WOOD RESEARCH Volume 64, Number 2, 2019
Reza Hosseinpourpia, Stergios Adamopoulos, Carsten Mai, and Hamid Reza Taghiyari

Properties of medium-density fibreboards bonded with dextrin-based wood adhesive

This study focuses on manufacturing of medium density fibreboard (MDF) panels bonded with dextrin-based wood adhesive and crosslinked in situ with various weight ratios of synthetic (e.g., polymeric-methane diphenyl-diisocyanate, pMDI) or bio-based (e.g., glyoxal) crosslinkers. The physical and mechanical properties of the panels were evaluated and compared with those from panels without crosslinker (control). Modulus of rupture (MOR) and internal bond (IB) strength of the MDF panels were considerably increased by increasing the crosslinkers’ content. While, slight improvements were observed in modulus of elasticity (MOE) of the panels as a function of crosslinker type and content. Addition of crosslinkers clearly reduced the thickness swelling (TS) and water absorption (WA) of the panels, whereas, the panels with pMDI showed superior performances than the control and glyoxal added ones within 4 h and 24 h immersion in water. The results indicate the potential of dextrin as wood panel adhesive along with the use of appropriate crosslinkers.

WOOD RESEARCH Volume 64, Number 2, 2019
Zhou Qiaofang, Chen Chuanfu, Zhao Xiangyu, Tu Dengyun, and Li Kaifu

The effect of thermal modification by hot pressing on the some physical and mechanical properties in rubberwood (Hevea brasiliensis)

Rubberwood (Hevea brasiliensis) was thermal modified by hot pressing in an open system at three different temperatures (170, 185, 200°C) and two different durations (1.5, 3 h), and the effect on the physical and mechanical properties was studied. Results show that the thermal modification increased the oven-dried density and decreased the EMC (equilibrium moisture content) by 7.93% and 37.15%, respectively, and the dimensions stability was improved. Hardness, bending strength, modulus of bending and compressive strength parallel to grain of modified samples basically decreased with increasing temperature and time, but they showed a meaningful increase compared to control samples. However, impacting bending and nail withdrawal resistance decreased after hot pressing and thermal treatment, and the failure of the compensation for the impairment was the rubberwood hot pressed and thermal treated in the presence of air, and the participation of oxygen provoked rapid degradation reactions during the treatment.

WOOD RESEARCH Volume 64, Number 1, 2019
Xiangyu Zhao, Dengyun Tu, Chuanfu Chen, and Qiangfang Zhou

Prediction of the mechanical properties of thermally-modified rubber wood on the basic of its surface characteristic

The goal of this research was to investigate the effect of thermal treatment on mechanical properties and surface characteristic of rubberwood (Hevea brasiliensis) and find the mathematical model to predict the mechanical properties used by its surface characteristic. Rubberwood specimens were treated by steaming at five different temperature levels of 170, 185, 200, 215, and 230°C for two different durations of 1.5 and 3 h. Based on the results, the values of bending strength, modulus of elasticity, compression strength and impact bending decreased, and the glossiness and chromatic aberration (∆E) increased with increasing temperature and enlarging duration further. This study revealed that chromaticity parameters b*, ∆E and the gloss of perpendicular to grain (GZT) could evaluate the mechanical properties of thermally-modified wood to achieve the mechanical properties detection without destruction.

WOOD RESEARCH Volume 66, Number 1, 2021
Dongna Li, JIANING LI, and Xiaojun Ma

Study on the structure and properties of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/ rubber wood fiber composites modified with titanate coupling agent

In this study, the biodegradable composites were prepared from rubber wood fibers (Hevea brasiliensis) and biopolymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) via hot pressing process, using the titanate as the coupling agent. The morphological, chemical structure, mechanical properties and water absorption (WA) of the composites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mechanical properties and WA analysis. Results showed that a new absorption peak of Ti-O-C was formed due to the addition of titanate, indicating that it was successfully grafted on the surface of wood fibers. In addition, the mechanical properties of the composites first increased and then decreased with the increasing of the titanate content. The obvious improvement of WA of composites was attributed to the inclusion of P34HB by titanate modified wood fiber. Moreover, it was also found that the optimal condition of the titanate coupling agent content was 1 wt%.