Particle Board and Oriented Strand Board Prepared with Nanocellulose-Reinforced Adhesive

Wolfgang Gindl-Altmutter,Martin Weigl,Jörn Rathke,Stefan Veigel

doi:10.1155/2012/158503

Abstract

Adhesives on the basis of urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) are extensively used in the production of wood-based panels. In the present study, the attempt was made to improve the mechanical board properties by reinforcing these adhesives with cellulose nanofibers (CNFs). The latter were produced from dissolving grade beech pulp by a mechanical homogenization process. Adhesive mixtures with a CNF content of 0, 1, and 3 wt% based on solid resin were prepared by mixing an aqueous CNF suspension with UF and MUF adhesives. Laboratory-scale particle boards and oriented strand boards (OSBs) were produced, and the mechanical and fracture mechanical properties were investigated. Particle boards prepared with UF containing 1 wt% CNF showed a reduced thickness swelling and better internal bond and bending strength than boards produced with pure UF. The reinforcing effect of CNF was even more obvious for OSB where a significant improvement of strength properties of 16% was found. For both, particle board and OSB, mode I fracture energy and fracture toughness were the parameters with the greatest improvement indicating that the adhesive bonds were markedly toughened by the CNF addition.

Highlights

Almost 80 years after its invention, particle board still represents the by far most important group of wood-based panels in Europe
Particle board and oriented strand boards (OSBs), mode I fracture energy and fracture toughness were the parameters with the greatest improvement indicating that the adhesive bonds were markedly toughened by the cellulose nanofibers (CNFs) addition
Since fracture energy of UF bonds filled with 2 wt% of CNF was up to 45% higher compared to pure UF bonds, this study proved the feasibility of toughening UF by the addition of CNF

Summary

Introduction

Almost 80 years after its invention, particle board still represents the by far most important group of wood-based panels in Europe. In 2010, the share of particle board in the overall wood-based panel production was around 63% [1]. For use as a construction material, mechanical board properties are of vital importance. In this regard, the quality of connections between wood particles is a key factor, which in turn is determined by the amount and type of adhesive used. In wood-based panel production, aminoplastic adhesives on the basis of urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) are prevalent. These adhesives offer a number of advantages for industrial application; the mechanical performance of UF and MUF wood adhesive bonds is limited. Stress concentrations along the bond line of a wood adhesive joint are generated [2,3,4] that reduce the overall strength of the joint

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