Utilization of Partially Liquefied Bark for Production of Particleboards

Wen Jiang,Milan Šernek,Jure Žigon,Reza Hosseinpourpia,Stergios Adamopoulos,Sergej Medved,Marko Petrič

doi:10.3390/app10155253

Wen Jiang, Milan Šernek + Show 5 more

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https://doi.org/10.3390/app10155253

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Journal: Applied Sciences	Publication Date: Jul 30, 2020
Citations: 13	License type: CC BY 4.0

Affiliation: University of Ljubljana, Linnaeus University

Abstract

Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol and sulfuric acid. Four types of particleboard panels were prepared with a PLB content of 4.7%, 9.1%, 20%, and 33.3%, respectively. Another five types of particleboard panels were manufactured by using similar amounts of PLB and 10 wt.% of melamine–urea–formaldehyde (MUF) adhesives. Characterization of bark and solid residues of PLB was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and automated vapor sorption (AVS). Mechanical and physical properties of the particleboard were tested according to the European standards EN 310 for determining modulus of elasticity and bending strength, EN 317 for determining thickness swelling after immersion in water, and EN 319 for determining internal bond strength. The results showed that the increase in PLB content improved the mechanical strength for the non-MUF boards, and the MUF-bonded boards with up to 20% of PLB met the requirements for interior uses in dry conditions according to EN 312. The non-MUF boards containing 33.3% of PLB and the MUF-bonded boards showed comparable thickness swelling and water absorption levels compared to the reference board.

Highlights

Particleboard is a panel product made from wood particles, originating from low value wooden raw material or other lignocellulosic materials, bonded by synthetic adhesives and pressed at high pressures and temperatures [1,2]
The results showed that the resol type adhesives prepared from bark, liquefied with sulfuric acid, had a higher viscosity compared to those made from liquefied bark with hydrochloric acid
Raw bark showed a strong absorption peak at 3350 cm−1, which corresponds to -OH stretch vibration in cellulose, lignin, and hemicelluloses

Summary

Introduction

Particleboard is a panel product made from wood particles, originating from low value wooden raw material (e.g., chips and shavings) or other lignocellulosic materials, bonded by synthetic adhesives and pressed at high pressures and temperatures [1,2]. Adhesives are an important element in the wood-based panel industry. Particleboard is traditionally produced with wood adhesives such as urea–formaldehyde (UF), melamine–urea–formaldehyde (MUF), and isocyanate-based adhesives. It is estimated that the adhesives used for particleboard production in Europe are split among UF (92%), MUF (7%), and isocyanates (1%) [5]. All these existing commercial adhesives are petroleum-based, and not sustainable [6]. The concern about formaldehyde emissions from wood-based

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