LU-8031 - High Irradiance UV Testers - Q-Lab

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Figure 12 Urethane Gloss Loss Gloss delta b 100 90 80 70 60 50 40 30 20 10 Material: Urethane Coating (gray) Test Conditions: QUV/se Lamp: UVA-340 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C 1.3 0 0 500 1000 1500 2000 2500 Figure 13 Yellowing 50 40 30 Hours QUV/se Exposure Material: ABS Sheet (white) 0.83 0.83 20 Test Conditions: QUV/se Lamp: UVA-340 10 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Figure 14 Hours QUV/se Exposure Polystyrene Yellowing 1.3 Figure 16 Polypropylene Yellowing delta b 12 10 8 6 4 Test Conditions: QUV/se Lamp: UVA-340 2 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Figure 17 Material: Polypropylene Sheet 1.3 Hours QUV/se Exposure Automotive Paint Gloss Loss Gloss 100 80 60 40 0.83 Test Conditions: QUV/se Lamp: UVA-340 20 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Hours QUV/se Exposure 0.83 Material: Automotive Coating (blue/gray) 1.3 0 Material: Polyesthylene Sheet Effect of Moisture delta b delta b -1 -2 Test Conditions: -3 QUV/se Lamp: UVA-340 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C -4 0 500 1000 1500 2000 2500 Figure 15 Nylon Yellowing 5 4 3 Material: Nylon Sheet Hours QUV/se Exposure 1.3 0.83 2 Test Conditions: QUV/se Lamp: UVA-340 1 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Hours QUV/se Exposure 1.3 0.83 For materials which are sensitive to moisture, there may be a further acceleration when moisture is added to the UV cycle. Furthermore, some materials may respond in a completely different fashion in the presence of moisture. To test this, materials were exposed under 4 different conditions: • 100% UV Cycle (at 50 o C) • UV + Moisture Cycle (4 hours UV at 50 o C, alternating with 4 hours condensation at 50 o C) • UV + Dark/dry Cycle (4 hours UV at 50 o C, alternating with 4 hours dark at 50 o C) • Moisture + Dark/dry Cycle (4 hours dark and dry at 50 o C, alternating with 4 hours condensation at 50 o C) On the blue vinyl film, the UV+Moisture Cycle degraded the material most rapidly. Although the 100% UV Cycle exposed the material to twice the UV “dosage,” the results were not as severe.
Figure 18 Vinyl Gloss Loss Gloss 100 100 90 80 70 60 50 40 Material: Vinyl Film (blue) Test Conditions: 30 QUV/se 20 Lamp: UVA-340 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm 10 Cycle: UV Only Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Figure 19 Urethane Gloss Loss Gloss 90 80 70 60 50 40 30 20 10 0 Figure 20 11 Hours QUV/se Exposure Material: Urethane Coating (gray) 100% UV UV + Moisture Moisture + Dark/Dry UV + Moisture UV + Dark/Dry 100% UV 0 500 1000 1500 2000 2500 3000 Hours QUV/se Exposure Polypropylene Gloss Loss Moisture + Dark/Dry UV + Dark/Dry Material: Polypropylene Sheet (natural) Test Conditions: QUV/se Lamp: UVA-340 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C Exposure Duration & Measurement Intervals As a general rule, exposures should be run until the material has reached complete failure. This is because the perceived difference in the rate of degradation between any two exposures may vary, depending on how the data is analyzed. Figure 21 shows how running an exposure test to a predetermined level of degradation (in this case, yellowing) can cause confusion. If the exposure had been terminated after a delta b of 8 was reached, the higher irradiance exposure would appear to be 48% faster. If the exposure had been terminated at a delta b of 34, the higher irradiance test would appear to be only 32% faster. Only running the test to complete failure shows the true relationship between the two exposures. Figure 21 Comparison at Varying Levels of Yellowing delta b 48 40 32 24 Material: ABS Sheet (white) delta b = 34 3% faster 0.83 16 Test Conditions: QUV/se Lamp: UVA-340 8 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm delta b = 8 Cycle: UV Only 4% faster Temperature: B.P. 50C 0 0 500 1000 1500 2000 2500 Hours QUV/se Exposure 1.3 delta b 9 7 5 3 1 -1 100% UV 0 1000 2000 3000 Hours QUV/se Exposure UV + Dark/Dry Test Conditions: QUV/se Lamp: UVA-340 Irradiance: 1.35 & 0.83 W/m2/nm @ 340nm Cycle: UV Only Temperature: B.P. 50C UV + Moisture Moisture + Dark/Dry Figure 22 shows the same data used in the previous figure. However, here the exposures were analysed after a predetermined number of hours. If the two exposures are compared at 500 hours, the difference appears to be 100%. If they are compared at 1000 hours, the difference is 22%. This moisture effect is even more dramatic on the urethane. Again, although the UV+Moisture Cycle exposed the material to only half the UV dosage as the 100% UV Cycle, the rate of degradation is much faster. Sometimes the presence of moisture effects both the rate and the type of degradation. This is illustrated in Figure 20. In this case, the UV+Moisture Cycle gave a very different result than the cycles that omitted moisture.
Page 1 and 2: TECHNICAL BULLETIN LU-8031 High Irr
Page 3: Figure 4 Acrylic Yellowing delta b
Page 7 and 8: Summary & Conclusions There is curr

LU-8031 - High Irradiance UV Testers - Q-Lab

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