New particleboards based on agricultural byproducts: physicochemical properties with different binders

Abstract

Because the timber market is more and more competitive, the particleboard manufacturers are looked for new sources of vegetal raw material supply. In the same time, the use of healthier, safer and more environmentally friendly materials become a priority in the building sector. In this context, some agricultural byproducts as annual plant stems can be an interesting alternative. In fact these resources are abundant, renewable and safe raw material. Moreover their porous structure gives them interesting properties for building materials such as lightness and thermal insulation capacity. In order to diversify raw material supply sources of a particleboard manufacturer, two agricultural byproducts have been studied: flax shives and sunflower bark. The particleboards are made at a laboratory scale by thermocompression of vegetal raw particles at a target density of 500 kg.m-3. Two particle sizes have been compared in the panels for each agroresource: 0.5-2 mm and 2-5mm. The vegetal particles are bonded by different methods: - without addition of any binder. In that case water is sprayed on the vegetal particles before the forming process at 80% w/w. The lignocellulosic compounds contained in the agroresources can act as binders. - with a biosourced binder based on casein, incorporated at different rates with the vegetal particles. The observed mechanical behavior (by bending test and internal bond) for the particleboards can be very different in function of the agroresource, the particle size and the binder used. The different materials are also compared by their thermal properties and their behavior with water. By using a biobased binder the mechanical properties of the particleboards are very better. For all studied properties, panels made with flax shives present better properties than these made with sunflower bark so flax shives seem more suitable for particleboard manufacturing. Butwith optimization of the formulation and the process, both studied agroresources could be used in particleboards for applications as furniture or door panel and efficient 100% biobased panels can be obtained.