Milestones In The Commercialization Of WPC's
In the USA, WPC's have been produce for several decades & even much earlier in Europe. However, major growth did not occur until fairly recently. Some of the major milestones are described in this section.
In 1983, American Woodstock, now part of Lear Corporation in Sheboygan, Wisconsin, began producing automotive interior substrates using Italian extrusion technology. Polypropylene extruded with approximately 50 % wood flour was extruded into a flat sheet that was then thermoformed into various shapes for automotive interior paneling. This was one of the first major applications of WPC technology in the US.
In the year 1991,Advanced Environmental Recycling Technologies (AERT, Junction Texas) and a division of Mobil Chemical Company that later became Trex (Winchester, Virginia) began producing solid WPC's consisting of 50% wood fiber in polyethylene. These composites were sold as deck boards, landscape timbers, picnic tables & industrial flooring. Similar composites were milled into window & door component profiles. Today, the decking market is the largest & fastest growing WPC market.
In 1993, Andersen Corporation (Bayport, Minnesota) began producing wood fiber – reinforced PVC subsills for French doors. Further development led to a wood – PVC composite window line. These products allowed Andersen to recycle wastes from both wood & plastics processing operations.
In the early 1990's Strandex Corporation (Madison, Wisconsin) patented technology for extruding high wood fiber content composites directly to final shape without the need for milling or further forming. Strandex continues to license its evolving technology.

The Current Status on Technology Of WPC's
Although the WPC industry is still only a fraction of a percent of the total wood products industry, it has made significant inroads in certain markets. According to estimates, the WPC market was 320,000 MT in 2001 and the volume is expected to more than double by 2005.

Thermoplastics Materials & Wood Filler
Because of the limited thermal stability of wood only thermoplastics that melt below 200 Deg C are commonly used in WPCs. Currently, most WPCs are made with PE, both virgin & recycled, for use in exterior building components. However, WPCs made with wood –PP are typically used in automotive & consumer products and very recently, these materials have been investigated for use in building profiles. Wood filled PVC composites typically used in window manufacture are now being used in decking as well. Polystyrene & ABS are also being used. The plastic is often selected based on its inherent properties, product need, availability, cost and the manufacturer's familiarity with the polymer.
The wood used in WPCs is most often in particulate form (wood flour) or very short fibers, rather than longer individual fibers. Products typically contain 50 % wood, although some composites contain very little wood
Others contain as high as 70 %. The relatively high bulk density & free flowing nature of wood flour compared with wood fibers or other longer natural fibers, as well as low cost, and availability, is attractive to WPC manufacturers and users. Common species used include pine, maple, & oak. Typical particle sizes are 10 to 80 mesh.

Since the early 1990's, the wood – plastic composite industry has grown significantly. Today, wood & other natural fibers account for 7% of the total 2.5 billion kgs filler & reinforcement used. This represents a 135 % increase in natural fiber demand since 1990 with most of the growth in the past five years. The price of wood is dependant on the location. Low cost wood in the USA can be attributed to the considerable amount of wood residues (60 Million metric tones) generated just from the primary timber processors. The growth of wood flour & fiber use in thermoplastics has outpaced that of other natural fibers. Natural fibers are roughly twice as expensive as wood fiber, but are still well below most other reinforcements such as glass fibers.

The use of natural fibers such as flax, hemp, sisal etc; is also increasing particularly in the automotive sector, both in Europe & USA. Despite lower strength compared to glass fiber, natural fibers are attractive due to their lower density. Recent growth in natural fiber- reinforced thermoplastics has led to large-scale reports of large glass fiber manufacturer's considering partnerships with natural fiber producers. However, natural fiber availability is regional. Transportation costs & storage issues are limiting their growth.