Exposure long-term outdoor

The outstanding characteristics of these rigid vinyls are chemical, solvent and water resistance resistance to weathering when properly stabilized, therefore permitting long-term outdoor exposure and low cost. Abrasion and impact resistance ate satisfactory. 

One major deficiency of these materials is their tendency to discolor, particularly under exposure to ultraviolet light during long term outdoor... 

Outdoor aging is currently being conducted on these polymers, and while accelerated aging may have limited value in predicting long term outdoor exposure, the accelerated aging studies of Jordan et al. (9) with poly (methyl methacrylate) copolymers and homopolymers indicated that a 2000-hour carbon-arc weatherometer period was a realistic exposure to screen the relative changes to be expected in about a two-year period in an outdoor environment—e.g., Florida or Arizona. 

Since polyolefins readily undergo oxidative deterioration on exposure to UV light, conventional stabilizers were found to be unsatisfactory for long-term outdoor applications. Therefore, more effective stabilizers for polyolefins were desired. 

Under long-term outdoor exposure, involving frost action and car-bonation, latex-modified mortar shows increased resistance to weathering in comparison with conventional mortar and concrete. The weatherability of the latex-modified mortars is shown in Fig. 4.69The exposure test was done at the Building Research Institute Outdoor Exposure Site in Ibaraki Prefecture, Japan. Except for PVAC-modified mortars, the flexural and compressive strengths of most latex-modified mortars under outdoor exposure conditions tend to become nearly constant at one year or more, and a weatherability factor is greater or similar to that of unmodified mortar. 

Hudson and Stanners (1953b) conducted long-term outdoor exposure tests in the United Kingdom on rolled zinc and correlated their results with the amount of sulfur trioxide deposited on lead peroxide (Table 2.7A). Their... 

The following remarks, classified by alloy, relate primarily to cases in which long-term outdoor atmosphere exposure data are available some references are also made to accelerated test results, to assist investigators. 

Davidson, D. D., Soreide, L. E., and Stephens, M. L. (1989). Assessment of the Chrysler chipping corrosion test using laboratory scab and long-term outdoor exposure testing. Galvatech 89, Iron and Steel Institute, Japan, pp. 536-544. 

Tisinger LG et al. (1990) Microstmctural Analysis of a Polypropylene Geotextile after Long-term Outdoor Exposure. In Koemer RM (ed) Geosynthetic Testing for Waste Containment Apphcations, ASTM Special Technical Publication 1081. ASTM, Philadelphia, USA, pp 335-354... 

Under long-term outdoor exposure, involving frost action and car-bonation, latex-modified mortar shows increased resistance to weathering in comparison with conventional mortar and concrete. The weatherability of the latex-modified mortars is shown in Fig. The exposure test was... 

Accelerated Weathering 2 No U.V. inhibitor not suggested for long term outdoor exposure Kodar 6763 Eastman... 

The specimen may be any shape. Artificial weathering has been defined by ASTM as The exposure of plastics to cyclic laboratory conditions involving changes in temperature, relative humidity, and ultraviolet (UV) radiant energy, with or without direct water spray, in an attempt to produce changes in the material similar to those observed after long-term continuous outdoor exposure. ... 

As described in Section V, A. 2, satisfactory long-term stability of sealed cells has been already achieved under relatively mild test conditions (low temperatures and no UV exposure). For outdoor applications, additional stability tests under more rigorous conditions will be required (e.g., high temperature such as 80°C, high humidity in the atmosphere, and UV exposure). 

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