Our Plastic & UV
Plastic products usually have UV inhibitors added to the plastics prior to the manufacturing of the end product. The UV inhibitor and the quantity used is closely related to the end use of the product to be manufactured. For example, a milk jug, or a bread bag is not required to last more than maybe a couple days or weeks at best, where as a Hdpe pipe, jug, pail, drum, or tank is engineered to last a significant amount of time in direct sunlight.
All materials absorb sunlight radiation – it’s what makes them heat up in the sunshine. While the effect of sunlight is minimal beyond just simple heating in many materials, some other materials are actually degraded by sunlight. Most plastics are in this latter group. Studies of the degradation of plastics by sunlight have shown that sunlight is a spectrum of frequencies and that the most destructive frequencies for plastics are those at the higher energy end of sunlight – in the ultraviolet range of the spectrum. The absorbed UV light breaks, or cleaves, the weak chemical bonds or molecular chains of the polymer material. This leads to shorter chains, which in turn causes the plastic material to become more brittle. This process is called, photo degradation, and it leads to loss of mechanical properties and/or discoloration, cracking, fading, and chalking. In other words photo degradation leads to weathering of plastics.
In order to protect outdoor plastic products from the damaging UV light, the plastic needs to be shielded from these harmful rays. Of course shielding from sunlight using some umbrella-like shading system is often impractical and could be very expensive. Therefore, a simple, inexpensive method is desirable and that system has been found with internal stabilizers. These stabilizers, an example of which is carbon black, are added to the plastic before molding. The stabilizers absorb or screen out the damaging UV light and transform the energy of the rays, the UV light, into heat, which is dissipated harmlessly throughout the product.
Although we don't add any additional UV inhibitors, Most of the plastics that we use are engineered with UV inhibitors. Our product may experience some fading and chalking due to the effects of UV, but we do not expect that it will have more than a slight cosmetic effect, due to the size of our products.
Expansion & Contraction
Our plastic lumber is less rigid than wood, and as such may require more support, and/or structural grade material, depending on the project. Plastic lumber has a higher rate of expansion and contraction , therefore it is often recommended to pre-drill holes to allow for some movement.
Our plastic lumber is 100% recycled plastic and therefore not structural. Structural plastic lumber often includes fiberglass or other materials in order to achieve additional flexural strength and reduce expansion and contraction caused by temperature variations.