Resistance of plastics to sunlight


Outdoor plastic items are exposed to partial or continuous solar radiation, which can lead to harmful effects on the integrity and durability of the materials that make up the plastic item.

An outdoor plastic item is also exposed to other environmental factors that can damage it such as acid rain or temperature fluctuations. One solution that is very often adopted is the use of UV-stabilizing additives in the article's compound. These allow preventing any aesthetic and structural damages that would take place after a few months with prolonged outdoor exposure.

Each plastic material has its own specific characteristics of resistance to these factors, but using UV protective additives can completely counteract the damaging effects that would fall on the performance of the articles. These additives fall into two categories:

UVA - Ultraviolet light absorbers, which are also called barrier effect additives
ALS - Sterically prevented amines.
The former act just like a barrier that repels UV rays directed toward the plastic article, while the latter prevent, in case the barrier would be breached, any damage to the polymer structure by acting as solar radiation inhibitors.

These two additives are largely used in combination in order to achieve both protection benefits. In Maspi, they are used for every plastic item produced, for example, in the furniture industry for outdoor plastic seating.

To check the amount of additive that needs to be included the article is tested in the VOM, a special machine that allows a plastic article to be irradiated in a short time to subject it to UV stress as if multiple years of outdoor exposure had passed. The VOM can be set to different durations depending on the desired result, it is important to understand where in the world and what climate the article will be part of and thus under what stress it will be subjected.

Finally, colors also have their influence on UV absorption, whiter colors will be less problematic, while fluorescent or bright colors will be less resistant.