaying theoretically. In the influnece of density gradient on board performance when was overlain, the influece of hot-pressing parameters-temperature, pressure and time, on straw board performance were listed: one is the influence of straw board surfacial bonding strength on board surfacial density when was overlaid, another was the influence of inner density on inner bonding strength, the other was the influence of all-layers density on thickness swelling. The optimal process was analyzed and obtained in theoretically. The results could be listed in the following: The surfacial free energy of straw was lower than that of wheat, and the free energy changed as measured part was changed. The gluing method was optimized by means of measuring surfacial straw board contact angle. The treating method with anhydrous ethanol was reasonable, and the treating method made for the bonding of straw board and UF resin. In certain range, the surfacial roughness made wettablity better. There was higher surfacial bonding strength when higher density board was used, and the higher inner bonding strength could be made when higher core density board was used. In hot-pressing process, temperature, pressure and time were lower than that samples could endured, and the destroy degree of substrate could be the lowest. Hot-pressing pressure lied on the core density of straw board.