Wet Extrusion of Wood Powder Using a Cellulose Derivative

Production of Pipe–shaped Material We call “Wood straw”

Abstract

Petroleum–based plastics are low in cost, light in weight, excellent in moldability, and used in large quantities, while environmental pollution by microplastics is considered serious. In this study, we aimed to replace them with natural materials and developed wet extrusion of wood powder using a cellulose derivative：hydroxypropyl methylcellulose （HPMC）. The influence of the water content, HPMC ratio and wood powder particle size on the extrusion fluidity at 30℃ was evaluated using a capillary rheometer. The ratio of wood powder and HPMC was changed from 8：2 to 5：5, and water was added at 70 to 233％ relative to the solid weight and kneaded. The material was non–Newtonian fluid exhibiting pseudoplastic flow with a yield value. Water, HPMC and smaller wood particle tended to improve the fluidity, and the water content particularly had a large effect. The kneaded materials were successfully extruded into pipe–shape with outer diameter of 6 mm, air–dried and named “Wood straw”. The larger ratio of HPMC gave smaller diameter and higher density of the material, resulting in higher strength. It is possible that the mixture of wood powder, HPMC and water with good extrudablity could be applied to other molding methods to produce all–wood–derived material with various shapes.