Milestones In The Commercialization
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
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
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
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
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.