Magalhães Roberto, Nogueira Beatriz, Costa Samaritana, Paiva Nádia, Ferra João M, Magalhães Fernão D, Martins Jorge, Carvalho Luisa H
EuroResinas-Indústrias Químicas, 7520-195 Sines, Portugal.
LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal.
Polymers (Basel). 2020 Dec 30;13(1):114. doi: 10.3390/polym13010114.
Wood-based products usually have serious limitations concerning contact with water, both because wood is a hygroscopic material and because the commonly used binder has low moisture resistance. This paper studies the effect of panel moisture content (MC) on the physico-mechanical properties of medium density fiberboards (MDF). Several commercial MDF boards produced in Europe were stored at room temperature and relative humidity (RH) for 9 weeks (approx. range 15-20 °C and 50-85% RH). Every week, a strip of each MDF board was cut out, divided into 5 × 5 cm test pieces and its internal bond strength (IB) was measured. A strong influence of MDF moisture content on internal bond strength was observed and therefore IB test pieces were stored in a climatic chamber (either at 20 °C, 55% RH and at 20 °C, 70% RH). A decreasing linear relation was established between IB and MC. It was found that this effect is reversible: after drying, internal bond strength rises again (following a slight hysteresis). This work reinforces the importance of conditioned storage before board properties analysis, as described in European Standard EN 319.
木质产品在与水接触方面通常存在严重限制，这既是因为木材是一种吸湿材料，也是因为常用的粘合剂耐湿性较低。本文研究了板材含水率（MC）对中密度纤维板（MDF）物理力学性能的影响。几种欧洲生产的商用中密度纤维板在室温及相对湿度（RH）条件下储存9周（温度约为15 - 20°C，相对湿度为50 - 85%）。每周从每个中密度纤维板上切下一条，分成5×5厘米的试件，并测量其内部结合强度（IB）。观察到中密度纤维板含水率对内部结合强度有很大影响，因此将IB试件储存在气候箱中（温度为20°C、相对湿度为55%以及温度为20°C、相对湿度为70%）。在IB和MC之间建立了线性递减关系。发现这种影响是可逆的：干燥后，内部结合强度再次上升（略有滞后）。如欧洲标准EN 319所述，这项工作强化了在分析板材性能之前进行调湿储存的重要性。
