Natural Exposure Testing VS Accelerated Weathering... The Right Choice.

Natural Exposure Testing VS Accelerated Weathering... The Right Choice.

Founded in 1956 Specialize in material durability testing equipment and services Bolton, England Q-Lab Europe Cleveland,Ohio Headquarters & Instrument Division Shanghai, China Q-Lab China Saarbrücken Germany

Q-Lab Weathering Research Services Miami, Florida Phoenix, AZ

Weatherability Testing A tool for improving product durability A tool for decision making

Case Study Large manufacturer of full product line of pressure sensitive tapes Concerned about degradation of adhesive, backing, and, in some products, color Various adhesive chemistries Tests both outdoor durable and general use tapes Testing is performed for R&D

Know Your Enemy Sunlight Temperature Moisture Other factors

Spectrum of Sunlight

Irradiance: The rate at which light energy falls on a surface, per unit area; W/m 2 ASTM G113 -Terminology

Irradiance W/m2/nm UV-C UV-B UV-A The Most Trusted Name In Weathering Summer Sunlight Standard 2.0 UV Region Visible Light 1.5 1.0 0.5 0.68 W/m 2 at 340 nm 0.0 250 350 450 550 650 Wav elength (nanometers)

Short Wavelengths - Polymer Degradation Long Wavelengths - Fading & Color Change

Seasonal Variation Intensity changes 8:1 @ 320 nm Cut-off shifts from 295 to 310 nm Summer Winter

Temperature

Thermal Cycling Effects Physical stress Coatings on plastics Assemblies

Darker Color = Higher Temperature Fischer and Ketola, 1993

Moisture

Q-Lab s TOW Research Things Are Wet Outdoors Longer Than You Think

TOW vs. Rainfall - Miami, FL

Don t Underestimate the Effect of Moisture Changes The Rate Changes Mode Of Degradation Difficult To Accelerate

The Most Trusted Name In Weathering

Exposure Locations Florida subtropical Arizona desert sunshine Others (www.q-lab.com for climate data)

Accelerated Outdoor

Irradiance (W/m²/nm) The Most Trusted Name In Weathering Summer Sunlight vs. Q-Trac 12 10 8 Q-Trac 6 4 Summer Sunlight 2 0 250 350 450 550 650 750 Wavelength (nm)

Outdoor Techniques Offer The Closest Simulation to Your Service Environment But remember: Weather varies greatly

Outdoors is best... But who can wait? Use Florida & Arizona, PLUS an accelerated test

Accelerated Lab Weathering

All Weathering Testers Are Screening Devices No Perfect Simulation

Xenon Arc Spectra filtering irradiance level control point

Irradiance (W/m²/nm) 3.0 2.5 2.0 The Most Trusted Name In Weathering SPD's of Q-Sun and UVA-340 Lamps vs. Sunlight Xenon With Daylight Filters Xenon with Daylight Filters 1.5 1.0 0.5 Sunlight 0.0 250 300 350 400 450 500 550 600 650 700 750 800 Wavelength (nm)

Irradiance (W/m²/nm) The Most Trusted Name In Weathering Xenon with Daylight Filters 1.2 1.0 Xenon with Daylight Filters 0.8 0.6 Sunlight 0.4 0.2 0.0 260 280 300 320 340 360 380 400 Wavelength (nm)

Irradiance (W/m²/nm) 3.0 2.5 2.0 1.5 The Most Trusted Name In Weathering Xenon with Window Glass Filters Sunlight Through Window Glass Sunlight 1.0 0.5 0.0 250 300 350 400 450 500 550 600 650 700 750 800 Xenon with Window Glass Filters Wavelength (nm)

Irradiance (W/m²/nm) The Most Trusted Name In Weathering Xenon with Window Glass Filters 1.2 1.0 Sunlight Through Window Glass Sunlight 0.8 0.6 Xenon with Window Glass Filters 0.4 0.2 0.0 260 280 300 320 340 360 380 400 Wavelength (nm)

Temperature Control

Temperature & Color Fischer and Ketola, 1993

Xenon Arc Summary full spectrum - UV, Visible, IR best simulation of long wave UV & visible calibration water spray relative humidity control

UV Fluorescent Weathering Tester Introduced 1970 model QUV/spray ASTM G154

Specimen Holders

Irradiance W/m²/nm The Most Trusted Name In Weathering UV-B Lamps 1.2 1.0 Sunlight 0.8 0.6 0.4 0.2 UVB-313 Lamps FS-40 Lamps 0.0 270 290 310 330 350 370 390 Wavelength (nm)

Irradiance (W/m²/nm) The Most Trusted Name In Weathering UVA-340 Lamps 1.2 1.0 0.8 0.6 Sunlight air mass=1.0 (CIE 85 table 4) QUV with UVA-340 lamps 0.68 W/m2 @ 340 nm 0.4 0.2 0.0 260 280 300 320 340 360 380 400 Wavelength (nm)

Irradiance (W/m²/nm) UVB-313 Lamps QUV/se 0.6 5,600-hour lamps 0.4 2-hour lamps 0.2 0.0 260 280 300 320 340 360 380 400 Wavelength (nm)

Irradiance (W/m²/nm) The Most Trusted Name In Weathering Effect of Intensity UVA-340 1.5 Intensified 75% Sunlight 1.0 Typical Intensity 0.5 0.0 270 290 310 330 350 370 390 Wavelength (nm)

Speed vs. Realism increasing the stresses often decreases correlation

Fluorescent Lamp Advantages fast results very stable spectrum minimal maintenance simple calibration low cost

QUV Moisture condensing humidity water spray

QUV Condensation

Condensation Advantages identical to natural wetness elevated temperature pure water easy to use

Temperature & Color Fischer and Ketola, 1993

QUV vs. Q-Sun UVA-340 best simulation of shortwave UV UVB-313 might be too severe no visible light stable spectrum irradiance control no RH control water spray or condensation full spectrum best simulation of long wave UV & visible light spectrum changes irradiance control relative humidity control water spray

Irradiance (W/m²/nm) The Most Trusted Name In Weathering QUV, Xenon, Sunlight... 3.0 2.5 Q-Sun with Daylight Filters 0.68 W/m2 @ 340 nm Sunlight air mass=1.0 (CIE 85 table 4) 2.0 1.5 1.0 QUV with UVA-340 lamps 0.68 W/m2 @ 340 nm 0.5 0.0 250 300 350 400 450 500 550 600 650 700 750 800 Wavelength (nm)

Xenon arc is Best For Testing Lightfastness / Color Degradation

QUV Is The Best For Polymer Degradation gloss loss yellowing chalking checking adhesion cracking tensile strength loss Impact resistance

UVA-340 Is the Best Available Simulation of Short-Wave UV

Case Study QUV Tests adhesive and also the backing facing the light Uses 12 x 9 glass substrates 5 pull-downs per specimen 1 pull down per time interval Generates time degradation curves

Case Study QUV material failure modes Adhesive residue left on glass Tape locks down on glass, falls apart when removed QUV Test Cycles 72 to 96 hours is usually enough to tell a good material from a bad one Uses various custom cycles

Case Study Q-Sun Xenon Test Chamber Used when color is a concern, usually for duct tapes Sometimes used to test adhesives of less durable materials; similar results to QUV Results typically take longer than QUV for adhesive and backing tests Custom cycles, plus ASTM D6551

Case Study-- Conclusions Results are comparative Degradation modes are correlated to outdoor testing Acceleration factors are not considered accurate because weather varies so much

Case Study-- Conclusions Benefits of Test Program Data is used to make good decisions Materials Processes Question: any stories to tell about product failures or catastrophes avoided? We haven t had any as far as I know.

Case Study Lessons Learned Define modes of degradation and test for each (color change, adhesive degradation, backing degradation) Define failure end-point UV fluorescent and xenon each have strengths Comparisons using rank order are very powerful! Must use outdoor testing to validate lab results Faster than you think! Inexpensive!

The Most Trusted Name In Weathering

Case Study Opportunities Use control specimens Use a well-understood good performer Learn from failures, retain a wellunderstood poor performer Develop time degradation curves for each control Laboratory AND outdoor

Ideal Test Program Outdoor weathering in FL, AZ, or both Real world data Correlation Accelerated weathering in UV fluorescent, Xenon, or Fresnel Concentrator or a combination Fast results Formulation changes QC

Questions?