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Abstract
The term “wood flour” is somewhat ambiguous. Reineke states that the term wood flour “is applied somewhat loosely to wood reduced to finely divided particles approximating those of cereal flours in size, appearance, and texture.” Though its definition is imprecise, the term wood flour is in common use. Practically speaking, wood flour usually refers to wood particles that are small enough to pass through a screen with 850 ìm openings (20 US standard mesh). Wood flour has been produced commercially since 1906 and has been used in many and varied products including soil amendments, extenders for glues, and absorbents for explosives. One of its earliest uses in plastics was in a phenol-formaldehyde and wood flour composite called Bakelite. Its first commercial product was reportedly a gearshift knob for Rolls Royce in 1916. Though once quite prevalent as filler for thermosets, its use has diminished over the years. In contrast to its use in thermosets, large-scale use of wood flour in thermoplastics has only occurred within the last few decades. Recent growth has been great; composites made from plastics and wood or other natural fibers have grown from less than 50 000 tons in 1995 to nearly 900 000 tons in 2007. Most of this is due to the rapid growth of wood-plastic composites in exterior building products, especially decking and railing. Due to its low thermal stability, wood flour is usually used as filler only in plastics that are processed at temperatures lower than about 200°C. The majority of wood-plastic composites use polyethylene as the matrix. This is, in part, due to that fact that much of the early wood-plastic composites were developed as an outlet for recycled film. Polypropylene is more commonly used in automotive applications, and polyethylene is more commonly used in exterior building applications.
Keywords
Wood-plastic composites,
polyethylene,
wood flour,
extrusion process,
injection molding of plastics,
thermoplastic composites,
mechanical properties,
fiber-reinforced plastics,
cellulose fibers,
composite materials,
polypropylene,
fillers,
fibrous composites,
polyvinyl chloride,
wood anatomy,
wood chemistry,
density,
moisture,
thermal properties,
elasticity,
flexure,
modulus of elasticity,
wood utilization,
wood-plastic materials,
polymers,
polymerization,
durability,
tensile strength
Citation
Clemons, Craig M. 2010. Wood flour. In: Functional fillers for plastics. Chapter 15. 2nd, updated and enl. ed. Weinheim, [Germany] : Wiley-VCH, c2010: p. 269-290: ISBN: 9783527323616 (hbk.): 3527323619 (hbk.).
