UV Weathering and Related Test Methods - Cabot Corporation

Artificial weathering chambers
a) QUV fluorescent light source
Weathering chambers have been developed to provide a QUV
weathering.
The QUV simulates the effect of sunlight with fluorescent ultraviolet
(UV) lamps, while rain and dew are simulated by the condensation of
humidity. As stated previously, the UV light only represents roughly 5%
of the sunlight but it is responsible for most of the polymer
degradation. Also, materials are often tested with equipment, which
simulate only the shortest wavelengths (UV).
The UV-B range includes the shortest wavelengths found in sunlight.
Therefore, for many applications, it is a fast and efficient method.
QUV equipment uses two main types of lamps: UVA-340 and UVB-
313.
As shown in Figures 1 and 2, while these lamps have different light
emission spectrum, they are both characterized by a maximum of
emission in the UV range.
UVA provides a reasonable match of the UV region of the solar
spectrum, but this match is no longer valid for the long wavelengths
(visible, IR).
UVB lamps also emit UV light, but the maximum of the emission
spectrum is shifted towards short wavelengths compared to the UVA
lamps. The UVB-313 lamp is a widely used type of fluorescent UV
lamp that provides fast test results. However, as shown in Figure 2,
the spectrum contains short wavelengths, which are not present in
the solar radiation.
Irradiance (W/2/nm)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
270
Figure 1: UVA-340 spectrum Figure 2: UVB-313 spectrum
UVA-340 versus Sunlight
UVA-340
290 310 330 350 370 390
Wavelength (nm)
Sunlight
By courtesy of QPanel
Irradiance (W/m2/nm)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
UVB Lamps versus Sunlight
UVB-313
QFS-40
270 290 310 330 350 370 390
Wavelength (Nm)
Sunlight
By courtesy of QPanel
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