Wood-plastic Composite - Advantages and Disadvantages

Advantages and Disadvantages

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. They have good workability and can be shaped using conventional woodworking tools. WPCs 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. They can however be recycled easily in a new wood-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 WPCs 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 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. 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.

As time goes on, product defects have become well known. The industry leader (Trex Corporation) has been involved in numerous lawsuits with home owners and installers in regards to mildew, discoloration and increased weakness in the fiber of the materials. As of mid 2008, Trex has replaced over 37,000 decks in regards to the issues previously stated and had to change their 'maintenance-free' claims to 'low-maintenance' explaining that decking would require cleaning multiple times every year to remove mildew spots.