Cork consolidated by hot compression as a viable bio-based alternative to polyolefines in decking boards: A preliminary study

Abstract

Currently, three classes of materials are used in deck boards production, i.e., wood, plastics and wood polymer composites. Wood is the best choice being bio-based, biodegradable and displaying better mechanical performance, but the environmental concerns deriving from forest depletion make the identification of a new bio-based solution necessary. In this sense, agglomerated cork is promising, being derived from the bark of the oak, but in its native form is not suitable for decking boards production due to low bending properties. The present work proposes a solution to use agglomerated cork in decking board manufacturing by converting its cellular structure in a consolidated one by hot compression. Design of Experiment was used to optimize consolidated cork mechanical properties as a function of the main manufacturing parameters, i.e., time and temperature. The exposure to high temperatures allows cork cell walls welding by developing adhesive properties, but it also induces a strong degradation of polysaccharides. It was discovered that the manufacturing parameters which maximize both flexural and tensile properties are a 180 °C operating temperature and a 31.5 min holding time. These conditions ensure a bending stiffness 40.9% and a bending strength 107.1% higher than the ASTM D6662 minimum requirements.