chapter  13
38 Pages

- Wood/Nonwood Thermoplastic Composites

Composites made from wood, other biomass resources and polymers have existed for a long time but the nature of many of these composites has changed in recent decades. Wood-thermoset composites date to the early 1900s. “Thermosets” or thermosetting polymers are plastics that, once cured, cannot be remelted by heating. These include cured resins such as epoxies and phenolics, plastics used as wood adhesives with which the forest products industry is traditionally most familiar (see Chapter 9). For example, an early commercial composite marketed under the trade name Bakelite was composed of phenol-formaldehyde and wood ¯our. Its ‹rst commercial use was reportedly as a gearshift knob for Rolls Royce in 1916 (Gordon 1988). “Thermoplastics” are plastics that can be repeatedly melted, such as polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC). Thermoplastics are used to make many diverse commercial products such as milk jugs, grocery bags, and siding for homes. In contrast to the wood-thermoset composites, woodthermoplastic composites have seen large growth in recent decades. Wood-thermoplastic composites

13.1 Wood Thermoplastics ........................................................................................................... 474 13.1.1 Thermoplastic Matrix Materials ............................................................................... 475 13.1.2 Additives ................................................................................................................... 478 13.1.3 Processing ................................................................................................................. 479 13.1.4 Performance .............................................................................................................. 481 13.1.5 Mechanical Properties .............................................................................................. 481 13.1.6 Durability .................................................................................................................. 481 13.1.7 Markets and Future Trends ....................................................................................... 483

13.2 Nonwood Fibers in Thermoplastic Composites ....................................................................485 13.2.1 Agricultural Fibers ...................................................................................................485 13.2.2 Other Fibers ..............................................................................................................487