Plastic lumber is a great alternative building material to traditional wood, metal and concrete for boardwalk and walkway applications. Why? Because plastic lumber is a durable, sustainable and a long-term solution. This environmentally-friendly product will hold up in wet environments, won’t break, splinter or rot and doesn’t need to be painted or stained.
While the benefits far outweigh the downsides of using this product, static electricity can be generated by a boardwalk or similar structure built using polyethylene lumber. We have all experienced static electricity: rubbing your hand over a balloon, walking on and off carpet; and while this is typically harmless, it can be a bit startling if you’re not expecting it.
Polyethylene lumber is a very common building material. You may be familiar with different types of this lumber, such as LDPE (Low-Density Polyethylene), HDPE (High-Density Polyethylene), and other composite plastic lumber that can be found at your local home improvement store.
To help you better understand this issue and offer some solutions, the engineering team at Bedford Technology addressed this issue, and here are their findings:
Polyethylene Lumber & Electrostatic Shock
At Bedford Technology, our five product lines are manufactured out of HDPE (high-density polyethylene). HDPE is sourced from household plastics like milk jugs and laundry detergent bottles, and is a strong and durable plastic. As a member of the polyethylene family, the electrostatic static issue relates to Bedford Technology products. So, let’s dig in a bit deeper.
Polyethylene is a static-generating material. It should be noted that this is a common issue with all such material, regardless of the manufacturer. Here’s how it works: plastic is a dielectric, or an insulating material. Soles of a typical pair of shoes are also dielectric. When two insulating materials rub together, a triboelectric, or static, charge is produced. So, when a person walks on a boardwalk made of plastic lumber, their shoes generate an electric charge which is held on the surface of the body until it is discharged. The release occurs when it comes in contact with a conductive object, such as a metal handrail, which results in a small shock, and usually a quiet “snap” noise.
One contributing factor to this “shocking” sensation is the environment in which the material is exposed. Areas that are dry generate more static voltage than high-humidity areas. No matter the environment, we have all experienced this sensation. And, while it can be a bit startling and unexpected, it is usually harmless.
But, is it Dangerous?
The short answer is no. When walking on a plastic lumber boardwalk, the electric charge that is produced is small and not strong enough to cause injury. Since static is primarily a ‘surface’ effect, the chance of damaging implanted medical devices, such as pacemakers, is small. There is little risk with plastic lumber because the amount of energy that can be stored is simply not enough to evoke injury.
How Do You Fix It?
While this phenomenon isn’t any real threat or danger, it is still worth addressing. Here are a few solutions that can be implemented to reduce the static electricity exposure.
Add Other Materials or Various Chemicals – Other materials like carbon (graphite) or waxes can be added to the plastic matrix to reduce the static effect. One limitation with adding materials like carbon is color options. Because carbon itself is black, the finished product, other than black, will show a darker tinge or tone because of the carbon. Also, adding materials can change the mechanical properties of plastic lumber, which may not always be acceptable. More permanent sophisticated chemistries can be added, but these solutions can be extremely expensive.
Note: This can only be applied to new lumber. If the lumber is already installed, other materials cannot be added.
Spray or Hose Down the Area – Adding moisture to the surface of the material will greatly reduce (and could even eliminate) the charge. Spraying or hosing down the area consistently can help solve this issue.
Insulate Any Exposed and Grounded Metal Surfaces – By insulating exposed metal surfaces, like metal framing, you are removing the conductive path through which the discharge is occurring.
Note: This can only reduce static-generating electricity if exposed metal is present.
Add A Topical Coating – A topical anti-static coating can be applied to non-porous surfaces to make them non-static generating. This solution, however, isn’t designed for full environmental exposure, and isn’t permanent. The frequency with which the coating needs to be reapplied depends on the environment the boardwalk or walkway is exposed.
Bedford Technology Recommendation
Use Plastic Lumber that Contains Glass Fiber – This solution faces the challenge head on, and is implemented during the manufacturing process. Due to inherent properties of glass fiber and the distribution within the plastic board, the static-generating ability is greatly reduced. FiberForce® by Bedford Technology utilizes glass fiber strand for added strength and stiffness, but also dramatically reduces the static generation.
While the other solutions can reduce and even eliminate the static-generating elements of the materials, not all of these solutions are practical. Due to either high cost or continuous maintenance, the engineers at Bedford Technology recommend using a polyethylene composite lumber with added fiberglass as a long-term solution. Instead of fixing the problem after it has already occurred, choose a strong and durable material that will avoid the problem before it starts.
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