Determination of the effects of additives added to pu glue on dimensional stability in fiberboards

Abstract

Today, there is an increasing trend towards the use of forest products in the form of composites, since the use of forest products as a solid material cannot adequately meet the demand and increases the cost of use. For this reason, fiber boards (MDF), which is one of the basic raw materials of the forest products industry and manufactured from wood-based raw materials, were chosen as the test material. Additives with various properties (beech fiber, degraded beech fiber and active carbon) were added at different rates (2.5%, 5%, 7.5%) into the polyurethane (PU) glue. Then, the effects on the dimensional stability of the board during the joining and bonding processes were investigated by applying adhesive with filler on the surface of the medium density standard fiber boards. Shiitake (Lentinus edodes) fungi was used to degrade beech fibers. In the test samples prepared for this purpose, water absorption values and thickness swelling tests were performed at 2 h, 24 h, 48 h, 72 h, 96 h and 336 h (2 weeks). As a result of the statistical analyzes of the obtained data, it was determined that the addition of additives had a significant effect on the water absorption and thickness swelling values of the samples at the confidence level (p<0.05). At the same time, in the water absorption values according to the sample group averages, the best values were measured in the additive of active carbon, and the worst in the degraded beech fiber group. Likewise, in thickness swelling tests, the best results were obtained in additive of beech fiber and the worst in additives of degraded beech fiber and active carbon samples. In line with these results, it is suggested that it is more suitable in terms of dimensional stability to be used in the related areas, considering the minimum water absorption and minimum expansion times and additive sample groups in the joining and bonding-like processes of fiberboards.

Keywords

• lif levha
• kayın lifleri
• aktif karbon
• su alma
• kalınlık artımı
• fiberboard
• beech fibers
• activated carbon
• water absorption
• thickness swelling