Regular Article

Physico-mechanical properties of plywood bonded with ecological adhesives from Acacia mollissima tannins and lignosulfonates^*

¹ LIMAT-Thermostructural Materials and Polymers Team, Faculty of Science Ben M’sik, University Hassan II of Casablanca,Boulevard Cdt Driss Harti, BP. 7955, Ben M’sik, Casablanca, Morocco
² CNRS/Univ. Pau & Pays Adour, Institut des Sciences Analytiques et de Physico-Chimie pour l’Environnement et lesMatériaux, UMR5254, BP 201, 40004 Mont-de-Marsan, France
³ ENFI, BP 511, Tabriquet, 11015 Salé, Morocco
⁴ Materials Science and Nanotechnology Department, University Mohammed VI Polytechnic, Lot 660 Hay Moulay Rachid, 43150 Ben Guerir, Morocco

^a e-mail: rhazinaima2@gmail.com
^b e-mail: fatima.charrier@univ-pau.fr

Received: 21 February 2017
Revised: 20 March 2017
Accepted: 21 March 2017
Published online: 14 June 2017

Abstract

The objective of this research was to develop ecological adhesives for bonding plywood panels using lignosulfonates, a common waste product of the wood pulp industry, and natural tannin extracted from Moroccan bark of Acacia mollissima using different process. Natural tannin and lignin were used in wood adhesives formulation to substitute resins based on phenol and formaldehyde. To achieve this, the lignosulfonates were glyoxalated to enhance their reactivity and the used tannins obtained by three different extraction methods were compared with commercial mimosa tannin. The proportion of Acacia mollissima tannins and lignosulfonates, the pressing time, the pressing temperature, and the pressure used were studied to improve mechanical properties, and bonding quality of plywood panel. The properties of plywood panels produced with these adhesives were tested in accordance with normative tests. Thus, the tensile strength, and the shear strength were measured. The results showed that the performance of the plywood panels made using biobased tannin adhesives was influenced by physical conditions such as pressure, press temperature as well as by chemical conditions, such as the tannin-lignin ratio. It exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. This study showed that biobased adhesives formulations presented good and higher mechanical performance and no formaldehyde emission.