Laboratory testing, polymer weathering

Table 10.29 ASTM standards for the outdoor weathering testing of polymers and laboratory testing devices...

There are several commercially available laboratory testing devices for artificial weathering of polymers and plastics for example [1762, 2343] ... 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

The standard tests for assessing the durability of polymers in outdoor exposure (and other degradative environments) have been listed and discussed by Brown [5]. He concluded that the standard tests are of little value in predicting service lifetime and discussed some of the reasons for this. He also noted the lack of correlation between the results of natural weathering and laboratory weathering, a topic also discussed by other authors [2, 4, 5]. 

Figure 1 Cracks formed in the surface of polypropylene samples during tensile testing after (a) weathering for 12 weeks in Jeddah, and (b) after 4 weeks laboratory ultraviolet exposure while held in bending. (See Qayyum, M.M. and White, J.R. (1993) Polym. Degrad. Stab. 41,163 and Tong, L. and White, J.R. (1996) Polym. Degrad. Stab. 53, 381).

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