Development of sustainable particle boards made from agricultural and forestry by-products
This research explores the utilisation of waste from the agricultural and local forestry industry; aiming to decrease the consumption of monocrops (pine wood) traditionally used in the production of panel board for the built environment. The replacement of oil based matrixes, loaded with carcinogen formaldehydes, for a recycled, non toxic or renewable one is evaluated. These panels also aim to solve one of the biggest problems for panel materials, the dimensional stability and swelling issues as the result of high moisture environments.
The generation of waste from human production activities is a not insignificant burden on the environment. For example, most agricultural and forestry industry activities result in large amounts of by-products that are often treated as waste and sent to landfill. Australia is the main commercial world producer of macadamia nuts, producing around 40,000 tons of macadamia nuts a year, out of a total global production of 100,000 tones. Australia has 122,400,000 planted hectares of radiata pine trees (www.fao.org). The silviculture company, Energy Seeds, produces 100 to 150 cubic meters of empty cones per year after seed extraction (Andy Cameron, Manager Pine Seed Production, SeedEnergy Pty Ltd, personal communication, October 19, 2009). Australia is also the main eucalyptus producer in the world, with 127,024,000 hectares planted. The shells, cones and capsules comprise 70% by weight and more of the macadamia nuts, and tree seeds. After the seeds and nuts are extracted, the shells, cones and capsules are used mainly as mulch and fuel, due to their high lignin and cellulose content. While this avoids being disposed in landfill, which is economically and practically prohibitive due to the sheer volume, it is nonetheless poor utilization of a potentially valuable resource (Wechsler et al., 2011).
Results of an exploration into macadamia shells, pine cones, and eucalyptus capsules; used as fillers; bonded with recycled polypropylene and castor oil based adhesive; to be used in composites panel materials is presented. The present study considers and explores the suitability of these materials for high-moisture environment furniture panel applications.
Relevant morphological, physical, mechanical properties and formaldehyde emissions are examined and a comparison with conventional panels based in radiata pine wood and two different matrixes; formaldehyde based adhesive and recycled polypropylene are provided.
The key findings in the present study are summarized as the main physical properties; the water absorption and swelling were up to 70-78% lower in the new proposed panels than in traditional pine wood panels. The mechanical properties presented a lower Modulus of Elasticity and an improved Internal Bonding when compared with their reference sample. And as expected, the formaldehyde emissions were dramatically being 99% lower in the panels with castor oil adhesive as a binder.
The new fibers considered in this paper, macadamia shells, pine cones, and eucalyptus capsules; have shown that they have acceptable properties for use as fillers and a new opportunity for composite panel application for the built environment, particularly in high moisture environments. As they are composites, their mechanical properties can be improved and analysed by further research. Their physical properties showed that the newly proposed fillers are applicable in panel furniture for high humidity areas.
This research was published in the journal Materials & Design, Macadamia (Macadamia integrifolia) shell and castor (Rícinos communis) oil based sustainable particleboard: A comparison of its properties with conventional wood based particleboard
Figure 1. Agricultural and forestry by-product panels
Figure 2. SEM of macadamia shells and castor oil adhesive panel
Figure 3. Comparative chart of formaldehyde emissions of agricultural and forestry by products panels compared with wood and traditional particleboards
Figure 4 Schematic diagram of production process of the panels