Weathering Florida

Comparison Different UV Stabilizers The addition of UV stabilizers leads to a tremendous increase of the stability of LLDPE during outdoor weathering (Florida). The addition of a combination of a Nickel Quencher (Ni-1) and a UVA (UVA-BP-1) lead to a six times larger lifetime. The additions of a HMW-HALS (HMW-HALS-2) leads even to alarger (> 10 times) increase in the lifetime (Fig. 17.8). In another comparison between different UV stabilizers (see Table 17.6) it is also shown that HALS is by far the best performing UV stabilizer. In this table it is also shown that UVA-BP-1 is the most effective UVA. 

Established PVDF-based products-Natural weathering (Florida, Arizona, in service)... 

Outdoor Weathering Florida, 45° south 180 4 65 80 Capron Allied Signal Specimen 0.4 mm (0.015 in) monofilament, unstabilized natural... 

Weathering. Articles fabricated from FEP are unaffected by weather, and thek resistance to extreme heat, cold, and uv kradiation suits them for apphcations in radar and other electronic components. For example, after 15 years of solar exposure in Florida, the tensile strength (73) and light transmission (96%) of a 25-p.m thick film was unchanged and the film remained crystal clear. Elongation increased slightly for the first 5 to 7 years of outdoor exposure, probably as a result of stress relaxation. Beyond 10 years, a small decrease was observed. 

The above-mentioned codes contain requirements for accelerated durabiUty tests. In addition, interlayer manufacturers and laminators expose test samples for several years under extreme weather conditions, eg, the Florida coast and Arizona desert. The laminated products weather extremely well, with no change in the plastic interlayer. Occasionally, clouding is noted around the edges when exposed to high humidity for long periods, but this is reversible. Colored areas of PVB laminates may fade while subjected to extensive uv/solar irradiation, which could cause an appearance issue. This has not, however, been shown to alter the laminate s other performance properties. 

Ilmenite is more abundant than mtile. Ilmenite world suppHes are estimated to meet the requirements of the Ti02 industry into the twenty-second century. The largest sources of ilmenite are in AustraHa, Canada, South Africa, Russia, and the United States. Large, unexplored sources also exist in China. About 9 million metric tons of ilmenite are mined aimuaHy. Long-term atmospheric effects weather ilmenite into leucoxene [1358-95-8], which contains most of its iron as Fe " . The majority of the world s supply of mtile comes from the beach sands of AustraHa, Florida, India, Bra2H, and South Africa. The total worldwide supply is estimated to be about 50 million metric tons. About 0.5 million tons are mined a year. The supply should last at least until the end of the twenty-first century. 

Exceptional weathering resistance. Samples exposed in Florida for 10 years showed little change in physical properties. 

The commercial polymers are mechanically similar to PTFE but with a somewhat greater impact strength. They also have the same excellent electrical insulation properties and chemical inertness. Weathering tests in Florida showed no change in properties after four years. The material also shows exceptional non-adhesiveness. The coefficient of friction of the resin is low but somewhat higher than that of PTFE. Films up to 0.010 in thick show good transparency. 

Although the subject of a standard weathering protocol is not within the scope of this present chapter, we wish to briefly comment that one must never look upon a year s exposure in any of these locations as reflecting a standard in exposure in an absolute sense. It should be intuitively obvious that there is not a Florida year , for example, as conditions do vary from year to year. For this reason, one always needs to expose the particular sample material of interest along with some standard material(s) for which the long-term exposure effects are well known, so that one may have a good basis for comparison. 

Dean, C. E. Weather fleck on Florida shadegroum tobacco. Tobacco Sci. 7 41-45. 1%3. 

Dean. C. E., and D. R. Davis. Ozone and soil moisture in relation to the occurrence of weather fleck on Florida cigar-wrapper tobacco in 1966. Plant Dis. Rep. 51 72-75, 1%7. 

The above ideal wastewater management, however, is infeasible during wet weather (rains of 3 in./day or 7.6 cm/day are frequent in the tropical climate of Florida), because more water goes into the lagoons than can be used by the washers, and the excess volume must be discharged... 

---