Weatherability
The appearance and mechanical properties of Bayblend ET1000 blends are adversely affected by outdoor exposure. The most detrimental factor in weathering is the exposure of the polymer blend to the ultraviolet (UV) radiation of sunlight. UV radiation promotes chemical reactions between the polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) components of the alloy resin, which may lead to a color shift, loss of gloss and loss of mechanical properties.
For outdoor applications, Bayer recommends protecting the part made with Bayblend ET1000 resin from the influences of UV light and rain by one of the following methods:
- coextruding a cap layer of a weatherable polymer onto the surface of the part (Bayer does not offer such a polymer at this time)
- laminating a weatherable film onto the surface of the part
- applying a weatherable paint to the part surface
It is important to note that protective layers of some polymers may lead to good weathering results, but they also may have detrimental effects on other factors, such as the ability to use regrind material.
Artificial weather testing provides some measure of assurance of performance. Bayer has exposed plaques of different materials to artificial weathering conditions according to the SAE J2527, cycle 1, standard. The results are shown in the following diagrams (click for larger images):
As is the case with any correlation of artificial weathering to actual outdoor weathering, results are dependent on variables, such as UV exposure of the parts, time, temperature, rain/water exposure, etc. and should serve only as a guideline. It is imperative that production parts be evaluated under actual application use conditions.
