In
some manufacturing facilities, the constituents are combined and processed in a
pelletizing extruder, which produces pellets of the new material. The pellets
are then re-melted and formed into the final shape. Other manufacturers complete
the finished part in a single step of mixing and extrusion.WPCs do not corrode
and are highly resistant to rot, decay, and Marine Borer attack, though they do
absorb water into the wood fibers embedded within the material[2]. They have
good workability and can be shaped using conventional woodworking tools. wood plastic composite
decking are often considered a sustainable material because they can be made
using recycled plastics and the waste products of the wood industry. Although
these materials continue the lifespan of used and discarded materials, and have
their own considerable half life; the polymers and adhesives added make
wood-plastic composite difficult to recycle again after use[citation needed].
They can however be recycled easily in a new wood
and plastic composite, much like concrete. One advantage over wood is the
ability of the material to be molded to meet almost any desired shape. A WPC
member can be bent and fixed to form strong arching curves. Another major
selling point of these materials is their lack of need for paint. They are
manufactured in a variety of colors, but are widely available in grays and earth
tones.Despite up to 70 percent cellulose content (although 50/50 is more
common), the mechanical behavior of wood plastic composite decking is most
similar to neat polymers. This means that they have a lower strength and
stiffness than wood, and they experience time and temperature-dependent behavior
[3] The wood particles are susceptible to fungal attack, though not as much so
as solid wood, and the polymer component is vulnerable to UV degradation.[4] It
is possible that the strength and stiffness may be reduced by moisture
absorption and freeze-thaw cycling, though testing is still being conducted in
this area. Some WPC formulations are also sensitive to staining from a variety
of agents.The next generation of composite decking includes a durable plastic
cap [5] that adds added protection. A PVC cap surrounding the wood
plastic composite material helps reduce staining, fading and scratching that
may occur with 1st generation composite decking. Capped composites cost
considerably less than pure plastic decking as the core is still wood plastic
composite materials.
没有评论:
发表评论