ISSN:
0193-7197
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
White PVC siding which has been exposed to sunlight will after removal from the sunlight develop a darker color (yellow-brown). The longer this sample remains unexposed to sunlight the greater the color development. Testing has indicated that one or more photochemical mechanisms are occurring during this color development. A sample which appears yellow upon arrival at the home location after outside exposure can be re-whitened by re-exposing the sample to sunlight. Drastic color change will occur within a short period of time, usually less than 72 hours. This sample will have attained its white color with little or no yellowing visible when an original unexposed sample is held next to it. Testing conducted at an Arizona test site has confirmed these theories. Six months and one year weathered white siding samples, when measured at the test site, both experimental and commercial, showed that when the weathered samples are removed from the test racks and tristimulus values are measured daily, marked color changes occur rapidly. This paper addresses data which indicate that color development does occur but only in the very thin surface (5 to 10 micron layer) of the weathered samples. If these samples are washed and the abrasive action is sufficient to remove the surface layer, color development will no longer occur during non-exposure to sunlight.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/vnl.730080212
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