Testing of Weathering Properties

UVA 340 lamps are normally used for generating UV radiation (as recommended in national standards, such as ISO or ASTM) to simulate the UV part of daylight. These lamps provide the best available simulation of sunlight in the critical short wavelength UV region between 360 nm and the solar cut off of 290 nm. They have a radiant 

The main effects of weathering on LPCs are color fading and loss in mechanical and physical properties. Studies have shown that, for both natural and accelerated weathering, longer exposure times increase the degree of color change and lightness, carbonyl concentrations, and fiber loss on weathered LPC surfaces. 

The change in surface color of the samples is normally measured with a photometer or chroma meter in which lightness (L ) and chromaticity coordinates a and b ) 

It should be noted that AE represents the magnitude of the color difference but does not indicate the direction of this difference. 

Whilst fading is more of an aesthetics issue, the loss in many other properties is crucial when these composites are to be used for outdoor applications. Both UV light and moisture degrade LPCs independently, but they can also act synergistically. The effects of weathering are measured in terms of retained physical, chemical and mechanical properties, by using techniques such as mechanical testing, microscopy, FTIR spectroscopy, and DSC analysis. 

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