Xenon arcs, polymer weathering

Fig. 5. Effect of uv exposure on nylon-6,6 yam tenacity and whiteness with and without copper salt and alkah haUde in polymer scoured 210-denier 34-filament yams exposed in Xenon-arc Ci65 Weather-Ometer using radiation intensity of 0.55 W/m at a wavelength of 340 nm. Exposure from 0 to 800...

Accelerated weathering test was carried out by the exposure of the films to a Sunshine weather meter with Xenon arc type accelerated weathering machine. HS-polymer s fihn does not chalk nor yellow. However under the conditions employed, polyimide (PI) is led to chalking and polyethylenenaphtalate (PEN), polycarbonate (PC) and polyethylenetelephtalate (PET) are led to yellowing (Table 1). 

The Ecolyte LDPE films are numbered in relation to the concentration of photosensitive vinyl ketone comonomer present in the polymer ie. 1>>2>3. The Ecolyte 1 LDPE containing the most vinyl ketone comonomer was brittle in 820 hr in the Weather-Ometer and 2.5 months outdoors. The Ecolyte 2 was brittle in Il80 hr and the Ecolyte 3 required ll+65 hr while the EcoPlastics Ltd. LDPE control required 2075 hr xenon arc irradiation to reach embrittlement. This series of Ecolytes demonstrates the varied and controlled lifetimes that can be designed into Degradable Plastics by controlling concentration of the photosensitizer. 

TABLE 16.2 Acceleration factors for some polymers, exposed in Atlas CiSOOO Xenon-arc weatherometer according to ASTM G26 (102 min UV 18 min UV + water spray 340 nm, 0.35 W/m, black panel temperature of 63°C) and on a weathering rack in Milwaukee, WI, oriented to face south at an inclination of 45°... 

In the studies presented here, HDPE from several post consumer sources (bottle crate and blow molded container) were tested for re-usability by weathering (Horida exposure and in a Xenon arc weatherometer) and reprocessing (extrusion studies) and by direct analysis of the polymer for oxidative by-products and residual additive levels after extrusion. 

Brennan, P Fedor, G., and Pausch, G.. Static and Rotating Xenon Arc Exposures Compared, 1 European weathering Symposium, Proceedings of the XXIII Colloquium of Danubian Countries on natural and Artificial Aging of Polymers, Prague, Sept. 2003. 

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